Just add those lines to your docker-compose.yml :
  sonar_db:
    image: postgres
    environment:
      - POSTGRES_USER=sonar
      - POSTGRES_PASSWORD=sonar
    volumes:
      - ./sonar/db/:/var/lib/postgresql
      - ./sonar/db/data/:/var/lib/postgresql/data
  sonarqube:
    image: sonarqube:5.6-alpine
    ports:
      - 9000:9000
      - 9002:9002
    links:
      - sonar_db
    environment:
      - SONARQUBE_JDBC_URL=jdbc:postgresql://sonar_db:5432/sonar
    volumes:
      - ./sonar/conf/:/opt/sonarqube/conf
      - ./sonar/data/:/opt/sonarqube/data
      - ./sonar/extensions/:/opt/sonarqube/extensions
      - ./sonar/bundled_plugins/:/opt/sonarqube/lib/bundled-plugins
  sonar_runner:
    image: pierrevincent/sonar-runner
    volumes:
      - .:/data
    links:
      - sonarqube
      - sonar_db
And add a sonar-project.properties at the root of your project.
A basic one :
# Required metadata
sonar.host.url=http://sonarqube:9000
sonar.projectKey=my-awesome-project
sonar.projectName=Aweseome project
sonar.projectVersion=1.0
# Comma-separated paths to directories with sources (required)
sonar.sources=rezdy
# Language
sonar.language=php
# Encoding of the source files
sonar.sourceEncoding=UTF-8
And just run docker-compose run --rm sonar_runner