Trying to use ReadySet with Lemmy 0.18.1 with PostgreSQL backend, confused about setup

[RocketDerp]

The ReadySet instructions say I should install a Docker postgresql, do I need to do this if I already have postgress with my live Lemmy application data? In other words, do I have to run a second instance of postgress dedicated to ReadySet?

Second question, do I need to use the 'postgress' username or can I use the 'lemmy' username when creating the ReadySet docker? Or does ReadySet need special low-level access of the postgress account?

docker run -d \
--name=readyset \
--publish=5433:5433 \
--platform=linux/arm64 \
--volume='readyset:/state' \
--pull=always \
-e DEPLOYMENT_ENV=quickstart_github \
public.ecr.aws/readyset/readyset:beta-2023-06-29 \
--standalone \
--deployment='github-postgres' \
--database-type=postgresql \
--upstream-db-url=postgres://lemmy:[email protected]:5432/lemmy \
--address=0.0.0.0:5433 \
--username='lemmy' \
--password='secretlemmypassword' \
--db-dir='/state'

The documentaiton for ReadySet says to set the upstream-db-url, but the username and password fields are also there? Should I be setting these to lemmy?

Thank you

[ayymart]

Hi @RocketDerp!

do I have to run a second instance of postgress dedicated to ReadySet?

No, you can provide ReadySet with the URL of your existing Postgres instance.

do I need to use the 'postgress' username or can I use the 'lemmy' username when creating the ReadySet docker?

The user account whose credentials you provide to ReadySet via --upstream-db-url must have the SUPERUSER Postgres role attribute. ReadySet requires this so it can create the triggers it uses as part of the replication process. Any user account that has SUPERUSER can be used.

The documentaiton for ReadySet says to set the upstream-db-url, but the username and password fields are also there?

There are two sets of credentials we're dealing with here: those that ReadySet uses to connect to your Postgres instance, and those that your client uses to connect to ReadySet. ReadySet connects to your Postgres instance using the credentials set via --upstream-db-url. Clients connect to ReadySet using the credentials set via --username and --password, if they were provided when running ReadySet. Otherwise, clients connect to ReadySet using the credentials specified in --upstream-db-url. This gives you the option of using different credentials for your ReadySet instance vs your Postgres instance, if you prefer.

I hope that helps! Let me know if you have further questions.

[RocketDerp]

ok, thank you for clarification

--platform=linux/arm64 isn't working for me, do you suggest I compile from source? Lemmy is written in Rust too, so the server should be ready to compile.

[ayymart]

You can definitely build ReadySet from source! Let me know if you have any questions about doing so.

Unfortunately, we currently only provide an amd64 i.e. x86_64 Docker image. If you are using Docker Desktop, you can use --platform=linux/amd64 and the container will run via emulation. This can also be done with other Docker environments, though additional setup may be required. Note that this won't be representative of native performance.