我正在寻找一种在ansible变量不是寄存器/未定义的情况下执行任务的方法,例如
-- name: some task
command: sed -n '5p' "{{app.dirs.includes}}/BUILD.info" | awk '{print $2}'
when: (! deployed_revision) AND ( !deployed_revision.stdout )
register: deployed_revision
答案 0 :(得分:173)
来自ansible docs: 如果尚未设置所需变量,则可以跳过或失败使用Jinja2定义的测试。例如:
tasks:
- shell: echo "I've got '{{ foo }}' and am not afraid to use it!"
when: foo is defined
- fail: msg="Bailing out. this play requires 'bar'"
when: bar is not defined
因此,在您的情况下,when: deployed_revision is not defined
应该正常工作
答案 1 :(得分:10)
根据最新的Ansible Version 2.5,要检查变量是否已定义,如果要运行任何任务,请使用undefined
关键字。
tasks:
- shell: echo "I've got '{{ foo }}' and am not afraid to use it!"
when: foo is defined
- fail: msg="Bailing out. this play requires 'bar'"
when: bar is undefined
答案 2 :(得分:4)
严格规定您必须检查以下所有内容:已定义,不为空且不为空。
对于“普通”变量,无论是否定义和设置,都会有所不同。请参见以下示例中的foo
和bar
。两者均已定义,但仅设置了foo
。
另一方面,已注册的变量设置为运行命令的结果,并且因模块而异。它们主要是json结构。您可能必须检查您感兴趣的子元素。请参见以下示例中的xyz
和xyz.msg
:
cat > test.yml <<EOF
- hosts: 127.0.0.1
vars:
foo: "" # foo is defined and foo == '' and foo != None
bar: # bar is defined and bar != '' and bar == None
tasks:
- debug:
msg : ""
register: xyz # xyz is defined and xyz != '' and xyz != None
# xyz.msg is defined and xyz.msg == '' and xyz.msg != None
- debug:
msg: "foo is defined and foo == '' and foo != None"
when: foo is defined and foo == '' and foo != None
- debug:
msg: "bar is defined and bar != '' and bar == None"
when: bar is defined and bar != '' and bar == None
- debug:
msg: "xyz is defined and xyz != '' and xyz != None"
when: xyz is defined and xyz != '' and xyz != None
- debug:
msg: "{{ xyz }}"
- debug:
msg: "xyz.msg is defined and xyz.msg == '' and xyz.msg != None"
when: xyz.msg is defined and xyz.msg == '' and xyz.msg != None
- debug:
msg: "{{ xyz.msg }}"
EOF
ansible-playbook -v test.yml