No support for Ubuntu Core?

[wills721]

Feature Description A short description of the feature you are proposing.

I currently run Greengrass Java version inside my Snap hosted by Ubuntu Core 24 (Snap is Core22). Our product has a Custom GW which runs on prem. I would really like to use instead Greengrass-lite. Doesn't seem to be designed at all for inside a Snap given all the systemctl service dependencies?

Use Case Why do you need this feature?

In order to run Greengrass lite on Ubuntu Core in an Embedded fashion. After all, this is what Ubuntu Core is for!?

Proposed Solution Please include prototype/workaround/sketch/reference
implementation

Support a process to incorporate inside a Snap?

Other Add detailed explanation, stacktraces, related issues, links for us to
have context, etc

• 👋 I am willing to implement this feature request
• ⚠️ This feature might incur a breaking change

[thomas-roos]

We already did some POC for running Greengrass lite inside a container. Installed by a snap. Would this be helpful for you? https://github.com/thomas-roos/container-snap

[wills721]

@thomas-roos

Thanks so much for this and responding. Yes and no. Trying to avoid Docker on embedded side as it is very memory and heavy space wise. The issue you solve inside Docker is the ability to kick off all the ggl* (etc) service daemons. systemctl is not available in a snap.

I am wondering though since there exists a deb to install lite that is there is a straightforward way to launch it? I mean add the deb to a snapcraft.yaml is easy enough -- it appears to put everything there but not the 'run_nucleus.sh' file.

Any reason why you didnt put docker inside the snap?

[wills721]

@thomas-roos Actually......

Ok. So maybe I will sign up for Docker. Basically, it takes everything out of the Snap. Not sure I'm crazy about that but maybe that is the only possible approach to running Lite on UC.

Question: I'm confused about something. In your container-snap (and thank you for sending you may have yourself a "customer" here) -- I'm not sure I see how the config.yaml (and certs) make it into the Docker container? I get the set-connection shell and the snap itself but it appears to write them all to docker-volume. I'm not seeing how this gets into the Docker container so it launches with the proper config.yaml (certs)?

[thomas-roos]

This is a POC for Bosch CtrlX OS - they have a docker service that starts different applications as containers.
One is greengrass lite here. Thus no docker inside or as a dependency of the snap. This is just bringing the container onto the device (could also be from somewhere else, but this is what they describe in their docs)
https://github.com/thomas-roos/container-snap/blob/101bbe8c2d202ffd4067bf37fae53c4c4290fe93/docker-compose/docker-compose.yml#L15 will mount the outside dir inside the docker, from inside it will use the config and certs.
Further also components could be placed outside and mapped inside (not tested).
Going further into this direction, the greengrass-lite container could be much smaller (done this with yocto here: https://github.com/aws4embeddedlinux/meta-aws-demos/blob/master/meta-aws-demos/recipes-core/images/aws-iot-greengrass-lite-container-demo-image/README.md - 43MB)
And then maybe the docker is "read only" and all write operations go just to the mapped devices.

This being said, this is the easiest to get greengrass lite running with snap. But ofc this also depends on your use case, your product...

Let me know what you think or what your constraints are - I mean if you are running snaps on ubuntu core you can also run docker there. Size wise IMHO this makes no sense, difference.

[wills721]

@thomas-roos Yes, that's exactly what I am trying out. Its almost like abandoning Snaps entirely in favor of running Docker. What you did here is a big help to me and I am working on getting it to work for my use-case. Thank you I will def keep you up to date.