environmentalDependencyCommands

[appsforartists]

Sometimes metadata about the environment is an important input to the build process (for instance, to include a Built at c9e6ee2 comment at the top of a bundled file).

Presently, wireit will return a cached output if the input files haven't changed, even if the environment has. There's no way to declare an explicit dependency on the environment. I propose we change that, with something like this:

{
  "wireit": {
    "build": {
      "command": "vite build",
      "files": [
        "dist/**/index.html",
        "dist/**/*.js",
        "vite.config.ts"
      ],
      "environmentalDependencyCommands": [
        "git rev-parse HEAD"
      ]
    }
  } 
}

where the results of each entry in environmentalDependencyCommands would be cached, and a rebuild would be triggered if any of them changed (just like any other dependency).

In this case, making a git commit would change HEAD, which would invalidate the build even if the enumerated files haven't changed.

[rictic]

You could support this use case within the existing API by declaring the command as a script that outputs to a file, has no deps and declares its output. The build script could depend on on the other env command script with cascade: false and add the env script's output file as one of its input files.

And git rev-parse HEAD specifically I think you could just depend on the file .git/ORIG_HEAD

[appsforartists]

ahh, yes, i meant to include that too. here was @aomarks workaround:

{
  "wireit": {
    "generate-git-hash": {
      "command": "git rev-parse HEAD > .head"
    },
    "git-hash": {
      "dependencies": [
        {
          "script": "generate-git-hash",
          "cascade": false
        }
      ],
      "files": [
        ".head"
      ],
      "output": []
    },
    "build": {
      "command": "vite",
      "dependencies": [
        "git-hash"
      ]
    }
  } 
}

thanks for the tip on ORIG_HEAD! looks like HEAD is refs/heads/macbook for me (which is unlikely to change), but ORIG_HEAD is effectively HEAD^, which may be a good, if imperfect, signal that a rebuild is due (especially if it's always a commit).

https://stackoverflow.com/questions/964876/head-and-orig-head-in-git