Docs: Network become for privilege mode (#33367)
* Network become for privilege mode * Document what privilege mode is * How to tell if you need it * How to enable * Tidy up formatting on page * authorize & auth_pass * network group_vars.
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John R Barker
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*****************************
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Become (Privilege Escalation)
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+++++++++++++++++++++++++++++
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*****************************
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Ansible can use existing privilege escalation systems to allow a user to execute tasks as another.
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.. contents:: Topics
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Become
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``````
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======
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Ansible allows you to 'become' another user, different from the user that logged into the machine (remote user). This is done using existing privilege escalation tools such as `sudo`, `su`, `pfexec`, `doas`, `pbrun`, `dzdo`, `ksu`, `runas` and others.
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.. note:: Prior to version 1.9, Ansible mostly allowed the use of `sudo` and a limited use of `su` to allow a login/remote user to become a different user and execute tasks and create resources with the second user's permissions. As of Ansible version 1.9, `become` supersedes the old sudo/su, while still being backwards compatible. This new implementation also makes it easier to add other privilege escalation tools, including `pbrun` (Powerbroker), `pfexec`, `dzdo` (Centrify), and others.
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.. note:: Become vars and directives are independent. For example, setting `become_user` does not set `become`.
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.. note:: Become vars and directives are independent. For example, setting ``become_user`` does not set ``become``.
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Directives
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-----------
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==========
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These can be set from play to task level, but are overridden by connection variables as they can be host specific.
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become
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set to 'true'/'yes' to activate privilege escalation.
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set to ``yes`` to activate privilege escalation.
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become_user
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set to user with desired privileges — the user you 'become', NOT the user you login as. Does NOT imply `become: yes`, to allow it to be set at host level.
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set to user with desired privileges — the user you `become`, NOT the user you login as. Does NOT imply ``become: yes``, to allow it to be set at host level.
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become_method
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(at play or task level) overrides the default method set in ansible.cfg, set to `sudo`/`su`/`pbrun`/`pfexec`/`doas`/`dzdo`/`ksu`/`runas`
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@ -37,20 +40,20 @@ For example, to manage a system service (which requires ``root`` privileges) whe
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service:
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name: httpd
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state: started
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become: true
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become: yes
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To run a command as the ``apache`` user::
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- name: Run a command as the apache user
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command: somecommand
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become: true
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become: yes
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become_user: apache
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To do something as the ``nobody`` user when the shell is nologin::
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- name: Run a command as nobody
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command: somecommand
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become: true
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become: yes
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become_method: su
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become_user: nobody
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become_flags: '-s /bin/sh'
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@ -63,23 +66,23 @@ ansible_become
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equivalent of the become directive, decides if privilege escalation is used or not.
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ansible_become_method
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allows to set privilege escalation method
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which privilege escalation method should be used
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ansible_become_user
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allows to set the user you become through privilege escalation, does not imply `ansible_become: True`
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set the user you become through privilege escalation; does not imply ``ansible_become: yes``
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ansible_become_pass
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allows you to set the privilege escalation password
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set the privilege escalation password. See :doc:`playbooks_vault` for details on how to avoid having secrets in plain text
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For example, if you want to run all tasks as ``root`` on a server named ``webserver``, but you can only connect as the ``manager`` user, you could use an inventory entry like this::
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webserver ansible_user=manager ansible_become=true
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webserver ansible_user=manager ansible_become=yes
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Command line options
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--------------------
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--ask-become-pass, -K
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ask for privilege escalation password, does not imply become will be used
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ask for privilege escalation password; does not imply become will be used. Note that this password will be used for all hosts.
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--become, -b
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run operations with become (no password implied)
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@ -109,7 +112,7 @@ Although privilege escalation is mostly intuitive, there are a few limitations
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on how it works. Users should be aware of these to avoid surprises.
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Becoming an Unprivileged User
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=============================
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Ansible 2.0.x and below has a limitation with regards to becoming an
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unprivileged user that can be a security risk if users are not aware of it.
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@ -179,21 +182,21 @@ modules you want to run there to be world readable, you can turn on
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a warning and allow the task to run as it did prior to 2.1.
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Connection Plugin Support
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=========================
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^^^^^^^^^^^^^^^^^^^^^^^^^
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Privilege escalation methods must also be supported by the connection plugin
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used. Most connection plugins will warn if they do not support become. Some
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will just ignore it as they always run as root (jail, chroot, etc).
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Only one method may be enabled per host
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=======================================
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Methods cannot be chained. You cannot use ``sudo /bin/su -`` to become a user,
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you need to have privileges to run the command as that user in sudo or be able
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to su directly to it (the same for pbrun, pfexec or other supported methods).
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Can't limit escalation to certain commands
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==========================================
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Privilege escalation permissions have to be general. Ansible does not always
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use a specific command to do something but runs modules (code) from
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@ -202,8 +205,109 @@ or '/bin/chmod' as the allowed commands this will fail with ansible as those
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paths won't match with the temporary file that ansible creates to run the
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module.
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.. _become-network:
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Become and Networks
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===================
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network_cli and become
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----------------------
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Ansible 2.5 added support for ``become`` to be used to enter `enable` mode (Privileged EXEC mode) on network devices that support it. This replaces the previous ``authorize`` and ``auth_pass`` options in ``provider``.
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This functionality requires the host connection type to be using ``connection: network_cli``. In Ansible 2.5 this is limited to ``eos`` and ``ios``.
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This allows privileges to be raised for the specific tasks that need them. Adding ``become: yes`` and ``become_method: enable`` informs Ansible to go into privilege mode before executing the task.
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If a task fails with the following then it's an indicator that `enable` mode is required:
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.. code-block:: console
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Invalid input (privileged mode required)
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The following example shows how to set enable mode for a specific task:
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.. code-block:: yaml
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- name: Gather facts (eos)
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eos_facts:
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gather_subset:
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- "!hardware"
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become: yes
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become_method: enable
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The following example shows how to set enable mode for `all` tests in this play:
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.. code-block:: yaml
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- hosts: eos-switches
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become: yes
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become_method: enable
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tasks:
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- name: Gather facts (eos)
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eos_facts:
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gather_subset:
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- "!hardware"
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FIXME: Can be specified per host
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Setting enable mode for all tasks
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---------------------------------
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Often you wish for all tasks to run using privilege mode, that is best achieved by using ``group_vars``:
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**group_vars/eos.yml**
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.. code-block:: yaml
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ansible_connection: network_cli
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ansible_network_os: eos
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ansible_user: myuser
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ansible_become: yes
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ansible_become_method: enable
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Passwords for enable mode
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^^^^^^^^^^^^^^^^^^^^^^^^^
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If a password is required to enter enable mode this can be specified by doing one of the following:
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* providing the :option:`--ask-become-pass <ansible-playbook --ask-become-pass>` command line option
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* setting the ``ansible_become_pass`` connection variable
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.. warning::
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As a reminder passwords should never be stored in plain text. See how encrypt secrets in vault :doc:`playbooks_vault` for more information.
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For more information about ``network_cli`` see :ref:`network-cli`.
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.. _become-network_auth_and_auth_password
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authorize and auth_pass
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-----------------------
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For network platforms that do not currently support ``connection: network_cli`` then the module options ``authorize`` and ``auth_pass`` can be used.
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.. code-block:: yaml
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- hosts: eos-switches
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ansible_connection: local
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tasks:
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- name: Gather facts (eos)
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eos_facts:
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gather_subset:
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- "!hardware"
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provider:
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authorize: yes
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auth_pass: " {{ secret_auth_pass }}"
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Note that over time more platforms will move to support ``become``. Check the :doc:`list_of_network_modules` for details.
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.. _become-windows:
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Become and Windows
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``````````````````
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==================
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Since Ansible 2.3, ``become`` can be used on Windows hosts through the
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``runas`` method. Become on Windows uses the same inventory setup and
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