deployments: Refactor locking libraries into zulip_tools.py.

The code in update-deployment and upgrade-zulip for managing the
deployment lock was nearly identical.

scripts/lib/upgrade-zulip

@@ -4,15 +4,13 @@ import shutil
 import sys
 import subprocess
 import logging
-import shutil
-import time
 
 TARBALL_ARCHIVE_PATH="/home/zulip/archives"
 os.environ["PYTHONUNBUFFERED"] = "y"
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..'))
-from zulip_tools import DEPLOYMENTS_DIR, LOCK_DIR, FAIL, WARNING, ENDC, \
-    mkdir_p, su_to_zulip
+from zulip_tools import DEPLOYMENTS_DIR, FAIL, WARNING, ENDC, \
+    mkdir_p, su_to_zulip, get_deployment_lock, release_deployment_lock
 
 logging.basicConfig(format="%(asctime)s upgrade-zulip: %(message)s",
                     level=logging.INFO)
@@ -27,25 +25,8 @@ if len(sys.argv) != 2:
 
 tarball_path = sys.argv[1]
 
-start_time = time.time()
-got_lock = False
-while time.time() - start_time < 300:
-    try:
-        os.mkdir(LOCK_DIR)
-        got_lock = True
-        break
-    except OSError:
-        print WARNING + "Another deployment in progress; waiting for lock... (If no deployment is running, rmdir %s)" % (LOCK_DIR,) + ENDC
-        time.sleep(3)
-
-if not got_lock:
-    print FAIL + "Deployment already in progress.  Please run\n" \
-               + "  %s/current/scripts/upgrade-zulip %s\n" % (DEPLOYMENTS_DIR, tarball_path) \
-               + "manually when the previous deployment finishes, or run\n" \
-               + "  rmdir %s\n"  % (LOCK_DIR,) \
-               + "if the previous deployment crashed." \
-               + ENDC
-    sys.exit(1)
+error_rerun_script = "%s/current/scripts/upgrade-zulip %s" % (DEPLOYMENTS_DIR, tarball_path)
+get_deployment_lock(error_rerun_script)
 
 try:
     # Copy the release tarball to an archival path that's readable by
@@ -72,4 +53,4 @@ try:
 
     logging.info("Deployment complete")
 finally:
-    shutil.rmtree(LOCK_DIR)
+    release_deployment_lock()

tools/update-deployment

@@ -3,14 +3,12 @@ import os
 import sys
 import subprocess
 import logging
-import datetime
-import shutil
-import time
 
 os.environ["PYTHONUNBUFFERED"] = "y"
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
-from zulip_tools import DEPLOYMENTS_DIR, LOCK_DIR, FAIL, WARNING, ENDC, make_deploy_path
+from zulip_tools import DEPLOYMENTS_DIR, FAIL, WARNING, ENDC, make_deploy_path, \
+    get_deployment_lock, release_deployment_lock
 
 logging.basicConfig(format="%(asctime)s update-deployment: %(message)s",
                     level=logging.INFO)
@@ -25,22 +23,8 @@ subprocess.check_call(["mkdir", '-p',
                        DEPLOYMENTS_DIR,
                        '/home/zulip/logs'])
 
-start_time = time.time()
-got_lock = False
-while time.time() - start_time < 300:
-    try:
-        os.mkdir(LOCK_DIR)
-        got_lock = True
-        break
-    except OSError:
-        print WARNING + "Another deployment in progress; waiting for lock..." + ENDC
-        time.sleep(3)
-
-if not got_lock:
-    print FAIL + "Deployment already in progress.  Please run\n" \
-               + "  %s/current/tools/update-deployment %s\n" % (DEPLOYMENTS_DIR, refname) \
-               + "manually when the current deployment finishes." + ENDC
-    sys.exit(1)
+error_rerun_script = "%s/current/tools/update-deployment %s" % (DEPLOYMENTS_DIR, refname)
+get_deployment_lock(error_rerun_script)
 
 try:
     deploy_path = make_deploy_path()
@@ -66,4 +50,4 @@ try:
     logging.info("Deployment complete")
     subprocess.check_call(["./scripts/purge-old-deployments"])
 finally:
-    shutil.rmtree(LOCK_DIR)
+    release_deployment_lock()

zulip_tools.py

@@ -1,10 +1,12 @@
 #!/usr/bin/env python2.7
 from __future__ import print_function
+import datetime
 import errno
 import os
-import sys
-import datetime
 import pwd
+import shutil
+import sys
+import time
 
 DEPLOYMENTS_DIR = "/home/zulip/deployments"
 LOCK_DIR = os.path.join(DEPLOYMENTS_DIR, "lock")
@@ -40,3 +42,27 @@ def mkdir_p(path):
             pass
         else:
             raise
+
+def get_deployment_lock(error_rerun_script):
+    start_time = time.time()
+    got_lock = False
+    while time.time() - start_time < 300:
+        try:
+            os.mkdir(LOCK_DIR)
+            got_lock = True
+            break
+        except OSError:
+            print(WARNING + "Another deployment in progress; waiting for lock... (If no deployment is running, rmdir %s)" % (LOCK_DIR,) + ENDC)
+            time.sleep(3)
+
+    if not got_lock:
+        print(FAIL + "Deployment already in progress.  Please run\n"
+              + "  %s\n" % (error_rerun_script,)
+              + "manually when the previous deployment finishes, or run\n"
+              + "  rmdir %s\n"  % (LOCK_DIR,)
+              + "if the previous deployment crashed."
+              + ENDC)
+        sys.exit(1)
+
+def release_deployment_lock():
+    shutil.rmtree(LOCK_DIR)