Support for monitoring rootless containers under multiple users #456
Description
Is your feature request related to a problem? Please describe.
Podman exporter seems to only support exporting metrics for containers under the same user as it is running. However, in some environments, for additional security, each service may run under its own Linux user, as a systemd user service. Currently, monitoring such environments is quite hard, as you have to run a separate exporter instance for each user, and export them to Prometheus separately (which can also use more system resources).
Describe the solution you'd like
It should be possible to monitor multiple/all containers on the system, even if running under different Linux users, from a single Podman exporter instance (provided that its user has the correct privileges).
Additional context
This was already requested in #13, but the issue was closed. If it is intentionally not supported, I kindly ask to reconsider this, as I think it would be quite useful for environments with different service users (which may be used for additional security), or at least document some easy-to-setup alternative way of monitoring.