ruby - 可靠的 : define when a command doesn't have to run (building ruby from source)

Question

这是我的剧本中负责从源代码下载和构建 ruby​​ 的部分:

  vars:
    ruby_version: '2.0.0-p247'
    ruby_url: 'ftp://ftp.ruby-lang.org//pub/ruby/2.0/ruby-{{ ruby_version }}.tar.gz'

  tasks: 

  - name: Ensure ruby dependencies are installed
    apt: pkg=$item state=installed update-cache=yes
    sudo: yes
    with_items:
      - build-essential
      - git-core
      - libreadline6-dev
      - libyaml-dev
      - libsqlite3-dev
      - sqlite3
      - libgdbm-dev
      - libncurses5-dev
      - libtool
      - bison
      - libffi-dev
      - libdigest-hmac-perl
      - unzip
      - zlib1g
      - zlib1g-dev

  - name: Ensure the ruby source is downloaded
    get_url: url=$ruby_url dest=/home/vagrant/ruby-{{ ruby_version }}.tar

  - name: Ensure the ruby source is extracted
    command: tar -zxf /home/vagrant/ruby-$ruby_version.tar creates=/home/vagrant/ruby-{{ ruby_version }}

  - name: Ensure ruby is installed
    command: $item chdir=/home/vagrant/ruby-$ruby_version
    with_items:
      - ./configure
      - make
      - sudo make install

最后一个任务(配置 make 和 make install)在每次配置时运行。

我可以使用 ruby -v 检查 ruby​​ 是否已经安装了正确的版本。我如何在我的剧本中定义这是运行此步骤的条件？

还有，有没有办法让这个成为整个任务列表的条件，而不仅仅是最后一个？

Answer 1

可以使用register任务参数将ruby -v的结果保存到一个变量中，然后使用when任务参数有条件地执行任务。

您的示例将如下所示:

  vars:
    ruby_version: '2.0.0-p247'
    ruby_url: 'ftp://ftp.ruby-lang.org//pub/ruby/2.0/ruby-{{ ruby_version }}.tar.gz'

  tasks:

  - name: get currently installed ruby version
    command: ruby -v
    register: result
    ignore_errors: True

  - name: Ensure ruby dependencies are installed
    apt: pkg={{ item }} state=installed update-cache=yes
    sudo: yes
    with_items:
      - build-essential
      - git-core
      - libreadline6-dev
      - libyaml-dev
      - libsqlite3-dev
      - sqlite3
      - libgdbm-dev
      - libncurses5-dev
      - libtool
      - bison
      - libffi-dev
      - libdigest-hmac-perl
      - unzip
      - zlib1g
      - zlib1g-dev
    when: result.rc !=0 or result.stdout.split()[1] != ruby_version

  - name: Ensure the ruby source is downloaded
    get_url: url={{ ruby_url }} dest=/home/vagrant/ruby-{{ ruby_version }}.tar
    when: result.rc !=0 or result.stdout.split()[1] != ruby_version

  - name: Ensure the ruby source is extracted
    command: tar -zxf /home/vagrant/ruby-{{ ruby_version }}.tar creates=/home/vagrant/ruby-{{ ruby_version }}
    when: result.rc !=0 or result.stdout.split()[1] != ruby_version

  - name: Ensure ruby is installed
    command: $item chdir=/home/vagrant/ruby-{{ ruby_version }}
    with_items:
      - ./configure
      - make
      - sudo make install
    when: result.rc !=0 or result.stdout.split()[1] != ruby_version

您还可以将任务移动到单独的文件(例如，install_ruby_from_source.yaml)，然后有条件地包含该文件:

  vars:
    ruby_version: '2.0.0-p247'
    ruby_url: 'ftp://ftp.ruby-lang.org//pub/ruby/2.0/ruby-{{ ruby_version }}.tar.gz'

  tasks:

  - name: get currently installed ruby version
    command: ruby -v
    register: result
    ignore_errors: True

  - include: /path/to/install_ruby_from_source.yaml
    when: result.rc !=0 or result.stdout.split()[1] != ruby_version