docker-compose - postgres health check - user does not exist error

[Richard Marshall]

Hi All.

I've just been installing a second Numbas Installation, and have encountered postgres container errors along the lines of user 'postgres' does not exist.

I believe the postgres healthcheck user should be changed from postgres to numbas_lti:

Here is a snippet from the  docker-compose.yml from the numbas git repo.:

<code>

postgres:
......
    healthcheck:
      test: "pg_isready -U postgres"

......

</code>

I believe this should be changed to this?

<code>

healthcheck:
      test: ["CMD-SHELL", "pg_isready -U numbas_lti -d numbas_lti"] 
</code>

[Richard Marshall]

The following is in my humble opinion, given learning Docker only recently, and with the benefit of asking around......

In addition:

<code>

numbas-setup:
 ......
    depends_on:
      - postgres
      - redis
.....
  Daphne:
.....
    depends_on:
      - postgres
      - redis
 .....
  huey:
  .....

    depends_on:
      - postgres
      - redis
   </code>

I believe this is slightly better?

<code>

numbas-setup:
.....
    depends_on:
      postgres:                          
        condition: service_healthy       
      redis:                             
        condition: service_started       
   .....
  daphne:
 .....
    depends_on:
      postgres:                          
        condition: service_healthy       
      redis:                             
        condition: service_started       
.....
  huey:
.....
      postgres:
        condition: service_healthy
      redis:
        condition: service_started
.....

</code>

[Richard Marshall]

further info - the above was after a fresh install - postgres user not existing in postgres container, just numbas_lti, hence health check failing with that user.   2 hours later, and  after further work and a rebuild of the container I now find postgres user now exists, and numbas_lti doesn't.  So I am thoroughly confused.

[Richard Marshall]

I believe I now understand.  postgres is the only linux user in the postgres container, and numbas_lti is the only role within the postgres application.  Hence the healthcheck needs to connect to the postgres app. as numbas_lti as I originally believed.

[Christian Lawson-Perfect]

Thanks for this. It turns out it wasn't even waiting for the health check anyway, because I have to explicitly say that each service depending on postgres should wait until it's healthy.

I've just pushed an updated docker compose file, which I've checked works from scratch.

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