Enable debugging of postgresql functions on database inside a docker container using pgAdmin

Question

I have a postgresql database running inside a docker container and want to debug functions on that database using pgAdmin. Doing that on my local postgres installation presents no issue when following the official guidelines. However, I am running into an issue when trying the same thing with the database inside the docker container.

To debug, I need this line: shared_preload_libraries = '$libdir/plugin_debugger.dll' in my postgresql.conf file. Editing the file in the docker container is easy enough, but when I do so and try to restart the container, it presents me with this message:

FATAL: could not access file "$libdir/plugin_debugger.so": No such file or directory

I tried following this gist, however, when git clone git://git.postgresql.org/git/pldebugger.git gets executed I am presented with the following message

fatal: remote error: access denied or repository not exported: /git/pldebugger.git

I'm using the official postgres:latest image. Does anyone know I can do this?

Answer 1

🗎 Dockerfile (This will install the required dependencies and then build the extension from source.)

FROM postgres:16.0

ENV POSTGRES_DB ""
ENV POSTGRES_USER ""
ENV POSTGRES_PASSWORD ""

RUN apt-get update -q && \
    apt-get install -q -y git make gcc libkrb5-dev postgresql-server-dev-16

WORKDIR /usr/share/postgresql/16/contrib

ENV USE_PGXS=1

RUN git clone https://github.com/EnterpriseDB/pldebugger.git && \
    cd pldebugger && \
    make

COPY setup-pg-admin.sh /docker-entrypoint-initdb.d/

🗎 setup-pg-admin.sh (This will ensure that the extension is loaded when the database starts.)

#!/bin/bash

cat <<EOT >> /var/lib/postgresql/data/postgresql.conf
shared_preload_libraries='/usr/share/postgresql/16/contrib/pldebugger/plugin_debugger.so'
EOT

🗎 docker-compose.yml (This is not strictly necessary, but it shows how to launch PostgreSQL with the required environment variables etc.)

version: '3'
services:
  data-pipeline-db:
    image: data-pipeline-db
    restart: always
    container_name: data-pipeline-db
    shm_size: 512mb
    build:
      context: .
      dockerfile: ./Dockerfile
    environment:
      - POSTGRES_DB=testing
      - POSTGRES_USER=test
      - POSTGRES_PASSWORD=test