gistfile1.txt

GAZELLE = "//:gazelle"
GVT = "//vendor/github.com/FiloSottile/gvt:gvt"
WORKSPACE = "//:WORKSPACE"

def _gvt_impl(ctx):
  result = ctx.new_file(ctx.label.name)
  gazelle = ctx.attr._gazelle.files.to_list()[0]
  gvt = ctx.attr._gvt.files.to_list()[0]
  workspace = ctx.attr._workspace.files.to_list()[0]
  print(ctx.attr._gazelle)
  ctx.file_action(output=result, executable=True, content="""#!/bin/bash

set -ux
WORKSPACE=$(dirname $(readlink {workspace}))
GVT=$(realpath {gvt})
GAZELLE=$(realpath {gazelle})


cd $WORKSPACE
$GVT $@

cd $(dirname $GAZELLE)
$GAZELLE
""".format(
    gazelle=gazelle.short_path,
    gvt=gvt.short_path,
    workspace=workspace.short_path
  ))
  return [DefaultInfo(runfiles=ctx.runfiles([gvt, workspace, gazelle]))]

gvt = rule(
  implementation=_gvt_impl,
  executable=True,
  attrs = {
    "_gazelle": attr.label(cfg = "host", executable = True, default = Label(GAZELLE)),
    "_gvt": attr.label(cfg = "host", allow_single_file=True, executable = True, default = Label(GVT)),
     "_workspace": attr.label(allow_single_file = True, default = Label(WORKSPACE)),
  },
)