• Choose base image and Install dependencies, create a Dockerfile:

FROM postgres:12.8-bullseye

ENV POSTGIS_MAJOR=3
ENV POSTGIS_VERSION=3.1.4+dfsg-1.pgdg100+1

RUN apt-get update \
    && apt-cache showpkg postgres-$PG_MAJOR-postgis-$POSTGIS_MAJOR \
    && apt-get install -y --no-install-recommends \
        postgresql-$PG_MAJOR-postgis-$POSTGIS_MAJOR \
        postgresql-$PG_MAJOR-postgis-$POSTGIS_MAJOR-scripts \
        postgresql-$PG_MAJOR-pgrouting \
    && rm -rf /var/lib/apt/list/*

RUN mkdir -p /docker-entrypoint-initdb.d/
COPY ./initdb-postgis.sh /docker-entrypoint-initdb.d/postgis.sh

• Setup postgres+postgis+pg_routing, create a file initdb-postgis.sh:

#!/bin/sh  

set -e   

## Perform all actions as $POSTGRES_USER 
export PGUSER="$POSTGRES_USER"  

"${psql[@]}" <<-EOSQL 		
    CREATE DATABASE template_postgis;
    UPDATE pg_database SET datistemplate = TRUE 
        WHERE datname = 'template_postgis';
EOSQL  

## Load PostGIS in both template_database and $POSTGRES_DB 
for DB in template_postgis "$POSTGRES_DB"; do
    echo "Loading PostGIS extensions into $DB"  
    "${psql[@]}" --dbname="$DB" <<-EOSQL
        CREATE EXTENSION IF NOT EXISTS postgis;
        CREATE EXTENSION IF NOT EXISTS postgis_topology;
        CREATE EXTENSION IF NOT EXISTS pgRouting;
    EOSQL
done

version: '3'
services:
  serv_pgrouting:
    build: .
    container_name: dc_pgrouting
    env_file: .env
    volumes:
      - ./db-data:/var/lib/postgresql/data
    ports:
      - 5433:5432
 
volumes:
  db-data:
    driver: local