When running single-server mode, use public_cluster_addr if given (#904)

When running single-server mode, use public_cluster_addr if given

Right now you don't need to specify a controller address and we use the
cluster listener address; this allows overriding it to the
public_cluster_addr if one is given.

If `controllers` is specified we allow it to be either the cluster
listener or the public cluster address if one is specified before trying
to parse and use it.

CHANGELOG.md

@@ -4,6 +4,12 @@ Canonical reference for changes, improvements, and bugfixes for Boundary.
 
 ## Next
 
+### New and Improved
+
+* server: When running single-server mode and `controllers` is not specified in
+  the `worker` block, use `public_cluster_addr` if given
+  ([PR](https://github.com/hashicorp/boundary/pull/904))
+
 ### Bug Fixes
 
 * api: Fix nil pointer panic that could occur when using TLS

internal/cmd/commands/server/server.go

@@ -229,11 +229,18 @@ func (c *Command) Run(args []string) int {
 		if c.Config.Controller != nil {
 			switch len(c.Config.Worker.Controllers) {
 			case 0:
+				if c.Config.Controller.PublicClusterAddr != "" {
+					clusterAddr = c.Config.Controller.PublicClusterAddr
+				}
 				c.Config.Worker.Controllers = []string{clusterAddr}
 			case 1:
 				if c.Config.Worker.Controllers[0] == clusterAddr {
 					break
 				}
+				if c.Config.Controller.PublicClusterAddr != "" &&
+					c.Config.Worker.Controllers[0] == c.Config.Controller.PublicClusterAddr {
+					break
+				}
 				// Best effort see if it's a domain name and if not assume it must match
 				host, _, err := net.SplitHostPort(c.Config.Worker.Controllers[0])
 				if err != nil && strings.Contains(err.Error(), "missing port in address") {