Update docker compose

* Change compose file format (version)
* Use more variables with fallback values, apply formatting, remove redundant comments and logging directives (for now)
* Closes #1

docker-compose.yml

-version: '3'
+version: '3.8'
 
 volumes:
   postgres_data:
-      driver: local
+    driver: local
   keycloak_data:
-      driver: local
+    driver: local
 
 services:
   postgres:
-      image: postgres:13
-      restart: always
-      ports:
-        - "5432:5432"
-      volumes:
-        - postgres_data:/var/lib/postgresql/data
-      environment:
-        POSTGRES_DB: keycloak
-        POSTGRES_USER: ${POSTGRES_USER}
-        POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
-      logging:
-        driver: gelf
-        options:
-          gelf-address: "udp://s63.dl.hpc.tuwien.ac.at:12201"
-          tag: "keycloak_db"
+    image: postgres:${POSTGRES_TAG:-latest}
+    restart: always
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    environment:
+      POSTGRES_DB: ${POSTGRES_DB:-keycloak}
+      POSTGRES_USER: ${POSTGRES_USER:-keycloak}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-keycloak}
 
   keycloak:
-      image: quay.io/keycloak/keycloak:16.1.1
-      restart: always
-      environment:
-        PROXY_ADDRESS_FORWARDING: "true"
-        DB_VENDOR: POSTGRES
-        DB_ADDR: postgres
-        DB_DATABASE: keycloak
-        DB_USER: ${POSTGRES_USER}
-        DB_PASSWORD: ${POSTGRES_PASSWORD}
-        DB_SCHEMA: public
-        KEYCLOAK_USER: ${KEYCLOAK_USER}
-        KEYCLOAK_PASSWORD: ${KEYCLOAK_PASSWORD}
-      ports:
-        - "8080:8080"
-        - "443:8443"
-      depends_on:
-        - postgres
-      logging:
-        driver: gelf
-        options:
-          gelf-address: "udp://s63.dl.hpc.tuwien.ac.at:12201"
-          tag: "keycloak_app"
-      volumes:
-        - keycloak_data:/opt/jboss/keycloak/standalone/data
-        - ./cert/:/etc/x509/https
-        - ./cli/json-logging.cli:/opt/jboss/startup-scripts/json-logging.cli
-#        - ./export:/tmp
-#      command:
-#        - "-b 0.0.0.0 -Dkeycloak.migration.action=export -Dkeycloak.migration.provider=singleFile -Dkeycloak.migration.file=/tmp/export/realms-export.json -Dkeycloak.profile.feature.upload_scripts=enabled"
+    image: quay.io/keycloak/keycloak:${KEYCLOAK_TAG:-latest}
+    restart: always
+    environment:
+      PROXY_ADDRESS_FORWARDING: "true"
+      DB_VENDOR: POSTGRES
+      DB_ADDR: postgres
+      DB_DATABASE: ${POSTGRES_DB:-keycloak}
+      DB_USER: ${POSTGRES_USER:-keycloak}
+      DB_PASSWORD: ${POSTGRES_PASSWORD:-keycloak}
+      DB_SCHEMA: public
+      KEYCLOAK_USER: ${KEYCLOAK_USER:-admin}
+      KEYCLOAK_PASSWORD: ${KEYCLOAK_PASSWORD:-admin}
+    ports:
+      - "8080:8080"
+      - "443:8443"
+    depends_on:
+      - postgres
+    volumes:
+      - keycloak_data:/opt/jboss/keycloak/standalone/data
+      - ./cert/:/etc/x509/https
+      - ./cli/json-logging.cli:/opt/jboss/startup-scripts/json-logging.cli
+      - ./export:/tmp
 
 networks:
   default: