Merge ~xavpaice/charm-logrotated:lp1955751 into charm-logrotated:master

[Xav Paice]

Added optional rotation of Juju unit/machine files

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

A CI job is currently in progress. A follow up comment will be added when it completes.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

FAILED: Continuous integration, rev:57d1d7da48efea95ee1a7f5da0b6cb50c3b255e4
https://jenkins.canonical.com/bootstack/job/lp-charm-logrotated-ci/3/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest/297/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/739/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-logrotated-ci/3//rebuild

review: Needs Fixing (continuous-integration)

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

A CI job is currently in progress. A follow up comment will be added when it completes.

[Xav Paice (xavpaice)]

resubmitted after a rebase, in order to retrigger CI

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

FAILED: Continuous integration, rev:c34b224abd7de7cf68cb23c7be5c6e8ab1859574
https://jenkins.canonical.com/bootstack/job/lp-charm-logrotated-ci/5/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-functest/564/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/1032/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-logrotated-ci/5//rebuild

review: Needs Fixing (continuous-integration)

[Paul Goins (vultaire)]

To consider: https://bugs.launchpad.net/juju/+bug/1078213
(Juju *does* have *some* rotation... but it seems unclear that there's any cut-off...)

[Xav Paice (xavpaice)]

Needs lint fixes to pass CI

review: Needs Fixing

Unmerged commits

c34b224... by Paul Goins on 2021-12-30

Added optional rotation of Juju unit/machine files

diff --git a/src/config.yaml b/src/config.yaml
index 813c7ce..0a65312 100644
--- a/src/config.yaml
+++ b/src/config.yaml
@@ -35,3 +35,13 @@ options:
       Mind the quotes for JSON properties/values!
       Valid options for rotate: any integer value
       Valid options for interval: 'daily', 'weekly', 'monthly', 'yearly'
+  enable-juju-unit-rotation:
+    type: boolean
+    default: False
+    description: |
+      Enable rotation of /var/log/juju/unit-*.log files.
+  enable-juju-machine-rotation:
+    type: boolean
+    default: False
+    description: |
+      Enable rotation of /var/log/juju/machine-*.log files.
diff --git a/src/reactive/logrotate.py b/src/reactive/logrotate.py
index 119ac96..adb301e 100644
--- a/src/reactive/logrotate.py
+++ b/src/reactive/logrotate.py
@@ -1,7 +1,9 @@
 """Reactive charm hooks."""
+import os
+
 from charmhelpers.core import hookenv
 
-from charms.reactive import set_flag, when, when_not
+from charms.reactive import set_flag, when, when_any, when_not
 
 from lib_cron import CronHelper
 
@@ -27,6 +29,43 @@ def install_logrotate():
     hookenv.status_set("active", "Unit is ready.")
     set_flag("logrotate.installed")
 
+@when_any("config.changed.enable-juju-unit-rotation", "config.changed.enable-juju-machine-rotation")
+def install_juju_rotation_files():
+    """Install log rotation files for Juju."""
+
+    # Rather than just rotating on /var/log/juju/* (as audit.log can be very useful on
+    # Juju controllers with longer history), I think we should break this apart into different
+    # groups:
+    #
+    # * unit logs (probably highest benefit in rotating)
+    # * machine and machine lock logs (lower benefit)
+    # * audit log (could be beneficial, but probably preferable not to rotate at the same cadence
+    #   as everything else)
+
+    for log_type, enabled in (
+        ("unit", hookenv.config("enable-juju-unit-rotation")),
+        ("machine", hookenv.config("enable-juju-machine-rotation")),
+        # Note: intentionally skipping audit log rotation in favor of keeping longer audit logs
+        # for investigating issues.
+    ):
+        filename = "/etc/logrotate.d/juju_{}s".format(log_type)
+        if enabled:
+            with open(filename, "w") as config_file:
+                # Install a base file.  This will be further customized by the charm later.
+                config_file.write("""\
+/var/log/juju/{}-*.log
+{{
+    missingok
+    daily
+    copytruncate
+    rotate 7
+    notifempty
+}}
+""".format(log_type))
+        else:
+            if os.path.exists(filename):
+                os.unlink(filename)
+
 
 @when("config.changed")
 def config_changed():