ipa-pki-retrieve-key: ensure we do not crash

If ipa-pki-retrieve-key fails for some reason (which may be a
"legitimate" reason, e.g. the server it is attempting to contact
being offline), the program terminates with an uncaught exception,
resulting in crash report.

Catch all exceptions; if an exception gets raised, report the
traceback and exit with nonzero status.

Fixes: https://pagure.io/freeipa/issue/7115
Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>

install/tools/ipa-pki-retrieve-key

@@ -4,12 +4,15 @@ from __future__ import print_function
 
 import os
 import sys
+import traceback
 
 from ipalib import constants
 from ipalib.config import Env
 from ipaplatform.paths import paths
 from ipaserver.secrets.client import CustodiaClient
 
+
+def main():
     env = Env()
     env._finalize()
 
@@ -30,3 +33,10 @@ client = CustodiaClient(
     # Print the response JSON to stdout; it is already in the format
     # that Dogtag's ExternalProcessKeyRetriever expects
     print(client.fetch_key(keyname, store=False))
+
+
+try:
+    main()
+except BaseException:
+    traceback.print_exc()
+    sys.exit(1)