149 lines
4.8 KiB
Markdown
149 lines
4.8 KiB
Markdown
# install-nix-action
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Installs [Nix](https://nixos.org/nix/) on GitHub Actions for the supported platforms: Linux and macOS.
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By default it has no nixpkgs configured, you have to set `nix_path`
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by [picking a channel](https://status.nixos.org/)
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or [pin nixpkgs yourself](https://nix.dev/reference/pinning-nixpkgs)
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(see also [pinning tutorial](https://nix.dev/tutorials/towards-reproducibility-pinning-nixpkgs)).
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# Features
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- Quick installation (~4s on Linux, ~20s on macOS)
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- Multi-User installation (with sandboxing enabled only on Linux)
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- [Self-hosted GitHub runner](https://docs.github.com/en/actions/hosting-your-own-runners/about-self-hosted-runners) support
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- Allows specifying Nix installation URL via `install_url` (the oldest supported Nix version is 2.3.5)
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- Allows specifying extra Nix configuration options via `extra_nix_config`
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- Allows specifying `$NIX_PATH` and channels via `nix_path`
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- Share `/nix/store` between builds using [cachix-action](https://github.com/cachix/cachix-action) for simple binary cache setup to speed up your builds and share binaries with your team
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- Enables `flakes` and `nix-command` experimental features by default (to disable, set `experimental-features` via `extra_nix_config`)
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## Usage
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Create `.github/workflows/test.yml` in your repo with the following contents:
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```yaml
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name: "Test"
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on:
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pull_request:
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push:
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jobs:
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tests:
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v3
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- uses: cachix/install-nix-action@v20
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with:
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nix_path: nixpkgs=channel:nixos-unstable
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- run: nix-build
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```
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## Usage with Flakes
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```yaml
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name: "Test"
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on:
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pull_request:
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push:
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jobs:
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tests:
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v3
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- uses: cachix/install-nix-action@v20
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with:
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github_access_token: ${{ secrets.GITHUB_TOKEN }}
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- run: nix build
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- run: nix flake check
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```
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To install Nix from any commit, go to [the corresponding installer_test action](https://github.com/NixOS/nix/runs/2219534360) and click on "Run cachix/install-nix-action@XX" step and expand the first line.
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## Inputs (specify using `with:`)
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- `extra_nix_config`: append to `/etc/nix/nix.conf`
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- `github_access_token`: configure Nix to pull from GitHub using the given GitHub token. This helps work around rate limit issues. Has no effect when `access-tokens` is also specified in `extra_nix_config`.
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- `install_url`: specify URL to install Nix from (useful for testing non-stable releases or pinning Nix, for example https://releases.nixos.org/nix/nix-2.3.7/install)
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- `install_options`: additional installer flags passed to the installer script.
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- `nix_path`: set `NIX_PATH` environment variable, for example `nixpkgs=channel:nixos-unstable`
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---
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## FAQ
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### How do I print nixpkgs version I have configured?
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```yaml
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- name: Print nixpkgs version
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run: nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
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```
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### How do I run NixOS tests?
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With the following inputs:
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```yaml
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- uses: cachix/install-nix-action@vXX
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with:
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extra_nix_config: "system-features = nixos-test benchmark big-parallel kvm"
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```
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[Note that there's no hardware acceleration on GitHub Actions.](https://github.com/actions/virtual-environments/issues/183#issuecomment-610723516).
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### How do I install packages via nix-env from the specified `nix_path`?
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```
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nix-env -i mypackage -f '<nixpkgs>'
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```
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### How do I add a binary cache?
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If the binary cache you want to add is hosted on [Cachix](https://cachix.org/) and you are
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using [cachix-action](https://github.com/cachix/cachix-action), you
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should use their `extraPullNames` input like this:
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```yaml
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- uses: cachix/cachix-action@vXX
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with:
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name: mycache
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authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
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extraPullNames: nix-community
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```
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Otherwise, you can add any binary cache to nix.conf using
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install-nix-action's own `extra_nix_config` input:
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```yaml
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- uses: cachix/install-nix-action@v20
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with:
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extra_nix_config: |
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trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
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substituters = https://hydra.iohk.io https://cache.nixos.org/
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```
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### How do I pass environment variables to commands run with `nix develop` or `nix shell`?
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Nix runs commands in a restricted environment by default, called `pure mode`.
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In pure mode, environment variables are not passed through to improve the reproducibility of the shell.
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You can use the `--keep / -k` flag to keep certain environment variables:
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```yaml
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- name: Run a command with nix develop
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run: nix develop --ignore-environment --keep MY_ENV_VAR --command echo $MY_ENV_VAR
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env:
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MY_ENV_VAR: "hello world"
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```
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Or you can disable pure mode entirely with the `--impure` flag:
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```
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nix develop --impure
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```
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