Alias generation script: retry on connection error

Signed-off-by: Aurélien Bompard <aurelien@bompard.org>

roles/fasjson/templates/fasjson-aliases.j2

@@ -1,18 +1,35 @@
 #!/usr/bin/python3
 import os
 import sys
+import time
 import tempfile
 import subprocess
+from functools import wraps
 
 from fasjson_client import Client, errors
 
 fasjson_url = "{{ fasjson_url }}"
 aliases_static_file = "/etc/aliases.static"
 aliases_file = "/etc/aliases"
+max_retries = 3
+
+
+def retry(func):
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        for attempt in range(max_retries):
+            try:
+                return func(*args, **kwargs)
+            except ConnectionError:
+                if attempt < max_retries - 1:
+                    time.sleep(1)
+                else:
+                    raise
+
+    return wrapper
 
 
 def gen_all_aliases():
-
     # API query
     try:
         client = Client(url=fasjson_url)
@@ -30,7 +47,7 @@ def gen_all_aliases():
                         temp.write(line)
                     for user in users:
                         username = user['username']
-                        userinfo = client.get_user(username=username).result
+                        userinfo = retry(client.get_user)(username=username).result
                         email = userinfo['emails'][0]
 
                         temp.write(f'{username}: {email} \n')
@@ -41,7 +58,8 @@ def gen_all_aliases():
                     sponsor_list = ','.join(
                         sponsor['username']
                         for sponsor in client.list_group_sponsors(
-                            groupname=groupname).result
+                            groupname=groupname
+                        ).result
                     )
                     if sponsor_list:
                         temp.write(
@@ -51,8 +69,9 @@ def gen_all_aliases():
 
                     member_list = ','.join(
                         member['username']
-                        for member in client.list_group_members(
-                            groupname=groupname).result
+                        for member in retry(client.list_group_members)(
+                            groupname=groupname
+                        ).result
                     )
 
                     if member_list:
@@ -60,7 +79,9 @@ def gen_all_aliases():
 
             rename(temporary_file.name, aliases_file)
         except errors.APIError as e:
-            print(f"Something went wrong querying the fasjson API. {e}", file=sys.stderr)
+            print(
+                f"Something went wrong querying the fasjson API. {e}", file=sys.stderr
+            )
             raise
         except IOError as e:
             print(e, file=sys.stderr)
@@ -102,18 +123,20 @@ def update_user(username):
 def rename(filename, aliases_file):
     try:
         os.rename(filename, aliases_file)
-        if (os.path.exists(filename)):
+        if os.path.exists(filename):
             os.remove(filename)
     except IOError as e:
         print(f"Error updating aliases file {e}", file=sys.stderr)
         raise
 
+
 def selinux():
     try:
         subprocess.check_call(['/usr/sbin/restorecon', '-R', aliases_file])
     except IOError as e:
         print(f"Error restoring file context {e}", file=sys.stderr)
 
+
 def main():
     args = sys.argv[1:]
 
@@ -121,10 +144,10 @@ def main():
     os.environ["KRB5_CLIENT_KTNAME"] = "/etc/krb5.keytab"
 
     if not args:
-       gen_all_aliases()
-       selinux()
-       # call newaliases script so postfix gets updated
-       subprocess.check_call(['/usr/bin/newaliases'])
+        gen_all_aliases()
+        selinux()
+        # call newaliases script so postfix gets updated
+        subprocess.check_call(['/usr/bin/newaliases'])
     elif len(args) == 2 and args[0] == "update":
         update_user(args[1])
         # call newaliases script so postfix gets updated