Ansible渲染Jinja2模板如何仅保留目标节点对应的Inventory配置

问题根因 #

你当前模板最外层遍历了groups['ceph_osd']下的所有主机，所以每个节点渲染脚本时，都会把三个节点的规则全部生成，最终所有节点的脚本内容完全一致。

具体修改步骤 #

1. 替换Jinja2模板内容 #

直接调用当前节点自身的rules变量即可，无需遍历所有主机，修改后的clean_bcache.sh.j2如下：

# clean_bcache.sh.j2
#!/bin/sh

{% for rule in rules.values() %}
{% if rule.bcache != 'none' %}
bcache_name=$(lsblk -o KNAME {{ rule.bcache }} | grep bcache)
cset.uuid=$(bcache-super-show {{ rule.bcache }} | grep cset.uuid | awk -F' ' '{print $2}')
echo ${cset.uuid} > /sys/block/$bcache_name/bcache/detach
sleep 1
echo 1 >/sys/fs/bcache/${cset.uuid}/unregister 
sleep 1
{% for backing_dev in rule.disks %}
echo 1 > /sys/block/{{backing_dev}}/bcache/stop
{% endfor %}
{% endif %}
{% endfor %}

2. （可选）优化Inventory变量格式 #

你当前Inventory里的rules是字符串格式，Ansible可能不会自动解析为字典，建议调整为合法可识别的格式，两种方案二选一即可：

方案A：修改为INI格式原生变量

[cluster]
ops1 ansible_host=192.168.15.80
ops2 ansible_host=192.168.15.81
ops3 ansible_host=192.168.15.82

[ceph_osd]
ops1 rules='{"rule1":{"bcache": "/dev/nvme1n1p7", "disks": ["/dev/sdb"]},"rule2":{"bcache": "/dev/nvme1n1p8", "disks": ["/dev/sdc"]}}'
ops2 rules='{"rule1":{"bcache": "/dev/nvme1n1p7", "disks": ["/dev/sdb"]},"rule2":{"bcache": "/dev/nvme1n1p8", "disks": ["/dev/sdd"]}}'
ops3 rules='{"rule1":{"bcache": "/dev/nvme1n1p7", "disks": ["/dev/sdc"]},"rule2":{"bcache": "/dev/nvme1n1p8", "disks": ["/dev/sdf"]}}'

同时模板里调用变量时加上JSON解析过滤：

{% for rule in (rules | from_json).values() %}

方案B：切换为YAML格式Inventory

cluster:
  hosts:
    ops1:
      ansible_host: 192.168.15.80
    ops2:
      ansible_host: 192.168.15.81
    ops3:
      ansible_host: 192.168.15.82
ceph_osd:
  hosts:
    ops1:
      rules:
        rule1:
          bcache: /dev/nvme1n1p7
          disks:
            - /dev/sdb
        rule2:
          bcache: /dev/nvme1n1p8
          disks:
            - /dev/sdc
    ops2:
      rules:
        rule1:
          bcache: /dev/nvme1n1p7
          disks:
            - /dev/sdb
        rule2:
          bcache: /dev/nvme1n1p8
          disks:
            - /dev/sdd
    ops3:
      rules:
        rule1:
          bcache: /dev/nvme1n1p7
          disks:
            - /dev/sdc
        rule2:
          bcache: /dev/nvme1n1p8
          disks:
            - /dev/sdf

这种格式无需额外处理，直接用修改后的模板即可正常渲染。

你的Ansible任务配置无需修改，执行后每个节点的脚本就只会包含自身对应的规则。

内容的提问来源于stack exchange，提问作者Phoenix Chao