fix(datasource/custom): do not run digest update on version updates

[marcoesters]

Changes

Add an exception for custom data sources to disallow digest updates when other updates are already in place.

Context

Relevant discussion: #28343

PR #28760 introduced the ability to perform digest updates, i.e., updating the digest without a version change. This had an unintended consequence under the following circumstances: if a version update also updates a digest, renovate will additionally try a digest update for the current version (not the updated version). If an API returns only the latest version (as shown in the k3s example), this will result in a misleading warning that a digest could not be found.

The following lines are the culprit:

    if (supportsDigests(config.datasource)) {
      if (config.currentDigest) {
        if (!config.digestOneAndOnly || !res.updates.length) {
          // digest update
          res.updates.push({
            updateType: 'digest',
            newValue: config.currentValue,
          });
        }

!res.updates.length is supposed to prevent such an extra update from happening. However, config.digestOneAndOnly is undefined for anything but Go and (sometimes) Bazel managers, so !config.digestOneAndOnly always evaluates to true.

I admit that this is a hack, but I don't have enough overview of the code base to replace digestOneAndOnly or find a way to change the condition without guaranteeing any fallout for other managers. This may need to be reevaluated comprehensively in the future.

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

A test repository can be found here: https://github.com/marcoesters/renovate-miniconda-digest-reproducer

It contains the original update, but I added some simplified json files. Expected behavior would be:

• major.json, minor.json, digest.json: update, no warnings
• warning.json: no update, warning issued

Currently, renovate does the following:

• digest.json: update, no warnings
• major.json, minor.json: update, warning issued
• warning.json: no update, warning issued

This PR results in the expected behavior

[rarkins]

@marcoesters thanks for this PR.

Could you:

1. Add a test (which would have failed prior to this PR)
2. Add a minimal reproduction repo demonstrating the new functionality?

[marcoesters]

@marcoesters thanks for this PR.

Could you:

1. Add a test (which would have failed prior to this PR)

2. Add a minimal reproduction repo demonstrating the new functionality?

I will try and work on the test (typescript isn't a language I'm super familiar with). I simplified the repository I mentioned in my PR description to have simple data sources and covert the scenarios mentioned in the discussion: https://github.com/marcoesters/renovate-miniconda-digest-reproducer

Do I need to add it somewhere into the code base?

[rarkins]

I'd like to convert this logic to an if/else to reduce the amount of negating. The if path can have logger.trace() inside it and the else then will contain the res.updates.push()

[rarkins]

(for future readability - the proposed change has definitely crossed a threshold for readability, maybe already had)

[marcoesters]

I tried a few logic combinations and they are all very much unreadable, so I resorted to a boolean that will hopefully add some more to the semantics.

This is, unfortunately, still all very hacky, but I think a more sustainable solution will require deeper insights into the renovate code bases and use cases than I currently possess.

[rarkins]

If it "already ran a version update" then wouldn't res.updates.length be non-zero length anyway?

[marcoesters]

That's correct, and !res.updates.length evaluates to false in this case. The problem in the original logic is config.digestOneAndOnly, which is true for gomod and undefined for other data sources.

So, for anything but gomod, the expression !config.digestOneAndOnly || !res.updates.length always evaluates to true no matter what res.updates.length is. So, renovate will try a "pure" digest update.

That pure digest update will look for the current version in the datasource. If the custom datasource only returns the latest version and that version is different from the current version, the digest update will fail and produce a warning.

[viceice]

then this isn't the right solution, because it should be possible to do digest only updates with regex manager. I do that heavily on jenkinsfiles for docker images

[marcoesters]

My solution here still allows for digest-only updates. My example repo covers scenarios for digest-only updates. The unit tests pass as well, which contain digest-only updates.

The problem was that renovate will do a digest-only additionally to a version + digest update for the same dependency. Under the circumstances above, this will result in an incorrect warning that renovate cannot look up a digest.