Linux (debian) multiarch support issues due to unpinned single-arch azure apt sources

[ryankurte]

Description
Nominally debian supports multiarch packages for cross-platform builds (via dpkg --add-architecture), however, the github actions linux environment adds a set of default repos (see below) that do not provide all common architectures thus breaking multiarch support.

This could be resolved by pinning the default non-multiarch apt repositories to [arch=amd64], mitigating the need for users to manually perform this patching to adding additional architectures.

Area for Triage:
Packages

Question, Bug, or Feature?:
Bug

Virtual environments affected

• Ubuntu 16.04
• Ubuntu 18.04
• Ubuntu 20.04
• macOS 10.15
• macOS 11.0
• Windows Server 2016 R2
• Windows Server 2019

Expected behavior
Running sudo dpkg --add-architecture armhf && sudo apt update should succeed and add support for installing :armhf packages.

Actual behavior
Following the addition of an architecture apt update fails due to missing architectures (from here:

Run sudo dpkg --add-architecture armhf
  sudo dpkg --add-architecture armhf
  sudo apt update -y
  sudo apt install -y libusb-1.0:armhf libusb-dev:armhf
  shell: /bin/bash -e {0}
  env:
    CARGO_TERM_COLOR: always
    GITHUB_REPOSITORY_SLUG: ryankurte-ringlight
    GITHUB_REPOSITORY_OWNER: ryankurte
    GITHUB_REPOSITORY_OWNER_SLUG: ryankurte
    GITHUB_REPOSITORY_NAME: ringlight
    GITHUB_REPOSITORY_NAME_SLUG: ringlight
    GITHUB_REF_SLUG: refs-heads-master
    GITHUB_REF_NAME: master
    GITHUB_REF_NAME_SLUG: master
    GITHUB_SHA_SHORT: c629b88d

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Hit:1 http://azure.archive.ubuntu.com/ubuntu bionic InRelease
...
Err:58 http://security.ubuntu.com/ubuntu bionic-security/main armhf Packages
  404  Not Found [IP: 91.189.88.152 80]
Ign:61 http://security.ubuntu.com/ubuntu bionic-security/restricted armhf Packages
Ign:64 http://security.ubuntu.com/ubuntu bionic-security/universe armhf Packages
Get:69 http://ppa.launchpad.net/ondrej/php/ubuntu bionic/main amd64 Packages [81.4 kB]
Ign:66 http://security.ubuntu.com/ubuntu bionic-security/multiverse armhf Packages
Get:70 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu bionic/main armhf Packages [23.4 kB]
Fetched 8516 kB in 4s (2299 kB/s)
Reading package lists...
E: Failed to fetch http://azure.archive.ubuntu.com/ubuntu/dists/bionic/main/binary-armhf/Packages  404  Not Found [IP: 52.252.75.106 80]
E: Failed to fetch http://azure.archive.ubuntu.com/ubuntu/dists/bionic-updates/main/binary-armhf/Packages  404  Not Found [IP: 52.252.75.106 80]
E: Failed to fetch http://azure.archive.ubuntu.com/ubuntu/dists/bionic-backports/main/binary-armhf/Packages  404  Not Found [IP: 52.252.75.106 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/bionic-security/main/binary-armhf/Packages  404  Not Found [IP: 91.189.88.152 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
Error: Process completed with exit code 100.

Repro steps

A build step that adds an architecture then attempts to update the repository listing.

    - name: Install libusb (apt armv7)
      if: ${{ matrix.os == 'ubuntu-latest' && matrix.target == 'armv7-unknown-linux-gnueabihf' }}
      run: |
        sudo dpkg --add-architecture armhf
        sudo apt update -y
        sudo apt install -y libusb-1.0:armhf libusb-dev:armhf

[dsame]

@ryankurte now the apt use default source.lists only for amd and i386 architectures, so you do not need to modify the existing sources to add another architectures.

Fill free to reopen this issue or to create a new one if you think your problem is not solved

[ryankurte]

thanks for looking at this! i can see the changes in master though they don't seem to have arrived in my builds, which report Environment: ubuntu-18.04 and Version: 20201115.1, do i need to do anything to prompt an update of the environment version?

[LeonidLapshin]

Hi, @ryankurte !
These changes will be applied with the next image rollout on the next week, I'll reopen this issue until next Ubuntu image release and report about it in this ticket :)
Thank you!

[ryankurte]

so this is fixed and landed! but, still requires some work as you then have to go and add standard / working sources.

i've wrapped this fix, as well as the rest of the required bits up into a composite action (now that's a thing) here so hopefully this helps others doing multiarch things with actions ^_^