feat: split postgres.Dockerfile in two stages to not include build pkgs into the final image. It also adds the postgres user at the end

protocol-testing/docker-compose.yaml

@@ -1,4 +1,3 @@
-version: "3.1"
 services:
   db:
     build:
@@ -7,13 +6,12 @@ services:
     restart: "always"
     environment:
       POSTGRES_PASSWORD: mypassword
-      POSTGRES_DATABASE: tycho_indexer_0
-      POSTGRES_USERNAME: postgres
-      POSTGRESQL_SHARED_PRELOAD_LIBRARIES: pg_cron
+      POSTGRES_USER: postgres
+      POSTGRES_DB: tycho_indexer_0
     ports:
       - "5431:5432"
     shm_size: "1gb"
     volumes:
       - postgres_data:/var/lib/postgresql/data
 volumes:
-  postgres_data:
+  postgres_data:

protocol-testing/postgres.Dockerfile

@@ -1,13 +1,13 @@
 # This Dockerfile creates a custom postgres image used for CI and local deployment.
-# This is required because we use some postgres extensions that aren't in the generic
-# Postgres image such as pg_partman or pg_cron.
+# Includes the extensions: pg_partman, pg_cron.
 
-# As an image with pg_partman already exist, we start from this one and add pg_cron
-# and possibly other extensions on top of that.
-FROM ghcr.io/dbsystel/postgresql-partman:15-5
+# Stage 1: Build pg_cron extension
+FROM ghcr.io/dbsystel/postgresql-partman:15-5 AS builder
 ARG PGCRON_VERSION="1.6.2"
 USER root
-RUN apk update && apk add --no-cache wget build-base clang19 llvm19
+
+RUN apk update && apk add --no-cache build-base clang19 llvm19 wget
+
 RUN cd /tmp \
     && wget "https://github.com/citusdata/pg_cron/archive/refs/tags/v${PGCRON_VERSION}.tar.gz" \
     && tar zxf v${PGCRON_VERSION}.tar.gz \
@@ -16,10 +16,16 @@ RUN cd /tmp \
     && make install \
     && cd .. && rm -r pg_cron-${PGCRON_VERSION} v${PGCRON_VERSION}.tar.gz
 
+# Stage 2: Final image, copy built extension
+FROM ghcr.io/dbsystel/postgresql-partman:15-5
+USER root
+
+COPY --from=builder /usr/local/lib/postgresql/pg_cron.so /usr/local/lib/postgresql/
+COPY --from=builder /usr/local/share/postgresql/extension/pg_cron* /usr/local/share/postgresql/extension/
+
 # Add configuration to postgresql.conf template
 # Start with postgres database, then switch to tycho_indexer_0 after it's created
 RUN echo "shared_preload_libraries = 'pg_partman_bgw,pg_cron'" >> /usr/local/share/postgresql/postgresql.conf.sample \
     && echo "cron.database_name = 'tycho_indexer_0'" >> /usr/local/share/postgresql/postgresql.conf.sample
 
-# Stay as root user for PostgreSQL to work properly
-# USER 1001
+USER postgres