repo: Add support for standalone manifests

Added --standalone_manifest to repo tool. If set, the
manifest is downloaded directly from the appropriate source
(currently, we only support GS) and used instead of creating
a manifest git checkout. The manifests.git repo is still created to
keep track of various config but is marked as being for a standalone
manifest so that the repo tool doesn't try to run networked git
commands in it.

BUG=b:192664812
TEST=existing tests (no coverage), manual runs

Change-Id: I84378cbc7f8e515eabeccdde9665efc8cd2a9d21
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/312942
Tested-by: Jack Neus <jackneus@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

1 files changed, 68 insertions, 15 deletions

diff --git a/subcmds/init.py b/subcmds/init.py
index 5671fc24..9c6b2ad9 100644
--- a/subcmds/init.py
+++ b/subcmds/init.py
@@ -15,6 +15,7 @@
 import os
 import platform
 import re
+import subprocess
 import sys
 import urllib.parse
 
@@ -24,6 +25,7 @@ from error import ManifestParseError
 from project import SyncBuffer
 from git_config import GitConfig
 from git_command import git_require, MIN_GIT_VERSION_SOFT, MIN_GIT_VERSION_HARD
+import fetch
 import git_superproject
 import platform_utils
 from wrapper import Wrapper
@@ -53,6 +55,12 @@ The optional -m argument can be used to specify an alternate manifest
 to be used. If no manifest is specified, the manifest default.xml
 will be used.
 
+If the --standalone-manifest argument is set, the manifest will be downloaded
+directly from the specified --manifest-url as a static file (rather than
+setting up a manifest git checkout). With --standalone-manifest, the manifest
+will be fully static and will not be re-downloaded during subsesquent
+`repo init` and `repo sync` calls.
+
 The --reference option can be used to point to a directory that
 has the content of a --mirror sync. This will make the working
 directory use as much data as possible from the local reference
@@ -112,6 +120,22 @@ to update the working directory files.
     m = self.manifest.manifestProject
     is_new = not m.Exists
 
+    # If repo has already been initialized, we take -u with the absence of
+    # --standalone-manifest to mean "transition to a standard repo set up",
+    # which necessitates starting fresh.
+    # If --standalone-manifest is set, we always tear everything down and start
+    # anew.
+    if not is_new:
+      was_standalone_manifest = m.config.GetString('manifest.standalone')
+      if opt.standalone_manifest or (
+          was_standalone_manifest and opt.manifest_url):
+        m.config.ClearCache()
+        if m.gitdir and os.path.exists(m.gitdir):
+          platform_utils.rmtree(m.gitdir)
+        if m.worktree and os.path.exists(m.worktree):
+          platform_utils.rmtree(m.worktree)
+
+    is_new = not m.Exists
     if is_new:
       if not opt.manifest_url:
         print('fatal: manifest url is required.', file=sys.stderr)
@@ -136,6 +160,19 @@ to update the working directory files.
 
       m._InitGitDir(mirror_git=mirrored_manifest_git)
 
+    # If standalone_manifest is set, mark the project as "standalone" -- we'll
+    # still do much of the manifests.git set up, but will avoid actual syncs to
+    # a remote.
+    standalone_manifest = False
+    if opt.standalone_manifest:
+      standalone_manifest = True
+    elif not opt.manifest_url:
+      # If -u is set and --standalone-manifest is not, then we're not in
+      # standalone mode. Otherwise, use config to infer what we were in the last
+      # init.
+      standalone_manifest = bool(m.config.GetString('manifest.standalone'))
+    m.config.SetString('manifest.standalone', opt.manifest_url)
+
     self._ConfigureDepth(opt)
 
     # Set the remote URL before the remote branch as we might need it below.
@@ -145,22 +182,23 @@ to update the working directory files.
       r.ResetFetch()
       r.Save()
 
-    if opt.manifest_branch:
-      if opt.manifest_branch == 'HEAD':
-        opt.manifest_branch = m.ResolveRemoteHead()
-        if opt.manifest_branch is None:
-          print('fatal: unable to resolve HEAD', file=sys.stderr)
-          sys.exit(1)
-      m.revisionExpr = opt.manifest_branch
-    else:
-      if is_new:
-        default_branch = m.ResolveRemoteHead()
-        if default_branch is None:
-          # If the remote doesn't have HEAD configured, default to master.
-          default_branch = 'refs/heads/master'
-        m.revisionExpr = default_branch
+    if not standalone_manifest:
+      if opt.manifest_branch:
+        if opt.manifest_branch == 'HEAD':
+          opt.manifest_branch = m.ResolveRemoteHead()
+          if opt.manifest_branch is None:
+            print('fatal: unable to resolve HEAD', file=sys.stderr)
+            sys.exit(1)
+        m.revisionExpr = opt.manifest_branch
       else:
-        m.PreSync()
+        if is_new:
+          default_branch = m.ResolveRemoteHead()
+          if default_branch is None:
+            # If the remote doesn't have HEAD configured, default to master.
+            default_branch = 'refs/heads/master'
+          m.revisionExpr = default_branch
+        else:
+          m.PreSync()
 
     groups = re.split(r'[,\s]+', opt.groups)
     all_platforms = ['linux', 'darwin', 'windows']
@@ -250,6 +288,16 @@ to update the working directory files.
     if opt.use_superproject is not None:
       m.config.SetBoolean('repo.superproject', opt.use_superproject)
 
+    if standalone_manifest:
+      if is_new:
+        manifest_name = 'default.xml'
+        manifest_data = fetch.fetch_file(opt.manifest_url)
+        dest = os.path.join(m.worktree, manifest_name)
+        os.makedirs(os.path.dirname(dest), exist_ok=True)
+        with open(dest, 'wb') as f:
+          f.write(manifest_data)
+      return
+
     if not m.Sync_NetworkHalf(is_new=is_new, quiet=opt.quiet, verbose=opt.verbose,
                               clone_bundle=opt.clone_bundle,
                               current_branch_only=opt.current_branch_only,
@@ -426,6 +474,11 @@ to update the working directory files.
     if opt.archive and opt.mirror:
       self.OptionParser.error('--mirror and --archive cannot be used together.')
 
+    if opt.standalone_manifest and (
+        opt.manifest_branch or opt.manifest_name != 'default.xml'):
+      self.OptionParser.error('--manifest-branch and --manifest-name cannot'
+                              ' be used with --standalone-manifest.')
+
     if args:
       if opt.manifest_url:
         self.OptionParser.error(