Creating a Catalog of operators

Add/Remove a collection of operators to/from a Catalog

Prerequisites

Note: This document discusses creating a catalog of operators using plaintext files to store catalog metadata, which is the latest feature of OLM catalogs. If you are looking to build catalogs using the deprecated sqllite database format to store catalog metadata instead, please read the v0.18.z version of this doc instead.

Creating a Catalog

OLM's CatalogSource CRD accepts a container image reference to a catalog of operators that can be made available to install in a cluster. You can make your operator bundle available to install in a cluster by adding it to a catalog, packaging the catalog in a container image, and then using that image reference in the CatalogSource. This image contains all of the metadata required for OLM to manage the lifecycle of all of the operators it contains.

OLM uses a plaintext file-based catalog format (JSON or YAML) to store these records in a Catalog, and opm has tooling that helps initialize a Catalog, add new operators into it, and then validate that the catalog is valid. Let’s walk through a simple example.

First, we need to initialize our Catalog, so we’ll make a directory for it, generate a Dockerfile that can build a Catalog image, and then populate our catalog with our operator.

Initialize the Catalog

$ mkdir cool-catalog
$ opm alpha generate dockerfile cool-catalog
$ opm init example-operator \
    --default-channel=preview \
    --description=./README.md \
    --icon=./example-operator.svg \
    --output yaml > cool-catalog/operator.yaml

Let’s validate our catalog to see if we’re ready to ship!

$ opm validate cool-catalog
FATA[0000] invalid index:
└── invalid package "example-operator":
    └── invalid channel "preview":
        └── channel must contain at least one bundle

Alright, so it’s not valid. It looks like we need to add a bundle, so let’s do that next…

Add a bundle to the Catalog

$ opm render quay.io/example-inc/example-operator-bundle:v0.1.0 \
    --output=yaml >> cool-catalog/operator.yaml

Let’s validate again:

$ opm validate cool-catalog
FATA[0000] package "example-operator", bundle "example-operator.v0.1.0" not found in any channel entries

Add a channel entry for the bundle

We rendered the bundle, but we still haven’t yet added it to any channels. Let’s initialize a channel:

cat << EOF >> cool-catalog/operator.yaml
---
schema: olm.channel
package: example-operator
name: preview
entries:
  - name: example-operator.v0.1.0
EOF

Is the third time the charm for opm validate?

$ opm validate cool-catalog
$ echo $?
0

Success! There were no errors and we got a 0 error code.

Summary

In the general case, adding a bundle involves three discreet steps:

  • Render the bundle into the catalog using opm render <bundleImage>.
  • Add the bundle into desired channels and update the channels’ upgrade edges to stitch the bundle into the correct place.
  • Validate the resulting catalog.

NOTE: catalog metadata should be stored in a version control system (e.g. git) and catalog images should be rebuilt from source whenever updates are made to ensure that all changes to the catalog are auditable. Here is an example of catalog metadata being stored in github: https://github.com/operator-framework/cool-catalog , with the catalog image being rebuilt whenever there is a change: https://github.com/operator-framework/cool-catalog/blob/main/.github/workflows/build-push.yml

Step 1 is just a simple opm render command.

Step 2 has no defined standards other than that the result must pass validation in step 3. Some operator authors may decide to hand edit channels and upgrade edges. Others may decide to implement automation (e.g. to idempotently build semver-based channels and upgrade graphs based solely on the versions of the operators in the package). There is no right or wrong answer for implementing this step as long as opm validate is successful.

There are some guidelines to keep in mind though:

  • Once a bundle is present in a Catalog, you should assume that one of your users has installed it. With that in mind, you should take care to avoid stranding users that have that version installed. Put another way, make sure that all previously published bundles in a catalog have a path to the current/new channel head.
  • Keep the semantics of the upgrade edges you use in mind. opm validate is not able to tell you if you have a sane upgrade graph. To learn more about the upgrade graph of an operator, checkout the creating an upgrade graph doc.

Build and push the catalog image

Lastly, we can build and push our catalog image:

$ docker build . \
    -f cool-catalog.Dockerfile \
    -t quay.io/example-inc/cool-catalog:latest
$ docker push quay.io/example-inc/cool-catalog:latest

Now the catalog image is available for clusters to use and reference with CatalogSources on their cluster.