fix: Exclude .deb files from release Docker image

[dwahler]

Currently, the codercom/code-server Docker image includes a copy of the release's .deb package files, even though they're only used in an intermediate layer. What's more, it includes packages from every architecture, not just the one being released.

This patch fixes this by updating the Dockerfile to use a multi-stage build. First, the packages are copied from the local build context into a temporary directory in a "scratch" build stage. Then, this directory is mounted into the main build, so that the appropriate .deb file can be installed without ever being actually stored in the image.

In my testing (with the 4.2.0 packages for linux-amd64) this reduces the total compressed and uncompressed size by a fairly substantial amount:

	Before	After	Change
compressed	637 MB	268 MB	-58%
uncompressed	1094 MB	724 MB	-34%

Partially fixes #4112

[dwahler]

I guess the "semantic pull request" check is failing because it wants a prefix on the PR title, but I'm not sure what would be most appropriate. It's not really a "feature", so maybe "perf"?

[code-asher]

Good question. perf seems good to me although we do not have that as an option so we would need to add it.

code-server/.github/semantic.yaml

Lines 37 to 66 in 5bc26e9

	types:
	# A build of any kind.
	- build
	# A user-facing change that corrects a defect in code-server.
	- fix
	# Any code task that is ignored for changelog purposes. Examples include
	# devbin scripts and internal-only configurations.
	- chore
	# Any work performed on CI.
	- ci
	# Work that directly implements or supports the implementation of a feature.
	- feat
	# A refactor changes code structure without any behavioral change.
	- refactor
	# A git revert for any style of commit.
	- revert
	# Adding tests of any kind. Should be separate from feature or fix
	# implementations. For example, if a commit adds a fix + test, it's a fix
	# commit. If a commit is simply bumping coverage, it's a test commit.
	- test
	# A new release.
	- release

[code-asher]

Those are some excellent savings. The multi-stage build is clever! Thanks for the improvement!

[codecov]

Codecov Report

Merging #5068 (63d0128) into main (5bc26e9) will not change coverage.
The diff coverage is n/a.

❗ Current head 63d0128 differs from pull request most recent head 163938d. Consider uploading reports for the commit 163938d to get more accurate results

@@           Coverage Diff           @@
##             main    #5068   +/-   ##
=======================================
  Coverage   71.30%   71.30%           
=======================================
  Files          30       30           
  Lines        1683     1683           
  Branches      373      373           
=======================================
  Hits         1200     1200           
  Misses        413      413           
  Partials       70       70           

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[jsjoeio]

Echoing Asher, those are some huge improvements. Thank you so much for doing this!