openstack/training-guides
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[upstream] systemd instead of screen for DevStack

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This updates the code-devstack slides to explain how
to use systemd instead of screen.  It notes that sceen
is now deprecated.  The exercise has been updated to
use systemd instead of screen.

Change-Id: Ie63249c98044b90bd64aa19a730792f26a2f7e3f
Co-Authored-By: Mars Toktonaliev <mars.toktonaliev@nokia.com>
Co-Authored-By: Jay S. Bryant <jsbryant@electronicjungle.net>
This commit is contained in:
Ian Y. Choi 2017-05-04 01:08:47 +02:00 committed by Ildiko Vancsa
parent 76a2a7e0ae
commit ccac650f41
1 changed files with 34 additions and 21 deletions
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55
doc/upstream-training/source/slides/code-devstack.rst
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@ -64,35 +64,28 @@ http://localhost/
.. image:: ./_assets/devstack-http-localhost.png
:width: 100%
Using Linux 'screen'
====================
Running services in DevStack
============================
- Access the terminals the installed services are running in
- Use command 'screen -ls' to see the running screen sessions
- Use command 'screen -R <session name>' or 'screen -C stack-screenrc' to
attach to or start a new session
- For further commands see the
`User's Manual <https://www.gnu.org/software/screen/manual/screen.html>`_
- ``screen`` command was used to access the virtual terminals running the
installed services
- ``screen`` use is now deprecated
- To use ``screen`` explicitly set ``USE_SCREEN=True`` option in
``local.conf``
- More details: `Developing with Devstack <https://docs.openstack.org/developer/devstack/development.html>`_
.. image:: ./_assets/devstack-screen.png
:width: 90%
:align: center
Exercise
========
- Ensure you have the DevStack repository cloned to the VM where you
would like to use it
- Using the 'screen' command determine if there is a screen session running
in your VM. If there is, attach to it. If not, start a new session.
- Once attached to a screen session switch between the running services to
get to your favorite service and try stopping and restarting the service.
- Disconnect from your screen session and ensure it is still running in the
background.
.. note::
- Commands needed:
- Screen is going away in Queens
: http://lists.openstack.org/pipermail/openstack-dev/2017-May/116301.html
- Useful screen commands:
- List sessions: screen -ls
- Connect: screen -R <session name>
@ -101,4 +94,24 @@ Exercise
- Kill and restart a service: <ctrl>-c , <up arrow> to retrieve command
- Disconnect: <ctrl>-a d
DevStack services with Systemd
==============================
- ``systemd`` is the replacement for ``screen``
- Services in DevStack are running as ``systemd`` units named
devstack@$servicename.service
- Interact with services using commands like
``sudo systemctl <start|stop|restart> devstack@$servicename.service``
- Follow logs with ``journalctl -f --unit devstack@$servicename.service``
- More details: `Using Systemd in DevStack <https://docs.openstack.org/developer/devstack/systemd.html>`_
Exercise
========
- Ensure you have the DevStack repository cloned to the VM where you
would like to use it
- Use ``systemctl status devstack@*`` to ensure devstack is running on your VM.
If it is not started, start it with ``systemctl start devstack@*``
- Use the ``journalctl`` command to view output from your favorite service
- Ensure you can use commands like ``cinder`` or ``nova`` to interact with
the services running on your VM