Merge ~zzehring/charm-mongodb:bugfix/lp1882641-trusty-charm-upgrade-fails-import-pip into charm-mongodb:master

[Zachary Zehring]

Add try/except around pip import and reorder distro import.

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

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

[Andrea Ieri (aieri)]

This looks fine, but I suspect hooks/install is run before hooks/hooks.py, so this could more simply become (in that file):

- declare -a DEPS=('apt' 'netaddr' 'netifaces' 'pip' 'yaml')
+ declare -a DEPS=('apt' 'netaddr' 'netifaces' 'pip' 'yaml' 'python3-pip')

[Drew Freiberger (afreiberger)]

While I believe @andrea's suggestion should be additionally added, I don't know that the install hook is run during an upgrade-charm event, and this is intended to solve upgrade-charm issues on already deployed trusty hosts.

[Drew Freiberger (afreiberger)]

+1 on this change.

I've created MR to add in code per Andrea's comment for future clean installs.

https://code.launchpad.net/~afreiberger/charm-mongodb/+git/mongodb-charm/+merge/387692

review: Approve

[Xav Paice (xavpaice)]

LGTM

review: Approve

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

Failed to merge change (unable to merge source repository due to conflicts), setting status to needs review.

[Drew Freiberger (afreiberger)]

This got superseded by https://code.launchpad.net/~afreiberger/charm-mongodb/+git/mongodb-charm/+merge/387959 due to need for rebase.

Unmerged commits

1c8fbf9... by Zachary Zehring on 2020-06-26

Add try/except around pip import and reorder distro import.

This ensures python3-pip is installed as this package is
missing from trusty series, which will break upgrades from
older charm revisions.

diff --git a/hooks/hooks.py b/hooks/hooks.py
index fab26b9..3df82d7 100755
--- a/hooks/hooks.py
+++ b/hooks/hooks.py
@@ -9,7 +9,6 @@ import collections
 import distutils
 import json
 import os
-import pip
 import pprint
 import re
 import signal
@@ -19,12 +18,6 @@ import sys
 import time
 
 try:
-    import distro  # flake8: noqa
-except ImportError:
-    pip.main(['install', "distro"])
-    import distro  # flake8: noqa
-
-try:
     import yaml  # flake8: noqa
 except ImportError:
     if sys.version_info.major == 2:
@@ -92,6 +85,18 @@ except ImportError:
     from pymongo import MongoClient
     from pymongo.errors import OperationFailure
 
+try:
+    import pip  # flake8: noqa
+except ImportError:
+    apt_install('python3-pip', fatal=True)
+    import pip  # flake8: noqa
+
+try:
+    import distro  # flake8: noqa
+except ImportError:
+    pip.main(['install', "distro"])
+    import distro  # flake8: noqa
+
 from charmhelpers.contrib.charmsupport.nrpe import NRPE
 
 hooks = Hooks()