Add support for socket connection to PostgreSQL

[onovy]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

Currently it's possible to connect to DB only over IP, but PostgreSQL supports Unix-domain socket connection. Can you add support to TeslaMate code + docker and Grafana docker please?

Probably best way to support this is to migrate to connection strings instead of host+port pair in envs.

Thanks.

Expected Behavior

No response

Steps To Reproduce

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Relevant log output

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Screenshots

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Additional data

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Type of installation

Docker

Version

1.30.1

[JakobLichterfeld]

Thanks for your suggestion.

Do you mean similar to using a reverse Proxy with Unix Domain Sockets with TeslaMate?

Btw. PR always welcome!

[brianmay]

If I am not mistaken I have come across this exact same issue.

He wants Teslamate to connect to postgresql using the socket, in my case that is /run/postgresql/.s.PGSQL.5432.

This results in less overheads (not sure how significant this is), and means we don't need to manage secrets for teslamate (because the database can do authentication based on the Unix user).

Ecto supports connecting via a socket. But unfortunately, AFAIK, ecto does not support connecting to a socket using a URL to the database. Which is unfortunate, it would mean we just need to support a URL and can connect anywhere. Rather the config needs :socket and :socket_dir values.

See elixir-ecto/postgrex#415

Note: need to check this is still correct. It is possible issue was fixed, but but bug report was not updated.

When I setup my new database I ended up using sockets where possible, and TCP using password authentication for the apps where this did not appear to be easy. Currently all my Elixir apps fall into this category.

[onovy]

Do you mean similar to using a reverse Proxy with Unix Domain Sockets with TeslaMate?

nope, that's different think. brianmay explained it exactly :)

My problem is not overhead nor secrets problem. I have PostgreSQL running on bare-metal, outside of docker. And in this setup it's much simpler to "mount" PostgreSQL socket into docker container instead of playing with TCP/IP.

Details:

• psql needs to bind to IP, "*" is not secure
• psql needs to bind to gateway IP (which is host itself) of docker bridge network to be accessible from docker container
• docker bridge network is dynamic, it can be recreated with different subnets/IPs
• I can setup static IPs, but that's anti-pattern for docker
• psql can't bind to non-existent IP
• bridge network interface with IPs is created dynamicaly, thus i need to start psql after dockerd

Thanks.