run copyright header check recursively

We have a few directories in this repo that will be remaining
MPL licensed (the provider protocol definitions). This is something
that the copywrite tool does not support out of the box - we need
to run the tool for each directory that contains a .copywrite.hcl
file in order to make sure that new files have the correct header.

To avoid adding yet more boilerplate with a `copyright_headers.go`
file in each package, let's move the copyright check to its own
make target and script the process of discovering all directories
with copywrite config.

.github/workflows/checks.yml

@@ -182,9 +182,9 @@ jobs:
 
       - name: "Code consistency checks"
         run: |
-          make fmtcheck importscheck generate staticcheck exhaustive protobuf
+          make fmtcheck importscheck generate staticcheck exhaustive protobuf copyright
           if [[ -n "$(git status --porcelain)" ]]; then
-            echo >&2 "ERROR: Generated files are inconsistent. Run 'make generate' and 'make protobuf' locally and then commit the updated files."
+            echo >&2 "ERROR: Generated files are inconsistent. Run 'make generate protobuf copyright' locally and then commit the updated files."
             git >&2 status --porcelain
             exit 1
           fi

Makefile

@@ -26,6 +26,9 @@ staticcheck:
 exhaustive:
 	"$(CURDIR)/scripts/exhaustive.sh"
 
+copyright:
+	"$(CURDIR)/scripts/copyright.sh"
+
 # Run this if working on the website locally to run in watch mode.
 website:
 	$(MAKE) -C website website

scripts/copyright.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: BUSL-1.1
+
+# This script checks that all files have the appropriate copyright headers,
+# according to their nearest .copywrite.hcl config file. The copyright tool
+# does not natively support repos with multiple licenses, so we have to
+# script this ourselves.
+
+set -euo pipefail
+
+# Find all directories containing a .copywrite.hcl config file
+directories=$(find . -type f -name '.copywrite.hcl' -execdir pwd \;)
+
+for dir in $directories; do
+    cd $dir && go run github.com/hashicorp/copywrite headers
+done

tools.go

@@ -11,6 +11,7 @@ package tools
 // Go toolchain to see that we need to include them in go.mod and go.sum.
 
 import (
+	_ "github.com/hashicorp/copywrite"
 	_ "github.com/nishanths/exhaustive/cmd/exhaustive"
 	_ "golang.org/x/tools/cmd/stringer"
 	_ "honnef.co/go/tools/cmd/staticcheck"