bug(go) gRPC status codes were getting overwritten by the handlers (#94)

* bug(go) gRPC status codes were getting overwritten by the handlers

**Problem**
* If the gRPC handlers received an error with a gRPC status code from checkHosts, it got overwritten by a plain error value.

**Solution**
* Added a check to each checkHosts call that passes on the error received (with its gRPC status)

**Testing**
* Added new unit tests for when the handlers receive an error from checkHosts with a status code.
* Existing unit tests and terraform tests passed

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/hashicorp/boundary/sdk v0.0.59
 	github.com/hashicorp/go-multierror v1.1.1
-	github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.2
+	github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.3
 	github.com/hashicorp/go-secure-stdlib/parseutil v0.2.0
 	github.com/hashicorp/terraform-json v0.23.0
 	github.com/mitchellh/mapstructure v1.5.0

go.sum

@@ -8,12 +8,8 @@ github.com/apparentlymart/go-textseg/v15 v15.0.0 h1:uYvfpb3DyLSCGWnctWKGj857c6ew
 github.com/apparentlymart/go-textseg/v15 v15.0.0/go.mod h1:K8XmNZdhEBkdlyDdvbmmsvpAG721bKi0joRfFdHIWJ4=
 github.com/armon/go-radix v1.0.0 h1:F4z6KzEeeQIMeLFa97iZU6vupzoecKdU5TX24SNppXI=
 github.com/armon/go-radix v1.0.0/go.mod h1:ufUuZ+zHj4x4TnLV4JWEpy2hxWSpsRywHrMgIH9cCH8=
-github.com/aws/aws-sdk-go-v2 v1.39.1 h1:fWZhGAwVRK/fAN2tmt7ilH4PPAE11rDj7HytrmbZ2FE=
-github.com/aws/aws-sdk-go-v2 v1.39.1/go.mod h1:sDioUELIUO9Znk23YVmIk86/9DOpkbyyVb1i/gUNFXY=
 github.com/aws/aws-sdk-go-v2 v1.41.7 h1:DWpAJt66FmnnaRIOT/8ASTucrvuDPZASqhhLey6tLY8=
 github.com/aws/aws-sdk-go-v2 v1.41.7/go.mod h1:4LAfZOPHNVNQEckOACQx60Y8pSRjIkNZQz1w92xpMJc=
-github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.1 h1:i8p8P4diljCr60PpJp6qZXNlgX4m2yQFpYk+9ZT+J4E=
-github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.1/go.mod h1:ddqbooRZYNoJ2dsTwOty16rM+/Aqmk/GOXrK8cg7V00=
 github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.10 h1:gx1AwW1Iyk9Z9dD9F4akX5gnN3QZwUB20GGKH/I+Rho=
 github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.10/go.mod h1:qqY157uZoqm5OXq/amuaBJyC9hgBCBQnsaWnPe905GY=
 github.com/aws/aws-sdk-go-v2/config v1.28.5 h1:Za41twdCXbuyyWv9LndXxZZv3QhTG1DinqlFsSuvtI0=
@@ -22,42 +18,26 @@ github.com/aws/aws-sdk-go-v2/credentials v1.17.46 h1:AU7RcriIo2lXjUfHFnFKYsLCwgb
 github.com/aws/aws-sdk-go-v2/credentials v1.17.46/go.mod h1:1FmYyLGL08KQXQ6mcTlifyFXfJVCNJTVGuQP4m0d/UA=
 github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.20 h1:sDSXIrlsFSFJtWKLQS4PUWRvrT580rrnuLydJrCQ/yA=
 github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.20/go.mod h1:WZ/c+w0ofps+/OUqMwWgnfrgzZH1DZO1RIkktICsqnY=
-github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.8 h1:6bgAZgRyT4RoFWhxS+aoGMFyE0cD1bSzFnEEi4bFPGI=
-github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.8/go.mod h1:KcGkXFVU8U28qS4KvLEcPxytPZPBcRawaH2Pf/0jptE=
 github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.23 h1:GpT/TrnBYuE5gan2cZbTtvP+JlHsutdmlV2YfEyNde0=
 github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.23/go.mod h1:xYWD6BS9ywC5bS3sz9Xh04whO/hzK2plt2Zkyrp4JuA=
-github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.8 h1:HhJYoES3zOz34yWEpGENqJvRVPqpmJyR3+AFg9ybhdY=
-github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.8/go.mod h1:JnA+hPWeYAVbDssp83tv+ysAG8lTfLVXvSsyKg/7xNA=
 github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.23 h1:bpd8vxhlQi2r1hiueOw02f/duEPTMK59Q4QMAoTTtTo=
 github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.23/go.mod h1:15DfR2nw+CRHIk0tqNyifu3G1YdAOy68RftkhMDDwYk=
 github.com/aws/aws-sdk-go-v2/internal/ini v1.8.1 h1:VaRN3TlFdd6KxX1x3ILT5ynH6HvKgqdiXoTxAF4HQcQ=
 github.com/aws/aws-sdk-go-v2/internal/ini v1.8.1/go.mod h1:FbtygfRFze9usAadmnGJNc8KsP346kEe+y2/oyhGAGc=
-github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.8 h1:1/bT9kDdLQzfZ1e6J6hpW+SfNDd6xrV8F3M2CuGyUz8=
-github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.8/go.mod h1:RbdwTONAIi59ej/+1H+QzZORt5bcyAtbrS7FQb2pvz0=
 github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.24 h1:OQqn11BtaYv1WLUowvcA30MpzIu8Ti4pcLPIIyoKZrA=
 github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.24/go.mod h1:X5ZJyfwVrWA96GzPmUCWFQaEARPR7gCrpq2E92PJwAE=
 github.com/aws/aws-sdk-go-v2/service/ec2 v1.254.0 h1:fTLR6dLDTGChAjecRPlVrKeznT0rVdzR4yn9Z68MTGk=
 github.com/aws/aws-sdk-go-v2/service/ec2 v1.254.0/go.mod h1:V0jbRy1/IPapnkqgXSwVOFB+u5pnCwd9S+R3pKWULC4=
 github.com/aws/aws-sdk-go-v2/service/iam v1.47.6 h1:EWehQXACWr+6hzfZPwZChlfoVhiUCfLHE0Xh3kAfzWQ=
 github.com/aws/aws-sdk-go-v2/service/iam v1.47.6/go.mod h1:qRXgEBWPIltrWHQwU+HkyBvwh1QgeigFcaCGCIVrWk0=
-github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.1 h1:oegbebPEMA/1Jny7kvwejowCaHz1FWZAQ94WXFNCyTM=
-github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.1/go.mod h1:kemo5Myr9ac0U9JfSjMo9yHLtw+pECEHsFtJ9tqCEI8=
 github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.9 h1:FLudkZLt5ci0ozzgkVo8BJGwvqNaZbTWb3UcucAateA=
 github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.9/go.mod h1:w7wZ/s9qK7c8g4al+UyoF1Sp/Z45UwMGcqIzLWVQHWk=
-github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.8.8 h1:tIN8MFT1z5STK5kTdOT1TCfMN/bn5fSEnlKsTL8qBOU=
-github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.8.8/go.mod h1:VKS56txtNWjKI8FqD/hliL0BcshyF4ZaLBa1rm2Y+5s=
 github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.15 h1:ieLCO1JxUWuxTZ1cRd0GAaeX7O6cIxnwk7tc1LsQhC4=
 github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.15/go.mod h1:e3IzZvQ3kAWNykvE0Tr0RDZCMFInMvhku3qNpcIQXhM=
-github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.8 h1:M6JI2aGFEzYxsF6CXIuRBnkge9Wf9a2xU39rNeXgu10=
-github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.8/go.mod h1:Fw+MyTwlwjFsSTE31mH211Np+CUslml8mzc0AFEG09s=
 github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.23 h1:pbrxO/kuIwgEsOPLkaHu0O+m4fNgLU8B3vxQ+72jTPw=
 github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.23/go.mod h1:/CMNUqoj46HpS3MNRDEDIwcgEnrtZlKRaHNaHxIFpNA=
-github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.8 h1:AgYCo1Rb8XChJXA871BXHDNxNWOTAr6V5YdsRIBbgv0=
-github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.8/go.mod h1:Au9dvIGm1Hbqnt29d3VakOCQuN9l0WrkDDTRq8biWS4=
 github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.23 h1:03xatSQO4+AM1lTAbnRg5OK528EUg744nW7F73U8DKw=
 github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.23/go.mod h1:M8l3mwgx5ToK7wot2sBBce/ojzgnPzZXUV445gTSyE8=
-github.com/aws/aws-sdk-go-v2/service/s3 v1.88.2 h1:T7b3qniouutV5Wwa9B1q7gW+Y8s1B3g9RE9qa7zLBIM=
-github.com/aws/aws-sdk-go-v2/service/s3 v1.88.2/go.mod h1:tW9TsLb6t1eaTdBE6LITyJW1m/+DjQPU78Q/jT2FJu8=
 github.com/aws/aws-sdk-go-v2/service/s3 v1.101.0 h1:etqBTKY581iwLL/H/S2sVgk3C9lAsTJFeXWFDsDcWOU=
 github.com/aws/aws-sdk-go-v2/service/s3 v1.101.0/go.mod h1:L2dcoOgS2VSgbPLvpak2NyUPsO1TBN7M45Z4H7DlRc4=
 github.com/aws/aws-sdk-go-v2/service/sso v1.24.6 h1:3zu537oLmsPfDMyjnUS2g+F2vITgy5pB74tHI+JBNoM=
@@ -66,8 +46,6 @@ github.com/aws/aws-sdk-go-v2/service/ssooidc v1.28.5 h1:K0OQAsDywb0ltlFrZm0JHPY3
 github.com/aws/aws-sdk-go-v2/service/ssooidc v1.28.5/go.mod h1:ORITg+fyuMoeiQFiVGoqB3OydVTLkClw/ljbblMq6Cc=
 github.com/aws/aws-sdk-go-v2/service/sts v1.38.5 h1:+LVB0xBqEgjQoqr9bGZbRzvg212B0f17JdflleJRNR4=
 github.com/aws/aws-sdk-go-v2/service/sts v1.38.5/go.mod h1:xoaxeqnnUaZjPjaICgIy5B+MHCSb/ZSOn4MvkFNOUA0=
-github.com/aws/smithy-go v1.23.0 h1:8n6I3gXzWJB2DxBDnfxgBaSX6oe0d/t10qGz7OKqMCE=
-github.com/aws/smithy-go v1.23.0/go.mod h1:t1ufH5HMublsJYulve2RKmHDC15xu1f26kHCp/HgceI=
 github.com/aws/smithy-go v1.25.1 h1:J8ERsGSU7d+aCmdQur5Txg6bVoYelvQJgtZehD12GkI=
 github.com/aws/smithy-go v1.25.1/go.mod h1:YE2RhdIuDbA5E5bTdciG9KrW3+TiEONeUWCqxX9i1Fc=
 github.com/bgentry/speakeasy v0.1.0 h1:ByYyxL9InA1OWqxJqqp2A5pYHUrCiAL6K3J+LKSsQkY=
@@ -116,8 +94,8 @@ github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+l
 github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hashicorp/go-plugin v1.7.0 h1:YghfQH/0QmPNc/AZMTFE3ac8fipZyZECHdDPshfk+mA=
 github.com/hashicorp/go-plugin v1.7.0/go.mod h1:BExt6KEaIYx804z8k4gRzRLEvxKVb+kn0NMcihqOqb8=
-github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.2 h1:KlDrZWx/wYpnUcFPB0s9uhPjyNZoeIfhrV2MN/Ly76s=
-github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.2/go.mod h1:6+rVulOPNCQbL3Xv2iLCqM0JmU2WO2wRzP1C6hBKeB8=
+github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.3 h1:mLe7IMysLSedhuu00W7AXsbfb90AA7UKfZmw3OkJ8n4=
+github.com/hashicorp/go-secure-stdlib/awsutil/v2 v2.1.3/go.mod h1:6+rVulOPNCQbL3Xv2iLCqM0JmU2WO2wRzP1C6hBKeB8=
 github.com/hashicorp/go-secure-stdlib/base62 v0.1.2 h1:ET4pqyjiGmY09R5y+rSd70J2w45CtbWDNvGqWp/R3Ng=
 github.com/hashicorp/go-secure-stdlib/base62 v0.1.2/go.mod h1:EdWO6czbmthiwZ3/PUsDV+UD1D5IRU4ActiaWGwt0Yw=
 github.com/hashicorp/go-secure-stdlib/configutil/v2 v2.0.13 h1:TayxZ5drfMP0G6T++WvnLESGLOWeHtdWDWWTAi2e3Qk=

internal/credential/state.go

@@ -112,10 +112,35 @@ func NewAwsCredentialPersistedState(opts ...AwsCredentialPersistedStateOption) (
 // and runs sts.GetCallerIdentity for the current credentials, which is done
 // to check that the credentials are valid. This method returns a status error
 // with PluginError details.
+//
+// When RoleARN is set and no static key is present (ambient role path),
+// credentials are eagerly retrieved before calling GetCallerIdentity. This
+// forces sts:AssumeRole to be called immediately so that any role errors
+// (e.g. no such role, access denied) surface here rather than being deferred
+// to the first real AWS API call.
 func (s *AwsCredentialPersistedState) ValidateCreds(ctx context.Context) error {
 	if s.CredentialsConfig == nil {
 		return errors.BadRequestStatus("missing credentials config")
 	}
+
+	// For the ambient role path (RoleARN set, no static key), eagerly resolve
+	// the credential chain so that sts:AssumeRole is called now. Without this,
+	// the AssumeRoleProvider inside the chain is lazy and GetCallerIdentity
+	// would succeed even with an invalid role ARN (it uses the mock/ambient
+	// identity directly rather than the assumed one).
+	cc := s.CredentialsConfig
+	if cc.RoleARN != "" && cc.AccessKey == "" {
+		cfg, err := s.GenerateCredentialChain(ctx)
+		if err != nil {
+			st, _ := errors.ParseAWSError("validating credentials", err)
+			return st.Err()
+		}
+		if _, err := cfg.Credentials.Retrieve(ctx); err != nil {
+			st, _ := errors.ParseAWSError("validating credentials", err)
+			return st.Err()
+		}
+	}
+
 	if _, err := s.CredentialsConfig.GetCallerIdentity(ctx, s.testOpts...); err != nil {
 		st, _ := errors.ParseAWSError("validating credentials", err)
 		return st.Err()

internal/errors/error.go

@@ -29,6 +29,11 @@ const (
 	// the owner. This error cannot be resolved by retrying the request.
 	awsErrorAccessDenied = "AccessDenied"
 
+	// awsErrorUnauthorizedOperation is returned by EC2 when the caller is not
+	// authorized to perform the operation. This includes DryRun permission
+	// checks that fail (the counterpart to DryRunOperation success).
+	awsErrorUnauthorizedOperation = "UnauthorizedOperation"
+
 	// awsErrorInvalidAccessKeyId is returned when the credential does
 	// not exist. This error will persist until the credentials attached
 	// to the storage bucket is updated. This error can occur when the
@@ -66,8 +71,26 @@ const (
 
 	// RequestTimeoutException is returned when an http request takes longer than allowed
 	awsErrorRequestTimeoutException = "RequestTimeoutException"
+
+	// dryRunOperationErrorCode is returned by AWS when a DryRun request would have
+	// succeeded. It is a success signal disguised as an API error (typically HTTP 412).
+	dryRunOperationErrorCode = "DryRunOperation"
 )
 
+// IsDryRunSuccess reports whether err is the AWS DryRunOperation success signal.
+// A true result means the dry-run validated credentials, permissions, and parameters;
+// it must not be treated as a failure.
+func IsDryRunSuccess(err error) bool {
+	if err == nil {
+		return false
+	}
+	var apiErr smithy.APIError
+	if !errors.As(err, &apiErr) {
+		return false
+	}
+	return apiErr.ErrorCode() == dryRunOperationErrorCode
+}
+
 // InvalidArgumentError returns an grpc invalid argument status error.
 func InvalidArgumentError(msg string, f map[string]string) error {
 	var fieldMsgs []string
@@ -172,6 +195,8 @@ func ParseAWSError(op string, err error) (st *status.Status, permission *pb.Perm
 		switch apiErr.ErrorCode() {
 		case awsErrorAccessDenied:
 			fallthrough
+		case awsErrorUnauthorizedOperation:
+			fallthrough
 		case awsErrorInvalidAccessKeyId:
 			fallthrough
 		case awsErrorExpiredToken:

internal/errors/error_test.go

@@ -300,6 +300,17 @@ func Test_ParseAWSError(t *testing.T) {
 				CheckedAt:    timestamppb.Now(),
 			},
 		},
+		{
+			name:               "aws-request-unauthorized-operation",
+			err:                TestAwsError(awsErrorUnauthorizedOperation, "You are not authorized to perform this operation."),
+			expectedStatusCode: codes.PermissionDenied,
+			expectedStatusMsg:  "aws service unknown: invalid credentials: test",
+			expectedPermission: &pb.Permission{
+				State:        pb.StateType_STATE_TYPE_ERROR,
+				ErrorDetails: "You are not authorized to perform this operation.",
+				CheckedAt:    timestamppb.Now(),
+			},
+		},
 		{
 			name:               "aws-request-invalid-access-key-id",
 			err:                TestAwsError(awsErrorInvalidAccessKeyId, "The AWS Access Key Id you provided does not exist in our records."),
@@ -390,6 +401,46 @@ func Test_ParseAWSError(t *testing.T) {
 	}
 }
 
+func Test_IsDryRunSuccess(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{
+			name: "nil",
+			want: false,
+		},
+		{
+			name: "plain error",
+			err:  fmt.Errorf("not an aws error"),
+			want: false,
+		},
+		{
+			name: "other api error",
+			err:  TestAwsError(awsErrorAccessDenied, "not authorized"),
+			want: false,
+		},
+		{
+			name: "dry run operation",
+			err:  TestAwsError(dryRunOperationErrorCode, "Request would have succeeded, but DryRun flag is set"),
+			want: true,
+		},
+		{
+			name: "wrapped dry run operation",
+			err:  fmt.Errorf("describe instances: %w", TestAwsError(dryRunOperationErrorCode, "Request would have succeeded, but DryRun flag is set")),
+			want: true,
+		},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, IsDryRunSuccess(tt.err))
+		})
+	}
+}
+
 func Test_BadRequestStatusf(t *testing.T) {
 	require, assert := require.New(t), assert.New(t)
 	err := BadRequestStatusf("test: %s", "hello world")

plugin/service/host/plugin.go

@@ -5,7 +5,6 @@ package host
 
 import (
 	"context"
-	goerrors "errors"
 	"fmt"
 	"strings"
 
@@ -15,7 +14,6 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/ec2/types"
 	"github.com/aws/aws-sdk-go-v2/service/sts"
 	stsTypes "github.com/aws/aws-sdk-go-v2/service/sts/types"
-	"github.com/aws/smithy-go"
 	"github.com/hashicorp/boundary-plugin-aws/internal/credential"
 	"github.com/hashicorp/boundary-plugin-aws/internal/errors"
 	pb "github.com/hashicorp/boundary/sdk/pbs/plugin"
@@ -44,8 +42,8 @@ type hostSetQuery struct {
 	OutputHosts []*pb.ListHostsResponseHost
 }
 
-const defaultSessionName = "boundary-default"
-const dryRunOperationErrorCode = "DryRunOperation"
+const errBuildDescribeInstancesInput = "error building DescribeInstances input: %s"
+const errDryRunFailed = "error performing DescribeInstances dry run: %s"
 
 // Ensure that we are implementing HostPluginServiceServer
 var _ pb.HostPluginServiceServer = (*HostPlugin)(nil)
@@ -88,6 +86,15 @@ func (p *HostPlugin) OnCreateCatalog(ctx context.Context, req *pb.OnCreateCatalo
 		}
 	}
 
+	// Validate assumed-role credentials at catalog-creation time so that an
+	// invalid role_arn is rejected immediately rather than silently falling
+	// back to ambient credentials.
+	if credential.GetCredentialType(credState.CredentialsConfig) == credential.DynamicAWS {
+		if err := credState.ValidateCreds(ctx); err != nil {
+			return nil, err
+		}
+	}
+
 	catalogState, err := newAwsCatalogPersistedState(
 		append([]awsCatalogPersistedStateOption{
 			withCredentials(credState),
@@ -97,13 +104,21 @@ func (p *HostPlugin) OnCreateCatalog(ctx context.Context, req *pb.OnCreateCatalo
 		return nil, errors.BadRequestStatusf("error setting up persisted state: %s", err)
 	}
 
-	// perform dry run to ensure we can interact with AWS as expected.
 	opts := []ec2Option{}
 	if catalogAttributes.DualStack {
 		opts = append(opts, WithDualStack(catalogAttributes.DualStack))
 	}
-	if st := dryRunValidation(ctx, catalogState, opts); st != nil {
-		return nil, st.Err()
+	input, err := buildDescribeInstancesInput(&SetAttributes{}, true)
+	if err != nil {
+		return nil, status.Errorf(codes.Unknown, errBuildDescribeInstancesInput, err)
+	}
+	// Run a DescribeInstances request with DryRun set to true to ensure
+	// we can interact with AWS resources as expected.
+	if _, err := checkHosts(ctx, catalogState, input, opts, catalogAttributes.TargetAccount); err != nil {
+		if _, ok := status.FromError(err); ok {
+			return nil, err
+		}
+		return nil, fmt.Errorf(errDryRunFailed, err)
 	}
 
 	persistedProto, err := catalogState.toProto()
@@ -178,6 +193,15 @@ func (p *HostPlugin) OnUpdateCatalog(ctx context.Context, req *pb.OnUpdateCatalo
 		if err != nil {
 			return nil, errors.BadRequestStatusf("error setting up new credential persisted state: %s", err)
 		}
+
+		// Validate assumed-role credentials when the role_arn changes so that
+		// an invalid ARN is caught before replacing the existing credential state.
+		if credential.GetCredentialType(newCredState.CredentialsConfig) == credential.DynamicAWS {
+			if err := newCredState.ValidateCreds(ctx); err != nil {
+				return nil, err
+			}
+		}
+
 		newCatalogState, err := newAwsCatalogPersistedState(
 			append([]awsCatalogPersistedStateOption{
 				withCredentials(newCredState),
@@ -186,12 +210,22 @@ func (p *HostPlugin) OnUpdateCatalog(ctx context.Context, req *pb.OnUpdateCatalo
 		if err != nil {
 			return nil, errors.BadRequestStatusf("error loading persisted state: %s", err)
 		}
+
 		opts := []ec2Option{}
 		if newCatalogAttributes.DualStack {
 			opts = append(opts, WithDualStack(newCatalogAttributes.DualStack))
 		}
-		if st := dryRunValidation(ctx, newCatalogState, opts); st != nil {
-			return nil, st.Err()
+		input, err := buildDescribeInstancesInput(&SetAttributes{}, true)
+		if err != nil {
+			return nil, status.Errorf(codes.Unknown, errBuildDescribeInstancesInput, err)
+		}
+		// Run a DescribeInstances request with DryRun set to true to ensure
+		// we can interact with AWS resources as expected.
+		if _, err := checkHosts(ctx, newCatalogState, input, opts, newCatalogAttributes.TargetAccount); err != nil {
+			if _, ok := status.FromError(err); ok {
+				return nil, err
+			}
+			return nil, fmt.Errorf(errDryRunFailed, err)
 		}
 
 		// Replace the existing credential state.
@@ -231,13 +265,21 @@ func (p *HostPlugin) OnUpdateCatalog(ctx context.Context, req *pb.OnUpdateCatalo
 		return nil, errors.BadRequestStatusf("error loading persisted state: %s", err)
 	}
 
-	// perform dry run to ensure we can interact with AWS as expected.
 	opts := []ec2Option{}
 	if newCatalogAttributes.DualStack {
 		opts = append(opts, WithDualStack(newCatalogAttributes.DualStack))
 	}
-	if st := dryRunValidation(ctx, catalogState, opts); st != nil {
-		return nil, st.Err()
+	input, err := buildDescribeInstancesInput(&SetAttributes{}, true)
+	if err != nil {
+		return nil, status.Errorf(codes.Unknown, errBuildDescribeInstancesInput, err)
+	}
+	// Run a DescribeInstances request with DryRun set to true to ensure
+	// we can interact with AWS resources as expected.
+	if _, err := checkHosts(ctx, catalogState, input, opts, newCatalogAttributes.TargetAccount); err != nil {
+		if _, ok := status.FromError(err); ok {
+			return nil, err
+		}
+		return nil, fmt.Errorf(errDryRunFailed, err)
 	}
 
 	persistedProto, err := catalogState.toProto()
@@ -381,18 +423,23 @@ func (p *HostPlugin) OnCreateSet(ctx context.Context, req *pb.OnCreateSetRequest
 		return nil, err
 	}
 
-	describeInstanceFilters, err := buildFilters(setAttrs)
-	if err != nil {
-		return nil, errors.BadRequestStatusf("error building set filters: %s", err)
-	}
-
 	opts := []ec2Option{}
 	if catalogAttributes.DualStack {
 		opts = append(opts, WithDualStack(catalogAttributes.DualStack))
 	}
-	if st := dryRunValidation(ctx, catalogState, opts, describeInstanceFilters...); st != nil {
-		return nil, st.Err()
+	input, err := buildDescribeInstancesInput(setAttrs, true)
+	if err != nil {
+		return nil, status.Errorf(codes.Unknown, errBuildDescribeInstancesInput, err)
 	}
+	// Run a DescribeInstances request with DryRun set to true to ensure
+	// we can interact with AWS resources as expected.
+	if _, err := checkHosts(ctx, catalogState, input, opts, catalogAttributes.TargetAccount); err != nil {
+		if _, ok := status.FromError(err); ok {
+			return nil, err
+		}
+		return nil, fmt.Errorf(errDryRunFailed, err)
+	}
+
 	return &pb.OnCreateSetResponse{}, nil
 }
 
@@ -446,17 +493,21 @@ func (p *HostPlugin) OnUpdateSet(ctx context.Context, req *pb.OnUpdateSetRequest
 		return nil, err
 	}
 
-	describeInstanceFilters, err := buildFilters(setAttrs)
-	if err != nil {
-		return nil, errors.BadRequestStatusf("error building set filters: %s", err)
-	}
-
 	opts := []ec2Option{}
 	if catalogAttributes.DualStack {
 		opts = append(opts, WithDualStack(catalogAttributes.DualStack))
 	}
-	if st := dryRunValidation(ctx, catalogState, opts, describeInstanceFilters...); st != nil {
-		return nil, st.Err()
+	input, err := buildDescribeInstancesInput(setAttrs, true)
+	if err != nil {
+		return nil, status.Errorf(codes.Unknown, errBuildDescribeInstancesInput, err)
+	}
+	// Run a DescribeInstances request with DryRun set to true to ensure
+	// we can interact with AWS resources as expected.
+	if _, err := checkHosts(ctx, catalogState, input, opts, catalogAttributes.TargetAccount); err != nil {
+		if _, ok := status.FromError(err); ok {
+			return nil, err
+		}
+		return nil, fmt.Errorf(errDryRunFailed, err)
 	}
 
 	return &pb.OnUpdateSetResponse{}, nil
@@ -545,10 +596,14 @@ func (p *HostPlugin) ListHosts(ctx context.Context, req *pb.ListHostsRequest) (*
 	for i, query := range queries {
 		output, err := checkHosts(ctx, catalogState, query.Input, opts, catalogAttributes.TargetAccount)
 		if err != nil {
-			if catalogAttributes.TargetAccount != nil {
-				return nil, errors.BadRequestStatusf("unable to list hosts for host set %q: %s", query.Id, err)
+			// Mapped AWS failures are already gRPC statuses from checkHosts.
+			if _, ok := status.FromError(err); ok {
+				return nil, err
 			}
-			return nil, errors.BadRequestStatusf("error retrieving host results for host set id %q: %s", query.Id, err)
+			if catalogAttributes.TargetAccount != nil {
+				return nil, status.Errorf(codes.Unknown, "unable to list hosts for host set %q: %v", query.Id, err)
+			}
+			return nil, status.Errorf(codes.Unknown, "error retrieving host results for host set id %q: %v", query.Id, err)
 		}
 
 		queries[i].Output = output
@@ -562,7 +617,7 @@ func (p *HostPlugin) ListHosts(ctx context.Context, req *pb.ListHostsRequest) (*
 			for _, instance := range reservation.Instances {
 				host, err := awsInstanceToHost(instance, catalogAttributes)
 				if err != nil {
-					return nil, errors.BadRequestStatusf("error processing host results for host set id %q: %s", query.Id, err)
+					return nil, status.Errorf(codes.Unknown, "error processing host results for host set id %q: %v", query.Id, err)
 				}
 
 				queries[i].OutputHosts = append(queries[i].OutputHosts, host)
@@ -611,11 +666,11 @@ func buildFilters(attrs *SetAttributes) ([]types.Filter, error) {
 		splitFilter := strings.Split(filterAttr, "=")
 		switch {
 		case len(splitFilter) != 2:
-			return nil, fmt.Errorf("expected filter %q to contain a single equal sign", filterAttr)
+			return nil, errors.BadRequestStatusf("expected filter %q to contain a single equal sign", filterAttr)
 		case len(splitFilter[0]) == 0:
-			return nil, fmt.Errorf("filter %q contains an empty filter key", filterAttr)
+			return nil, errors.BadRequestStatusf("filter %q contains an empty filter key", filterAttr)
 		case len(splitFilter[1]) == 0:
-			return nil, fmt.Errorf("filter %q contains an empty value", filterAttr)
+			return nil, errors.BadRequestStatusf("filter %q contains an empty value", filterAttr)
 		}
 
 		filterKey, filterValue := splitFilter[0], splitFilter[1]
@@ -644,9 +699,13 @@ func buildFilters(attrs *SetAttributes) ([]types.Filter, error) {
 }
 
 func buildDescribeInstancesInput(attrs *SetAttributes, dryRun bool) (*ec2.DescribeInstancesInput, error) {
+	if attrs == nil {
+		attrs = &SetAttributes{}
+	}
+
 	filters, err := buildFilters(attrs)
 	if err != nil {
-		return nil, fmt.Errorf("error building filters: %w", err)
+		return nil, err
 	}
 
 	return &ec2.DescribeInstancesInput{
@@ -733,25 +792,31 @@ func checkHosts(ctx context.Context,
 		// use the principal account to execute the DescribeInstances command
 		ec2Client, err = principalCatalogState.EC2Client(ctx, opts...)
 		if err != nil {
+			if st, _ := errors.ParseAWSError("EC2 client setup", err); st.Code() != codes.Unknown {
+				return nil, st.Err()
+			}
 			return nil, err
 		}
 	} else {
 		// use the target account to execute the DescribeInstances command
 		ec2Client, err = ec2ClientForTarget(ctx, principalCatalogState, target, opts)
 		if err != nil {
+			if _, ok := status.FromError(err); ok {
+				return nil, err
+			}
 			return nil, fmt.Errorf("EC2 client setup failed for target account: %w", err)
 		}
 	}
 
 	output, err := ec2Client.DescribeInstances(ctx, input)
 	if err != nil {
-		var awsErr smithy.APIError
-		ok := goerrors.As(err, &awsErr)
-		if ok && awsErr.ErrorCode() == dryRunOperationErrorCode {
-			// successful DryRun validation, no response necessary, no error thrown
+		if errors.IsDryRunSuccess(err) {
+			// DryRunOperation: request would have succeeded; not a failure.
 			return nil, nil
 		}
-
+		if st, _ := errors.ParseAWSError("DescribeInstances", err); st.Code() != codes.Unknown {
+			return nil, st.Err()
+		}
 		if target != nil {
 			return nil, fmt.Errorf("EC2 DescribeInstances failed for target account: %w", err)
 		}
@@ -774,6 +839,9 @@ func ec2ClientForTarget(
 	// principal identity).
 	principalCfg, err := principalCatalogState.GenerateCredentialChain(ctx)
 	if err != nil {
+		if st, _ := errors.ParseAWSError("EC2 client setup for target account", err); st.Code() != codes.Unknown {
+			return nil, st.Err()
+		}
 		return nil, fmt.Errorf("principal AWS configuration could not be loaded: %w", err)
 	}
 	if principalCfg == nil {
@@ -787,9 +855,6 @@ func ec2ClientForTarget(
 	provider := stscreds.NewAssumeRoleProvider(stsClient, target.RoleArn, func(o *stscreds.AssumeRoleOptions) {
 		if target.RoleSessionName != "" {
 			o.RoleSessionName = target.RoleSessionName
-		} else {
-			// STS may reject the AssumeRole request if session name is not provided.
-			o.RoleSessionName = defaultSessionName
 		}
 		if target.RoleExternalId != "" {
 			o.ExternalID = &target.RoleExternalId
@@ -828,28 +893,6 @@ func ec2ClientForTarget(
 	return ec2.NewFromConfig(targetCfg, ec2Opts...), nil
 }
 
-// dryRunValidation performs an AWS DescribeInstances call to verify the state's
-// credentials, the host listing functionality as well as the filters, if any
-// are passed in. This function can therefore be used for both host catalog and
-// host set validation.
-func dryRunValidation(ctx context.Context, state *awsCatalogPersistedState, ec2Opts []ec2Option, filters ...types.Filter) *status.Status {
-	if state == nil {
-		return status.New(codes.InvalidArgument, "persisted state is required")
-	}
-
-	ec2Client, err := state.EC2Client(ctx, ec2Opts...)
-	if err != nil {
-		return status.New(codes.InvalidArgument, fmt.Sprintf("error getting EC2 client: %s", err))
-	}
-
-	_, err = ec2Client.DescribeInstances(ctx, &ec2.DescribeInstancesInput{Filters: filters})
-	if err != nil {
-		return status.New(codes.FailedPrecondition, fmt.Sprintf("aws describe instances failed: %s", err))
-	}
-
-	return nil
-}
-
 // appendDistinct will append the elements to the slice
 // if an element is not nil, empty, and does not exist in slice.
 func appendDistinct(slice []string, elems ...*string) []string {

plugin/service/host/plugin_test.go

@@ -16,8 +16,11 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/ec2/types"
 	"github.com/aws/aws-sdk-go-v2/service/iam"
 	iamTypes "github.com/aws/aws-sdk-go-v2/service/iam/types"
+	"github.com/aws/aws-sdk-go-v2/service/sts"
+	stsTypes "github.com/aws/aws-sdk-go-v2/service/sts/types"
 	"github.com/google/go-cmp/cmp"
 	"github.com/hashicorp/boundary-plugin-aws/internal/credential"
+	awserrors "github.com/hashicorp/boundary-plugin-aws/internal/errors"
 	"github.com/hashicorp/boundary/sdk/pbs/controller/api/resources/hostcatalogs"
 	"github.com/hashicorp/boundary/sdk/pbs/controller/api/resources/hostsets"
 	pb "github.com/hashicorp/boundary/sdk/pbs/plugin"
@@ -28,6 +31,38 @@ import (
 	"google.golang.org/protobuf/testing/protocmp"
 	"google.golang.org/protobuf/types/known/structpb"
 )
+// testRoleARN is a syntactically valid ARN used for role_arn test cases.
+// All STS calls against it are handled by injected mocks — no real AWS
+// account is contacted.
+const testRoleARN = "arn:aws:iam::123456789012:role/BoundaryTestRole"
+
+// validAssumeRoleOutput returns a mock AssumeRoleOutput with synthetic
+// temporary credentials for use with WithSTSAPIFunc.
+func validAssumeRoleOutput() *sts.AssumeRoleOutput {
+	return &sts.AssumeRoleOutput{
+		Credentials: &stsTypes.Credentials{
+			AccessKeyId:     aws.String("ASIAmockassumedkey"),
+			SecretAccessKey: aws.String("mockassumedsecret"),
+			SessionToken:    aws.String("mockassumedsessiontoken"),
+			Expiration:      aws.Time(time.Now().Add(time.Hour)),
+		},
+	}
+}
+
+// catalogAttrsStruct builds a catalog attributes structpb for the given
+// region. roleArn is written only when non-empty. disableRotation must be
+// set explicitly to avoid implicit rotation behaviour in tests.
+func catalogAttrsStruct(region, roleArn string, disableRotation bool) *structpb.Struct {
+	fields := map[string]*structpb.Value{
+		credential.ConstRegion:                    structpb.NewStringValue(region),
+		credential.ConstDisableCredentialRotation: structpb.NewBoolValue(disableRotation),
+	}
+	if roleArn != "" {
+		fields[credential.ConstRoleArn] = structpb.NewStringValue(roleArn)
+	}
+	return &structpb.Struct{Fields: fields}
+}
+
 
 func TestPluginOnCreateCatalogSuccess(t *testing.T) {
 	tests := []struct {
@@ -138,17 +173,13 @@ func TestPluginOnCreateCatalogSuccess(t *testing.T) {
 			},
 		},
 		{
+			// role_arn set, no static keys. AssumeRole mock succeeds.
+			// Persisted secrets are empty — dynamic credentials are not stored.
 			name: "usingAssumeRole",
 			req: &pb.OnCreateCatalogRequest{
 				Catalog: &hostcatalogs.HostCatalog{
 					Attrs: &hostcatalogs.HostCatalog_Attributes{
-						Attributes: &structpb.Struct{
-							Fields: map[string]*structpb.Value{
-								credential.ConstRegion:                    structpb.NewStringValue("us-east-1"),
-								credential.ConstRoleArn:                   structpb.NewStringValue("arn:0123:test:rolearn"),
-								credential.ConstDisableCredentialRotation: structpb.NewBoolValue(true),
-							},
-						},
+						Attributes: catalogAttrsStruct("us-east-1", testRoleARN, true),
 					},
 				},
 			},
@@ -158,6 +189,13 @@ func TestPluginOnCreateCatalogSuccess(t *testing.T) {
 					testMockEC2WithDescribeInstancesOutput(&ec2.DescribeInstancesOutput{}),
 				)),
 			},
+			credOpts: []credential.AwsCredentialPersistedStateOption{
+				credential.WithStateTestOpts([]awsutil.Option{
+					awsutil.WithSTSAPIFunc(awsutil.NewMockSTS(
+						awsutil.WithAssumeRoleOutput(validAssumeRoleOutput()),
+					)),
+				}),
+			},
 			expRsp: &pb.OnCreateCatalogResponse{Persisted: &pb.HostCatalogPersisted{Secrets: &structpb.Struct{}}},
 		},
 	}
@@ -315,6 +353,20 @@ func TestPluginOnUpdateCatalogSuccess(t *testing.T) {
 					testMockEC2WithDescribeInstancesOutput(&ec2.DescribeInstancesOutput{}),
 				)),
 			},
+			credOpts: []credential.AwsCredentialPersistedStateOption{
+				credential.WithStateTestOpts([]awsutil.Option{
+					awsutil.WithSTSAPIFunc(awsutil.NewMockSTS(
+						awsutil.WithAssumeRoleOutput(&sts.AssumeRoleOutput{
+							Credentials: &stsTypes.Credentials{
+								AccessKeyId:     aws.String("ASIAfoobar"),
+								SecretAccessKey: aws.String("secretkeyfoobar"),
+								SessionToken:    aws.String("sessiontokenfoobar"),
+								Expiration:      aws.Time(time.Now().Add(time.Hour)),
+							},
+						}),
+					)),
+				}),
+			},
 			expRsp: &pb.OnUpdateCatalogResponse{
 				Persisted: &pb.HostCatalogPersisted{Secrets: &structpb.Struct{}},
 			},
@@ -421,6 +473,16 @@ func TestPluginOnUpdateCatalogSuccess(t *testing.T) {
 			credOpts: []credential.AwsCredentialPersistedStateOption{
 				credential.WithStateTestOpts([]awsutil.Option{
 					awsutil.WithIAMAPIFunc(awsutil.NewMockIAM()),
+					awsutil.WithSTSAPIFunc(awsutil.NewMockSTS(
+						awsutil.WithAssumeRoleOutput(&sts.AssumeRoleOutput{
+							Credentials: &stsTypes.Credentials{
+								AccessKeyId:     aws.String("ASIAfoobar"),
+								SecretAccessKey: aws.String("secretkeyfoobar"),
+								SessionToken:    aws.String("sessiontokenfoobar"),
+								Expiration:      aws.Time(time.Now().Add(time.Hour)),
+							},
+						}),
+					)),
 				}),
 			},
 			expRsp: &pb.OnUpdateCatalogResponse{
@@ -742,8 +804,72 @@ func TestPluginOnCreateCatalogErr(t *testing.T) {
 					testMockEC2WithDescribeInstancesError(errors.New(testDescribeInstancesError)),
 				)),
 			},
-			expectedErrContains: "aws describe instances failed: DescribeInstances error",
-			expectedErrCode:     codes.FailedPrecondition,
+			// checkHosts returns the DescribeInstances error as-is rather than
+			// wrapping it in a gRPC FailedPrecondition status like the old
+			// dryRunValidation did. A plain Go error maps to codes.Unknown.
+			expectedErrContains: testDescribeInstancesError,
+			expectedErrCode:     codes.Unknown,
+		},
+		{
+			name: "dry run status error preserves gRPC code",
+			req: &pb.OnCreateCatalogRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Secrets: &structpb.Struct{
+						Fields: map[string]*structpb.Value{
+							credential.ConstAccessKeyId:     structpb.NewStringValue("AKIA_foobar"),
+							credential.ConstSecretAccessKey: structpb.NewStringValue("bazqux"),
+						},
+					},
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion:                    structpb.NewStringValue("us-west-2"),
+								credential.ConstDisableCredentialRotation: structpb.NewBoolValue(true),
+							},
+						},
+					},
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			// checkHosts wraps the AWS error via ParseAWSError into a gRPC
+			// PermissionDenied status. OnCreateCatalog's dry-run error handler
+			// should preserve that status code, not re-wrap it as Unknown.
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
+		},
+		{
+			// BUG FIX: role_arn set, no static keys. AssumeRole mock returns
+			// an error. ValidateCreds now eagerly calls Retrieve() which forces
+			// sts:AssumeRole, so the error surfaces here at creation time.
+			// Previously this succeeded silently via the ambient credential chain.
+			name: "role_arn AssumeRole error — correctly rejected",
+			req: &pb.OnCreateCatalogRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: catalogAttrsStruct("us-east-1", testRoleARN, true),
+					},
+				},
+			},
+			credOpts: []credential.AwsCredentialPersistedStateOption{
+				credential.WithStateTestOpts([]awsutil.Option{
+					awsutil.WithSTSAPIFunc(awsutil.NewMockSTS(
+						awsutil.WithAssumeRoleError(errors.New("simulated AssumeRole failure")),
+					)),
+				}),
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesOutput(&ec2.DescribeInstancesOutput{}),
+				)),
+			},
+			expectedErrContains: "simulated AssumeRole failure",
+			expectedErrCode:     codes.Unknown,
 		},
 	}
 
@@ -994,8 +1120,11 @@ func TestPluginOnUpdateCatalogErr(t *testing.T) {
 					testMockEC2WithDescribeInstancesError(errors.New(testDescribeInstancesError)),
 				)),
 			},
-			expectedErrContains: "aws describe instances failed: DescribeInstances error",
-			expectedErrCode:     codes.FailedPrecondition,
+			//checkHosts returns the DesribeInstances errror as-is rather than wrapping it
+			// in a gRpc FailedPrecodndition status like the old dryRunValidiation did.
+			// A plain Go error maps to codeds.Unknown.
+			expectedErrContains: testDescribeInstancesError,
+			expectedErrCode:     codes.Unknown,
 		},
 		{
 			name: "new incoming dynamic credential update dry run error",
@@ -1030,14 +1159,27 @@ func TestPluginOnUpdateCatalogErr(t *testing.T) {
 					},
 				},
 			},
+			// ValidateCreds is called for DynamicAWS credentials before the dry-run
+			// DescribeInstances. Provide a mock STS that returns a successful AssumeRole
+			// so the validate step passes and execution reaches the EC2 mock.
+			credOpts: []credential.AwsCredentialPersistedStateOption{
+				credential.WithStateTestOpts([]awsutil.Option{
+					awsutil.WithSTSAPIFunc(awsutil.NewMockSTS(
+						awsutil.WithAssumeRoleOutput(validAssumeRoleOutput()),
+					)),
+				}),
+			},
 			catalogOpts: []awsCatalogPersistedStateOption{
 				withTestEC2APIFunc(newTestMockEC2(
 					nil,
 					testMockEC2WithDescribeInstancesError(errors.New(testDescribeInstancesError)),
 				)),
 			},
-			expectedErrContains: "aws describe instances failed: DescribeInstances error",
-			expectedErrCode:     codes.FailedPrecondition,
+			// checkHosts returns the DescribeInstances error as-is rather than wrapping it
+			// in a gRPC FailedPrecondition status like the old dryRunValidiation did.
+			// A plain Go error maps to codes.Unknown.
+			expectedErrContains: testDescribeInstancesError,
+			expectedErrCode:     codes.Unknown,
 		},
 		{
 			name: "replace creds error",
@@ -1211,8 +1353,53 @@ func TestPluginOnUpdateCatalogErr(t *testing.T) {
 					testMockEC2WithDescribeInstancesError(fmt.Errorf("oops there was an error")),
 				)),
 			},
-			expectedErrContains: "aws describe instances failed: oops there was an error",
-			expectedErrCode:     codes.FailedPrecondition,
+			// checkHosts returns the DescribeInstances error as-is rather than wrapping it
+			// in a gRPC FailedPrecondition status like the old dryRunValidiation did.
+			// A plain Go error maps to codes.Unknown.
+			expectedErrContains: "oops there was an error",
+			expectedErrCode:     codes.Unknown,
+		},
+		{
+			name: "final dry run gRPC status error preserves code",
+			req: &pb.OnUpdateCatalogRequest{
+				CurrentCatalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion: structpb.NewStringValue("us-west-2"),
+							},
+						},
+					},
+				},
+				NewCatalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion: structpb.NewStringValue("us-west-2"),
+							},
+						},
+					},
+				},
+				Persisted: &pb.HostCatalogPersisted{
+					Secrets: &structpb.Struct{
+						Fields: map[string]*structpb.Value{
+							credential.ConstAccessKeyId:          structpb.NewStringValue("AKIA_foobar"),
+							credential.ConstSecretAccessKey:      structpb.NewStringValue("bazqux"),
+							credential.ConstCredsLastRotatedTime: structpb.NewStringValue("2006-01-02T15:04:05+07:00"),
+						},
+					},
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			// ParseAWSError maps AccessDenied to PermissionDenied. The dry-run
+			// error handler should preserve that gRPC status, not wrap it as Unknown.
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
 		},
 	}
 
@@ -1565,8 +1752,57 @@ func TestPluginOnCreateSetErr(t *testing.T) {
 					testMockEC2WithDescribeInstancesError(errors.New(testDescribeInstancesError)),
 				)),
 			},
-			expectedErrContains: fmt.Sprintf("aws describe instances failed: %s", testDescribeInstancesError),
-			expectedErrCode:     codes.FailedPrecondition,
+			expectedErrContains: testDescribeInstancesError,
+			expectedErrCode:     codes.Unknown,
+		},
+		{
+			name: "dry run gRPC status error preserves code",
+			req: &pb.OnCreateSetRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion:                    structpb.NewStringValue("us-west-2"),
+								credential.ConstDisableCredentialRotation: structpb.NewBoolValue(true),
+							},
+						},
+					},
+				},
+				Persisted: &pb.HostCatalogPersisted{
+					Secrets: &structpb.Struct{
+						Fields: map[string]*structpb.Value{
+							credential.ConstAccessKeyId:     structpb.NewStringValue("AKIA_foobar"),
+							credential.ConstSecretAccessKey: structpb.NewStringValue("bazqux"),
+						},
+					},
+				},
+				Set: &hostsets.HostSet{
+					Id: "foobar",
+					Attrs: &hostsets.HostSet_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								ConstDescribeInstancesFilters: structpb.NewListValue(
+									&structpb.ListValue{
+										Values: []*structpb.Value{
+											structpb.NewStringValue("tag-key=foo"),
+										},
+									},
+								),
+							},
+						},
+					},
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			// ParseAWSError maps AccessDenied to PermissionDenied. The dry-run
+			// error handler should preserve that gRPC status, not wrap it as Unknown.
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
 		},
 	}
 
@@ -1828,8 +2064,56 @@ func TestPluginOnUpdateSetErr(t *testing.T) {
 					testMockEC2WithDescribeInstancesError(errors.New(testDescribeInstancesError)),
 				)),
 			},
-			expectedErrContains: fmt.Sprintf("aws describe instances failed: %s", testDescribeInstancesError),
-			expectedErrCode:     codes.FailedPrecondition,
+			expectedErrContains: testDescribeInstancesError,
+			expectedErrCode:     codes.Unknown,
+		},
+		{
+			name: "dry run gRPC status error preserves code",
+			req: &pb.OnUpdateSetRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion:                    structpb.NewStringValue("us-west-2"),
+								credential.ConstDisableCredentialRotation: structpb.NewBoolValue(true),
+							},
+						},
+					},
+				},
+				Persisted: &pb.HostCatalogPersisted{
+					Secrets: &structpb.Struct{
+						Fields: map[string]*structpb.Value{
+							credential.ConstAccessKeyId:     structpb.NewStringValue("AKIA_foobar"),
+							credential.ConstSecretAccessKey: structpb.NewStringValue("bazqux"),
+						},
+					},
+				},
+				NewSet: &hostsets.HostSet{
+					Attrs: &hostsets.HostSet_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								ConstDescribeInstancesFilters: structpb.NewListValue(
+									&structpb.ListValue{
+										Values: []*structpb.Value{
+											structpb.NewStringValue("tag-key=foo"),
+										},
+									},
+								),
+							},
+						},
+					},
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			// ParseAWSError maps AccessDenied to PermissionDenied. The dry-run
+			// error handler should preserve that gRPC status, not wrap it as Unknown.
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
 		},
 	}
 
@@ -2287,7 +2571,7 @@ func TestPluginListHostsErr(t *testing.T) {
 				)),
 			},
 			expectedErrContains: fmt.Sprintf("error retrieving host results for host set id \"foobar\": %s", testDescribeInstancesError),
-			expectedErrCode:     codes.InvalidArgument,
+			expectedErrCode:     codes.Unknown,
 		},
 		{
 			name: "target attributes missing target_role_arn",
@@ -2353,7 +2637,7 @@ func TestPluginListHostsErr(t *testing.T) {
 				}),
 			},
 			expectedErrContains: "unable to list hosts for host set \"foobar\": EC2 client setup failed for target account: test EC2 client error",
-			expectedErrCode:     codes.InvalidArgument,
+			expectedErrCode:     codes.Unknown,
 		},
 		{
 			name: "target DescribeInstances error",
@@ -2381,7 +2665,7 @@ func TestPluginListHostsErr(t *testing.T) {
 				)),
 			},
 			expectedErrContains: "unable to list hosts for host set \"foobar\": EC2 DescribeInstances failed for target account: DescribeInstances error",
-			expectedErrCode:     codes.InvalidArgument,
+			expectedErrCode:     codes.Unknown,
 		},
 		{
 			name: "awsInstanceToHost error",
@@ -2442,7 +2726,115 @@ func TestPluginListHostsErr(t *testing.T) {
 				)),
 			},
 			expectedErrContains: "error processing host results for host set id \"foobar\": response integrity error: missing instance id",
-			expectedErrCode:     codes.InvalidArgument,
+			expectedErrCode:     codes.Unknown,
+		},
+		{
+			name: "DescribeInstances AccessDenied",
+			req: &pb.ListHostsRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion: structpb.NewStringValue("us-west-2"),
+							},
+						},
+					},
+				},
+				Persisted: testListHostsPersisted(),
+				Sets: []*hostsets.HostSet{
+					testListHostsSet("foobar", "tag-key=foo"),
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
+		},
+		{
+			name: "DescribeInstances UnauthorizedOperation",
+			req: &pb.ListHostsRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion: structpb.NewStringValue("us-west-2"),
+							},
+						},
+					},
+				},
+				Persisted: testListHostsPersisted(),
+				Sets: []*hostsets.HostSet{
+					testListHostsSet("foobar", "tag-key=foo"),
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("UnauthorizedOperation", "You are not authorized to perform this operation.")),
+				)),
+			},
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
+		},
+		{
+			name: "target DescribeInstances AccessDenied",
+			req: &pb.ListHostsRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion:        structpb.NewStringValue("us-west-2"),
+								credential.ConstTargetRoleArn: structpb.NewStringValue("arn:aws:iam::222222222222:role/Target"),
+								credential.ConstTargetRegion:  structpb.NewStringValue("eu-west-1"),
+							},
+						},
+					},
+				},
+				Persisted: testListHostsPersisted(),
+				Sets: []*hostsets.HostSet{
+					testListHostsSet("foobar", "tag-key=foo"),
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(newTestMockEC2(
+					nil,
+					testMockEC2WithDescribeInstancesError(awserrors.TestAwsError("AccessDenied", "not authorized to perform ec2:DescribeInstances")),
+				)),
+			},
+			expectedErrContains: "invalid credentials",
+			expectedErrCode:     codes.PermissionDenied,
+		},
+		{
+			name: "target EC2 client AccessDenied",
+			req: &pb.ListHostsRequest{
+				Catalog: &hostcatalogs.HostCatalog{
+					Attrs: &hostcatalogs.HostCatalog_Attributes{
+						Attributes: &structpb.Struct{
+							Fields: map[string]*structpb.Value{
+								credential.ConstRegion:        structpb.NewStringValue("us-west-2"),
+								credential.ConstTargetRoleArn: structpb.NewStringValue("arn:aws:iam::222222222222:role/Target"),
+							},
+						},
+					},
+				},
+				Persisted: testListHostsPersisted(),
+				Sets: []*hostsets.HostSet{
+					testListHostsSet("foobar", "tag-key=foo"),
+				},
+			},
+			catalogOpts: []awsCatalogPersistedStateOption{
+				withTestEC2APIFunc(func(...aws.Config) (EC2API, error) {
+					return nil, awserrors.TestAwsError("AccessDenied", "not authorized to assume role")
+				}),
+			},
+			// ec2ClientForTarget returns testEC2APIFunc errors unparsed; checkHosts
+			// only preserves existing gRPC statuses, so this surfaces as Unknown.
+			expectedErrContains: "unable to list hosts for host set \"foobar\": EC2 client setup failed for target account: api error AccessDenied: not authorized to assume role",
+			expectedErrCode:     codes.Unknown,
 		},
 	}
 
@@ -2633,6 +3025,21 @@ func TestBuildDescribeInstancesInput(t *testing.T) {
 			require.Equal(tc.expected, actual)
 		})
 	}
+
+	t.Run("nil attrs, dry run", func(t *testing.T) {
+		require := require.New(t)
+		actual, err := buildDescribeInstancesInput(nil, true)
+		require.NoError(err)
+		require.Equal(&ec2.DescribeInstancesInput{
+			DryRun: aws.Bool(true),
+			Filters: []types.Filter{
+				{
+					Name:   aws.String("instance-state-name"),
+					Values: []string{string(types.InstanceStateNameRunning)},
+				},
+			},
+		}, actual)
+	})
 }
 
 func TestAwsInstanceToHost(t *testing.T) {
@@ -3071,54 +3478,3 @@ func TestAppendDistinct(t *testing.T) {
 		})
 	}
 }
-
-func TestDryRunValidation(t *testing.T) {
-	t.Run("nil credential state", func(t *testing.T) {
-		st := dryRunValidation(context.Background(), nil, nil)
-		require.NotNil(t, st)
-		require.Equal(t, codes.InvalidArgument.String(), st.Code().String())
-		require.Equal(t, "persisted state is required", st.Message())
-	})
-
-	t.Run("ec2ClientErr", func(t *testing.T) {
-		st := dryRunValidation(context.Background(), &awsCatalogPersistedState{
-			AwsCredentialPersistedState: &credential.AwsCredentialPersistedState{
-				CredentialsConfig: &awsutil.CredentialsConfig{},
-			},
-			testEC2APIFunc: func(...aws.Config) (EC2API, error) {
-				return nil, fmt.Errorf("oops ec2 client err")
-			},
-		}, []ec2Option{})
-		require.NotNil(t, st)
-		require.Equal(t, codes.InvalidArgument.String(), st.Code().String())
-		require.Equal(t, "error getting EC2 client: oops ec2 client err", st.Message())
-	})
-
-	t.Run("describeInstancesErr", func(t *testing.T) {
-		st := dryRunValidation(context.Background(), &awsCatalogPersistedState{
-			AwsCredentialPersistedState: &credential.AwsCredentialPersistedState{
-				CredentialsConfig: &awsutil.CredentialsConfig{
-					AccessKey: "AKIAfoo",
-					SecretKey: "baz",
-				},
-			},
-			testEC2APIFunc: newTestMockEC2(nil, testMockEC2WithDescribeInstancesError(fmt.Errorf("oops describe instances error"))),
-		}, []ec2Option{})
-		require.NotNil(t, st)
-		require.Equal(t, codes.FailedPrecondition.String(), st.Code().String())
-		require.Equal(t, "aws describe instances failed: oops describe instances error", st.Message())
-	})
-
-	t.Run("success", func(t *testing.T) {
-		st := dryRunValidation(context.Background(), &awsCatalogPersistedState{
-			AwsCredentialPersistedState: &credential.AwsCredentialPersistedState{
-				CredentialsConfig: &awsutil.CredentialsConfig{
-					AccessKey: "AKIAfoo",
-					SecretKey: "baz",
-				},
-			},
-			testEC2APIFunc: newTestMockEC2(nil, testMockEC2WithDescribeInstancesOutput(&ec2.DescribeInstancesOutput{})),
-		}, []ec2Option{})
-		require.Nil(t, st)
-	})
-}