*: Migrate to Nix flakes, deprecate non-GHA CI

This simplifies the project setup and makes it easier to maintain the
CI pipeline.

.build.yml

@@ -1,48 +0,0 @@
-image: "nixos/latest"
-packages:
-    - nixos.go
-    - nixos.git
-    - nixos.gcc
-sources:
-    - https://github.com/diamondburned/arikawa
-secrets:
-    # Integration test secrets.
-    - f51d6157-b4be-4697-99d0-6cd129243f63
-environment:
-    GO111MODULE: "on"
-    CGO_ENABLED: "1"
-    # Integration test variables.
-    SHARD_COUNT: "2"
-    tested: "./api,./gateway,./bot,./discord"
-    cov_file: "/tmp/cov_results"
-    dismock: "github.com/mavolin/dismock/v2/pkg/dismock"
-    dismock_v: "259685b84e4b6ab364b0fd858aac2aa2dfa42502"
-
-tasks:
-    - generate: |-
-        cd arikawa
-        go generate ./...
-
-        if [[ "$(git status --porcelain)" ]]; then
-            echo "Repository differ after regeneration."
-            exit 1
-        fi
-
-    - build: cd arikawa && go build ./...
-    - unit:  cd arikawa && go test -tags unitonly -race ./...
-
-    - integration: |-
-        sh -c '
-            test -f ~/.env || {
-                echo "Skipped integration tests."
-                exit 0
-            }
-
-            cd arikawa
-            go get ./...
-            go get $dismock@$dismock_v
-
-            source ~/.env
-            go test -coverpkg $tested -coverprofile $cov_file -race ./... $dismock
-            go tool cover -func $cov_file
-        '

.github/workflows/test.yml

@@ -12,24 +12,13 @@ on:
         type: boolean
 
 jobs:
-  nix-env:
-    name: Initialize Nix
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-
-      - name: Install Nix packages
-        uses: diamondburned/cache-install@main
-
   generate:
     name: Generate
-    needs: [nix-env]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-
+      - uses: DeterminateSystems/nix-installer-action@main
-      - name: Install Nix packages
+      - uses: DeterminateSystems/magic-nix-cache-action@main
-        uses: diamondburned/cache-install@main
 
       - name: Generate
         run: |
@@ -46,35 +35,36 @@ jobs:
           fi
         env:
           GITHUB_REF: ${{ github.ref }}
+        shell: nix develop -c {0}
 
   build:
     name: Build
     runs-on: ubuntu-latest
     needs: [generate]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-
+      - uses: DeterminateSystems/nix-installer-action@main
-      - name: Install Nix packages
+      - uses: DeterminateSystems/magic-nix-cache-action@main
-        uses: diamondburned/cache-install@main
 
       - name: Build
-        run: go build ./...
+        run: go build -v ./...
+        shell: nix develop -c {0}
 
   unit-test:
     name: Unit Test
     runs-on: ubuntu-latest
     needs: [build]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-
+      - uses: DeterminateSystems/nix-installer-action@main
-      - name: Install Nix packages
+      - uses: DeterminateSystems/magic-nix-cache-action@main
-        uses: diamondburned/cache-install@main
 
       - name: Test
         run: go test $TEST_FLAGS ./...
         env:
           TEST_FLAGS: >-
             -v=${{ runner.debug && '1' || '0' }}
+        shell: nix develop -c {0}
 
   integration-test:
     name: Integration Test
@@ -82,10 +72,9 @@ jobs:
     runs-on: ubuntu-latest
     needs: [build]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-
+      - uses: DeterminateSystems/nix-installer-action@main
-      - name: Install Nix packages
+      - uses: DeterminateSystems/magic-nix-cache-action@main
-        uses: diamondburned/cache-install@main
 
       - name: Test
         run: |
@@ -99,6 +88,7 @@ jobs:
           GUILD_ID: ${{ secrets.GUILD_ID }}
           VOICE_ID: ${{ secrets.VOICE_ID }}
           BOT_TOKEN: ${{ secrets.BOT_TOKEN }}
+        shell: nix develop -c {0}
 
       - name: Upload coverage profile
         uses: actions/upload-artifact@v3

.gitlab-ci.yml

@@ -1,53 +0,0 @@
-{
-  "image": "golang:alpine",
-  "variables": {
-    "GO111MODULE": "on",
-    "CGO_ENABLED": "1", # for the race detector
-    "COV": "/tmp/cov_results",
-    "dismock": "github.com/mavolin/dismock/v3/pkg/dismock",
-    "dismock_v": "259685b84e4b6ab364b0fd858aac2aa2dfa42502",
-    # used only in integration_test
-    "tested": "./api,./gateway,./bot,./discord"
-  },
-  "before_script": [
-    "apk add git build-base"
-    "go get ./...",
-    "go get $dismock@$dismock_v",
-  ],
-  "stages": [
-    "build",
-    "test"
-  ],
-  "build_test": {
-    "stage": "build",
-    "script": [
-      "go build ./..."
-    ]
-  },
-  "unit_test": {
-    "stage": "test",
-    "timeout": "4m", # 4 minutes
-    # Don't run the test if we have a $BOT_TOKEN, because
-    # integration_test will run instead.
-    "except": {
-      "variables": [ "$BOT_TOKEN" ]
-    },
-    "script": [
-      "go test -coverpkg $tested -coverprofile $COV -tags unitonly -v -race ./... $dismock",
-      "go tool cover -func $COV"
-    ]
-  },
-  "integration_test": {
-    "stage": "test",
-    "timeout": "8m", # 8 minutes
-    # Run the test only if we have $BOT_TOKEN, else fallback to unit
-    # tests.
-    "only": {
-      "variables": [ "$BOT_TOKEN", "$CHANNEL_ID", "$VOICE_ID" ]
-    },
-    "script": [
-      "go test -coverpkg $tested -coverprofile $COV -v -race ./... $dismock",
-      "go tool cover -func $COV"
-    ]
-  }
-}

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1726560853,
+        "narHash": "sha256-X6rJYSESBVr3hBoH0WbKE5KvhPU5bloyZ2L4K60/fPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c1dfcf08411b08f6b8615f7d8971a2bfa81d5e8a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1728492678,
+        "narHash": "sha256-9UTxR8eukdg+XZeHgxW5hQA9fIKHsKCdOIUycTryeVw=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "5633bcff0c6162b9e4b5f1264264611e950c8ec7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,31 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            go_1_22
+            gopls
+            go-tools
+
+            nixfmt-rfc-style
+          ];
+        };
+      }
+    );
+}

shell.nix

@@ -1,11 +0,0 @@
-{ pkgs ? import <nixpkgs> {} }:
-
-pkgs.mkShell {
-	buildInputs = with pkgs; [
-		go
-		gopls
-		go-tools
-	];
-
-	CGO_ENABLED = "1";
-}