Support fetching yml config file from remote repository

git_build_branch/branch_builder.py

@@ -16,13 +16,15 @@
 from .gitutils import (  # noqa E402
     MissingRemote,
     OriginalBranch,
+    ensure_repository_is_up_to_date,
     get_git,
     get_local_ref,
     git_recent_tags,
     has_local,
     has_merge_conflict,
     origin,
     print_merge_details,
+    show_most_recent_change,
 )
 
 from .sh_verbose import ShVerbose  # noqa E402
@@ -304,22 +306,42 @@ def inner(text, bold=False):
 def main():
     parser = argparse.ArgumentParser(description='Rebuild the deploy branch for an environment')
     parser.add_argument("config_path", help="Path to the YAML configuration file")
+    remote_repo_group = parser.add_argument_group("remote repo")
+    remote_repo_group.add_argument("--remote-url", help="Remote url to clone repository from")
+    remote_repo_group.add_argument("--repo-root", help="Path where repository is checked out")
+    remote_repo_group.add_argument("--repo-filepath", help="Relative path to YAML configuration file")
     parser.add_argument("actions", nargs="*")
     parser.add_argument("-p", "--path", default=".", help="Path to the repository")
     parser.add_argument("-v", "--verbose", action="store_true")
     parser.add_argument("--push", action="store_true", help="Push the changes to remote git repository.")
     args = parser.parse_args()
 
     git = get_git()
+
+    config_path = args.config_path
+    remote_repo_args = [args.remote_url, args.repo_root, args.repo_filepath]
+    if any(remote_repo_args) and not all(remote_repo_args):
+        arg_names = [action.option_strings[0] for action in
+                     remote_repo_group._group_actions]
+        print(
+            red(f"All of the following arguments are required to use a remote "
+                f"repository: {arg_names}"))
+        exit(1)
+
+    if args.remote_url and args.repo_root and args.repo_filepath:
+        ensure_repository_is_up_to_date(git, args.remote_url, args.repo_root)
+        show_most_recent_change(git, args.repo_root, args.repo_filepath)
+        config_path = f"{args.repo_root}/{args.repo_filepath}"
+
     print("Fetching master")
     git.fetch("origin", "master")
     if args.push:
         print("Checking branch config for modifications")
-        if git.diff("origin/master", "--", args.config_path):
-            print(red("'{}' on this branch different from the one on master".format(args.config_path)))
+        if git.diff("origin/master", "--", config_path):
+            print(red("'{}' on this branch different from the one on master".format(config_path)))
             exit(1)
 
-    with open(args.config_path) as config_yaml:
+    with open(config_path) as config_yaml:
         config = yaml.safe_load(config_yaml)
 
     code_root = os.path.abspath(args.path)

git_build_branch/gitutils.py

@@ -2,6 +2,7 @@
 import re
 
 import sh
+import sys
 
 from .sh_verbose import ShVerbose
 
@@ -218,6 +219,29 @@ def print_merge_details(branch1, branch2, git, known_branches=None):
                                 known_branches=known_branches)
 
 
+def ensure_repository_is_up_to_date(git, remote_url, local_path):
+    """
+    Clones repository to local_path if it does not already exist, otherwise
+    pulls the latest changes from main
+    :param git: sh command instance
+    :param remote_url: url of repository to clone/update
+    :param local_path: local path to directory to clone repository into
+    """
+    if not os.path.exists(local_path):
+        git.clone(remote_url, local_path)
+    else:
+        # -C repo needs to come right after git in shell, so cannot use C=repo
+        git("-C", local_path, "pull", "origin", "main")
+
+
+def show_most_recent_change(git, repo, filepath):
+    """
+    :param repo: local path to repository
+    :param filepath: relative path to file from base of repository
+    """
+    git("-C", repo, "show", "-n", 1, "--", filepath, _in=sys.stdin, _out=sys.stdout)
+
+
 if __name__ == '__main__':
     import sys
     args = sys.argv[1:]