"charm build ..." always adds "xenial" and "trusty" to series

[dreibh]

Checklist

• Confirmed this is an issue with charm-tools, not charmstore-client
• Provide versions of tools used
• Described the feature or ways to replicate the issue

What version am I running?

I ran the following command: snap info charm and got the following ouput:

name:      charm
summary:   charm and charm-tools
publisher: Canonical✓
store-url: https://snapcraft.io/charm
contact:   https://discourse.juju.is/c/charming
license:   unset
description: |
  charmstore-client and charm-tools
commands:
  - charm
snap-id:      2Rryoc2ylScfbFl4eQtpntHD9iuZuMvt
tracking:     latest/stable
refresh-date: 3 days ago, at 16:17 CEST
channels:
  latest/stable:    2.8.2               2021-02-01 (609) 119MB classic
  latest/candidate: 2.8.2               2021-02-01 (609) 119MB classic
  latest/beta:      2.8.2               2021-02-01 (609) 119MB classic
  latest/edge:      2.8.3+git-1-736b1ad 2021-02-23 (620) 119MB classic
installed:          2.8.2                          (609) 119MB classic

I am using: Ubuntu 18.04 LTS, with the "charm" snap from latest/stable.

Issue/Feature

I have a simple proxy charm for Open Source MANO (OSM), where I set the series to "bionic" and "focal" in metadata.yaml.
Then, I run charm build ...
The resulting build contains the specified series, plus "xenial" and "trusty".

I expect/expected the following

The build probably should only contain the specified series, not adding "xenial" and "trusty".
I would in the following assume that OSM's Juju installation creates a container with one of my specified series, not using "xenial" (which is quite old now).

What I got

Give us what you got, commands run, output, etc. If this is a feature request, delete this section.

...
"series":
- "xenial"
- "bionic"
- "focal"
- "trusty"
...

Manually removing "xenial" from the build's metadata.yaml does not lead to OSM's Juju installation use "xenial". It always uses "xenial", regardless of what is specified in the metadata.yaml. But this is probably a separate bug?

[ajkavanagh]

Hi, which version of juju are you using? The latest version deploys charms from the charmhub instead of the charmstore, and there is IIRC, a bug in juju that always picks xenial (https://bugs.launchpad.net/juju/+bug/1927135); however this might not be related. If you use the cs: prefix for a charm, it will come from the charmstore (rather than the newer charmhub).

Please could you provide a link to you charm layer (assuming it's open source), so we can see what the build is building from. Thanks.

[dreibh]

The charm I use is built from sources (basically, it is the "simple" charm of the "hackfest_proxycharm_vnf") using "charm build ...". It is not downloaded from a store.

$ juju --version
2.8.10-bionic-amd64

This is the version installed by the installer (for both, Release EIGHT and Release NINE).