title: ERROR: yaml.parser.ParserError: while parsing a block mapping
body: <p>I'm building Iroha for which i'm running a script for environment setup which is internally calling the docker-compose.yml, where i"m getting the error:</p>
  
  <pre><code>ERROR: yaml.parser.ParserError: while parsing a block mapping
    in "/home/cdac/iroha/docker/docker-compose.yml", line 3, column 5
  expected &lt;block end&gt;, but found '&lt;scalar&gt;'
    in "/home/cdac/iroha/docker/docker-compose.yml", line 13, column 6
  </code></pre>
  
  <p>docker-compose.yml file is showing below.</p>
  
  <pre><code>services:
    node:
      image: hyperledger/iroha:develop-build
      ports:
        - "${IROHA_PORT}:50051"
        - "${DEBUGGER_PORT}:20000"
      environment:
        - IROHA_POSTGRES_HOST=${COMPOSE_PROJECT_NAME}_postgres_1
        - IROHA_POSTGRES_PORT=5432
        - IROHA_POSTGRES_USER=iroha
        - IROHA_POSTGRES_PASSWORD=helloworld
        - CCACHE_DIR=/tmp/ccache
       export G_ID=$(id -g $(whoami))
       export U_ID=$(id -g $(whoami))
      user: ${U_ID:-0}:${G_ID:-0}
      depends_on:
        - postgres
      tty: true
      volumes:
        - ../:/opt/iroha
        - ccache-data:/tmp/ccache
      working_dir: /opt/iroha
      cap_add:
        - SYS_PTRACE
      security_opt:
        - seccomp:unconfined
  
    postgres:
      image: postgres:9.5
      environment:
        - POSTGRES_USER=iroha
        - IROHA_POSTGRES_PASSWORD=helloworld
      command: -c 'max_prepared_transactions=100'
  
  volumes:
    ccache-data:
  </code></pre>
  
  <p>any help will be appreciate, thanks in advance.</p>