Kernel plugin: Avoid redownloading os.snap on a local Git repo

[Dalton Durst]

Currently, if I make a change to my kernel source (I'm using a source in '.' in my case) then commit it, Snapcraft simply ignores the changes since it has pulled the source previously, printing 'Skipping pull kernel (already ran)'. I have to run 'snapcraft clean' in order to get it to pull the (local) source again. Snapcraft then goes on and redownloads 'os.snap', a 60MB file. On a fast connection, this is no problem. I'm on a slightly slower connection that also has a data cap, so this is a waste of both time and bits.

It seems like there are two ways to avoid this: Cache os.snap locally, or have Snapcraft run 'git pull' to grab source changes into its working directory. The second option seems better as it will behave similar to a non-snap build, where editing the source code has an immediate change.

[Kyle Fazzari (kyrofa)]

@Dalton, I don't quite understand what your source is in this case. It initially says that it's in '.' but then suggests using `git pull` as a solution. Any chance your project is public so we can take a look? Even if you could just paste a snippet of your YAML for the kernel part that would be useful.

[Dalton Durst (universalsuperbox)]

Hello Kyle,

This is the source of the kernel I'm using: https://github.com/ubports/android_kernel_fairphone_fp2/tree/snappy-experimental . More specifically, here's the snapcraft.yaml: https://github.com/ubports/android_kernel_fairphone_fp2/blob/snappy-experimental/snapcraft.yaml

This repository is cloned locally.

The kernel's source directory is . and its type is Git. When I run `snapcraft --target-arch=armhf` in the source directory, Snapcraft uses the local repo as a mirror and clones it into `./parts/kernel/src`.

[Kyle Fazzari (kyrofa)]

Excellent, thank you. All is clear now.