PostgREST on Google Cloud SQL: unix socket URI format? - google-cloud-sql

Question

Any of you with experience with PostgREST and Cloud SQL ?
I have my SQL instance ready with open access (0.0.0.0/0) and I can access it with local PostGREST using the Cloud proxy app.
Now I want to run Postgrest from an instance of the same project but
I can't find an URI format for Postgrest that supports Cloud SQL format, as
Google SQL Cloud uses only unix sockets like /cloudsql/INSTANCE_CONNECTION_NAME
Config 1
db-uri = "postgres://postgres:password#/unix(/cloudsql/INSTANCE_CONNECTION_NAME)/mydatabase"
db-schema = "api"
jwt-secret = "OOcJ7VoSY1mXqod4MKtb9WCCwt9erJkRQ2tzYmLb4Xe="
db-anon-role = "web_anon"
server-port=3000
Returns {"details":"could not translate host name \"unix(\" to address: Unknown host\n","code":"","message":"Database connection error"}
Config 2
db-uri = "postgres://postgres:password#/mydatabase?unix_socket=/cloudsql/INSTANCE_CONNECTION_NAME"
db-schema = "api"
jwt-secret = "OOcJ7VoSY1mXqod4MKtb9WCCwt9erJkRQ2tzYmLb4Xe="
db-anon-role = "web_anon"
server-port=3000
The parser rejects the question mark
{"details":"invalid URI query parameter: \"unix_socket\"\n","code":"","message":"Database connection error"}
Config 3
db-uri = "postgres://postgres:password#/mydatabase"
db-schema = "api"
jwt-secret = "OOcJ7VoSY1mXqod4MKtb9WCCwt9erJkRQ2tzYmLb4Xe="
db-anon-role = "web_anon"
server-port=3000
server-unix-socket= "/cloudsql/INSTANCE_CONNECTION_NAME"
server-unix-socket appears to only take socket lock file path. Feeding it /cloudsql/INSTANCE_CONNECTION_NAME tries to delete file as in `postgrest.exe: /cloudsql/INSTANCE_CONNECTION_NAME: DeleteFile "/cloudsql/INSTANCE_CONNECTION_NAME": invalid argument t (The filename, directory name, or volume label syntax is incorrect.)
Documentation
Cloud SQL Doc
https://cloud.google.com/sql/docs/mysql/connect-run
PostgREST
http://postgrest.org/en/v6.0/configuration.html
https://github.com/PostgREST/postgrest/issues/1186
https://github.com/PostgREST/postgrest/issues/169
Environment
PostgreSQL version:11
PostgREST version: 6.0.2
Operating system: Win10 and Alpine

Answer 1

First you have to add the Cloud SQL connection to the Cloud Run instance:
https://cloud.google.com/sql/docs/postgres/connect-run#configuring
After that, the DB connection will be available in the service on a Unix domain socket at path /cloudsql/<cloud_sql_instance_connection_name> and you can set the PGRST_DB_URI environment variable to reflect that.
Here's the correct format:
postgres://<pg_user>:<pg_pass>#/<db_name>?host=/cloudsql/<cloud_sql_instance_connection_name>
e.g.
postgres://postgres:postgres#/postgres?host=/cloudsql/project-id:zone-id-1:sql-instance

Answer 2

According with Connecting with CloudSQL, the example is:
# postgres+pg8000://<db_user>:<db_pass>#/<db_name>?unix_sock=/cloudsql//.s.PGSQL.5432
Then you can try with (Just as #marian.vladoi mentioned):
db-uri = "postgres://postgres:password#/mydatabase?unix_socket=/cloudsql/INSTANCE_CONNECTION_NAME/.s.PGSQL.5432"
Keep in mind that the connection name should include:
ProjectID:Region:DatabaseName
For example: myproject:myregion:myinstance
Anyway, you can find here more options to connect from external applications and from within Google Cloud.

Answer 3

I tried many variations but couldn't get it to work out of the box, however I'll post this workaround.
FWIW I was able to use an alternate socket location with postgrest locally, but then when trying to use the cloudsql location it doesn't seem to interpret it right - perhaps the colons in the socket path are throwing it off?
In any case as #Steve_Chávez mentions, this approach does work db-uri = postgres:///user:password#/dbname and defaults to the postgrest default socket location (/run/postgresql/.s.PGSQL.5432). So in the docker entrypoint we can symlink this location to the actual socket injected by Cloud Run.
First, add the following to the Dockerfile (above USER 1000):
RUN mkdir -p /run/postgresql/ && chown postgrest:postgrest /run/postgresql/
Then add an executable file at /etc/entrypoint.bash containing:
set -eEux pipefail
CLOUDSQL_INSTANCE_NAME=${CLOUDSQL_INSTANCE_NAME:-PROJECT_REGION_INSTANCE_NAME}
POSTGRES_SOCKET_LOCATION=/run/postgresql
ln -s /cloudsql/${CLOUDSQL_INSTANCE_NAME}/.s.PGSQL.5432 ${POSTGRES_SOCKET_LOCATION}/.s.PGSQL.5432
postgrest /etc/postgrest.conf
Change the Dockefile entrypoint to CMD /etc/entrypoint.sh. Then add CLOUDSQL_INSTANCE_NAME as an env var in cloud run. The PGRST_DB_URI env var is like so postgres://authenticator:password#/postgres
An alternative approach if you don't like this, would be to connect via serverless vpc connector.

Answer 4

I struggled with this too.
I end up doing a one-liner for DB-URI env variable
host=/cloudsql/project-id:zone:instance-id user=user port=5432 dbname=dbname password=password
However, I have postgrest running on cloud run that lets you specify the instance connection name via
INSTANCE_CONNECTION_NAME=/cloudsql/project-id:zone:instance-id
Maybe you can host it there and you end up doing it serverless Im not sure where are you running it currently.
https://cloud.google.com/sql/docs/mysql/connect-run