Multitenancy support

[abc3]

What kind of change does this PR introduce?

This PR adds support for multitenancy. Different credentials can be stored in the database and managed by HTTP API.

The tenant record includes the external_id column, which will store the Supabase project id.

During connections, pg_edge gets the external_id value from the query parameters "options".

Additional context

How to start it

At first, we need to reinitialize a database image:

make db_rebuild

pg_edge keeps tables in the pgedge schema. The schema should be created automatically by the dev/postgres/00-setup.sql file. Make sure that this schema exists if got troubles with migrations.

Then we need to apply migrations:

mix ecto.migrate --prefix pgedge --log-migrator-sql

Launch the pg_edge application as usual:

make dev

When you start the application, you can try following commands to add tenants to the database

add/update tenant:

curl -X PUT \
  'http://localhost:4000/api/tenants/dev_tenant' \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZSIsInJvbGUiOiJhbm9uIiwiaWF0IjoxNjQ1MTkyODI0LCJleHAiOjE5NjA3Njg4MjR9.M9jrxyvPLkUxWgOYSf5dNdJ8v_eRrq810ShFRT8N-6M' \
  --header 'Content-Type: application/json' \
  --data-raw '{
  "tenant": {
      "db_host": "localhost",
      "db_port": 6432, 
      "db_user": "postgres",
      "db_database": "postgres",
      "db_password": "postgres",
      "pool_size": 20
  }
}'

and now it's possible to connect through the proxy

psql postgresql://postgres:no_pass@localhost:7654/postgres?options=tenant%20dev_tenant

delete tenant:

curl -X DELETE \
  'http://localhost:4000/api/tenants/dev_tenant' \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZSIsInJvbGUiOiJhbm9uIiwiaWF0IjoxNjQ1MTkyODI0LCJleHAiOjE5NjA3Njg4MjR9.M9jrxyvPLkUxWgOYSf5dNdJ8v_eRrq810ShFRT8N-6M'

[abc3]

Hey, @supabase/dashbit team, another day, another PR for the review!
You can ignore files lib/pg_edge/client_handler.ex and lib/pg_edge/db_handler.ex. I hope we can replace poolboy with some more performance approach like what @wojtekmach suggested here #4 (review)

[wojtekmach]

just a friendly reminder that while it is of course totally fine to configure each parameter separately, on very DB-centric projects where I would often jump between system/docker/hosted pg and elixir/psql, I found it very convenient to configure the connection through the URL:

url: System.get_env("DATABASE_URL", "ecto://postgres:postgres@localhost:6432/postgres?pool_size=5")

(yup, we can configure pool_size like this too!)

Again, no need for the change, just something to keep in mind in case you weren't aware!

[abc3]

Sometimes it's handy to update only a single value in production, for example, only pool size. In the case of URL, it needs to copy and find all credentials.

[wojtekmach]

unless you get significant benefits out of using Joken, I'd go for the JOSE library directly to keep dependencies to minimum as well as if you do need to debug something you'll have less layers to peel off. But if for your use case Joken is not just delegating to JOSE but actually encapsulates a lot of logic that you'd rather not implement yourself, by all means go for it!

[abc3]

Added cloak_ecto for password encryption