feat(workers): worker operational state (#2427)

* feat(workers): worker operational state

internal/db/schema/migrations/oss/postgres/52/01_worker_operational_state.up.sql

@@ -0,0 +1,76 @@
+begin;
+
+create table server_worker_operational_state_enm (
+  state text primary key
+  constraint only_predefined_operational_states_allowed
+    check (
+      state in (
+        'active',
+        'shutdown',
+        'unknown'
+      )
+    )
+);
+comment on table server_worker_operational_state_enm is
+  'server_worker_operational_state_enm is an enumeration table for worker operational states.';
+
+insert into server_worker_operational_state_enm (state) values
+  ('active'),
+  ('shutdown'),
+  ('unknown');
+
+alter table server_worker
+  add column operational_state text not null default 'active'
+    constraint server_worker_operational_state_enm_fkey
+      references server_worker_operational_state_enm (state)
+      on delete restrict
+      on update cascade;
+
+drop view server_worker_aggregate;
+-- Updates view created in 51/01_server_worker_release_version.up.sql to add the worker operational state
+create view server_worker_aggregate as
+with worker_config_tags(worker_id, source, tags) as (
+  select
+    ct.worker_id,
+    ct.source,
+    -- keys and tags can be any lowercase printable character so use uppercase characters as delimitors.
+    string_agg(distinct concat_ws('Y', ct.key, ct.value), 'Z') as tags
+  from server_worker_tag ct
+  group by ct.worker_id, ct.source
+),
+connection_count (worker_id, count) as (
+ select
+   worker_id,
+   count(1) as count
+ from session_connection
+ where closed_reason is null
+ group by worker_id
+)
+select
+  w.public_id,
+  w.scope_id,
+  w.description,
+  w.name,
+  w.address,
+  w.create_time,
+  w.update_time,
+  w.version,
+  w.last_status_time,
+  w.type,
+  w.release_version,
+  w.operational_state,
+  cc.count as active_connection_count,
+  -- keys and tags can be any lowercase printable character so use uppercase characters as delimitors.
+  wt.tags as api_tags,
+  ct.tags as worker_config_tags
+from server_worker w
+ left join worker_config_tags wt on
+    w.public_id = wt.worker_id and wt.source = 'api'
+ left join worker_config_tags ct on
+    w.public_id = ct.worker_id and ct.source = 'configuration'
+ left join connection_count as cc on
+    w.public_id = cc.worker_id;
+comment on view server_worker_aggregate is
+  'server_worker_aggregate contains the worker resource with its worker provided config values and its configuration and api provided tags.';
+
+commit;