Added option to select sslmode when connecting to DB in Grafana

[LeeHanYeong]

In teslamate, you can configure an SSL connection with the DB using the DATABASE_SSL environment variable.
https://docs.teslamate.org/docs/configuration/environment_variables

But grafana doesn't have that option.

I found the sslmode option of DB connection in Grafana's documentation. This is in the jsonData entry in datasources.yml.
https://grafana.com/docs/grafana/latest/administration/provisioning/#data-sources

Guide documentation
I configured it to receive this as an environment variable. I also added information to the traefik and apache guides documentation.

  grafana:
    image: teslamate/grafana:latest
    restart: always
    environment:
      - DATABASE_USER=${TM_DB_USER}
      - DATABASE_PASS=${TM_DB_PASS}
      - DATABASE_NAME=${TM_DB_NAME}
      - DATABASE_HOST=database
      - DATABASE_SSLMODE=disable  # this line

Dockerfile
By adding the ENV to Dockerfile, users who don't have this option in docker-compose can use it without any problems.

FROM grafana/grafana:8.5.9

ENV GF_ANALYTICS_REPORTING_ENABLED=FALSE \
    ...
    DATABASE_SSLMODE=disable

When I ran grafana using the Dockerfile with this option added, it was confirmed that it was connected to PostgreSQL using SSL.

• Using DockerImage: https://hub.docker.com/repository/docker/azelf/grafana

This is also related to #447 from about 2 years ago. It seems that the user who opened the issue had the same problem.

Thank you for your review. have a good day :)

[LeeHanYeong]

This problem has not been resolved for several years. I didn't make it an environment variable option like {TM_DB_...} in docker-compose.yml because I thought it wasn't a frequently used option.
I expect users who need this option to modify docker-compose.yml appropriately.

[mikesmitty]

Seconded, this would be a nice and simple quality of life change. Manually updating the datasource every time the grafana container restarts is a little less than ideal.

[LeeHanYeong]

@adriankumpf
It would be great if you could review this PR. I need to create a custom Grafana image when updating the TeslaMate version to apply SSL to the DB connection.
Thank you :)

[JakobLichterfeld]

Thanks for your suggestion!

[JakobLichterfeld]

Since this is the default value, I vote not to include it in the documentation at this location.

[JakobLichterfeld]

Since this is the default value, I vote not to include it in the documentation at this location.

[DrMichael]

Good practise is to include the default action commented out
# - DATABASE_SSLMODE=disable # defaults to disable