No way to retrieve root CA through Vault relation

[Nobuto Murata]

The charm has ssl_ca option to upload a custom CA. However, using Vault as a root CA or an intermediate CA and getting the CA file through vault:certificates relation is also common in OpenStack deployments.
https://jaas.ai/prometheus-openstack-exporter#charm-config-ssl_ca

It would be nice to have a Vault relation with prometheus-openstack-exporter so it works out of the box. At this moment, this kind of SSL errors are not surfaced to an user in a nice way like juju status or /metrics endpoint so it's tricky to troubleshoot sometimes.
https://bugs.launchpad.net/prometheus-openstack-exporter-snap/+bug/1823011/comments/4

[Nobuto Murata (nobuto)]

Current manual way is as follows after the initial deployment:

$ juju config prometheus-openstack-exporter \
    ssl_ca="$(juju run -u vault/leader -- leader-get root-ca)"