Do you really need LXD?

[rswindell]

So I started down the snapcraft path and totally missed the instructions about LXD (install and use) and was making a lot of progress when I then noticed the instructions about installing/using LXD at:
https://docs.snapcraft.io/build-snaps/get-started-snapcraft

This got me totally derailed as I inadvertently installed the LXD Debian package instead of the LXD snap and ran into (known) problems (‘snapcraft cleanbuild’ failures), so I then uninstalled the .deb and eventually out of frustration uninstalled the LXD snap as well and now I’m back to successfully creating .snaps. So what gives? Is LXD really needed or it is just an obsolete requirement that wasn’t removed from the docs?

Thanks,

-Rob

[bashfulrobot]

It is primarily a clean build environment.

Have a peek at the first paragraph on this post as it gives a trail high level chunk of info.

Build providers

Snapcraft makes use of LXD and Multipass to both simplify the build process and to confine the build environment. LXD and Multipass are referred to as providers because they provide snapcraft with build environments. Choosing a provider Depending on which core you’re using as a base for Snapcraft, are a handful of ways to declare which provider to use. core22 and later On Linux, LXD is the default provider. On other systems (macOS and Windows), Multipass is the default. There are three ways t…

[Lin-Buo-Ren]

@rswindell

‘snapcraft cleanbuild’ failures

In fact, snapcraft’s cleanbuild is practically creating a new LXD container and run the build in it. The point is to provide a clean environment while not contaminating your working environment and is VERY useful. The LXD installation is from snap or debian package shouldn’t really matter much(though personally I never tried the snap installation), if it does then maybe there’s a bug to deal with.

Here’s a tutorial I wrote for making an LXD container for snap developing without the cleanbuild’s “feature” that destroys the container everytime a build is ended:

How to create a LXD container for snap development

Deprecation notice Snapcraft now supports the --use-lxd command-line option, which can create a clean, compatible LXD container for snap building instead of using a Multipass VM. While the instructions in this topic should still work to a degree we recommend using the built-in feature whenever possible to benefit from the upstream’s enhancements. License Creative Commons — Attribution-ShareAlike 4.0 International — CC BY-SA 4.0+, with an exception of explicitly licensed to be compatible with t…

[Lin-Buo-Ren]

Also if you encountered issues when running snapcraft cleanbuild there’s an --debug option to make it drop into a shell and let you debug the problem.

[Wimpress]

@rswindell At the time of writing snaps need to be built using an Ubuntu 16.04 host/container/VM. Installing LXD allows you to run Ubuntu 18.04 yet still build in 16.04 containers. More importantly, using LXD containers and snapcraft cleanbuild ensure you have a clean build environment for your snaps.

However, we do realise that using LXD and snapcraft cleanbuild is not an obvious route. To remedy this the Snapcraft team have been working on “Build VMs” to transparently create clean build environments for you. You can read more about it here:

[DRAFT] Consistent Build Environments: Build VMs

This is an initial draft subject to change Introduction snapcraft has always assumed that the build environment the developer was triggering the build from was the appropriate one for the snap at run-time. This assumption has many fallacies from the point of view of the current environment. It assumes the association with what is called the core snap today is well known and that it is based out of Ubuntu 16.04LTS. Furthermore, when building on an environment different than Ubuntu…