snap: set compression to lzo, #117852

[soredake]

On ryzen 1800x + nvme first launch of vscode takes 6-7 seconds, that's too much.

https://ubuntu.com//blog/snap-speed-improvements-with-new-compression-algorithm
https://snapcraft.io/blog/why-lzo-was-chosen-as-the-new-compression-method

This PR fixes #117852

[joaomoreno]

Thanks!

[RMacfarlane]

I've temporarily reverted this since the builds are failing with "Issues while validating snapcraft.yaml: Additional properties are not allowed ('compression' was unexpected)". We're using snapcraft version 4.4.4, I suspect we just need to update to the newest version

[joaomoreno]

This is strange, since it should be supported according to canonical/snapcraft@48c8047

[soredake]

Any progress on this?

[joaomoreno]

Feel free to do some investigation why this doesn't seem to work from the docker image we're using:

vscode/build/azure-pipelines/product-build.yml

Line 119 in 640fa1a

image: snapcore/snapcraft:stable

[soredake]

Feel free to do some investigation why this doesn't seem to work from the docker image we're using:

vscode/build/azure-pipelines/product-build.yml

Line 119 in 640fa1a

image: snapcore/snapcraft:stable

Dunno what's wrong, i've successfully built snap with lzo compression in stable container.

[anonymouse64]

just a note that if you are unable to upgrade the version of snapcraft you are using, you can always just use the passthrough key for situations like this:

name: code
version: ....

passthrough:
  compression: lzo

see https://snapcraft.io/docs/using-in-development-features

[soredake]

#119067

[joaomoreno]

I've used passthrough in https://github.com/microsoft/vscode/tree/joao/retry-pr-118116 and that didn't work:

$ unsquashfs -s code-insider-x64-1615902963.snap | grep Compression
Compression xz

I'm currently reaching out to the Snap team via e-mail. Will let you know the outcome.

[anonymouse64]

@joaomoreno ah yeah that's correct that the compression setting is only consumed by snapcraft and not by snapd sorry about that ...

However, if you still are unable to upgrade the version of snapcraft you are using to build with to one that supports the compression setting, you can manually change it by doing something like this:

$ snapcraft prime
... gives you the prime directory which is everything that goes into the snap
$ snap pack --compression=lzo prime
... gives you a LZO compressed snap

[joaomoreno]

@anonymouse64 I really wouldn't know how to do that since we just call snapcraft:

vscode/build/azure-pipelines/linux/snap-build-linux.yml

Line 51 in a23d2d4

(cd $SNAP_ROOT/code-* && sudo --preserve-env snapcraft snap $SNAPCRAFT_TARGET_ARGS --output "$SNAP_PATH")

PR welcome!

[anonymouse64]

@joaomoreno Ah so this is actually a snapcraft working as "intended", VS code is not using base: in it's snapcraft.yaml, so it is getting built with the legacy version of snapcraft which does not get feature updates and thus doesn't understand compression. I think the best way to fix this is for you to add base: core to your snapcraft.yaml, then make sure the snap still works (as you might have to change a few things in the snapcraft.yaml to accommodate slightly stricter rules about things that the new version of snapcraft requires), and then after that change the snapcraft.yaml to use compression: lzo.

[joaomoreno]

Right, if that's the way to go, we're gonna have to wait. TBH doing big updates on snap has always been quite the adventure with an often large tail of issues. I've created this as a follow-up: #119436

[anonymouse64]

@joaomoreno I understand, in the meantime I can try and submit a PR changing your build script as linked to do the snap pack workaround instead, I don't know how to test out the changes locally but it looks straight forward and it should be run as part of a PR I open, correct? Anyways, perhaps we can continue discussion on the PR I will open momentarily changing your build script...

[joaomoreno]

Merged #119478