Check for existing tag in remote repo before building. (#764)

webapps are meant to be build-once/deploy-many, but we were rebuilding them for every request.  This changes that, so that we rebuild only for every unique ApplicationRecord.

When we push the image, we now tag it according to its ApplicationRecord.

We don't want to use that tag directly in the compose file for the deployment, however, as the deployment needs to be able to adjust to new builds w/o re-writing the file all the time.  Instead, we use a per-deployment unique tag (same as before), we just update what image it references as needed.

Reviewed-on: #764

stack_orchestrator/deploy/webapp/deploy_webapp_from_registry.py

@@ -24,6 +24,7 @@ import uuid
 
 import click
 
+from stack_orchestrator.deploy.images import remote_image_exists, add_tags_to_image
 from stack_orchestrator.deploy.webapp import deploy_webapp
 from stack_orchestrator.deploy.webapp.util import (LaconicRegistryClient,
                                                    build_container_image, push_container_image,
@@ -43,6 +44,7 @@ def process_app_deployment_request(
     deployment_parent_dir,
     kube_config,
     image_registry,
+    force_rebuild=False,
     log_file=None
 ):
     # 1. look up application
@@ -91,7 +93,9 @@ def process_app_deployment_request(
     deployment_record = laconic.get_record(app_deployment_crn)
     deployment_dir = os.path.join(deployment_parent_dir, fqdn)
     deployment_config_file = os.path.join(deployment_dir, "config.env")
+    # TODO: Is there any reason not to simplify the hash input to the app_deployment_crn?
     deployment_container_tag = "laconic-webapp/%s:local" % hashlib.md5(deployment_dir.encode()).hexdigest()
+    app_image_shared_tag = f"laconic-webapp/{app.id}:local"
     #   b. check for deployment directory (create if necessary)
     if not os.path.exists(deployment_dir):
         if deployment_record:
@@ -106,11 +110,20 @@ def process_app_deployment_request(
     needs_k8s_deploy = False
     # 6. build container (if needed)
     if not deployment_record or deployment_record.attributes.application != app.id:
-        # TODO: pull from request
-        extra_build_args = []
-        build_container_image(app, deployment_container_tag, extra_build_args, log_file)
-        push_container_image(deployment_dir, log_file)
         needs_k8s_deploy = True
+        # check if the image already exists
+        shared_tag_exists = remote_image_exists(image_registry, app_image_shared_tag)
+        if shared_tag_exists and not force_rebuild:
+            # simply add our unique tag to the existing image and we are done
+            print(f"Using existing app image {app_image_shared_tag} for {deployment_container_tag}", file=log_file)
+            add_tags_to_image(image_registry, app_image_shared_tag, deployment_container_tag)
+        else:
+            extra_build_args = []  # TODO: pull from request
+            build_container_image(app, deployment_container_tag, extra_build_args, log_file)
+            push_container_image(deployment_dir, log_file)
+            # The build/push commands above will use the unique deployment tag, so now we need to add the shared tag.
+            print(f"Updating app image tag {app_image_shared_tag} from build of {deployment_container_tag}", file=log_file)
+            add_tags_to_image(image_registry, deployment_container_tag, app_image_shared_tag)
 
     # 7. update config (if needed)
     if not deployment_record or file_hash(deployment_config_file) != deployment_record.attributes.meta.config:
@@ -171,12 +184,13 @@ def dump_known_requests(filename, requests, status="SEEN"):
 @click.option("--dry-run", help="Don't do anything, just report what would be done.", is_flag=True)
 @click.option("--include-tags", help="Only include requests with matching tags (comma-separated).", default="")
 @click.option("--exclude-tags", help="Exclude requests with matching tags (comma-separated).", default="")
+@click.option("--force-rebuild", help="Rebuild even if the image already exists.", is_flag=True)
 @click.option("--log-dir", help="Output build/deployment logs to directory.", default=None)
 @click.pass_context
 def command(ctx, kube_config, laconic_config, image_registry, deployment_parent_dir,  # noqa: C901
             request_id, discover, state_file, only_update_state,
             dns_suffix, record_namespace_dns, record_namespace_deployments, dry_run,
-            include_tags, exclude_tags, log_dir):
+            include_tags, exclude_tags, force_rebuild, log_dir):
     if request_id and discover:
         print("Cannot specify both --request-id and --discover", file=sys.stderr)
         sys.exit(2)
@@ -306,6 +320,7 @@ def command(ctx, kube_config, laconic_config, image_registry, deployment_parent_
                     os.path.abspath(deployment_parent_dir),
                     kube_config,
                     image_registry,
+                    force_rebuild,
                     run_log_file
                 )
                 status = "DEPLOYED"