This is a Bazel Runfiles lookup library for Bazel-built Python binaries and tests.

Learn about runfiles: read Runfiles guide or watch Fabian's BazelCon talk.

1. Add the 'bazel-runfiles' dependency along with other third-party dependencies, for example in your requirements.txt file.

2. Depend on this runfiles library from your build rule, like you would other third-party libraries:

   py_binary(
       name = "my_binary",
       ...
       deps = [requirement("bazel-runfiles")],
   )
   

3. Import the runfiles library:

   import runfiles  # not "from runfiles import runfiles"
   

4. Create a Runfiles object and use rlocation to look up runfile paths:

   r = runfiles.Create()
   ...
   with open(r.Rlocation("my_workspace/path/to/my/data.txt"), "r") as f:
     contents = f.readlines()
     ...
   

   The code above creates a manifest- or directory-based implementations based on the environment variables in os.environ. See Create() for more info.

   If you want to explicitly create a manifest- or directory-based implementations, you can do so as follows:

   r1 = runfiles.CreateManifestBased("path/to/foo.runfiles_manifest")
   
   r2 = runfiles.CreateDirectoryBased("path/to/foo.runfiles/")
   

   If you want to start subprocesses, and the subprocess can't automatically find the correct runfiles directory, you can explicitly set the right environment variables for them:

   import subprocess
   import runfiles
   
   r = runfiles.Create()
   env = {}
   ...
   env.update(r.EnvVars())
   p = subprocess.Popen([r.Rlocation("path/to/binary")], env, ...)