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README.md

This repository holds the configuration for automation-related VM and container images. CI/CD automation in this repo. revolves around producing new images. It does only very minimal testing of image suitability for use by other containers org. repos.

Contributing

  1. Thanks!

  2. This repo. follows the fork & pull model When ready for review, somebody besides the author must click the green Review changes button within the PR.

  3. Please create new pull-requests as drafts and/or mark them with a WIP: title-prefix while you're working on them.

  4. Strict-merging is enabled, therefore all pull requests must be kept up to date with the base branch (i.e. re-based).

Automation-control Magic strings

Not all changes require building and testing every container and VM image. For example, changes that only affect documentation. When this is the case, pull-requests may include one of the following magic strings in their title text:

  • [CI:DOCS] - Only perform steps necessary for general validation. Checking the actual documentation text is left up to human reviewers.

  • OR

  • [CI:TOOLING] - Only perform validation steps, then build and test the tooling container images only.

Additionally, you may use one/more PR labels to disable certain builds.

Building VM Images

Process Overview

There are four parts to the automated (and manual) process. For the vast majority of cases, you will likely only be interested in the forth (final) step. However, all steps are listed below for completeness.

For more information on the overall process of importing custom GCE VM Images, please refer to the documentation. For references to the latest pre-build AWS EC2 Fedora AMI's see the upstream cloud page. For more information on the primary tool (packer) used for this process, please see it's documentation page.

  1. Build and import a VM image with necessary packages and metadata for running nested VMs. For details on why this step is necessary, please refer to the documentation.

  2. Two types of container images are built. The first set includes both current and "prior" flavor of Fedora. The second set is of tooling container images. Tooling required for VM image maintenance, artifact uploads, and debugging.

  3. Boot a GCE VM running the image-builder-image (from step 1). Use this VM to build and then import base-level VM image for supported platforms (Fedora or Debian; as of this writing). For GCE use, convert the generic distribution provided QCOW files, into bootable GCE VMs. For AWS, boot the pre-build AMI's, add minimal tooling, and save them as private, non-expiring AMIs. In parallel, build Fedora and Debian container images and push them to quay.io/libpod/<name>_podman

  4. Boot VMs from each image produced in step 3. Execute the necessary scripts to customize images for use by various containers-project automation. Mainly this involves installing build & test dependencies, but also includes some kernel and systemd services configuration.

Bypassing certain builds

With a large number of VM and Container images to build, it's inevitable that a flake will occur on an image the author does not care about. For example, if you're building images only to update Buildah CI, you don't care to produce the fedora-netavark VM image nor the skopeo_cidev container image.

Should a flake occur on an build that's inconsequential to a specific CI environment, there is a mechanism to bypass certain builds.

Note: This will not bypass container tooling images (they're always required). Nor will it properly handle any build dependencies. For example skipping a fedora build will cause a failure in build-push(since it depends on the fedora base image).

To bypass a specific build, find a no_<name> GitHub label matching the build name. Add that label to the PR and re-push or re-run a previously failed build. It will then skip + automatically succeed. Similarly, if you make a mistake with the labels, you can remove or change them and re-run any affected tasks.

The last part first (overview step 4)

a.k.a. Cache Images

These are the VM Images actually used by other repositories for automated testing. So, assuming you just need to update packages or tweak the list, start here. Though be aware, this repository does not perform much/any testing of the images. That's your secondary responsibility, see step 4 below.

Notes:

  • VM configuration starts with one of the cache_images/*_setup.sh scripts. Normally you probably won't need/want to mess with these.

  • The bulk of the packaging work occurs next, from the cache_images/*_packaging.sh scripts. This is most likely what you want to modify.

  • Unlike the Fedora and Debian scripts, the build-push VM image is not for general-purpose use. It's intended to be used by it's embedded main.sh script, in downstream repositories for building container images. The image and main.sh are both tightly coupled with build-push tool in the containers/automation repository.

  • Some non-packaged/source-based tooling is installed using the cache_images/podman_tooling.sh script. These are slightly fragile, as they always come from upstream (master) podman. Avoid adding/changing anything here if alternatives exist.

  • Warning: Before you go deleting seemingly "unnecessary" packages and "extra" code, remember these VM images are shared by automation in multiple repositories.

Process:

  1. Whether or not you made any script changes, before pushing to a PR run make IMG_SFX and commit the change. This helps avoid overwriting existing images - potentially already in use by CI. The 'validate' CI task will asserts every PR makes changes to this file.

  2. The name of all output images will share a common IMG_SFX value Assuming a successful image-build, a github-action will post the types and names of all built images as a comment in the PR. If this automation breaks, you may need to figure the ID out the hard way. For AWS EC2 images, every one will have a unique AMI ID assigned. You'll need to look these up separately until the github action is fixed.

  3. Go over to whatever other containers/repository needed the image update. Open the .cirrus.yml file, and find the 'env' line referencing the image ID and/or AMI. It will likely be named IMAGE_SUFFIX: or something similar. Paste in the image ID (it should begin with the letter c).

  4. Open up a PR with this change, and push it. Once all tests pass and you're satisfied with the image changes, ask somebody to review/approve both PRs for merging. If you're feeling generous, perhaps provide cross-links between the two PRs in comments, for future reference.

  5. After all the PRs are merged, you're done.

Looking up an image ID:

A image ID is simply the IMG_SFX value prefixed by a letter. The letter b represents base-images, and 'c' represents cache-images. You may need to look the value up if (for example), the automated comment posting github-action failed.

  1. In any PR, find and click the details link for one of the build tasks. Near the top of the Cirrus-CI WebUI, will be a section labeled 'Artifacts'.

  2. Click the manifest artifact.

  3. Click the nested folder name (if there is one).

  4. Click the manifest.json file, it should open in your browser window.

  5. For GCE images look at the artifact_id field. It will contain the full image id value in the form c<IMG_SFX>.

  6. For AWS EC2 images look under the custom_data field for the IMG_SFX value. If this was a base-image, simply prefix the value with a b, or a c for a cache-image.

The image-builder image (overview step 1)

Google compute engine (GCE) does not provide a wide selection of ready-made VM images for use. Instead, a lengthy and sophisticated process is involved to prepare, properly format, and import external VM images for use. In order to perform these steps within automation, a dedicated VM image is needed which itself has been prepared with the necessary incantations, packages, configuration, and magic license keys.

The Fedora project does provide AWS Elastic Compute Cloud (EC2) images for all supported releases (the two most recent ones). These are ready to go, but have depreciation times set on them. This is no good for direct use, as the image may get deleted if not used frequently enough. So copies must be made.

For normal day-to-day use, this process should not need to be modified or maintained much. However, on the off-chance that's ever not true, here is an overview of the process followed by automation to produce the image-building VM image:

  1. Build the container defined in the ci subdirectory's ContainerFile. Start this container with a copy of the current repository code provided in the $CIRRUS_WORKING_DIR directory. For example on a Fedora host:

    podman run -it --rm --security-opt label=disable -v $PWD:$PWD -w $PWD ci_image

  2. From within the ci container (above), in the repository root volume, execute the make image_builder target.

  3. The image_builder/gce.yml file is converted into JSON format for consumption by the Hashicorp packer utility. This generated file may be ignored, make will be regenerate it upon any changes to the YAML file.

  4. Packer will spin up a GCE VM based on CentOS Stream. It will then install the necessary packages and attach a nested-virtualization "license" to the VM. Be patient until this process completes.

  5. Near the end of the process, packer deletes temporary files, ssh host keys, etc. and then shut down the GCE VM.

  6. Packer should then automatically call into the google cloud APIs and coordinate conversion of the VM disk into a bootable image. Please be patient for this process to complete, it may take several minutes.

  7. When finished, packer will write the freshly created image name and other metadata details into the local image_builder/manifest.json file for reference and future use. The details may be useful for debugging, or the file can be ignored/disregarded.

  8. Automation scoops up the manifest.json file and archives it along with the build logs.

Container images (overview step 2)

Podman

Several instances of the image-builder VM are used to create container images. In particular, Fedora and Debian images are created that more-or-less duplicate the setup of the VM Cache-images. They are then automatically pushed to:

The meaning of prior and current, is defined by the contents of the *_RELEASE values in the Makefile. The images will be tagged with the value within the IMG_SFX file. Additionally, the most recently merged PR on this repo will tag its images latest.

Tooling

In addition to the "podman" container images, several automation tooling images are also built. These are always referenced by downstream using their "latest" tag (unlike the podman and VM images). In addition to the VM lifecycle tooling images, the following are built:

  • gcsupld image is used for publishing artifacts into google cloud storage.

  • get_ci_vm image is used by the containers-org repository's hack/get_ci_vm.sh script. It should never be used directly. It also requires one or more special accounts to be created, therefore is limited to use by Red Hat employees on an as-needed basis. If you need access, please ask a maintainer. For operational details, see the docs.

In all cases, when automation runs on a branch (i.e. after a PR is merged) the actual image tagged latest will be pushed. When running in a PR, only validation and test images are produced.

The Base Images (overview step 3)

VM Images in GCE depend upon certain google-specific systemd-services to be running on boot. Additionally, in order to import external OS images, google needs a specific partition and archive file layout. Lastly, importing images must be done indirectly, through Google Cloud Storage (GCS).

VM images in AWS EC2 are basically ready-to go as-is. Only a copy needs to be made to remove the depreciation metadata and install some basic automation tooling libraries used by nearly all downstream automation.

As with the image-builder image, this process is mainly orchestrated by Packer:

  1. A GCE VM is booted from the image-builder image, produced in overview step 1.

  2. On the image-builder VM, the (upstream) generic-cloud images for each distribution are downloaded and verified. This is very networking-intense.

  3. For GCE, the image-builder VM then boots (nested) KVM VMs for the downloaded images. These local VMs are then updated, installed, and prepared with the necessary packages and services as described above. This is very disk and CPU intense.

  4. For AWS, the pre-built Fedora project AMI's are simply booted in EC2.

  5. All the automation-deities pray with us, that the nested VMs setup correctly and completely. Debugging them can be incredibly difficult and painful.

  6. Packer (running on the image-builder VM), shuts down the VMs, and performs the import/conversion process. Creating compressed tarballs, uploading to GCS, then importing into GCP VM images. AWS EC2 instances are snapshotted, and an AMI is created from the snapshot.

  7. Packer deletes the VM, and writes the freshly created image name and other metadata details into a image_builder/manifest.json file for reference.

  8. Automation scoops up the manifest.json file and archives it along with the build logs.

VM Image lifecycle management

There is no built-in mechanism for removing disused VM images. In GCE, there isn't any built-in tracking information, recording which VM images are currently being used by one or more containers-repository automation. In AWS 'Last launched' metadata is recorded automatically. Three containers and two asynchronous processes are responsible for tracking and preventing infinite-growth of the VM image count.

  • imgts Runs as part of automation for every repository, every time any VM is utilized. It records the usage details, along with a timestamp into the GCE VM image "labels" (metadata). Failure to update metadata is considered critical, and the task will fail to prompt immediate corrective action by automation maintainers. When this container detects it's running on behalf of a release-branch, it will make a best-effort attempt to flag all VM images for permanent retention.

  • imgobsolete is triggered periodically by cirrus-cron only on this repository. It scans through all GCE VM Images, filtering any which haven't been used within the last 30 days (according to imgts updated labels). Excluding any images which are marked for permanent retention, disused images are deprecated by marking them as obsolete in GCE. This will cause an error in any CI run which references them. The images will still be recoverable manually, using the gcloud utility.

  • imgprune also runs periodically, immediately following imgobsolete. It scans all currently obsolete GCE images, filtering any which were deprecated more than 30 days ago (according to deprecation metadata). It will fail with a loud error message should it encounter a image marked obsolete and labeled for permanent retention. Otherwise, Images which have been obsolete for more than 30 days, are permanently removed.

Debugging / Locally driving VM Image production

Much of the CI and image-build process is containerized, so it may be debugged locally on your laptop/workstation. However, this process will still involve interfacing with GCE and AWS. Therefore, you must be in possession of a Google Application Credentials (GAC) JSON and AWS credentials INI file.

The GAC JSON file should represent a service account (contrasted to a user account, which always uses OAuth2). The name of the service account doesn't matter, but it must have the following roles granted to it:

  • Compute Instance Admin (v1)
  • Compute OS Admin Login
  • Service Account User
  • Storage Admin
  • Storage Object Admin

The service account for AWS may be personal or a shared account. It must have one the following (custom) IAM policies enabled:

  • Admin
  • Packer

Somebody familiar with Google and AWS IAM will need to provide you with the credential files and ensure correct account configuration. Having these files stored in your home directory on your laptop/workstation, the process of building and entering the debug containers is as follows:

  1. Ensure you have podman installed, and lots of available network and CPU resources (i.e. turn off YouTube, shut down background VMs and other hungry tasks).

  2. Build and enter either the ci_debug or the image_builder_debug container image, by executing:

    make <ci_debug|image_builder_debug> \
     GAC_FILEPATH=</home/path/to/gac.json> \
     AWS_SHARED_CREDENTIALS_FILE=</path/to/credentials>
    • The ci_debug image is significantly smaller, and only intended for rudimentary cases, for example running the scripts under the ci subdirectory.
    • The image_builder_debug image is larger, and has KVM virtualization enabled. It's needed for more extensive debugging of the packer-based image builds.

  3. Both containers will place you in the default shell, inside a volume-mount of the repository root. This environment is practically identical to what is used in Cirrus-CI.

  4. For the image_builder_debug container, If you wish to build only a subset of available images, list the names you want as comma-separated values of the PACKER_BUILDS variable. Be sure you export this variable so that make has access to it. For example, export PACKER_BUILDS=debian,prior-fedora.

  5. Still within the container, again ensure you have plenty of network and CPU resources available. Build the VM Base images by executing the command make base_images. This is the equivalent operation as documented by overview step 2. N/B The GCS -> GCE image conversion can take some time, be patient. Packer may not produce any output for several minutes while the conversion is happening.

  6. When successful, the names of the produced images will all be referenced in the base_images/manifest.json file. If there are problems, fix them and remove the manifest.json file. Then re-run the same make command as before, packer will force-overwrite any broken/partially created images automatically.

  7. Produce the VM Cache Images, equivalent to the operations outlined in overview step 3. Execute the following command (still within the debug image-builder container): make cache_images.

  8. Again when successful, you will find the image names are written into the cache_images/manifest.json file. If there is a problem, remove this file, fix the problem, and re-run the make command. No cleanup is necessary, leftover/disused images will be automatically cleaned up eventually.