Support for adding user snippets to the user-data -- Perhaps a systemd unit abstraction ?

[hsyed]

My current use case is to mount an EFS drive on all cluster nodes. Perhaps there is support for doing this with DaemonSets -- or there is some other k8s mechanism for it. Regardless it would be nice if we could have abstractions for just verbatim appending user supplied chunks of data to the user-data scripts.

It would be fantastic if we could get some support at the level of coreos cloud-config minus the open ended and easy-to-get wrong nature of cloud-init and cloud-config.

An abstraction for supplying a directory with systemd unit files would be fantastic -- perhaps the abstraction could be made drop-in aware somehow ? All the operating systems under consideration have first class systemd support so it seems a clean and logical approach for user extension.

[chrislovecnm]

We are installing the base install. Bare bones. If you need CM after the fact. I encourage you to do that.

[krisnova]

Pointing #791 and #789 to each other..

More use cases for extending kops

[justinsb]

Daemonsets are the "k8s systemd unit file", so I think if we're going to support some extension mechanism, we should prefer that.

That said, I think we've agreed to support a post-boot shell-script or similar. Every time you use it an angel will lose its wings, but there will be that mechanism also.

[mdbishop]

Just wanted to add a vote for this. Our use case it to add system monitoring which is "unsupported" at this time running containerized so we'd like to have the agent install itself once a node is turned up. Especially with spot or preemptible's, taking this on as a one-off is untenable.

I'd be quite happy with nothing fancy -- just a bash script that could run after all the other init scripts have completed would be all I'd need. If folks had requirements more involved, the script could drop in a chef agent for instance, and (with all the caveats about not clobbering the carefully written k8s scripts) be good to go.

[sellers]

Being able to inject into the cloud-init user data would be helpful for being able to modify the results of the LC w/o having to build a custom AMI.

[KashifSaadat]

I believe this is covered by the implementation of Hooks (https://github.com/kubernetes/kops/blob/master/docs/cluster_spec.md#hooks), but otherwise extension of the user-data scripts may be covered in PR #3633.

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