Docker error: local user with ID 991 does not exist

[alirezaalavi87]

Hi. I couldn't resolve my issue by asking in the matrix server. I use docker compose to run the app:

# This compose file is compatible with Compose itself, it might need some
# adjustments to run properly with stack.

version: '3'

services:

  synapse:
    build:
        context: ../..
        dockerfile: docker/Dockerfile
    image: docker.io/matrixdotorg/synapse:latest
    # Since synapse does not retry to connect to the database, restart upon
    # failure
    restart: unless-stopped
    # See the readme for a full documentation of the environment settings
    # NOTE: You must edit homeserver.yaml to use postgres, it defaults to sqlite
    environment:
      - SYNAPSE_CONFIG_PATH=/data/homeserver.yaml
    volumes:
      # You may either store all the files in a local folder
      - ./files:/data
    depends_on:
      - db
    # In order to expose Synapse, remove one of the following, you might for
    # instance expose the TLS port directly:
    ports:
      - 8008:8008/tcp

  db:
    image: docker.io/postgres:12-alpine
    # Change that password, of course!
    environment:
      - POSTGRES_USER=synapse
      - POSTGRES_PASSWORD=123
      # ensure the database gets created correctly
      # https://matrix-org.github.io/synapse/latest/postgres.html#set-up-database
      - POSTGRES_INITDB_ARGS=--encoding=UTF-8 --lc-collate=C --lc-ctype=C
    volumes:
      # You may store the database tables in a local folder..
      - ./schemas:/var/lib/postgresql/data
      # .. or store them on some high performance storage for better results
      # - /path/to/ssd/storage:/var/lib/postgresql/data

And I get this error:

synapse-synapse-1  |  Error during initialisation:
synapse-synapse-1  |      Traceback (most recent call last):
synapse-synapse-1  |        File "/usr/local/lib/python3.11/site-packages/synapse/app/homeserver.py", line 353, in setup
synapse-synapse-1  |          hs.setup()
synapse-synapse-1  |        File "/usr/local/lib/python3.11/site-packages/synapse/server.py", line 340, in setup
synapse-synapse-1  |          self.datastores = Databases(self.DATASTORE_CLASS, self)
synapse-synapse-1  |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
synapse-synapse-1  |        File "/usr/local/lib/python3.11/site-packages/synapse/storage/databases/__init__.py", line 65, in __init__
synapse-synapse-1  |          with make_conn(database_config, engine, "startup") as db_conn:
synapse-synapse-1  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
synapse-synapse-1  |        File "/usr/local/lib/python3.11/site-packages/synapse/storage/database.py", line 161, in make_conn
synapse-synapse-1  |          native_db_conn = engine.module.connect(**db_params)
synapse-synapse-1  |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
synapse-synapse-1  |        File "/usr/local/lib/python3.11/site-packages/psycopg2/__init__.py", line 122, in connect
synapse-synapse-1  |          conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
synapse-synapse-1  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
synapse-synapse-1  |      psycopg2.OperationalError: local user with ID 991 does not exist

I have found this related issue: https://github.com/matrix-org/synapse/issues/13190 but still don't understand what causes it and how to fix it.

[clokep]

Did you make any changes to your Dockerfile?

Does removing the following fix the issue?

    build:
        context: ../..
        dockerfile: docker/Dockerfile

Please use synapse admins for support requests.

[alirezaalavi87]

No it doesn't. also I figured (with the help of friends in matrix group) that my docker is in rootless mode. but still pruning everything and running with sudo doesn't fix the issue.

I asked in the matrix chat and they tried to help, but issue didn't get fixed. and wouldn't having issues and their solutions in here be better since they're easily searchable?

[reivilibre]

have you specified a Postgres host and username in your database configuration? I can see this happening if psycopg2 is about to try to connect to the (hypothetical in this case) local Postgres server using a UNIX socket and is attempting to determine the local user's name.

[alirezaalavi87]

@reivilibre yes, the configs are correct. I am no longer trying to run synapse, but I think adding this to the docker-compose.yml fixed the issue:

    environment:
      - UID=0

I will close this issue since I'm not trying to run a synapse server at the moment and am not 100% sure how I fixed the issue (or did I fix it at all) but anyone with the same issue can open it again