Add support for using podman + skopeo with Tilt (azimuth-cloud#194)

* Add support for using podman with Tilt

* Add docs for using podman + skopeo

Author: Matt Pryor

Tiltfile

@@ -34,6 +34,13 @@ if not os.path.exists(SETTINGS_FILE):
 # Load the settings
 settings = deep_merge(
     {
+        # The engine that will be used to build container images for your changes
+        # Supported options are docker, podman
+        "build_engine": "docker",
+        # The engine that will be used to mirror container images when required
+        # Supported options are skopeo (recommended), docker, podman
+        # Defaults to the build engine
+        # "mirror_engine": "skopeo",
         # The components that will be managed by Tilt, if locally available
         # By default, we search for local checkouts as siblings of this checkout
         "components": {
@@ -101,27 +108,23 @@ def build_image(name, context, build_args = None):
     """
     Defines an image build and returns the image name.
     """
+    build_engine = settings["build_engine"]
+    if build_engine not in ["docker", "podman"]:
+        fail("unknown build engine - %s" % build_engine)
     image = image_name(name)
-    # The Azimuth CaaS operator relies on the .git folder to be in the Docker build context
-    # This is because it uses pbr for versioning
-    # Unfortunately, Tilt's docker_build function _always_ ignores the .git directory :-(
+    # Some of the Azimuth components rely on the .git folder to be in the build context (pbr)
+    # Unfortunately, Tilt's {docker,podman}_build functions _always_ ignores the .git directory
     # So we use a custom build command
-    build_command = [
-        "docker",
-        "build",
-        "-t",
-        "$EXPECTED_REF",
-        "--platform",
-        "linux/amd64",
-        context,
-    ]
-    if build_args:
-        for arg_name, arg_value in build_args.items():
-            build_command.extend([
-                "--build-arg",
-                "'%s=%s'" % (arg_name, arg_value),
-            ])
-    custom_build(image, " ".join(build_command), [context])
+    build_args = " ".join([
+        item
+        for arg_name, arg_value in (build_args or {}).items()
+        for item in ["--build-arg", "'%s=%s'" % (arg_name, arg_value)]
+    ])
+    build_command = (
+        "%s build -t $EXPECTED_REF --platform linux/amd64 %s %s && " % (build_engine, build_args, context) +
+        "%s push $EXPECTED_REF" % build_engine
+    )
+    custom_build(image, build_command, [context], skips_local_docker = True)
     return image
 
 
@@ -130,14 +133,18 @@ def mirror_image(name, source_image):
     Defines a mirrored image and returns the image name.
     """
     image = image_name(name)
-    custom_build(
-        image,
-        (
-            "docker pull --platform linux/amd64 {source_image} && " +
-            "docker tag {source_image} $EXPECTED_REF"
-        ).format(source_image = source_image),
-        []
-    )
+    mirror_engine = settings.get("mirror_engine") or settings["build_engine"]
+    if mirror_engine in ["docker", "podman"]:
+        mirror_command = (
+            "%s pull --platform linux/amd64 %s && " % (mirror_engine, source_image) +
+            "%s tag %s $EXPECTED_REF && " % (mirror_engine, source_image) +
+            "%s push $EXPECTED_REF" % mirror_engine
+        )
+    elif mirror_engine == "skopeo":
+        mirror_command = "skopeo copy --all docker://%s docker://$EXPECTED_REF" % source_image
+    else:
+        fail("unrecognised mirror engine - %s" % mirror_engine)
+    custom_build(image, mirror_command, [], skips_local_docker = True)
     return image
 
 

docs/configuration/04-target-cloud/index.md

@@ -63,7 +63,7 @@ First, the Keystone configuration of the target cloud must be modified to add Az
 [trusted dashboard](https://docs.openstack.org/keystone/latest/admin/federation/configure_federation.html#add-a-trusted-dashboard-websso),
 otherwise it will be unable to retrieve a token via the federated flow. When configuring Azimuth as a
 trusted dashboard, you must specify the URL that will receive token data, where the portal domain
-depends on the [ingress configuration](./06-ingress.md):
+depends on the [ingress configuration](../06-ingress.md):
 
 ```ini  title="Keystone configuration"
 [federation]

docs/developing/index.md

@@ -108,21 +108,25 @@ In order to use Tilt to develop Azimuth, the following tools must be available o
 development machine (in addition to those required to install Azimuth itself):
 
   * The [Tilt CLI](https://docs.tilt.dev/install.html)
-  * A `docker` command, e.g. [Docker Desktop](https://docs.docker.com/desktop/)
+  * A `docker` or `podman` command,
+    e.g. [Docker Desktop](https://docs.docker.com/desktop/) or [Podman Desktop](https://podman-desktop.io/)
   * The [kubectl command](https://kubernetes.io/docs/tasks/tools/#kubectl)
   * The [Helm CLI](https://helm.sh/docs/intro/install/)
+  * The [skopeo CLI](https://github.com/containers/skopeo) (optional)
 
 For developing the Azimuth UI, the following are also required:
 
   * [node.js](https://nodejs.org)
   * The [Yarn Classic](https://classic.yarnpkg.com/lang/en/docs/install/) package manager
 
-### Configuring a container registry
+### Tilt settings
 
 Azimuth's Tilt configuration looks for a file called `tilt-settings.yaml` that defines settings
 for the development environment. This file is specific to you and should not be added to version
 control (it is specified in `.gitignore`).
 
+#### Configuring a container registry
+
 In order to get the code under development into your running Azimuth instance, Tilt must have
 access to a container registry that is accessible to both your development machine and the
 Azimuth instance. In response to code changes, Tilt will automatically build and push images
@@ -150,6 +154,31 @@ image_prefix: ghcr.io/jbloggs
     your Azimuth instance can use them. Until you do this, you will see image pull errors in
     the Tilt interface.
 
+#### Using Podman for builds
+
+In situations where using Docker is not viable, e.g. due to licensing constraints, Azimuth's
+Tilt configuration also supports using [Podman](https://podman.io/) to build and push container
+images.
+
+To configure Tilt to use `podman` to build container images, use the following setting:
+
+```yaml  title="tilt-settings.yaml"
+build_engine: podman
+```
+
+#### Using skopeo to mirror images
+
+Some Azimuth components require images to be mirrored. By default, Azimuth's Tilt configuration
+uses the configured build engine for this by pulling, re-tagging and pushing the specified image.
+
+[skopeo](https://github.com/containers/skopeo) is a tool that is built for performing operations
+on container images, such as efficiently copying an image from one repository to another, and
+Azimuth's Tilt configuration supports using this to mirror images:
+
+```yaml  title="tilt-settings.yaml"
+mirror_engine: skopeo
+```
+
 ### Using the Tilt environment
 
 Tilt will look for checkouts of Azimuth components as siblings of your Azimuth configuration