feat: add lifecycle.Executor to manage autostart and autostop (#1183)

This PR adds a package lifecycle and an Executor implementation that attempts to schedule a build of workspaces with autostart configured.

- lifecycle.Executor takes a chan time.Time in its constructor (e.g. time.Tick(time.Minute))
- Whenever a value is received from this channel, it executes one iteration of looping through the workspaces and triggering lifecycle operations.
- When the context passed to the executor is Done, it exits.
- Only workspaces that meet the following criteria will have a lifecycle operation applied to them:
  - Workspace has a valid and non-empty autostart or autostop schedule (either)
  - Workspace's last build was successful
- The following transitions will be applied depending on the current workspace state:
  - If the workspace is currently running, it will be stopped.
  - If the workspace is currently stopped, it will be started.
  - Otherwise, nothing will be done.
- Workspace builds will be created with the same parameters and template version as the last successful build (for example, template version)

coderd/database/queries.sql.go

@@ -3202,6 +3202,55 @@ func (q *sqlQuerier) GetWorkspaceOwnerCountsByTemplateIDs(ctx context.Context, i
 	return items, nil
 }
 
+const getWorkspacesAutostartAutostop = `-- name: GetWorkspacesAutostartAutostop :many
+SELECT
+	id, created_at, updated_at, owner_id, organization_id, template_id, deleted, name, autostart_schedule, autostop_schedule
+FROM
+	workspaces
+WHERE
+	deleted = false
+AND
+(
+	autostart_schedule <> ''
+	OR
+	autostop_schedule <> ''
+)
+`
+
+func (q *sqlQuerier) GetWorkspacesAutostartAutostop(ctx context.Context) ([]Workspace, error) {
+	rows, err := q.db.QueryContext(ctx, getWorkspacesAutostartAutostop)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Workspace
+	for rows.Next() {
+		var i Workspace
+		if err := rows.Scan(
+			&i.ID,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+			&i.OwnerID,
+			&i.OrganizationID,
+			&i.TemplateID,
+			&i.Deleted,
+			&i.Name,
+			&i.AutostartSchedule,
+			&i.AutostopSchedule,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const getWorkspacesByOrganizationID = `-- name: GetWorkspacesByOrganizationID :many
 SELECT id, created_at, updated_at, owner_id, organization_id, template_id, deleted, name, autostart_schedule, autostop_schedule FROM workspaces WHERE organization_id = $1 AND deleted = $2
 `