Issues with Portainer on Synology, Can't reach database server

[amommersteeg]

When launching the stack through Portainer I get the following errors, and postgres looks to be connecting on the right port.

affine_migration_job

Datasource "db": PostgreSQL database "affine", schema "public" at "postgres:5432"
Error: P1001: Can't reach database server at `postgres:5432`
Please make sure your database server is running at `postgres:5432`.

affine_server

Can't reach database server at `postgres:5432`
Please make sure your database server is running at `postgres:5432`.

affine_postgres

025-11-17 01:55:59.742 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2025-11-17 01:55:59.742 UTC [1] LOG:  listening on IPv6 address "::", port 5432
2025-11-17 01:55:59.935 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"

My compose is copied from repo the only difference being the following for Portainer. I have set the Environment variables and inspecting the containers they are being used.

  env_file:
      - stack.env

Any suggestions of what to try is very much appreciated. I had v0.23.0 running through Container Manager, but started porting everything to Portainer and ran into this issue.

[malibu1966]

I ran into the same thing myself. The initialization script for the database seems to not work even if you change the references from .env to stack.env in the composer yml. I don't know if this will help you for a NAS, but I got around it by installing docker composer and using the 'docker composer up -d' method rather than using portainer. Everything worked fine as long as the environment file name stayed .env and portainer still picks up the containers.

[amommersteeg]

I just figured it out and got it working on Portainer.
I needed to add POSTGRES_HOST: postgres to the postgres environment variables.

  postgres:
    image: pgvector/pgvector:pg16
    container_name: affine_postgres
    hostname: postgres
    volumes:
      - ${DB_DATA_LOCATION}:/var/lib/postgresql/data
    environment:
      POSTGRES_USER: ${DB_USERNAME}
      POSTGRES_PASSWORD: ${DB_PASSWORD}
      POSTGRES_DB: ${DB_DATABASE:-affine}
      POSTGRES_HOST: postgres
      POSTGRES_INITDB_ARGS: '--data-checksums'
      # you better set a password for you database
      # or you may add 'POSTGRES_HOST_AUTH_METHOD=trust' to ignore postgres security policy
      POSTGRES_HOST_AUTH_METHOD: trust
    healthcheck:
      test:
        ['CMD', 'pg_isready', '-U', "${DB_USERNAME}", '-d', "${DB_DATABASE:-affine}"]
      interval: 10s
      timeout: 5s
      retries: 5
    restart: unless-stopped

I am not sure why I had to do this now but must be forcing the host so that the connection strings works.