Have a source of truth that's in another github repository? Maybe OpenAPI specifications, Binary Protocols, etc? Just a few settings and CI will guarantee correctness between repositories.

To use sbt-github-download in an existing SBT project, add the following dependencies to your project/plugins.sbt depending on your needs:

addSbtPlugin(
  "io.chrisdavenport" %% "sbt-github-download" % "<version>"
)

This has relatively simple settings

githubDownloadTargets which is a setting of Seq[GithubDownloadTarget], each file will be able to download and directly map to a local file. The class it aligns to is below

case class GithubDownloadTarget(
  org: String,
  repo: String,
  repoPath: String,
  localPath: String,
  ref: Option[String] = None
)

githubDownloadToken is the token to use to download the file. It is optional, if it is not present, it will attempt to retrieve the file unauthed which will only work against public github repositories.

githubDownloadExecute is the task that will download and create the file locally from the remote github repo. It will overwrite whatever is presently at that file location with the content.

githubDownloadCheck is a task that will get the github file and compare it to the file saved locally at that location. It checks the sha1 hash of the two files to confirm that they are exactly the same, if they are not the task fails and informs you which file was not correct.

So lets say you have 1 file that you want to keep up to date between repositories. This can be any file, but I'll use a simple file here. We'll also assume in this example that you check this file into version control, so you want reproducible builds. Add this to your projects build.sbt

githubDownloadTargets ++= Seq(
  GithubDownloadTarget(
    "davenverse", // owner
    "mules",  // repository
    "LICENSE", // relative path from base of github repository
    "licenses/MULES_LICENSE", // relative path from base of local repository
    None // ref, when None will use the repository default branch
  )
),

// If you want to use auth
// for example if you wanted to talk to a private repository
// Can not set at all if you can access your files via github publicly.
githubDownloadToken := scala.sys.env.get("GITHUB_TOKEN")

If the file is not already in the repository or you'd like to update the file execute, sbt githubDownloadExecute

Then in whatever your CI is you'd want to run a check to confirm that your file is correct sbt githubDownloadCheck which will fail your CI if it is not up to date.