Merge lp:~ursinha/landscape-charm/bug-1625307-ignore-tar-warnings into lp:~landscape/landscape-charm/tools

[Ursula Junque]

Fixes bug #1625307: In _create_log_tarball, ignores all exceptions caused by tar returning 1 (warnings).

Fixes bug #1625307: In _create_log_tarball, ignores all exceptions caused by tar returning 1 (warnings).

This needs tests, but I'd need to move things around a bit to be able to do that. I'd rather do that in another branch, to get this fixed asap - we're ending up with empty logs and that makes virtually impossible to debug post-mortem system-tests.

[🤖 Landscape Builder (landscape-builder)]

review: Abstain (executing tests)

[🤖 Landscape Builder (landscape-builder)]

Command: make ci-test
Result: Success
Revno: 32
Branch: lp:~ursinha/landscape-charm/bug-1625307-ignore-tar-warnings
Jenkins: https://ci.lscape.net/job/latch-test-xenial/9/

review: Approve (test results)

[Francis Ginther (fginther)]

Approve

review: Approve

[Andreas Hasenack (ahasenack)]

+1, thanks for the long comments

review: Approve

=== modified file 'collect-logs'
--- collect-logs	2016-09-15 17:34:07 +0000
+++ collect-logs	2016-09-19 18:55:42 +0000
@@ -264,10 +264,15 @@
         try:
             check_output(args, stderr=STDOUT, env=juju.env)
         except CalledProcessError as e:
-            # Note: tar commands can fail since we are backing up log files
-            # that are actively being written, ignoring such errors is what we
-            # can and should do now. Everything else we might retry as usual.
-            if e.returncode == 1 and "file changed as we read it" in e.output:
+            # Note: tar command returns 1 for everything it considers a
+            # warning, 2 for fatal errors. Since we are backing up
+            # log files that are actively being written, or part of a live
+            # system, logging and ignoring such warnings (return code 1) is
+            # what we can do now.
+            # Everything else we might retry as usual.
+            if e.returncode == 1:
+                log.warning(
+                    "tar returned 1, proceeding anyway: {}".format(e.output))
                 break
             log.warning(
                 "Failed to archive log files on unit {}".format(unit))