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Constructing and Privately Caching x86 and aarch64 NixOS Programs with Github Actions :: LGUG2Z

Constructing and Privately Caching x86 and aarch64 NixOS Programs with Github Actions :: LGUG2Z

2024-01-22 10:42:18

Within the previous
article

we walked via methods to arrange our very personal Nix binary
cache
.

It’s nice having the ability to run attic push system /run/current-system on
whichever machine we’re at present utilizing, however the the probabilities are that if you happen to
use Nix to handle your system configurations, you’ve got a system configuration
monorepo, and relying on what number of machines and architectures you’re
concentrating on, it might probably rapidly change into tiresome to manually push to the cache from
every of them.

My configuration repo presently has 4 targets:

  • NixOS VM that runs on WSL (x86_64)
  • Naked steel Hetzner server (x86_64)
  • Raspberry Pi operating in my residence community (aarch64)
  • Manufacturing occasion of https://notado.app (x86_64)

Constructing NixOS system configurations

NixOS system configurations are primarily construct artifacts. Since they’re
construct artifacts, it is smart to construct, cache and push them in CI pipelines,
proper? Proper!

Though GitHub Actions is
awful
, it may be made
siginificantly much less terrible by putting in Nix instantly after we run
actions/checkout@v4. As soon as we’ve got Nix put in, we are able to side-step the poorly
maintained npm-esque “actions” ecosystem nearly totally.

When you’ve got subscribed to my YouTube
channel

you could have seen a video the place I constructed the system configurations for my NixOS
starter
templates

on GitHub Actions.

Right here is an instance construct.yml from the
nixos-hetzner-robot-starter
template.

title: "construct"

jobs:
  construct:
    runs-on: ubuntu-latest
    steps:
      - makes use of: actions/checkout@v4
      - makes use of: DeterminateSystems/nix-installer-action@fundamental
      - makes use of: DeterminateSystems/magic-nix-cache-action@fundamental
      - run: nix construct -L .#deploy.nodes.robotic.profiles.system.path

Painless, proper? We simply checkout the repo, set up Nix, optionally set up
magic-nix-cache, after which run a nix construct command!

Constructing extra advanced NixOS system configurations

Starter templates are fairly simple to construct, however as soon as we begin including issues
like secrets and techniques and packages from personal repositories, totally different structure
targets and many others. to our system configurations, naturally we’ll must adapt our
construct.yml

Dealing with personal repositories

The nix-installer-action has a useful enter the place you may put a generated
GitHub token with entry to the personal repositories you want. This shall be
used at any time when the construct wants to tug one thing like a flake enter from certainly one of
your personal repos. While you add this as a GitHub Actions secret, observe that you just
gained’t be capable of use the GITHUB_ prefix for the title as that’s reserved.

Moreover, you can even configure git to make use of this token, which is helpful
if that you must try any personal submodules in your configuration repo
earlier than you may run nix construct.

- makes use of: DeterminateSystems/nix-installer-action@fundamental
  with:
    github-token: ${{ secrets and techniques.GH_TOKEN }}
- run: |
    git config --global url."https://${{ secrets and techniques.GH_TOKEN }}@github.com".insteadOf https://github.com    

Dealing with secrets and techniques encrypted with git-crypt

Whereas secrets and techniques encrypted with sops-nix are left out gracefully throughout a
system construct, git-crypted recordsdata which are utilized in a system configuration will
end in a construct error if they don’t seem to be decrypted.

We are able to deal with this state of affairs by exporting a symmetric key, encoding it in
base64, including it as a secret variable in GitHub Actions after which decoding it
to decrypt the related recordsdata in our construct job.

git-crypt export-key ./exported-key
cat exported-key | base64 --encode > encoded-key

# Retailer the worth of `encoded-key` as a secret variable in GitHub Actions

With the encoded key in place as a GitHub Actions secret, we are able to add a step to
decode it and decrypt any git-crypted recordsdata in our repo.

- run: |
    echo "${{ secrets and techniques.GIT_CRYPT_KEY }}" | base64 --decode > key
    nix profile set up nixpkgs#git-crypt
    git-crypt unlock key    

Dealing with totally different architectures

Usually if you wish to construct packages for an aarch64-linux machine on an
x86_64-linux machine, you simply must specify that structure as an
emulated system.

{
    boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
}

I got here throughout an article by David
Wagner

which confirmed methods to replicate this in GitHub Actions with a combination of
docker-setup-qemu
and specifying aarch64-linux as an extra-platform in nix.conf.

jobs:
  construct:
    runs-on: ubuntu-latest
    steps:
      - makes use of: actions/checkout@v4
      - makes use of: docker/setup-qemu-action@v3
      - makes use of: DeterminateSystems/nix-installer-action@fundamental
        with:
          extra-conf: |
            extra-platforms = aarch64-linux            

That is nice, however we don’t really want to run docker-setup-qemu once we are
constructing x86_64-linux programs, so let’s tweak this a little bit.

See Also

We are able to introduce a matrix which comprises every of our machines and their
respective platforms, and use that data to solely run the
docker-setup-qemu step if we’re constructing an aarch64 system.

jobs:
  construct:
    runs-on: ubuntu-latest
    technique:
      matrix:
        machine:
          - host: nixsl
            platform: x86-64-linux
          - host: hetzner
            platform: x86-64-linux
          - host: notado
            platform: x86-64-linux
          - host: pi3
            platform: aarch64-linux
    steps:
      - makes use of: actions/checkout@v4
      - if: matrix.machine.platform == 'aarch64-linux'
        makes use of: docker/setup-qemu-action@v3

Configuring entry to our Attic binary cache

In case you recall from the earlier article, to be able to work together with our Attic binary cache, we needed to do three issues.

  • Log in with our token to have the ability to push
- run: |
    nix run github:zhaofengli/attic#default login fly https://<your fly app title>.fly.dev ${{ secrets and techniques.ATTIC_TOKEN }}    
  • Add our token to a netrc file to be licensed to question
- run: |
    sudo mkdir -p /and many others/nix
    echo "machine <your fly app title>.fly.dev password ${{ secrets and techniques.ATTIC_TOKEN }}" | sudo tee /and many others/nix/netrc > /dev/null    
  • Replace our substituters and trusted-public-keys to have the ability to question throughout builds
- makes use of: DeterminateSystems/nix-installer-action@fundamental
  with:
    extra-conf: |
      substituters = https://<your fly app title>.fly.dev/system?precedence=43 https://nix-community.cachix.org?precedence=41 https://numtide.cachix.org?precedence=42 https://cache.nixos.org/
      trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= system:5M8uBPjS68HTadSbeCs0Jiu0Z1tJBNdahtKBCXhl+Z0= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs= numtide.cachix.org-1:2ps1kLBUWjxIneOy1Ik6cQjb41X0iXVXeHigGmycPPE=      

Placing all of it collectively

title: "construct"

jobs:
  construct:
    runs-on: ubuntu-latest
    technique:
      fail-fast: false
      # Right here we specify the matrix of our hosts and their goal platform architectures
      matrix:
        machine:
          - host: nixsl
            platform: x86-64-linux
          - host: hetzner
            platform: x86-64-linux
          - host: notado
            platform: x86-64-linux
          - host: pi3
            platform: aarch64-linux

    steps:
      - makes use of: actions/checkout@v4

      # We solely run this if we're constructing an aarch64-linux system
      - if: matrix.machine.platform == 'aarch64-linux'
        makes use of: docker/setup-qemu-action@v3

      # We make our netrc file that's used to make licensed requests to Attic
      # We additionally ensure that we use our customized GitHub token if we have to clone submodules or something like that
      - run: |
          sudo mkdir -p /and many others/nix
          echo "machine <your fly app title>.fly.dev password ${{ secrets and techniques.ATTIC_TOKEN }}" | sudo tee /and many others/nix/netrc > /dev/null
          git config --global url."https://${{ secrets and techniques.GH_TOKEN }}@github.com".insteadOf https://github.com          

      - makes use of: DeterminateSystems/nix-installer-action@fundamental
        with:
          # We set our customized GitHub token for any personal flake inputs we would have
          github-token: ${{ secrets and techniques.GH_TOKEN }}
          # We add all of the config for additional platforms, different binary caches and to lift the variety of connections that may be made
          extra-conf: |
            fallback = true
            http-connections = 128
            max-substitution-jobs = 128
            extra-platforms = aarch64-linux
            substituters = https://<your fly app title>.fly.dev/system?precedence=43 https://nix-community.cachix.org?precedence=41 https://numtide.cachix.org?precedence=42 https://cache.nixos.org/
            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= system:5M8uBPjS68HTadSbeCs0Jiu0Z1tJBNdahtKBCXhl+Z0= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs= numtide.cachix.org-1:2ps1kLBUWjxIneOy1Ik6cQjb41X0iXVXeHigGmycPPE=            
      - makes use of: DeterminateSystems/magic-nix-cache-action@fundamental
      # We ensure that any git-crypted recordsdata are decrypted earlier than we start to construct
      - run: |
          echo "${{ secrets and techniques.GIT_CRYPT_KEY }}" | base64 --decode > key
          nix profile set up nixpkgs#git-crypt
          git-crypt unlock key          

      # We construct every system in a separate job, concentrating on the configuration utilizing matrix.machine.host
      # As soon as constructed, we login to Attic and push the constructed system to our `system` cache!
      - title: Construct and push system
        run: |
          nix construct .#nixosConfigurations.${{ matrix.machine.host }}.config.system.construct.toplevel
          nix run github:zhaofengli/attic#default login fly https://<your fly app title>.fly.dev ${{ secrets and techniques.ATTIC_TOKEN }}
          nix run github:zhaofengli/attic#default push system outcome -j 2          

When you’ve got any questions or feedback you may attain out to me on
Twitter and
Mastodon.

In case you’re fascinated about what I learn to provide you with options like this one,
you may subscribe to my Software Development RSS
feed
.

In case you’d like to observe me writing code whereas explaining what I’m doing, you may
additionally subscribe to my YouTube
channel
.

In case you discovered this content material helpful, or in case you are a contented consumer of the
komorebi tiling window supervisor or my
NixOS starter
templates
,
please take into account sponsoring me on GitHub
or tipping me on Ko-fi.



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