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

.gitea/workflows/fixturenet-eth-plugeth-arm-test.yml

@@ -0,0 +1,45 @@
+name: Fixturenet-Eth-Plugeth-Arm-Test
+
+on:
+  push:
+    branches: '*'
+    paths:
+      - '!**'
+      - '.gitea/workflows/triggers/fixturenet-eth-plugeth-arm-test'
+  schedule: # Note: coordinate with other tests to not overload runners at the same time of day
+    - cron: '2 14 * * *'
+
+# Needed until we can incorporate docker startup into the executor container
+env:
+  DOCKER_HOST: unix:///var/run/dind.sock
+
+
+jobs:
+  test:
+    name: "Run an Ethereum plugeth fixturenet test"
+    runs-on: ubuntu-latest-arm
+    steps:
+      - name: "Clone project repository"
+        uses: actions/checkout@v3
+      # At present the stock setup-python action fails on Linux/aarch64
+      # Conditional steps below workaroud this by using deadsnakes for that case only
+      - name: "Install Python for ARM on Linux"
+        if: ${{ runner.arch == 'arm64' && runner.os == 'Linux' }}
+        uses: deadsnakes/action@v3.0.1
+        with:
+          python-version: '3.8'
+      - name: "Install Python cases other than ARM on Linux"
+        if: ${{ ! (runner.arch == 'arm64' && runner.os == 'Linux') }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.8'
+      - name: "Print Python version"
+        run: python3 --version
+      - name: "Install shiv"
+        run: pip install shiv
+      - name: "Generate build version file"
+        run: ./scripts/create_build_tag_file.sh
+      - name: "Build local shiv package"
+        run: ./scripts/build_shiv_package.sh
+      - name: "Run fixturenet-eth tests"
+        run: ./tests/fixturenet-eth-plugeth/run-test.sh

.gitea/workflows/test-database.yml

@@ -48,5 +48,5 @@ jobs:
         run: |
           source /opt/bash-utils/cgroup-helper.sh
           join_cgroup
-          CERC_SCRIPT_DEBUG=1 ./tests/database/run-test.sh
+          ./tests/database/run-test.sh
 

.gitea/workflows/triggers/fixturenet-eth-plugeth-arm-test

@@ -0,0 +1,2 @@
+Change this file to trigger running the fixturenet-eth-plugeth-arm-test CI job
+

stack_orchestrator/build/build_containers.py

@@ -27,8 +27,11 @@ import subprocess
 import click
 import importlib.resources
 from pathlib import Path
-from stack_orchestrator.util import include_exclude_check, get_parsed_stack_config, stack_is_external, warn_exit
+from stack_orchestrator.opts import opts
+from stack_orchestrator.util import include_exclude_check, get_parsed_stack_config, stack_is_external, error_exit, warn_exit
 from stack_orchestrator.base import get_npm_registry_url
+from stack_orchestrator.build.build_types import BuildContext
+from stack_orchestrator.build.publish import publish_image
 
 # TODO: find a place for this
 #    epilog="Config provided either in .env or settings.ini or env vars: CERC_REPO_BASE_DIR (defaults to ~/cerc)"
@@ -59,69 +62,58 @@ def make_container_build_env(dev_root_path: str,
     return container_build_env
 
 
-def process_container(stack: str,
-                      container,
-                      container_build_dir: str,
-                      container_build_env: dict,
-                      dev_root_path: str,
-                      quiet: bool,
-                      verbose: bool,
-                      dry_run: bool,
-                      continue_on_error: bool,
-                      ):
-    if not quiet:
-        print(f"Building: {container}")
+def process_container(build_context: BuildContext) -> bool:
+    if not opts.o.quiet:
+        print(f"Building: {build_context.container}")
 
-    default_container_tag = f"{container}:local"
-    container_build_env.update({"CERC_DEFAULT_CONTAINER_IMAGE_TAG": default_container_tag})
+    default_container_tag = f"{build_context.container}:local"
+    build_context.container_build_env.update({"CERC_DEFAULT_CONTAINER_IMAGE_TAG": default_container_tag})
 
     # Check if this is in an external stack
-    if stack_is_external(stack):
-        container_parent_dir = Path(stack).joinpath("container-build")
-        temp_build_dir = container_parent_dir.joinpath(container.replace("/", "-"))
+    if stack_is_external(build_context.stack):
+        container_parent_dir = Path(build_context.stack).joinpath("container-build")
+        temp_build_dir = container_parent_dir.joinpath(build_context.container.replace("/", "-"))
         temp_build_script_filename = temp_build_dir.joinpath("build.sh")
         # Now check if the container exists in the external stack.
         if not temp_build_script_filename.exists():
             # If not, revert to building an internal container
-            container_parent_dir = container_build_dir
+            container_parent_dir = build_context.container_build_dir
     else:
-        container_parent_dir = container_build_dir
+        container_parent_dir = build_context.container_build_dir
 
-    build_dir = container_parent_dir.joinpath(container.replace("/", "-"))
+    build_dir = container_parent_dir.joinpath(build_context.container.replace("/", "-"))
     build_script_filename = build_dir.joinpath("build.sh")
 
-    if verbose:
+    if opts.o.verbose:
         print(f"Build script filename: {build_script_filename}")
     if os.path.exists(build_script_filename):
         build_command = build_script_filename.as_posix()
     else:
-        if verbose:
+        if opts.o.verbose:
             print(f"No script file found: {build_script_filename}, using default build script")
-        repo_dir = container.split('/')[1]
+        repo_dir = build_context.container.split('/')[1]
         # TODO: make this less of a hack -- should be specified in some metadata somewhere
         # Check if we have a repo for this container. If not, set the context dir to the container-build subdir
-        repo_full_path = os.path.join(dev_root_path, repo_dir)
+        repo_full_path = os.path.join(build_context.dev_root_path, repo_dir)
         repo_dir_or_build_dir = repo_full_path if os.path.exists(repo_full_path) else build_dir
-        build_command = os.path.join(container_build_dir,
+        build_command = os.path.join(build_context.container_build_dir,
                                      "default-build.sh") + f" {default_container_tag} {repo_dir_or_build_dir}"
-    if not dry_run:
+    if not opts.o.dry_run:
         # No PATH at all causes failures with podman.
-        if "PATH" not in container_build_env:
-            container_build_env["PATH"] = os.environ["PATH"]
-        if verbose:
-            print(f"Executing: {build_command} with environment: {container_build_env}")
-        build_result = subprocess.run(build_command, shell=True, env=container_build_env)
-        if verbose:
+        if "PATH" not in build_context.container_build_env:
+            build_context.container_build_env["PATH"] = os.environ["PATH"]
+        if opts.o.verbose:
+            print(f"Executing: {build_command} with environment: {build_context.container_build_env}")
+        build_result = subprocess.run(build_command, shell=True, env=build_context.container_build_env)
+        if opts.o.verbose:
             print(f"Return code is: {build_result.returncode}")
         if build_result.returncode != 0:
-            print(f"Error running build for {container}")
-            if not continue_on_error:
-                print("FATAL Error: container build failed and --continue-on-error not set, exiting")
-                sys.exit(1)
-            else:
-                print("****** Container Build Error, continuing because --continue-on-error is set")
+            return False
+        else:
+            return True
     else:
         print("Skipped")
+        return True
 
 
 @click.command()
@@ -129,17 +121,14 @@ def process_container(stack: str,
 @click.option('--exclude', help="don\'t build these containers")
 @click.option("--force-rebuild", is_flag=True, default=False, help="Override dependency checking -- always rebuild")
 @click.option("--extra-build-args", help="Supply extra arguments to build")
+@click.option("--publish-images", is_flag=True, default=False, help="Publish the built images in the specified image registry")
+@click.option("--image-registry", help="Specify the image registry for --publish-images")
 @click.pass_context
-def command(ctx, include, exclude, force_rebuild, extra_build_args):
+def command(ctx, include, exclude, force_rebuild, extra_build_args, publish_images, image_registry):
     '''build the set of containers required for a complete stack'''
 
-    quiet = ctx.obj.quiet
-    verbose = ctx.obj.verbose
-    dry_run = ctx.obj.dry_run
-    debug = ctx.obj.debug
     local_stack = ctx.obj.local_stack
     stack = ctx.obj.stack
-    continue_on_error = ctx.obj.continue_on_error
 
     # See: https://stackoverflow.com/questions/25389095/python-get-path-of-root-project-structure
     container_build_dir = Path(__file__).absolute().parent.parent.joinpath("data", "container-build")
@@ -150,12 +139,16 @@ def command(ctx, include, exclude, force_rebuild, extra_build_args):
     else:
         dev_root_path = os.path.expanduser(config("CERC_REPO_BASE_DIR", default="~/cerc"))
 
-    if not quiet:
+    if not opts.o.quiet:
         print(f'Dev Root is: {dev_root_path}')
 
     if not os.path.isdir(dev_root_path):
         print('Dev root directory doesn\'t exist, creating')
 
+    if publish_images:
+        if not image_registry:
+            error_exit("--image-registry must be supplied with --publish-images")
+
     # See: https://stackoverflow.com/a/20885799/1701505
     from stack_orchestrator import data
     with importlib.resources.open_text(data, "container-image-list.txt") as container_list_file:
@@ -170,21 +163,38 @@ def command(ctx, include, exclude, force_rebuild, extra_build_args):
     else:
         containers_in_scope = all_containers
 
-    if verbose:
+    if opts.o.verbose:
         print(f'Containers: {containers_in_scope}')
         if stack:
             print(f"Stack: {stack}")
 
     container_build_env = make_container_build_env(dev_root_path,
                                                    container_build_dir,
-                                                   debug,
+                                                   opts.o.debug,
                                                    force_rebuild,
                                                    extra_build_args)
 
     for container in containers_in_scope:
         if include_exclude_check(container, include, exclude):
-            process_container(stack, container, container_build_dir, container_build_env,
-                              dev_root_path, quiet, verbose, dry_run, continue_on_error)
+
+            build_context = BuildContext(
+                stack,
+                container,
+                container_build_dir,
+                container_build_env,
+                dev_root_path
+            )
+            result = process_container(build_context)
+            if result:
+                if publish_images:
+                    publish_image(f"{container}:local", image_registry)
+            else:
+                print(f"Error running build for {build_context.container}")
+                if not opts.o.continue_on_error:
+                    error_exit("container build failed and --continue-on-error not set, exiting")
+                    sys.exit(1)
+                else:
+                    print("****** Container Build Error, continuing because --continue-on-error is set")
         else:
-            if verbose:
+            if opts.o.verbose:
                 print(f"Excluding: {container}")

stack_orchestrator/build/build_types.py

@@ -0,0 +1,29 @@
+# Copyright © 2024 Vulcanize
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http:#www.gnu.org/licenses/>.
+
+
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Mapping
+
+
+@dataclass
+class BuildContext:
+    stack: str
+    container: str
+    container_build_dir: Path
+    container_build_env: Mapping[str,str]
+    dev_root_path: str
+

stack_orchestrator/build/build_webapp.py

@@ -21,11 +21,14 @@
 # TODO: display the available list of containers; allow re-build of either all or specific containers
 
 import os
+import sys
+
 from decouple import config
 import click
 from pathlib import Path
 from stack_orchestrator.build import build_containers
 from stack_orchestrator.deploy.webapp.util import determine_base_container
+from stack_orchestrator.build.build_types import BuildContext
 
 
 @click.command()
@@ -39,12 +42,9 @@ def command(ctx, base_container, source_repo, force_rebuild, extra_build_args, t
     '''build the specified webapp container'''
 
     quiet = ctx.obj.quiet
-    verbose = ctx.obj.verbose
-    dry_run = ctx.obj.dry_run
     debug = ctx.obj.debug
     local_stack = ctx.obj.local_stack
     stack = ctx.obj.stack
-    continue_on_error = ctx.obj.continue_on_error
 
     # See: https://stackoverflow.com/questions/25389095/python-get-path-of-root-project-structure
     container_build_dir = Path(__file__).absolute().parent.parent.joinpath("data", "container-build")
@@ -65,8 +65,17 @@ def command(ctx, base_container, source_repo, force_rebuild, extra_build_args, t
     container_build_env = build_containers.make_container_build_env(dev_root_path, container_build_dir, debug,
                                                                     force_rebuild, extra_build_args)
 
-    build_containers.process_container(None, base_container, container_build_dir, container_build_env, dev_root_path, quiet,
-                                       verbose, dry_run, continue_on_error)
+    build_context_1 = BuildContext(
+        stack,
+        base_container,
+        container_build_dir,
+        container_build_env,
+        dev_root_path,
+    )
+    ok = build_containers.process_container(build_context_1)
+    if not ok:
+        print("ERROR: Build failed.", file=sys.stderr)
+        sys.exit(1)
 
     # Now build the target webapp.  We use the same build script, but with a different Dockerfile and work dir.
     container_build_env["CERC_WEBAPP_BUILD_RUNNING"] = "true"
@@ -80,5 +89,14 @@ def command(ctx, base_container, source_repo, force_rebuild, extra_build_args, t
     else:
         container_build_env["CERC_CONTAINER_BUILD_TAG"] = tag
 
-    build_containers.process_container(None, base_container, container_build_dir, container_build_env, dev_root_path, quiet,
-                                       verbose, dry_run, continue_on_error)
+    build_context_2 = BuildContext(
+        stack,
+        base_container,
+        container_build_dir,
+        container_build_env,
+        dev_root_path,
+    )
+    ok = build_containers.process_container(build_context_2)
+    if not ok:
+        print("ERROR: Build failed.", file=sys.stderr)
+        sys.exit(1)

stack_orchestrator/build/publish.py

@@ -0,0 +1,48 @@
+# Copyright © 2024 Vulcanize
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http:#www.gnu.org/licenses/>.
+
+from datetime import datetime
+from python_on_whales import DockerClient
+
+from stack_orchestrator.opts import opts
+from stack_orchestrator.util import error_exit
+
+
+def _publish_tag_for_image(local_image_tag: str, remote_repo: str, version: str):
+    # Turns image tags of the form: foo/bar:local into remote.repo/org/bar:deploy
+    (image_name, image_version) = local_image_tag.split(":")
+    if image_version == "local":
+        return f"{remote_repo}/{image_name}:{version}"
+    else:
+        error_exit("Asked to publish a non-locally built image")
+
+
+def publish_image(local_tag, registry):
+    if opts.o.verbose:
+        print(f"Publishing this image: {local_tag} to this registry: {registry}")
+    docker = DockerClient()
+    # Figure out the target image tag
+    # Eventually this version will be generated from the source repo state
+    # Using a timestemp is an intermediate step
+    version = datetime.now().strftime("%Y%m%d%H%M")
+    remote_tag = _publish_tag_for_image(local_tag, registry, version)
+    # Tag the image thus
+    if opts.o.debug:
+        print(f"Tagging {local_tag} to {remote_tag}")
+    docker.image.tag(local_tag, remote_tag)
+    # Push it to the desired registry
+    if opts.o.verbose:
+        print(f"Pushing image {remote_tag}")
+    docker.image.push(remote_tag)

stack_orchestrator/data/compose/docker-compose-container-registry.yml

@@ -5,9 +5,11 @@ services:
     environment:
       REGISTRY_LOG_LEVEL: ${REGISTRY_LOG_LEVEL}
     volumes:
+      - config:/config:ro
       - registry-data:/var/lib/registry
     ports:
       - "5000"
 
 volumes:
+  config:
   registry-data:

stack_orchestrator/data/container-build/cerc-webapp-base/scripts/start-serving-app.sh

@@ -3,13 +3,28 @@ if [ -n "$CERC_SCRIPT_DEBUG" ]; then
     set -x
 fi
 
+CERC_LISTEN_PORT=${CERC_LISTEN_PORT:-80}
 CERC_WEBAPP_FILES_DIR="${CERC_WEBAPP_FILES_DIR:-/data}"
 CERC_ENABLE_CORS="${CERC_ENABLE_CORS:-false}"
+CERC_SINGLE_PAGE_APP="${CERC_SINGLE_PAGE_APP}"
+
+if [ -z "${CERC_SINGLE_PAGE_APP}" ]; then
+  if [ 1 -eq $(find "${CERC_WEBAPP_FILES_DIR}" -name '*.html' | wc -l) ] && [ -d "${CERC_WEBAPP_FILES_DIR}/static" ]; then
+    CERC_SINGLE_PAGE_APP=true
+  else
+    CERC_SINGLE_PAGE_APP=false
+  fi
+fi
 
 if [ "true" == "$CERC_ENABLE_CORS" ]; then
   CERC_HTTP_EXTRA_ARGS="$CERC_HTTP_EXTRA_ARGS --cors"
 fi
 
+if [ "true" == "$CERC_SINGLE_PAGE_APP" ]; then
+  # Create a catchall redirect back to /
+  CERC_HTTP_EXTRA_ARGS="$CERC_HTTP_EXTRA_ARGS --proxy http://localhost:${CERC_LISTEN_PORT}?"
+fi
+
 LACONIC_HOSTED_CONFIG_FILE=${LACONIC_HOSTED_CONFIG_FILE}
 if [ -z "${LACONIC_HOSTED_CONFIG_FILE}" ]; then
   if [ -f "/config/laconic-hosted-config.yml" ]; then
@@ -20,8 +35,8 @@ if [ -z "${LACONIC_HOSTED_CONFIG_FILE}" ]; then
 fi
 
 if [ -f "${LACONIC_HOSTED_CONFIG_FILE}" ]; then
-  /scripts/apply-webapp-config.sh $LACONIC_HOSTED_CONFIG_FILE ${CERC_WEBAPP_FILES_DIR}
+  /scripts/apply-webapp-config.sh $LACONIC_HOSTED_CONFIG_FILE "${CERC_WEBAPP_FILES_DIR}"
 fi
 
 /scripts/apply-runtime-env.sh ${CERC_WEBAPP_FILES_DIR}
-http-server $CERC_HTTP_EXTRA_ARGS -p ${CERC_LISTEN_PORT:-80} ${CERC_WEBAPP_FILES_DIR}
+http-server $CERC_HTTP_EXTRA_ARGS -p ${CERC_LISTEN_PORT} "${CERC_WEBAPP_FILES_DIR}"

stack_orchestrator/data/stacks/uniswap-urbit-app/README.md

@@ -33,23 +33,29 @@ laconic-so --stack uniswap-urbit-app deploy init --output uniswap-urbit-app-spec
 
 ### Ports
 
-Edit `network` in spec file to map container ports to same ports in host:
+Edit `uniswap-urbit-app-spec.yml` such that it looks like:
 
 ```yml
-...
+stack: uniswap-urbit-app
+deploy-to: compose
 network:
   ports:
-    urbit-fake-ship:
-      - '8080:80'
     proxy-server:
       - '4000:4000'
+    urbit-fake-ship:
+      - '8080:80'
     ipfs:
-      - '8081:8080'
-      - '5001:5001'
-...
+     - '4001'
+     - '8081:8080'
+     - 0.0.0.0:5001:5001
+volumes:
+  urbit_app_builds: ./data/urbit_app_builds
+  urbit_data: ./data/urbit_data
+  ipfs-import: ./data/ipfs-import
+  ipfs-data: ./data/ipfs-data
 ```
 
-Note: Skip the `ipfs` ports if need to use an externally running IPFS node
+Note: Skip the `ipfs` ports if using an externally running IPFS node, set via `config.env`, below.
 
 ### Data volumes
 

stack_orchestrator/deploy/deployment_create.py

@@ -327,12 +327,14 @@ def init_operation(deploy_command_context, stack, deployer_type, config,
     default_spec_file_content = call_stack_deploy_init(deploy_command_context)
     spec_file_content = {"stack": stack, constants.deploy_to_key: deployer_type}
     if deployer_type == "k8s":
-        if kube_config is None:
+        if kube_config:
+            spec_file_content.update({constants.kube_config_key: kube_config})
+        else:
             error_exit("--kube-config must be supplied with --deploy-to k8s")
-        if image_registry is None:
-            error_exit("--image-registry must be supplied with --deploy-to k8s")
-        spec_file_content.update({constants.kube_config_key: kube_config})
-        spec_file_content.update({constants.image_registry_key: image_registry})
+        if image_registry:
+            spec_file_content.update({constants.image_registry_key: image_registry})
+        else:
+            print("WARNING: --image-registry not specified, only default container registries (eg, Docker Hub) will be available")
     else:
         # Check for --kube-config supplied for non-relevant deployer types
         if kube_config is not None:

stack_orchestrator/deploy/images.py

@@ -29,6 +29,29 @@ def _image_needs_pushed(image: str):
     return image.endswith(":local")
 
 
+def remote_image_exists(remote_repo_url: str, local_tag: str):
+    docker = DockerClient()
+    try:
+        remote_tag = remote_tag_for_image(local_tag, remote_repo_url)
+        result = docker.manifest.inspect(remote_tag)
+        return True if result else False
+    except Exception:  # noqa: E722
+        return False
+
+
+def add_tags_to_image(remote_repo_url: str, local_tag: str, *additional_tags):
+    if not additional_tags:
+        return
+
+    if not remote_image_exists(remote_repo_url, local_tag):
+        raise Exception(f"{local_tag} does not exist in {remote_repo_url}")
+
+    docker = DockerClient()
+    remote_tag = remote_tag_for_image(local_tag, remote_repo_url)
+    new_remote_tags = [remote_tag_for_image(tag, remote_repo_url) for tag in additional_tags]
+    docker.buildx.imagetools.create(sources=[remote_tag], tags=new_remote_tags)
+
+
 def remote_tag_for_image(image: str, remote_repo_url: str):
     # Turns image tags of the form: foo/bar:local into remote.repo/org/bar:deploy
     major_parts = image.split("/", 2)

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"