Failed to connect to the host via ssh

[chusiang]

當不使用 ssh key 而是使用 ansible_ssh_pass 和 ansible_sudo_pass 來處理連線的認證資訊時，有機會遇到 Failed to connect to the host via ssh 的錯誤訊。

Error message:

$ ansible all -m ping
server1 | UNREACHABLE! => {
    "changed": false,
    "msg": "Failed to connect to the host via ssh: Control socket connect(/root/.ansible/cp/570a47a2a4): Connection refused\r\nFailed to connect to new control master\r\n",
    "unreachable": true
}

版本資訊：

$ cat /etc/alpine-release
3.4.6

$ ansible --version
ansible 2.3.0.0
  config file = /srv/ansible_playbooks/ansible.cfg
  configured module search path = Default w/o overrides
  python version = 2.7.12 (default, Jun 29 2016, 08:57:23) [GCC 5.3.0]

[chusiang]

搞了半天，在下最後用了 -c paramiko 來避開此問題。Orz

$ ansible all -m ping -c paramiko
server1 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Reference

1. SSH works, but ansible throws unreachable error ansible/ansible#15321 (comment)
2. Failed to connect to the host via ssh. ansible/ansible#16354
3. 如何在執行 ansible-playbook 時，自動輸入 sudo 密碼？ #17
4. SSH bug?? Connection refused Failed to connect to new control master . semaphoreui/semaphore#309

[chusiang]

我想我知道為什麼了，@William-Yeh 包的 image 沒有安裝 openssh-client，而我一裝起它 Ansible 就會改用 SSH 的方式連接 managed node，而不是透過 paramiko。

或許在 Ansible 2.3 裡，ansible_ssh_pass 只有用 paramike 實作！？可我印象中在 Ansible 2.0 時不曾特別用 -c 來切換 paramiko 模式就可以用了啊。

[chusiang]

哈，果然把 openssh-client 給移除就不需要特別用 -c paramiko 了！

/srv # apk del openssh-client
WARNING: Ignoring APKINDEX.167438ca.tar.gz: No such file or directory
WARNING: Ignoring APKINDEX.a2e6dac0.tar.gz: No such file or directory
(1/1) Purging openssh-client (7.2_p2-r4)
Executing busybox-1.24.2-r13.trigger
OK: 111 MiB in 42 packages

$ ansible all -m ping
server1 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

[chusiang]

附上來自 Python 模塊基礎 | w3cschool 的 paramiko 介紹。

paramiko 是一個用於做遠程控制的模塊，使用該模塊可以對遠程服務器進行命令或文件操作，值得一說的是，fabric 和 ansible 內部的遠程管理就是使用的 paramiko 來實現。

[chusiang]

If we want to use the ssh mode, not paramiko, we need to setting something like this !

$ vim ./ansible.cfg
[defaults]
hostfile = hosts
transport = ssh
host_key_checking = False

[ssh_connection]
ssh_args =
scp_if_ssh = True

Reference

• SFTP disable な CentOS 環境で ansible を使う | たごもりすメモ
• Ansible Ad-hoc commands: failed to open a SFTP connection on Yocto Ansible Ad-hoc commands: failed to open a SFTP connection on Yocto #26