OTA-1404: Add Support for a Configuration File: Creation of a Periodic Check

[DavidHurta]

The first PR in the series to enable the CVO to read a configuration file periodically for updates.

The goal of this PR is to create a new config-file flag and create a gated periodic check with a placeholder logic.
The following PR will add logic to read, parse, and configure the CVO's verbosity of logs based on the file.

---

cvo: Add config-file flag
Add a new flag instead of a new environment variable to specify the path of the
configuration file. Using env variables has the benefit of better backwards
compatibility, for example, specifying not used env variable has no impact. Using
a not-implemented flag results in an error. The flag is primarily intended for use
in HyperShift, thus, these topics are relevant.

In case the feature gate does not get into default, we must not drop the flag
out of nowhere, which could cause issues in HyperShift. However, the new API
is very small, and it is not likely for this functionality to be dropped
along the way. An alternative is to use an env variable before the feature gets
into default; however, I do not think this is worth the risk at the moment.

---

pkg/cvo: Create periodic check for configuration file
Right now, a placeholder log is present.

The log will be exchanged with the actual logic to sync
the configuration file later on.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: DavidHurta

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[DavidHurta]

Maybe 15 seconds is too little; however, the logic won't be that extensive.

[DavidHurta]

Testing.

Default Cluster - not run as expected.

$ grep -e "config-file" default-flag.txt 
I0507 19:26:12.201962  121192 cvo.go:485] The ClusterVersionOperatorConfiguration feature gate is disabled, HyperShift is detected or --config-file flag is used; the configuration sync routine will not run.
I0507 19:26:12.201978  121192 cvo.go:501] The ClusterVersionOperatorConfiguration feature gate is disabled or --config-file flag is not used; the configuration file sync routine will not run.

Locally built and run CVO with the flag specified. As expected.

$ ./_output/linux/amd64/cluster-version-operator -v5 start --release-image 4.20.0-0-2025-05-15-124627-test-ci-ln-k4x6l9k-latest --listen="" --config-file=SOMEPATHDOESNOTEXIST > log.log 2>&1
$ grep -E "(config-file|configuration file)" log.log 
I0515 17:45:27.227247   40599 cvo.go:485] The ClusterVersionOperatorConfiguration feature gate is disabled, HyperShift is detected or --config-file flag is used; the configuration sync routine will not run.
I0515 17:45:27.227342   40599 cvo.go:493] Syncing configuration file
I0515 17:45:42.228019   40599 cvo.go:493] Syncing configuration file
I0515 17:45:57.228480   40599 cvo.go:493] Syncing configuration file
I0515 17:46:12.229317   40599 cvo.go:493] Syncing configuration file
I0515 17:46:27.230200   40599 cvo.go:493] Syncing configuration file
I0515 17:46:34.782414   40599 cvo.go:545] Collected cvo configuration file goroutine.

Locally built and run CVO with the flag NOT specified. As expected.

$ grep -E "(config-file|configuration file)" log-notset.log
I0515 18:07:54.731258   42568 cvo.go:498] The ClusterVersionOperatorConfiguration feature gate is disabled or --config-file flag is not used; the configuration file sync routine will not run.

[openshift-ci-robot]

@DavidHurta: This pull request references OTA-1404 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.20.0" version, but no target version was set.

In response to this:

The first PR in the series to enable the CVO to read a configuration file periodically for updates.

The goal of this PR is to create a new config-file flag and create a gated periodic check with a placeholder logic.
The following PR will add logic to read, parse, and configure the CVO's verbosity of logs based on the file.

---

cvo: Add config-file flag
Add a new flag instead of a new environment variable to specify the path of the
configuration file. Using env variables has the benefit of better backwards
compatibility, for example, specifying not used env variable has no impact. Using
a not-implemented flag results in an error. The flag is primarily intended for use
in HyperShift, thus, these topics are relevant.

In case the feature gate does not get into default, we must not drop the flag
out of nowhere, which could cause issues in HyperShift. However, the new API
is very small, and it is not likely for this functionality to be dropped
along the way. An alternative is to use an env variable before the feature gets
into default; however, I do not think this is worth the risk at the moment.

---

pkg/cvo: Create periodic check for configuration file
Right now, a placeholder log is present.

The log will be exchanged with the actual logic to sync
the configuration file later on.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci]

@DavidHurta: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-hypershift	55d2d56	link	true	/test e2e-hypershift
ci/prow/e2e-agnostic-operator-devpreview	55d2d56	link	false	/test e2e-agnostic-operator-devpreview

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[DavidHurta]

The force push has updated commit messages. The failing HyperShift job does not seem to be caused by the PR.

[petr-muller]

/cc

[DavidHurta]

/hold

Checking out using related libraries.

[DavidHurta]

/unhold

The periodic checking will be replaced with a more proper solution in a later PR.