Mongo 7 with a replica set with only one node in docker compose

compose.yaml

version: "3.7"

services:
  # simple
  mongo:
    image: mongo
    command: mongod --replSet rs0 --bind_ip_all
    healthcheck:
      test: |
        mongosh --eval "try { rs.status().ok } catch (e) { rs.initiate({ _id: 'rs0', members: [{ _id: 0, host: 'localhost:27017' }] }).ok }"
      start_period: 0s
      interval: 500ms
      timeout: 5s
      retries: 5
    ports: [27017:27017]
    volumes:
      - ./mongodb/data:/data/db

  # with auth
  mongo:
    image: mongo
    entrypoint: >
      /bin/bash -c '
      openssl rand -base64 756 > /data/keyfile &&
      chmod 400 /data/keyfile &&
      chown mongodb:mongodb /data/keyfile &&
      /usr/local/bin/docker-entrypoint.sh mongod --replSet rs0 --keyFile /data/keyfile --bind_ip_all'
    healthcheck:
      test: >
        mongosh
        -u $${MONGO_INITDB_ROOT_USERNAME}
        -p $${MONGO_INITDB_ROOT_PASSWORD}
        --eval "try { rs.status().ok } catch (e) { rs.initiate({ _id: 'rs0', members: [{ _id: 0, host: 'localhost:27017' }] }).ok }"
      start_period: 0s
      interval: 500ms
      timeout: 5s
      retries: 5
    ports: [27017:27017]
    environment:
      - MONGO_INITDB_ROOT_USERNAME=root
      - MONGO_INITDB_ROOT_PASSWORD=example
    volumes:
      - ./mongodb/data:/data/db