upgrade-zulip-from-git: Create deployment directories with git worktree.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

scripts/lib/upgrade-zulip-from-git

@@ -63,7 +63,7 @@ try:
         logging.info("Cloning the repository")
         subprocess.check_call(
             ["git", "clone", "-q", remote_url, "--mirror", LOCAL_GIT_CACHE_DIR],
-            stdout=open("/dev/null", "w"),
+            stdout=subprocess.DEVNULL,
         )
     if os.stat(LOCAL_GIT_CACHE_DIR).st_uid == 0:
         subprocess.check_call(["chown", "-R", "zulip:zulip", LOCAL_GIT_CACHE_DIR])
@@ -83,13 +83,17 @@ try:
     logging.info("Fetching the latest commits")
     subprocess.check_call(["git", "fetch", "-q", "--tags", "--all"], preexec_fn=su_to_zulip)
 
-    # Generate the deployment directory via git clone from our local repository.
+    # Generate the deployment directory via git worktree from our local repository.
     subprocess.check_call(
-        ["git", "clone", "-q", "-b", refname, LOCAL_GIT_CACHE_DIR, deploy_path],
-        stdout=open("/dev/null", "w"),
+        ["git", "worktree", "add", "--detach", deploy_path, refname],
+        stdout=subprocess.DEVNULL,
         preexec_fn=su_to_zulip,
     )
     os.chdir(deploy_path)
+    subprocess.check_call(
+        ["git", "checkout", "-qtb", "deployment-" + os.path.basename(deploy_path), refname],
+        preexec_fn=su_to_zulip,
+    )
 
     overwrite_symlink("/etc/zulip/settings.py", "zproject/prod_settings.py")
 

scripts/purge-old-deployments

@@ -7,7 +7,12 @@ from typing import Set
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.append(ZULIP_PATH)
-from scripts.lib.zulip_tools import DEPLOYMENTS_DIR, get_recent_deployments, may_be_perform_purging
+from scripts.lib.zulip_tools import (
+    DEPLOYMENTS_DIR,
+    get_recent_deployments,
+    may_be_perform_purging,
+    su_to_zulip,
+)
 
 
 def parse_args() -> argparse.Namespace:
@@ -70,6 +75,10 @@ def main() -> None:
     )
 
     if not args.dry_run:
+        subprocess.check_call(
+            ["git", "worktree", "prune"], cwd="/srv/zulip.git", preexec_fn=su_to_zulip
+        )
+
         print("Deployments cleaned successfully...")
         print("Cleaning orphaned/unused caches...")