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.. _faq:
FAQ
***
How do I get help?
==================
Having trouble? We would like to help!
- First go through this page with answers to common questions
- Use the search bar at the upper left to search these docs
- Ask a question in the ``#cloud-init`` IRC channel on Freenode
- Join and ask questions on the `cloud-init mailing list <https://launchpad.net/~cloud-init>`_
- Find a bug? Check out the :ref:`reporting_bugs` topic for
how to report one
Where are the logs?
===================
Cloud-init uses two files to log to:
- `/var/log/cloud-init-output.log`: captures the output from each stage of
cloud-init when it runs
- `/var/log/cloud-init.log`: very detailed log with debugging output,
detailing each action taken
- `/run/cloud-init`: contains logs about how cloud-init decided to enable or
disable itself, as well as what platforms/datasources were detected. These
logs are most useful when trying to determine what cloud-init ran or did not
run.
Be aware that each time a system boots, new logs are appended to the files in
`/var/log`. Therefore, the files may have more than one boot worth of
information present.
When reviewing these logs look for any errors or Python tracebacks to check
for any errors.
Where are the configuration files?
==================================
Cloud-init config is provided in two places:
- `/etc/cloud/cloud.cfg`
- `/etc/cloud/cloud.cfg.d/*.cfg`
These files can define the modules that run during instance initialization,
the datasources to evaluate on boot, and other settings.
Where are the data files?
=========================
Inside the `/var/lib/cloud/` directory there are two important subdirectories:
instance
--------
The `/var/lib/cloud/instance` directory is a symbolic link that points
to the most recenlty used instance-id directory. This folder contains the
information cloud-init received from datasources, including vendor and user
data. This can be helpful to review to ensure the correct data was passed.
It also contains the `datasource` file that containers the full information
about what datasource was identified and used to setup the system.
Finally, the `boot-finished` file is the last thing that cloud-init does.
data
----
The `/var/lib/cloud/data` directory contain information related to the
previous boot:
* `instance-id`: id of the instance as discovered by cloud-init. Changing
this file has no effect.
* `result.json`: json file will show both the datasource used to setup
the instance, and if any errors occured
* `status.json`: json file shows the datasource used and a break down
of all four modules if any errors occured and the start and stop times.
What datasource am I using?
===========================
To correctly setup an instance, cloud-init must correctly identify the
cloud that it is on. Therefore knowing what datasource is used on an
instance launch can help aid in debugging.
To find what datasource is getting used run the `cloud-id` command:
.. code-block:: shell-session
$ cloud-id
nocloud
If the cloud-id is not what is expected, then running the `ds-identify`
script in debug mode and providing that in a bug can help aid in resolving
any issues:
.. code-block:: shell-session
$ sudo DEBUG_LEVEL=2 DI_LOG=stderr /usr/lib/cloud-init/ds-identify --force
The force parameter allows the command to be run again since the instance has
already launched. The other options increase the verbosity of logging and
put the logs to STDERR.
How can I debug my user data?
=============================
Two of the most common issues with user data, that also happens to be
cloud-config is:
1. Incorrectly formatted YAML
2. First line does not contain `#cloud-config`
To verify your YAML, we do have a short script called `validate-yaml.py`_
that can validate your user data offline.
.. _validate-yaml.py: https://github.com/canonical/cloud-init/blob/master/tools/validate-yaml.py
Another option is to run the following on an instance when debugging:
.. code-block:: shell-session
$ sudo cloud-init query userdata > user-data.yaml
$ cloud-init devel schema -c user-data.yaml --annotate
As launching instances in the cloud can cost money and take a bit longer,
sometimes it is easier to launch instances locally using Multipass or LXD:
Multipass
---------
`Multipass`_ is a cross-platform tool to launch Ubuntu VMs across Linux,
Windows, and macOS.
When a user launches a Multipass VM, user data can be passed by adding the
`--cloud-init` flag and the appropriate YAML file containing user data:
.. code-block:: shell-session
$ multipass launch bionic --name test-vm --cloud-init userdata.yaml
Multipass will validate the YAML syntax of the cloud-config file before
attempting to start the VM! A nice addition to help save time when
experimenting with launching instances with various cloud-configs.
Multipass only supports passing user-data and only as YAML cloud-config
files. Passing a script, a MIME archive, or any of the other user-data
formats cloud-init supports will result in an error from the YAML syntax
validator.
.. _Multipass: https://multipass.run/
LXD
---
`LXD`_ offers a streamlined user experience for using linux system
containers. With LXD, a user can pass:
* user data
* vendor data
* metadata
* network configuration
The following initializes a container with user data:
.. code-block:: shell-session
$ lxc init ubuntu-daily:bionic test-container
$ lxc config set test-container user.user-data - < userdata.yaml
$ lxc start test-container
To avoid the extra commands this can also be done at launch:
.. code-block:: shell-session
$ lxc launch ubuntu-daily:bionic test-container --config=user.user-data="$(cat userdata.yaml)"
Finally, a profile can be setup with the specific data if a user needs to
launch this multiple times:
.. code-block:: shell-session
$ lxc profile create dev-user-data
$ lxc profile set dev-user-data user.user-data - < cloud-init-config.yaml
$ lxc launch ubuntu-daily:bionic test-container -p default -p dev-user-data
The above examples all show how to pass user data. To pass other types of
configuration data use the config option specified below:
+----------------+---------------------+
| Data | Config Option |
+================+=====================+
| user data | user.user-data |
+----------------+---------------------+
| vendor data | user.vendor-data |
+----------------+---------------------+
| metadata | user.meta-data |
+----------------+---------------------+
| network config | user.network-config |
+----------------+---------------------+
See the LXD `Instance Configuration`_ docs for more info about configuration
values or the LXD `Custom Network Configuration`_ document for more about
custom network config.
.. _LXD: https://linuxcontainers.org/
.. _Instance Configuration: https://lxd.readthedocs.io/en/latest/instances/
.. _Custom Network Configuration: https://lxd.readthedocs.io/en/latest/cloud-init/
Where can I learn more?
========================================
Below are some videos, blog posts, and white papers about cloud-init from a
variety of sources.
- `Cloud Instance Initialization with cloud-init (Whitepaper)`_
- `cloud-init Summit 2018`_
- `cloud-init - The cross-cloud Magic Sauce (PDF)`_
- `cloud-init Summit 2017`_
- `cloud-init - Building clouds one Linux box at a time (Video)`_
- `cloud-init - Building clouds one Linux box at a time (PDF)`_
- `Metadata and cloud-init`_
- `The beauty of cloud-init`_
- `Introduction to cloud-init`_
.. _Cloud Instance Initialization with cloud-init (Whitepaper): https://ubuntu.com/blog/cloud-instance-initialisation-with-cloud-init
.. _cloud-init Summit 2018: https://powersj.io/post/cloud-init-summit18/
.. _cloud-init - The cross-cloud Magic Sauce (PDF): https://events.linuxfoundation.org/wp-content/uploads/2017/12/cloud-init-The-cross-cloud-Magic-Sauce-Scott-Moser-Chad-Smith-Canonical.pdf
.. _cloud-init Summit 2017: https://powersj.io/post/cloud-init-summit17/
.. _cloud-init - Building clouds one Linux box at a time (Video): https://www.youtube.com/watch?v=1joQfUZQcPg
.. _cloud-init - Building clouds one Linux box at a time (PDF): https://annex.debconf.org/debconf-share/debconf17/slides/164-cloud-init_Building_clouds_one_Linux_box_at_a_time.pdf
.. _Metadata and cloud-init: https://www.youtube.com/watch?v=RHVhIWifVqU
.. _The beauty of cloud-init: http://brandon.fuller.name/archives/2011/05/02/06.40.57/
.. _Introduction to cloud-init: http://www.youtube.com/watch?v=-zL3BdbKyGY
.. vi: textwidth=79
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