摘要：如果任何主机无法访问，则立即中止ansible playbook的更好方法。
如果任何一个主机无法访问，有没有办法中止Ansible playbook。我发现，如果它无法到达主机，它仍将继续执行并执行剧本中的所有播放/任务。
我的所有剧本我指定max_fail_percentage为0，但在这种情况下，ansible不会抱怨，因为所有可访问的主机都可以执行所有播放。
目前我有一个简单而又hacky的解决方案，但看看是否有更好的答案。
自从作为运行剧本的一部分的第一步，ansible收集所有主机的事实。如果主机无法访问，则无法访问。我在剧本的最开始写了一个简单的剧本，它将使用一个事实。如果主机无法访问，则任务将因“未定义的变量错误”而失败。任务只是一个虚拟任务，如果所有主机都可以访问，它将始终通过。
见下面我的例子：
- name: Check Ansible connectivity to all hosts
hosts: host_all
user: "{{ remote_user }}"
sudo: "{{ sudo_required }}"
sudo_user: root
connection: ssh # or paramiko
max_fail_percentage: 0
tasks:
- name: check connectivity to hosts (Dummy task)
shell: echo " {{ hostvars[item]['ansible_hostname'] }}"
with_items: groups['host_all']
register: cmd_output
- name: debug ...
debug: var=cmd_output
如果主机无法访问，您将收到如下错误：
TASK: [c.. *****************************************************
fatal: [172.22.191.160] => One or more undefined variables: 'dict object' has no attribute 'ansible_hostname'
fatal: [172.22.191.162] => One or more undefined variables: 'dict object' has no attribute 'ansible_hostname'
FATAL: all hosts have already failed -- aborting
或者，这看起来更简单，更具表现力
- hosts: myservers
become: true
pre_tasks:
- name: Check ALL hosts are reacheable before doing the release
assert:
that:
- ansible_play_hosts == groups.myservers
fail_msg: 1 or more host is UNREACHABLE
success_msg: ALL hosts are REACHABLE, go on
run_once: yes
roles:
- deploy
https://github.com/ansible/ansible/issues/18782#issuecomment-319409529
你可以对这个检查更明确一些：
- fail: Abort if hosts are unreachable
when: "'ansible_hostname' not in hostvars[item]"
with_items: groups['all']
我认为你可以制作一个callback plugin来实现这一目标。就像是：
class CallbackModule(object):
def runner_on_unreachable(self, host, res):
raise Exception("Aborting due to unreachable host " + host)
除了我找不到从该回调中止整个剧本的任何好方法（例外不起作用，返回值被忽略，虽然你可能滥用self.playbook来阻止事情，但我没有看到公共API）。
您可以将any_errors_fatal: true或max_fail_percentage: 0与gather_facts: false结合使用，然后运行一个在主机离线时将失败的任务。在剧本顶部的这样的东西应该做你需要的：
- hosts: all
gather_facts: false
max_fail_percentage: 0
tasks:
- action: ping
奖励是，这也适用于限制匹配主机的-l SUBSET选项。
我发现一种方法可以在gather_facts完成后立即使用回调来中止播放。
通过将_play_hosts设置为空集，没有主机可以继续播放。
class CallbackModule(object):
def runner_on_unreachable(self, host, res):
# Truncate the play_hosts to an empty set to fail quickly
self.play._play_hosts = []
结果如下：
PLAY [test] *******************************************************************
GATHERING FACTS ***************************************************************
fatal: [haderp] => SSH Error: ssh: Could not resolve hostname haderp: nodename nor servname provided, or not known
It is sometimes useful to re-run the command using -vvvv, which prints SSH debug output to help diagnose the issue.
ok: [derp]
TASK: [set a fact] ************************************************************
FATAL: no hosts matched or all hosts have already failed -- aborting
PLAY RECAP ********************************************************************
to retry, use: --limit @/Users/jkeating/foo.yaml.retry
derp : ok=1 changed=0 unreachable=0 failed=0
haderp : ok=0 changed=0 unreachable=1 failed=0
灵感来自其他答案。
使用ansible-playbook 2.7.8。
检查每个所需主机是否有任何ansible_facts对我来说更明确。
# my-playbook.yml
- hosts: myservers
tasks:
- name: Check ALL hosts are reacheable before doing the release
fail:
msg: >
[REQUIRED] ALL hosts to be reachable, so flagging {{ inventory_hostname }} as failed,
because host {{ item }} has no facts, meaning it is UNREACHABLE.
when: "hostvars[item].ansible_facts|list|length == 0"
with_items: "{{ groups.myservers }}"
- debug:
msg: "Will only run if all hosts are reacheable"
$ ansible-playbook -i my-inventory.yml my-playbook.yml
PLAY [myservers] *************************************************************************************************************************************************************************************************************
TASK [Gathering Facts] *********************************************************************************************************************************************************************************************************
fatal: [my-host-03]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: ssh: Could not resolve hostname my-host-03: Name or service not known", "unreachable": true}
fatal: [my-host-04]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: ssh: Could not resolve hostname my-host-04: Name or service not known", "unreachable": true}
ok: [my-host-02]
ok: [my-host-01]
TASK [Check ALL hosts are reacheable before doing the release] ********************************************************************************************************************************************************************************************************************
failed: [my-host-01] (item=my-host-03) => {"changed": false, "item": "my-host-03", "msg": "[REQUIRED] ALL hosts to be reachable, so flagging my-host-01 as failed, because host my-host-03 has no facts, meaning it is UNREACHABLE."}
failed: [my-host-01] (item=my-host-04) => {"changed": false, "item": "my-host-04", "msg": "[REQUIRED] ALL hosts to be reachable, so flagging my-host-01 as failed, because host my-host-04 has no facts, meaning it is UNREACHABLE."}
failed: [my-host-02] (item=my-host-03) => {"changed": false, "item": "my-host-03", "msg": "[REQUIRED] ALL hosts to be reachable, so flagging my-host-02 as failed, because host my-host-03 has no facts, meaning it is UNREACHABLE."}
failed: [my-host-02] (item=my-host-04) => {"changed": false, "item": "my-host-04", "msg": "[REQUIRED] ALL hosts to be reachable, so flagging my-host-02 as failed, because host my-host-04 has no facts, meaning it is UNREACHABLE."}
skipping: [my-host-01] => (item=my-host-01)
skipping: [my-host-01] => (item=my-host-02)
skipping: [my-host-02] => (item=my-host-01)
skipping: [my-host-02] => (item=my-host-02)
to retry, use: --limit @./my-playbook.retry
PLAY RECAP *********************************************************************************************************************************************************************************************************************
my-host-01 : ok=1 changed=0 unreachable=0 failed=1
my-host-02 : ok=1 changed=0 unreachable=0 failed=1
my-host-03 : ok=0 changed=0 unreachable=1 failed=0
my-host-04 : ok=0 changed=0 unreachable=1 failed=0