ostree commit hash is different on remote than on the local machine

[davisRoman]

After ostree-push runs, the commit hash on the remote server is different than the commit on the local machine. This is very confusing to users. Is it supposed to be this way? Is there a way to push a commit hash that doesn't get changed on the remote ostree server?

[dbnicholson]

They are different because a new commit object is created on the server. There are 2 reasons for this:

1. The commit hash depends on the parent commit's hash. In order to maintain history on the remote server, the existing commit on the ref is used as the parent for the newly created commit. Typically you wouldn't have any history on the builder, although it is possible.
2. OSTree commits have 2 fields in the commit metadata used for binding them to specific refs and repos. These might not be correct in the uploaded commit.

In the past I had some code that tried harder to reuse the uploaded commit as is if it already had the appropriate metadata but it never quite worked right. So, at the moment there isn't a way to maintain the commit hash, but I can try to look at that again if it's important to you.

[davisRoman]

Your explanation makes sense but perhaps it'll help if I explain my end goal. We have a jenkins CI/CD pipeline that runs yocto ( a linux distribution generator) and when it's done building, it generates an ostree commit with hash X and this gets displayed on our Jenkins dashboard (to correlate jenkins build number to ostree hashes). As a final stage in our pipeline, we run ostree-push to copy the commit to our OTA deployment server but my surprise, the commit gets stored as hash Y. So just to double confirm, is there anything on my end that I cab do differently in order for the commits not to change or is the only remedy to make some modification on the tool itself? If a modification is in fact needed on the ostree-push command itself, then yes, it would really help a lot if you could help us with this. Thank you.

[dbnicholson]

What I'd suggest in the short term is that you query the current revision after pushing and use that in the Jenkins description. There are 2 ways I'd do it.

1. ostree pull --commit-metadata-only "$remote" "$ref" && rev=$(ostree rev-parse "$remote:$ref"). This will work on very old ostree versions.
2. rev=$(ostree remote refs --revision "$remote" | awk "\$1 == \"$ref\" {print \$2}"). The --revision option for remote refs is only in ostree 2023.1, though.