Cannot add telegraf-devs/ppa repository behind proxy

[Drew Freiberger]

The following errors were witnessed when installing telegraf charm behind an http proxy:

gpg: keyring `/tmp/tmphx3xn4br/secring.gpg' created
gpg: keyring `/tmp/tmphx3xn4br/pubring.gpg' created
gpg: requesting key C94406F5 from hkp server keyserver.ubuntu.com
?: [fd 4]: read error: Connection reset by peer
gpgkeys: HTTP fetch error 7: couldn't connect: eof
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
gpg: keyserver communications error: keyserver unreachable
gpg: keyserver communications error: public key not found
gpg: keyserver receive failed: public key not found
Failed to add key.

It was noticed that https_proxy is properly passed to the call to apt-add-repository, but this PPA seems to also require http_proxy to be passed.

I've submitted an upstream bug to charm-helpers and opened a PR that resolves this issue. This bug is to track integrating latest charmhelpers once this upstream PR or issue is closed.

Issue is described in greater detail here:
https://github.com/juju/charm-helpers/issues/544

https://github.com/juju/charm-helpers/pull/545

Workaround is to apply the PR to venv.

/var/lib/juju/agents/unit-telegraf-*/.venv/lib/python3.*/site-packages/charmhelpers/fetch/ubuntu.py. On line 649, add 'http' in the list with 'https' like:

        cmd_env=env_proxy_settings(['https', 'http']))

[Eric Chen (eric-chen)]

This issue was pending long time. Is it still valid?
Furthermore, soon or later, the monitoring system will migrate to COS. Telegraf will be replaced by grafana-agent. Therefore, we won't follow up this issue. But welcome to reopen it when anyone encounter this issue again.
(https://charmhub.io/topics/canonical-observability-stack)