条件不满足时如何跳过任务答案

【问题标题】：How to skip task when condition is not satisfied条件不满足时如何跳过任务
【发布时间】：2019-03-18 17:14:27
【问题描述】：

如果 my_environment var 是 "prod"，则具有以下任务的角色，该任务应该创建一个 cron 作业。

当条件不满足时，我希望剧本跳过此任务而不是失败：

---
- name: Configure cron job to export patch logs
  cron:
    name: export patch logs daily
    minute: 0
    hour: 0
    user: root
    cron_file: patch_logs
    job: "/usr/local/bin/aws s3 cp /var/log/dpkg.log s3://{{ patch_logs_bucket }}/dpkg.log.$(hostname).$(date +\\%F)"
  when: my_environment == "prod"

失败信息：

TASK [ansible-contxt-base : Configure cron job to export patch logs] ***********
    fatal: [ubuntu-1604]: FAILED! => {"msg": "The conditional check 'scx_environment == \"prod\"' failed. The error was: error while evaluating conditional (scx_environment == \"prod\"): 'my_environment' is undefined\n\nThe error appears to have been in '/**<path>**/tasks/base.yml': line 125, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Configure cron job to export patch logs\n  ^ here\n"}

【问题讨论】：

标签： python ansible yaml conditional-statements

【解决方案1】：

我们可以使用 jinja2 的快捷方式来表示 'default(False) ': 'd(False)'。

when: my_environment|d(False) == "prod"

【讨论】：

【解决方案2】：

when:

my_environment is defined

my_environment != ”prod”

【讨论】：

请解释一下

【解决方案3】：

在这里找到https://ansible-docs.readthedocs.io/zh/stable-2.0/rst/playbooks_conditionals.html#the-when-statement

- shell: echo "This certainly isn't epic!"
  when: not epic

或

- fail: msg="Bailing out. this play requires 'bar'"
  when: bar is undefined

【讨论】：