Feature request: Custom/user definable cloud-init user-data

[james beedy]

Capabilty to specify custom user-data would make customizing juju deployed instances a breeze for admins.

I don't know how difficult of a task this would be to incorporate/implement into juju, but it sure would be cool!

[Anastasia (anastasia-macmood)]

Partial fix will be done when https://bugs.launchpad.net/juju/+bug/1615876 is addressed.

[Dmitrii Shcherbakov (dmitriis)]

Use-case:

* a multi-homed host which needs to set rp_filter to 0 (which is set to 1 on ubuntu by default)
* no way to do this other than by setting sysctls
* for bare-metal hosts & MAAS this can be done via curtin
* for LXD containers this is not possible (one would use this in manual setups https://github.com/lxc/lxd/blob/master/doc/cloud-init.md)

[Kevin W Monroe (kwmonroe)]

Any update on this? I see the following option in model-config:

-----
$ juju model-config| grep user
cloudinit-userdata default ""
-----

But I can't find docs to go along with it. Is this option meant to customize cloud-init for new machines in the model?

[james beedy (jamesbeedy)]

@kwmonroe that is just super!

[james beedy (jamesbeedy)]

I haven't heard of/seen it until now.

Please report back if/when you find out how to use this.

Possibly a docs bug might help expose it better?

[Heather Lanigan (hmlanigan)]

This functionality is available in juju 2.3.1+.

Here's a rough cut/paste on using the model config variable for now. I'll look at adding to the docs.

Note: This is a sharp knife feature - be careful with it!

Cloudinit-userdata

Allows the user to provide additional cloudinit data to be included in the cloudinit data created by juju. In general, specifying a key will overwrite what juju puts in the cloudinit file with the following caveats:
 * Users and bootcmd keys will cause an error
 * The packages key will be appended to the packages listed by juju
 * The runcmds key will cause an error. You can specify preruncmd and postruncmd keys to prepend and append the runcmd created by juju
Included in juju 2.3.1.

Using

Create a file, cloudinit-userdata.yaml, which starts with the cloudinit-userdata key and data you wish to include in the cloudinit file. Note: juju reads the value as a string, though formatted as yaml.
  juju model-config cloudinit-userdata.yaml
  juju model-config cloudinit-userdata
sample yaml:
cloudinit-userdata: |
  packages:
    - 'python-keystoneclient'
    - 'python-glanceclient'

[Heather Lanigan (hmlanigan)]

https://github.com/juju/juju/pull/8177
https://github.com/juju/juju/pull/8188
https://github.com/juju/juju/pull/8211
https://github.com/juju/juju/pull/8218

[Dmitrii Shcherbakov (dmitriis)]

\o/