Ansible:对变量进行迭代，如果定义了变量，则运行命令

Question

我希望使用ansible在/etc/rupv.conf中设置名称服务器。我基本上希望设置变量(DNS1、DNS2、DNS3)。我只希望在定义DNS#的情况下应用它。到目前为止，我有以下几点。

# Run this playbook on all hosts that should query the DNS server.
- hosts: all
  vars:
    # dns_server: 192.168.1.190
    nameserver_ip: 192.168.1.214
    DNS2: 192.168.1.1
  tasks:
    - name: Add DNS server's IPv4 address to /etc/resolv.conf
      command: "nmcli con mod {{ ansible_default_ipv4['interface'] }} ipv4.dns {{ nameserver_ip }}"
    - name: Add non-authoritative DNS servers to /etc/resolv.conf
      shell: "nmcli con mod {{ ansible_default_ipv4['interface'] }} +ipv4.dns {{ item }}"
      when:  item is defined
      with_items:
        - DNS2
        - DNS3
    - name: Restart default network interface to update /etc/resolv.conf
      shell: "nmcli con reload && nmcli con up {{ ansible_default_ipv4['interface'] }}"

但是，当我运行这个程序时，我会得到以下错误

[root@ns1 dns]# ansible-playbook --user root -i ftp.home, dns_client.yaml -k
...
...
TASK [Add non-authoritative DNS servers to /etc/resolv.conf] *****************************************************************************************************************************************************
failed: [ftp.home] (item=DNS2) => {"changed": true, "cmd": "nmcli con mod eth0 +ipv4.dns DNS2", "delta": "0:00:00.055982", "end": "2019-04-01 12:25:53.029983", "item": "DNS2", "msg": "non-zero return code", "rc": 2, "start": "2019-04-01 12:25:52.974001", "stderr": "Error: failed to modify ipv4.dns: invalid IPv4 address 'DNS2'.", "stderr_lines": ["Error: failed to modify ipv4.dns: invalid IPv4 address 'DNS2'."], "stdout": "", "stdout_lines": []}
failed: [ftp.home] (item=DNS3) => {"changed": true, "cmd": "nmcli con mod eth0 +ipv4.dns DNS3", "delta": "0:00:00.056684", "end": "2019-04-01 12:25:53.782999", "item": "DNS3", "msg": "non-zero return code", "rc": 2, "start": "2019-04-01 12:25:53.726315", "stderr": "Error: failed to modify ipv4.dns: invalid IPv4 address 'DNS3'.", "stderr_lines": ["Error: failed to modify ipv4.dns: invalid IPv4 address 'DNS3'."], "stdout": "", "stdout_lines": []}
        to retry, use: --limit @/root/ansible/dns/dns_client.retry

看起来，它不是使用DNS{2,3}的值，而是使用变量名称(字面上是DNS2和DNS3 )。我在这里做错什么了？

Answer 1

我想通了。我忘记了，为了在Ansible中使用变量的值，必须在"{{…}“中包围变量名。以下更改解决了我的问题。

  with_items:
    - "{{ DNS2 }}"
    - "{{ DNS3 }}"