ci(lightwalletd): Zebra's Dockerfile needs latest lwd image

[gustavovalverde]

Motivation

We need to add this condition to lightwalletd docker build, to always create a latest tag when merging to the default branch: main, as we're fetching this tag from the Zebra Dockerfile build, but this tag is not being added when building lightwalletd

Fixes #4590

Designs

By default docker/metadata-action creates tags based on the event being triggered, but the latest tag is reserved for releases. As we can't wait releases for this specific use case, we're building the latest when merging to the default branch.

Solution

• Add this condition to docker/metadata-action --> type=raw,value=latest,enable={{is_default_branch}}

Review

Anyone from @ZcashFoundation/devops-reviewers or @conradoplg

[conradoplg]

I'm not sure if this completely solves the problem. What happens if we need to update the image? The PR that changes it will use the latest image which will not be the updated one and it will fail CI.

[teor2345]

I'm not sure if this completely solves the problem. What happens if we need to update the image? The PR that changes it will use the latest image which will not be the updated one and it will fail CI.

I had the same thought, it makes testing a bit tricky.

We might want to use the same algorithm we use for the state:

• wait for the image from the current PR, if it is being rebuilt, or
• use the image from main

[upbqdn]

I can't figure out why GitHub says this:

above Teor's comment.

[teor2345]

I can't figure out why GitHub says this: above Teor's comment.

The commit text contains #4599, so GitHub automatically mentions that commit on PR #4599.