just-lock: Try also mirrors when importing known commit from Git repos

When commit to fetch is known, check mirrors before going to the
main URL.

While there, ensure the context for logging in the checkout method is
not replaced, but appended to.

1 files changed, 65 insertions, 16 deletions

diff --git a/bin/just-lock.py b/bin/just-lock.py
index 3e22be0a..5156c8f2 100755
--- a/bin/just-lock.py
+++ b/bin/just-lock.py
@@ -426,39 +426,87 @@ def handle_import(remote_type: str, remote_stub: Dict[str, Any],
 
 
 ###
+# Git utils
+##
+
+
+def git_url_is_path(url: str) -> Optional[str]:
+    """Get the path a URL refers to if it is in a supported path format,
+    and None otherwise."""
+    if url.startswith('/'):
+        return url
+    if url.startswith('./'):
+        return url[len('./'):]
+    if url.startswith('file://'):
+        return url[len('file://'):]
+    return None
+
+
+###
 # Import from Git
 ##
 
 
 def git_checkout(url: str, branch: str, *, commit: Optional[str],
-                 mirrors: List[str],
-                 inherit_env: List[str]) -> Tuple[str, Dict[str, Any], str]:
+                 mirrors: List[str], inherit_env: List[str],
+                 fail_context: str) -> Tuple[str, Dict[str, Any], str]:
     """Clone a given remote Git repository and checkout a specified branch.
     Return the checkout location, the repository description stub to use for
     rewriting 'file'-type dependencies, and the temp dir to later clean up."""
     workdir: str = tempfile.mkdtemp()
     srcdir: str = os.path.join(workdir, "src")
+    fetch_url = git_url_is_path(url)
+    if fetch_url is None:
+        fetch_url = url
+    else:
+        fetch_url = os.path.abspath(fetch_url)
 
-    fail_context: str = "While checking out branch %r of %r:" % (branch, url)
+    fail_context += "While checking out branch %r of %r:\n" % (branch, url)
     if commit is None:
-        # If no commit given, do shallow clone and get HEAD commit
-        run_cmd(g_LAUNCHER +
-                [g_GIT, "clone", "-b", branch, "--depth", "1", url, "src"],
-                cwd=workdir,
-                fail_context=fail_context)
+        # If no commit given, do shallow clone and get HEAD commit from
+        # definitive source location
+        run_cmd(
+            g_LAUNCHER +
+            [g_GIT, "clone", "-b", branch, "--depth", "1", fetch_url, "src"],
+            cwd=workdir,
+            fail_context=fail_context)
         commit = run_cmd(g_LAUNCHER + [g_GIT, "log", "-n", "1", "--pretty=%H"],
                          cwd=srcdir,
                          stdout=subprocess.PIPE,
                          fail_context=fail_context)[0].decode('utf-8').strip()
         report("Importing remote Git commit %s" % (commit, ))
     else:
-        # To get a specified commit, clone the specified branch fully and reset
-        run_cmd(g_LAUNCHER + [g_GIT, "clone", "-b", branch, url, "src"],
-                cwd=workdir,
-                fail_context=fail_context)
-        run_cmd(g_LAUNCHER + [g_GIT, "reset", "--hard", commit],
-                cwd=srcdir,
-                fail_context=fail_context)
+        # To get a specified commit, clone the specified branch fully and reset;
+        # Try mirrors first, as they are closer
+        cloned: bool = False
+        for source in mirrors:
+            fetch_source = git_url_is_path(source)
+            if fetch_source is None:
+                fetch_source = source
+            else:
+                fetch_source = os.path.abspath(fetch_source)
+            if (run_cmd(g_LAUNCHER +
+                        [g_GIT, "clone", "-b", branch, fetch_source, "src"],
+                        cwd=workdir,
+                        fail_context=None)[1] == 0
+                    and run_cmd(g_LAUNCHER + [g_GIT, "reset", "--hard", commit],
+                                cwd=srcdir,
+                                fail_context=None)[1] == 0):
+                cloned = True
+                break
+        if not cloned:
+            # Try definitive source location
+            if (run_cmd(g_LAUNCHER +
+                        [g_GIT, "clone", "-b", branch, fetch_url, "src"],
+                        cwd=workdir,
+                        fail_context=None)[1] == 0
+                    and run_cmd(g_LAUNCHER + [g_GIT, "reset", "--hard", commit],
+                                cwd=srcdir,
+                                fail_context=None)[1] != 0):
+                fail(fail_context +
+                     "Failed to clone Git repository.\nTried locations:\n%s" %
+                     ("\n".join(["\t%s" % (x, ) for x in mirrors + [url]]), ))
+
     # Prepare the description stub used to rewrite "file"-type dependencies
     repo_stub: Dict[str, Any] = {
         "type": "git",
@@ -538,7 +586,8 @@ def import_from_git(core_repos: Json, imports_entry: Json) -> Json:
                                                     branch,
                                                     commit=commit,
                                                     mirrors=mirrors,
-                                                    inherit_env=inherit_env)
+                                                    inherit_env=inherit_env,
+                                                    fail_context=fail_context)
 
     # Read in the foreign config file
     if foreign_config_file: