Цель

Хотел бы понять механизм, почему использование становится , чтобы быть доступным пользователем, вызывает "

DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"

Связанные проблемы

• Ansible с Github: Permission denied (Publickey)
• Как исправить «Permission denied (publickey)». Проблема с Ansible и "git clone"
• Доступ к SSH_AUTH_SOCK от другого пользователя без полномочий root

Консоль -vvvvv output

TASK [check out the repository on the host] ************************************
task path: /home/ansible/playbooks/git.yml:12
Using module file /usr/lib/python2.7/site-packages/ansible/modules/core/source_control/git.py
<ub01> ESTABLISH SSH CONNECTION FOR USER: None
<ub01> SSH: ansible.cfg set ssh_args: (-o)(ControlMaster=auto)(-o)(ControlPersist=60s)(-o)(ForwardAgent=yes)
<ub01> SSH: ansible_password/ansible_ssh_pass not set: (-o)(KbdInteractiveAuthentication=no)(-o)(PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey)(-o)(PasswordAuthentication=no)
<ub01> SSH: ANSIBLE_TIMEOUT/timeout set: (-o)(ConnectTimeout=10)
<ub01> SSH: PlayContext set ssh_common_args: ()
<ub01> SSH: PlayContext set ssh_extra_args: ()
<ub01> SSH: found only ControlPersist; added ControlPath: (-o)(ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r)
<ub01> SSH: EXEC ssh -vvv -o ControlMaster=auto -o ControlPersist=60s -o ForwardAgent=yes -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r ub01 '/bin/sh -c '"'"'( umask 77 && mkdir -p "` echo /tmp/ansible-tmp-1485919043.94-240537002849590 `" && echo ansible-tmp-1485919043.94-240537002849590="` echo /tmp/ansible-tmp-1485919043.94-240537002849590 `" ) && sleep 0'"'"''
<ub01> PUT /tmp/tmpAjaOMc TO /tmp/ansible-tmp-1485919043.94-240537002849590/git.py
<ub01> SSH: ansible.cfg set ssh_args: (-o)(ControlMaster=auto)(-o)(ControlPersist=60s)(-o)(ForwardAgent=yes)
<ub01> SSH: ansible_password/ansible_ssh_pass not set: (-o)(KbdInteractiveAuthentication=no)(-o)(PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey)(-o)(PasswordAuthentication=no)
<ub01> SSH: ANSIBLE_TIMEOUT/timeout set: (-o)(ConnectTimeout=10)
<ub01> SSH: PlayContext set ssh_common_args: ()
<ub01> SSH: PlayContext set sftp_extra_args: ()
<ub01> SSH: found only ControlPersist; added ControlPath: (-o)(ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r)
<ub01> SSH: EXEC sftp -b - -vvv -o ControlMaster=auto -o ControlPersist=60s -o ForwardAgent=yes -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r '[ub01]'
<ub01> ESTABLISH SSH CONNECTION FOR USER: None
<ub01> SSH: ansible.cfg set ssh_args: (-o)(ControlMaster=auto)(-o)(ControlPersist=60s)(-o)(ForwardAgent=yes)
<ub01> SSH: ansible_password/ansible_ssh_pass not set: (-o)(KbdInteractiveAuthentication=no)(-o)(PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey)(-o)(PasswordAuthentication=no)
<ub01> SSH: ANSIBLE_TIMEOUT/timeout set: (-o)(ConnectTimeout=10)
<ub01> SSH: PlayContext set ssh_common_args: ()
<ub01> SSH: PlayContext set ssh_extra_args: ()
<ub01> SSH: found only ControlPersist; added ControlPath: (-o)(ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r)
<ub01> SSH: EXEC ssh -vvv -o ControlMaster=auto -o ControlPersist=60s -o ForwardAgent=yes -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r ub01 '/bin/sh -c '"'"'setfacl -m u:ansible:r-x /tmp/ansible-tmp-1485919043.94-240537002849590/ /tmp/ansible-tmp-1485919043.94-240537002849590/git.py && sleep 0'"'"''
<ub01> ESTABLISH SSH CONNECTION FOR USER: None
<ub01> SSH: ansible.cfg set ssh_args: (-o)(ControlMaster=auto)(-o)(ControlPersist=60s)(-o)(ForwardAgent=yes)
<ub01> SSH: ansible_password/ansible_ssh_pass not set: (-o)(KbdInteractiveAuthentication=no)(-o)(PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey)(-o)(PasswordAuthentication=no)
<ub01> SSH: ANSIBLE_TIMEOUT/timeout set: (-o)(ConnectTimeout=10)
<ub01> SSH: PlayContext set ssh_common_args: ()
<ub01> SSH: PlayContext set ssh_extra_args: ()
<ub01> SSH: found only ControlPersist; added ControlPath: (-o)(ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r)
<ub01> SSH: EXEC ssh -vvv -o ControlMaster=auto -o ControlPersist=60s -o ForwardAgent=yes -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r -tt ub01 '/bin/sh -c '"'"'sudo -H -S -n -u ansible /bin/sh -c '"'"'"'"'"'"'"'"'echo BECOME-SUCCESS-cxuzmrsbxdvydelfnjrsmgvocgkeptxd; /usr/bin/python /tmp/ansible-tmp-1485919043.94-240537002849590/git.py'"'"'"'"'"'"'"'"' && sleep 0'"'"''
<ub01> ESTABLISH SSH CONNECTION FOR USER: None
<ub01> SSH: ansible.cfg set ssh_args: (-o)(ControlMaster=auto)(-o)(ControlPersist=60s)(-o)(ForwardAgent=yes)
<ub01> SSH: ansible_password/ansible_ssh_pass not set: (-o)(KbdInteractiveAuthentication=no)(-o)(PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey)(-o)(PasswordAuthentication=no)
<ub01> SSH: ANSIBLE_TIMEOUT/timeout set: (-o)(ConnectTimeout=10)
<ub01> SSH: PlayContext set ssh_common_args: ()
<ub01> SSH: PlayContext set ssh_extra_args: ()
<ub01> SSH: found only ControlPersist; added ControlPath: (-o)(ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r)
<ub01> SSH: EXEC ssh -vvv -o ControlMaster=auto -o ControlPersist=60s -o ForwardAgent=yes -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ansible/.ansible/cp/ansible-ssh-%h-%p-%r ub01 '/bin/sh -c '"'"'rm -f -r /tmp/ansible-tmp-1485919043.94-240537002849590/ > /dev/null 2>&1 && sleep 0'"'"''
fatal: [ub01]: FAILED! => {
    "changed": false,
    "cmd": "/usr/bin/git clone --origin origin '' /home/ansible/project/mezzanine-example",
    "failed": true,
    "invocation": {
        "module_args": {
            "accept_hostkey": true,
            "bare": false,
            "clone": true,
            "depth": null,
            "dest": "/home/ansible/project/mezzanine-example",
            "executable": null,
            "force": false,
            "key_file": null,
            "recursive": true,
            "reference": null,
            "refspec": null,
            "remote": "origin",
            "repo": "git@github.com:lorin/mezzanine-example.git",
            "ssh_opts": null,
            "track_submodules": false,
            "umask": null,
            "update": true,
            "verify_commit": false,
            "version": "HEAD"
        },
        "module_name": "git"
    },
    "msg": "Cloning into '/home/ansible/project/mezzanine-example'...\nPermission denied (publickey).\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.",
    "rc": 128,
    "stderr": "Cloning into '/home/ansible/project/mezzanine-example'...\nPermission denied (publickey).\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.\n",
    "stdout": "",
    "stdout_lines": []
}
        to retry, use: --limit @/home/ansible/playbooks/git.retry

PLAY RECAP *********************************************************************
ub01                       : ok=1    changed=0    unreachable=0    failed=1

Обновление

Благодаря ответу @Jakuje и другим статьям мы поняли, что агент SSH прослушивает файл сокета UNIX. Имя файла хранится в переменной среды SSH_AUTH_SOCK. Однако SUDO исключает переменные среды, поэтому SSH-клиент sudo-ed не знает, как общаться с SSH-агентом. Следовательно, невозможно пройти аутентификацию SSH.

• Общие сведения о ssh-agent и ssh-add
• Полное руководство по SSH 6.3. Агенты SSH
• Иллюстрированное руководство по пересылке агентов SSH

Решение в статье, предоставленной @Jakuje.