Install nixos

.github/actions/build-n-upload-action/Dockerfile

@@ -5,6 +5,10 @@ ENV TZ=Europe/Helsinki
 
 RUN apt-get update && apt-get -y install curl xz-utils git
 
+# Install nixos
+COPY install_nix.sh /install_nix.sh
+RUN /install_nix.sh
+
 # Copies your code file from your action repository to the filesystem path `/` of the container
 COPY entrypoint.sh /entrypoint.sh
 

.github/actions/build-n-upload-action/install_nix.sh

@@ -0,0 +1,101 @@
+#!/usr/bin/env bash
+
+# Based on install-nix-action by Cachix.
+# See:
+# https://github.com/cachix/install-nix-action/blob/master/install-nix.sh
+
+# shellcheck shell=bash
+
+NIX_VERSION='2.18.1'
+
+set -euo pipefail
+
+# Check if Nix is already installed
+if nix_path="$(type -p nix || command -v nix)"; then
+        echo "Aborting: Nix is already installed at ${nix_path}"
+        exit
+fi
+
+echo "Installing Nix version ${NIX_VERSION}"
+
+# Create a temporary workdir
+workdir=$(mktemp -d)
+trap 'rm -rf "$workdir"' EXIT
+
+# Helper function for writing Nix configuration
+function add_config() {
+        [[ -n $1 ]] && echo "$1" >>"${workdir}/nix.conf"
+}
+
+# Add header comment
+add_config "# Nix configuration reference:"
+add_config "# https://nixos.org/manual/nix/stable/command-ref/conf-file.html"
+
+# Basic config
+add_config "experimental-features = nix-command flakes repl-flake"
+add_config "system-features = nixos-test benchmark big-parallel kvm"
+add_config "use-xdg-base-directories = true"
+add_config "extra-nix-path = nixpkgs=flake:nixpkgs"
+
+# Allow binary caches for user
+add_config "trusted-users = root ${USER-}"
+
+# Add default NixOS binary cache
+add_config "substituters = https://cache.nixos.org/"
+add_config "trusted-substituters = https://cache.nixos.org/"
+add_config "trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+add_config "substitute = true"
+
+# Optimize store disk usage
+# add_config "auto-optimise-store = true"
+
+# Set GC thresholds to instruct Nix to do GC if available disk-space
+# in '/nix/store' drops below 'min-free' bytes during build.
+# Nix keeps doing GC until there is no more garbage, or until 'max-free'
+# bytes of disk space is available.
+# add_config "min-free = $((25 * 1024 * 1024 * 1024))"
+# add_config "max-free = $((50 * 1024 * 1024 * 1024))"
+
+# Keep compilers, derivations and such when running GC.
+# Also show stack trace on evaluation errors.
+# add_config "keep-outputs = true"
+# add_config "keep-derivations = true"
+add_config "show-trace = true"
+
+# Enable sandbox feature
+add_config "sandbox = true"
+
+# Maximum number of Nix jobs to build in parallel, 'auto' uses all available CPUs.
+add_config "max-jobs = auto"
+
+# This option controls the the parallelism of the builders, enabling
+# parallel building at the discretion of the builders (by setting the
+# NIX_BUILD_CORES env variable). For example for GNU Make this works
+# just like passing the '-jN' flag to Make. Setting of '0' means
+# use all available CPUs.
+add_config "cores = 0"
+
+unset -f add_config
+
+# Nix installer flags
+installer_options=(
+        --nix-extra-conf-file "${workdir}/nix.conf"
+        --daemon
+        --yes
+)
+
+echo "Nix installer options:"
+echo "${installer_options[*]}"
+
+# There is --retry-on-errors, but only newer curl versions support that
+curl_retries=5
+while ! curl -sS -o "${workdir}/install" -v --fail -L "https://releases.nixos.org/nix/nix-${NIX_VERSION}/install"; do
+        sleep 1
+        ((curl_retries--))
+        if [[ ${curl_retries} -le 0 ]]; then
+                echo "curl retries failed" >&2
+                exit 1
+        fi
+done
+
+sh "${workdir}/install" "${installer_options[@]}"