feat(coderd/database): add task status and status view (#20235)

This change updates the `task_workspace_apps` table structure for
improved linking to workspace builds and adds queries to manage tasks
and a view to expose task status.

Updates coder/internal#948
Supersedes coder/coder#20212
Supersedes coder/coder#19773

coderd/database/migrations/000379_create_tasks_with_status_view.down.sql

@@ -0,0 +1,33 @@
+DROP VIEW IF EXISTS tasks_with_status;
+DROP TYPE IF EXISTS task_status;
+
+DROP INDEX IF EXISTS tasks_organization_id_idx;
+DROP INDEX IF EXISTS tasks_owner_id_idx;
+DROP INDEX IF EXISTS tasks_workspace_id_idx;
+
+ALTER TABLE task_workspace_apps
+	DROP CONSTRAINT IF EXISTS task_workspace_apps_pkey;
+
+-- Add back workspace_build_id column.
+ALTER TABLE task_workspace_apps
+	ADD COLUMN workspace_build_id UUID;
+
+-- Try to populate workspace_build_id from workspace_builds.
+UPDATE task_workspace_apps
+SET workspace_build_id = workspace_builds.id
+FROM workspace_builds
+WHERE workspace_builds.build_number = task_workspace_apps.workspace_build_number
+	AND workspace_builds.workspace_id IN (
+		SELECT workspace_id FROM tasks WHERE tasks.id = task_workspace_apps.task_id
+	);
+
+-- Remove rows that couldn't be restored.
+DELETE FROM task_workspace_apps
+WHERE workspace_build_id IS NULL;
+
+-- Restore original schema.
+ALTER TABLE task_workspace_apps
+	DROP COLUMN workspace_build_number,
+	ALTER COLUMN workspace_build_id SET NOT NULL,
+	ALTER COLUMN workspace_agent_id SET NOT NULL,
+	ALTER COLUMN workspace_app_id SET NOT NULL;

coderd/database/migrations/000379_create_tasks_with_status_view.up.sql

@@ -0,0 +1,104 @@
+-- Replace workspace_build_id with workspace_build_number.
+ALTER TABLE task_workspace_apps
+	ADD COLUMN workspace_build_number INTEGER;
+
+-- Try to populate workspace_build_number from workspace_builds.
+UPDATE task_workspace_apps
+SET workspace_build_number = workspace_builds.build_number
+FROM workspace_builds
+WHERE workspace_builds.id = task_workspace_apps.workspace_build_id;
+
+-- Remove rows that couldn't be migrated.
+DELETE FROM task_workspace_apps
+WHERE workspace_build_number IS NULL;
+
+ALTER TABLE task_workspace_apps
+	DROP COLUMN workspace_build_id,
+	ALTER COLUMN workspace_build_number SET NOT NULL,
+	ALTER COLUMN workspace_agent_id DROP NOT NULL,
+	ALTER COLUMN workspace_app_id DROP NOT NULL,
+	ADD CONSTRAINT task_workspace_apps_pkey PRIMARY KEY (task_id, workspace_build_number);
+
+-- Add indexes for common joins or filters.
+CREATE INDEX IF NOT EXISTS tasks_workspace_id_idx ON tasks (workspace_id);
+CREATE INDEX IF NOT EXISTS tasks_owner_id_idx ON tasks (owner_id);
+CREATE INDEX IF NOT EXISTS tasks_organization_id_idx ON tasks (organization_id);
+
+CREATE TYPE task_status AS ENUM (
+	'pending',
+	'initializing',
+	'active',
+	'paused',
+	'unknown',
+	'error'
+);
+
+CREATE VIEW
+	tasks_with_status
+AS
+	SELECT
+		tasks.*,
+		CASE
+			WHEN tasks.workspace_id IS NULL OR latest_build.job_status IS NULL THEN 'pending'::task_status
+
+			WHEN latest_build.job_status = 'failed' THEN 'error'::task_status
+
+			WHEN latest_build.transition IN ('stop', 'delete')
+				AND latest_build.job_status = 'succeeded' THEN 'paused'::task_status
+
+			WHEN latest_build.transition = 'start'
+				AND latest_build.job_status = 'pending' THEN 'initializing'::task_status
+
+			WHEN latest_build.transition = 'start' AND latest_build.job_status IN ('running', 'succeeded') THEN
+				CASE
+					WHEN agent_status.none THEN 'initializing'::task_status
+					WHEN agent_status.connecting THEN 'initializing'::task_status
+					WHEN agent_status.connected THEN
+						CASE
+							WHEN app_status.any_unhealthy THEN 'error'::task_status
+							WHEN app_status.any_initializing THEN 'initializing'::task_status
+							WHEN app_status.all_healthy_or_disabled THEN 'active'::task_status
+							ELSE 'unknown'::task_status
+						END
+					ELSE 'unknown'::task_status
+				END
+
+			ELSE 'unknown'::task_status
+		END AS status
+	FROM
+		tasks
+	LEFT JOIN LATERAL (
+		SELECT workspace_build_number, workspace_agent_id, workspace_app_id
+		FROM task_workspace_apps task_app
+		WHERE task_id = tasks.id
+		ORDER BY workspace_build_number DESC
+		LIMIT 1
+	) task_app ON TRUE
+	LEFT JOIN LATERAL (
+		SELECT
+			workspace_build.transition,
+			provisioner_job.job_status,
+			workspace_build.job_id
+		FROM workspace_builds workspace_build
+		JOIN provisioner_jobs provisioner_job ON provisioner_job.id = workspace_build.job_id
+		WHERE workspace_build.workspace_id = tasks.workspace_id
+			AND workspace_build.build_number = task_app.workspace_build_number
+	) latest_build ON TRUE
+	CROSS JOIN LATERAL (
+		SELECT
+			COUNT(*) = 0 AS none,
+			bool_or(workspace_agent.lifecycle_state IN ('created', 'starting')) AS connecting,
+			bool_and(workspace_agent.lifecycle_state = 'ready') AS connected
+		FROM workspace_agents workspace_agent
+		WHERE workspace_agent.id = task_app.workspace_agent_id
+	) agent_status
+	CROSS JOIN LATERAL (
+		SELECT
+			bool_or(workspace_app.health = 'unhealthy') AS any_unhealthy,
+			bool_or(workspace_app.health = 'initializing') AS any_initializing,
+			bool_and(workspace_app.health IN ('healthy', 'disabled')) AS all_healthy_or_disabled
+		FROM workspace_apps workspace_app
+		WHERE workspace_app.id = task_app.workspace_app_id
+	) app_status
+	WHERE
+		tasks.deleted_at IS NULL;

coderd/database/migrations/testdata/fixtures/000379_create_tasks_with_status_view.up.sql

@@ -0,0 +1,6 @@
+INSERT INTO public.task_workspace_apps VALUES (
+    'f5a1c3e4-8b2d-4f6a-9d7e-2a8b5c9e1f3d', -- task_id
+    NULL,                                   -- workspace_agent_id
+    NULL,                                   -- workspace_app_id
+    99                                      -- workspace_build_number
+) ON CONFLICT DO NOTHING;