Fix conflicts with main

Update `detsys-ts`:

.editorconfig

@@ -1,15 +1,10 @@
-# EditorConfig helps developers define and maintain consistent
-# coding styles between different editors and IDEs
-# editorconfig.org
-
+# https://editorconfig.org
 root = true
 
 [*]
-charset = utf-8
-end_of_line = lf
-insert_final_newline = true
-trim_trailing_whitespace = true
 indent_style = space
-
-[*.{yml,yaml}]
 indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

.envrc

@@ -0,0 +1 @@
+use flake

.eslintrc.json

@@ -0,0 +1,74 @@
+{
+  "plugins": ["@typescript-eslint"],
+  "extends": ["plugin:github/recommended"],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 9,
+    "sourceType": "module",
+    "project": "./tsconfig.json"
+  },
+  "settings": {
+    "import/resolver": {
+      "typescript": {}
+    }
+  },
+  "rules": {
+    "i18n-text/no-en": "off",
+    "eslint-comments/no-use": "off",
+    "import/no-namespace": "off",
+    "no-unused-vars": "off",
+    "@typescript-eslint/no-unused-vars": [
+      "error",
+      {
+        "argsIgnorePattern": "^_"
+      }
+    ],
+    "@typescript-eslint/explicit-member-accessibility": [
+      "error",
+      {
+        "accessibility": "no-public"
+      }
+    ],
+    "@typescript-eslint/no-base-to-string": "error",
+    "@typescript-eslint/no-require-imports": "error",
+    "@typescript-eslint/array-type": "error",
+    "@typescript-eslint/await-thenable": "error",
+    "@typescript-eslint/ban-ts-comment": "error",
+    "camelcase": "error",
+    "@typescript-eslint/consistent-type-assertions": "error",
+    "@typescript-eslint/explicit-function-return-type": [
+      "error",
+      {
+        "allowExpressions": true
+      }
+    ],
+    "@typescript-eslint/func-call-spacing": ["error", "never"],
+    "@typescript-eslint/no-array-constructor": "error",
+    "@typescript-eslint/no-empty-interface": "error",
+    "@typescript-eslint/no-explicit-any": "error",
+    "@typescript-eslint/no-floating-promises": "error",
+    "@typescript-eslint/no-extraneous-class": "error",
+    "@typescript-eslint/no-for-in-array": "error",
+    "@typescript-eslint/no-inferrable-types": "error",
+    "@typescript-eslint/no-misused-new": "error",
+    "@typescript-eslint/no-namespace": "error",
+    "@typescript-eslint/no-non-null-assertion": "warn",
+    "@typescript-eslint/no-unnecessary-qualifier": "error",
+    "@typescript-eslint/no-unnecessary-type-assertion": "error",
+    "@typescript-eslint/no-useless-constructor": "error",
+    "@typescript-eslint/no-var-requires": "error",
+    "@typescript-eslint/prefer-for-of": "warn",
+    "@typescript-eslint/prefer-function-type": "warn",
+    "@typescript-eslint/prefer-includes": "error",
+    "@typescript-eslint/prefer-string-starts-ends-with": "error",
+    "@typescript-eslint/promise-function-async": "error",
+    "@typescript-eslint/require-array-sort-compare": "error",
+    "@typescript-eslint/restrict-plus-operands": "error",
+    "@typescript-eslint/type-annotation-spacing": "error",
+    "@typescript-eslint/unbound-method": "error"
+  },
+  "env": {
+    "node": true,
+    "es6": true
+  }
+}

.github/workflows/ci.yml

@@ -5,8 +5,8 @@ on:
     branches: [main]
 
 jobs:
-  shellcheck:
-    runs-on: ubuntu-latest
+  typescript-action:
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
         with:
@@ -15,5 +15,19 @@ jobs:
         uses: DeterminateSystems/nix-installer-action@main
       - name: Enable magic Nix cache
         uses: DeterminateSystems/magic-nix-cache-action@main
-      - name: Shellcheck
-        run: nix-shell --run 'shellcheck $(find . -type f -name "*.sh" -executable)'
+      - name: Install pnpm dependencies
+        run: nix develop --command pnpm install
+      - name: Check formatting
+        run: nix develop --command pnpm run check-fmt
+      - name: Lint
+        run: nix develop --command pnpm run lint
+      - name: Build
+        run: nix develop --command pnpm run build
+      - name: Run test suite
+        run: nix develop --command pnpm run test
+      - name: Package
+        run: nix develop --command pnpm run package
+      - name: Check git status
+        run: git status --porcelain=v1
+      - name: Ensure no staged changes
+        run: git diff --exit-code

.github/workflows/update.yml

@@ -2,7 +2,7 @@ name: update-flake-lock
 on:
   workflow_dispatch:
   schedule:
-    - cron: '0 0 * * 0'
+    - cron: "0 0 * * 0"
 
 jobs:
   lockfile:
@@ -18,3 +18,5 @@ jobs:
         uses: DeterminateSystems/flake-checker-action@main
       - name: Update flake.lock
         uses: ./.
+        with:
+          _internal-strict-mode: true

.github/workflows/validate.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   validate:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
         with:

.gitignore

@@ -0,0 +1,2 @@
+# JS dependencies
+node_modules/

.prettierignore

@@ -0,0 +1,5 @@
+dist/
+lib/
+node_modules/
+pnpm-lock.yaml
+README.md

README.md

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@main
       - name: Update flake.lock
@@ -50,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -75,7 +75,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -98,7 +98,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -127,7 +127,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -138,6 +138,23 @@ jobs:
           path-to-flake-dir: 'nix/' # in this example our flake doesn't sit at the root of the repository, it sits under 'nix/flake.nix'
 ```
 
+You can also run the update operation in multiple directories, provided that each directory is a valid flake:
+
+```yaml
+- name: Update flake.lock
+  uses: DeterminateSystems/update-flake-lock@vX
+  with:
+    flake-dirs: |
+      flake1
+      flake2
+      flake3
+```
+
+> **Warning**: If you choose multiple directories, `update-flake-lock` can only update all flake inputs,
+> meaning that you can't set the `inputs` parameter. This is due to limitations in input handling in
+> GitHub Actions, which only allows for strings, numbers, Booleans, and arrays but not objects, which
+> would be the much preferred data type for expressing per-directory inputs.
+
 ## Example using a different Git user
 
 If you want to change the author and / or committer of the flake.lock update commit, you can tweak the `git-{author,committer}-{name,email}` options:
@@ -154,7 +171,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -199,7 +216,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -234,7 +251,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
@@ -296,7 +313,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock

action.yml

@@ -1,35 +1,65 @@
-name: 'Update Nix Flake Lock'
-description: 'Update your Nix flake.lock and send a PR'
+name: "Update Nix Flake Lock"
+description: "Update your Nix flake.lock and send a PR"
 inputs:
   inputs:
-    description: 'A space-separated list of inputs to update. Leave empty to update all inputs.'
+    description: "A space-separated list of inputs to update. Leave empty to update all inputs."
     required: false
-    default: ''
+    default: ""
   token:
-    description: 'GITHUB_TOKEN or a `repo` scoped Personal Access Token (PAT)'
+    description: "GITHUB_TOKEN or a `repo` scoped Personal Access Token (PAT)"
     required: false
     default: ${{ github.token }}
-  commit-msg:
-    description: 'The message provided with the commit'
+  commit-msg-template:
+    description: |
+      The commit message template to use. You can use these variables in your template:
+
+      * `{{ flake_dot_lock }}` is the path to the `flake.lock` file being updated
+      * `{{ flake_dot_lock_dir }}` is the `flake.lock` file's directory
+
+      If you set both this and `commit-msg`, the `commit-msg` setting is used (it does not support templating).
+    required: false
+    default: |
+      flake.lock: Updated in {{ flake_dot_lock_dir }}
+  commit-msg:
+    description: |
+      The message provided with the commit.
     required: false
-    default: "flake.lock: Update"
   base:
     description: "Sets the pull request base branch. Defaults to the branch checked out in the workflow."
     required: false
   branch:
-    description: 'The branch of the PR to be created'
+    description: "The branch of the PR to be created"
     required: false
     default: "update_flake_lock_action"
   path-to-flake-dir:
-    description: 'The path of the directory containing `flake.nix` file within your repository. Useful when `flake.nix` cannot reside at the root of your repository.'
+    description: |
+      The path of the directory containing `flake.nix` file within your repository.
+      Useful when `flake.nix` cannot reside at the root of your repository.
     required: false
-    default: ''
+  flake-dirs:
+    description: |
+      A space-separated list of directories containing `flake.nix` files within your repository.
+      Useful when you have multiple flakes in your repository.
+    required: false
+    default: ""
   pr-title:
-    description: 'The title of the PR to be created'
+    description: "The title of the PR to be created"
     required: false
     default: "flake.lock: Update"
+  pr-body-template:
+    description: |
+      The pull request body template to use. You can use these variables in your template:
+
+      * `{{ comma_separated_dirs }}` is the flake directories that were updated separated by comma
+      * `{{ space_separated_dirs }}` is the flake directories that were updated separated by space
+      * `{{ updated_dirs_list }}` is the flake directories that were updated as a Markdown list
+
+      If you set both this and `pr-body`, the `pr-body` setting is used (it does not support templating).
+    required: false
+    default: |
+      Just testing.
   pr-body:
-    description: 'The body of the PR to be created'
+    description: "The body of the PR to be created"
     required: false
     default: |
       Automated changes by the [update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock) GitHub Action.
@@ -53,58 +83,62 @@ inputs:
       ```
 
   pr-labels:
-    description: 'A comma or newline separated list of labels to set on the Pull Request to be created'
+    description: "A comma or newline separated list of labels to set on the Pull Request to be created"
     required: false
-    default: ''
+    default: ""
   pr-assignees:
-    description: 'A comma or newline separated list of assignees (GitHub usernames).'
+    description: "A comma or newline separated list of assignees (GitHub usernames)."
     required: false
-    default: ''
+    default: ""
   pr-reviewers:
-    description: 'A comma or newline separated list of reviewers (GitHub usernames) to request a review from.'
+    description: "A comma or newline separated list of reviewers (GitHub usernames) to request a review from."
     required: false
-    default: ''
+    default: ""
   git-author-name:
-    description: 'Author name used for commit. Only used if sign-commits is false.'
+    description: "Author name used for commit. Only used if sign-commits is false."
     required: false
-    default: 'github-actions[bot]'
+    default: "github-actions[bot]"
   git-author-email:
-    description: 'Author email used for commit. Only used if sign-commits is false.'
+    description: "Author email used for commit. Only used if sign-commits is false."
     required: false
-    default: 'github-actions[bot]@users.noreply.github.com'
+    default: "github-actions[bot]@users.noreply.github.com"
   git-committer-name:
-    description: 'Committer name used for commit. Only used if sign-commits is false.'
+    description: "Committer name used for commit. Only used if sign-commits is false."
     required: false
-    default: 'github-actions[bot]'
+    default: "github-actions[bot]"
   git-committer-email:
-    description: 'Committer email used for commit. Only used if sign-commits is false.'
+    description: "Committer email used for commit. Only used if sign-commits is false."
     required: false
-    default: 'github-actions[bot]@users.noreply.github.com'
+    default: "github-actions[bot]@users.noreply.github.com"
   sign-commits:
-    description: 'Set to true if the action should sign the commit with GPG'
+    description: "Set to true if the action should sign the commit with GPG"
     required: false
-    default: 'false'
+    default: "false"
   gpg-private-key:
-    description: 'GPG Private Key with which to sign the commits in the PR to be created'
+    description: "GPG Private Key with which to sign the commits in the PR to be created"
     required: false
-    default: ''
+    default: ""
   gpg-fingerprint:
-    description: 'Fingerprint of specific GPG subkey to use'
+    description: "Fingerprint of specific GPG subkey to use"
     required: false
   gpg-passphrase:
-    description: 'GPG Private Key Passphrase for the GPG Private Key with which to sign the commits in the PR to be created'
+    description: "GPG Private Key Passphrase for the GPG Private Key with which to sign the commits in the PR to be created"
     required: false
-    default: ''
+    default: ""
   nix-options:
-    description: 'A space-separated list of options to pass to the nix command'
+    description: "A space-separated list of options to pass to the nix command"
     required: false
-    default: ''
+    default: ""
+  _internal-strict-mode:
+    description: Whether to fail when any errors are thrown. Used only to test the Action; do not set this in your own workflows.
+    required: false
+    default: false
 outputs:
   pull-request-number:
-    description: 'The number of the opened pull request'
+    description: "The number of the opened pull request"
     value: ${{ steps.create-pr.outputs.pull-request-number }}
   pull-request-operation:
-    description: 'The pull request operation performed by the action, `created`, `updated` or `closed`.'
+    description: "The pull request operation performed by the action, `created`, `updated` or `closed`."
     value: ${{ steps.create-pr.outputs.pull-request-operation }}
 runs:
   using: "composite"
@@ -115,7 +149,7 @@ runs:
       uses: crazy-max/ghaction-import-gpg@v6
       with:
         gpg_private_key: ${{ inputs.gpg-private-key }}
-        fingerprint: ${{ inputs.gpg-fingerprint }}
+        fingerprint: ${{ inputs.gpg-fingerprint }}
         passphrase: ${{ inputs.gpg-passphrase }}
         git_config_global: true
         git_user_signingkey: true
@@ -142,23 +176,44 @@ runs:
         echo "GIT_AUTHOR_EMAIL=<${{ inputs.git-author-email }}>" >> $GITHUB_ENV
         echo "GIT_COMMITTER_NAME=${{ inputs.git-committer-name }}" >> $GITHUB_ENV
         echo "GIT_COMMITTER_EMAIL=<${{ inputs.git-committer-email }}>" >> $GITHUB_ENV
-    - name: Run update-flake-lock.sh
-      run: $GITHUB_ACTION_PATH/update-flake-lock.sh
+    - name: Run update-flake-lock
+      id: update-flake-lock
       shell: bash
+      run: node "$GITHUB_ACTION_PATH/dist/index.js"
       env:
-        GIT_AUTHOR_NAME: ${{ env.GIT_AUTHOR_NAME }}
-        GIT_AUTHOR_EMAIL: ${{ env.GIT_AUTHOR_EMAIL }}
-        GIT_COMMITTER_NAME: ${{ env.GIT_COMMITTER_NAME }}
-        GIT_COMMITTER_EMAIL: ${{ env.GIT_COMMITTER_EMAIL }}
-        NIX_OPTIONS: ${{ inputs.nix-options }}
-        TARGETS: ${{ inputs.inputs }}
-        COMMIT_MSG: ${{ inputs.commit-msg }}
-        PATH_TO_FLAKE_DIR: ${{ inputs.path-to-flake-dir }}
+        # The following manually exposes all of the action inputs into INPUT_ environment variables so actionsCore.getInput works:
+        # https://github.com/actions/toolkit/blob/ae38557bb0dba824cdda26ce787bd6b66cf07a83/packages/core/src/core.ts#L126
+        INPUT_BASE: ${{ inputs.base }}
+        INPUT_BRANCH: ${{ inputs.branch }}
+        INPUT_COMMIT-MSG: ${{ inputs.commit-msg }}
+        INPUT_COMMIT-MSG-TEMPLATE: ${{ inputs.commit-msg-template }}
+        INPUT_GIT-AUTHOR-EMAIL: ${{ inputs.git-author-email }}
+        INPUT_GIT-AUTHOR-NAME: ${{ inputs.git-author-name }}
+        INPUT_GIT-COMMITTER-EMAIL: ${{ inputs.git-committer-email }}
+        INPUT_GIT-COMMITTER-NAME: ${{ inputs.git-committer-name }}
+        INPUT_GPG-FINGERPRINT: ${{ inputs.gpg-fingerprint }}
+        INPUT_GPG-PASSPHRASE: ${{ inputs.gpg-passphrase }}
+        INPUT_GPG-PRIVATE-KEY: ${{ inputs.gpg-private-key }}
+        INPUT_INPUTS: ${{ inputs.inputs }}
+        INPUT_NIX-OPTIONS: ${{ inputs.nix-options }}
+        INPUT_PATH-TO-FLAKE-DIR: ${{ inputs.path-to-flake-dir }}
+        INPUT_FLAKE-DIRS: ${{ inputs.flake-dirs }}
+        INPUT_PR-ASSIGNEES: ${{ inputs.pr-assignees }}
+        INPUT_PR-BODY: ${{ inputs.pr-body }}
+        INPUT_PR-BODY-TEMPLATE: ${{ inputs.pr-body-template }}
+        INPUT_PR-LABELS: ${{ inputs.pr-labels }}
+        INPUT_PR-REVIEWERS: ${{ inputs.pr-reviewers }}
+        INPUT_PR-TITLE: ${{ inputs.pr-title }}
+        INPUT_PULL-REQUEST-NUMBER: ${{ inputs.pull-request-number }}
+        INPUT_PULL-REQUEST-OPERATION: ${{ inputs.pull-request-operation }}
+        INPUT_SIGN-COMMITS: ${{ inputs.sign-commits }}
+        INPUT_TOKEN: ${{ inputs.token }}
+        INPUT__INTERNAL-STRICT-MODE: ${{ inputs._internal-strict-mode }}
     - name: Save PR Body as file
       uses: DamianReeves/write-file-action@v1.3
       with:
         path: pr_body.template
-        contents: ${{ inputs.pr-body }}
+        contents: ${{ steps.update-flake-lock.outputs.pr-body }}
       env: {}
     - name: Set additional env variables (GIT_COMMIT_MESSAGE)
       shell: bash
@@ -172,8 +227,8 @@ runs:
     - name: Interpolate PR Body
       uses: pedrolamas/handlebars-action@v2.4.0
       with:
-        files: 'pr_body.template'
-        output-filename: 'pr_body.txt'
+        files: "pr_body.template"
+        output-filename: "pr_body.txt"
     - name: Read pr_body.txt
       id: pr_body
       uses: juliangruber/read-file-action@v1

dist/index.d.ts

@@ -0,0 +1,2 @@
+
+export {  }

dist/package.json

@@ -0,0 +1,3 @@
+{
+  "type": "module"
+}

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1696604326,
-        "narHash": "sha256-YXUNI0kLEcI5g8lqGMb0nh67fY9f2YoJsILafh6zlMo=",
-        "rev": "87828a0e03d1418e848d3dd3f3014a632e4a4f64",
-        "revCount": 533189,
+        "lastModified": 1713537308,
+        "narHash": "sha256-XtTSSIB2DA6tOv+l0FhvfDMiyCmhoRbNB+0SeInZkbk=",
+        "rev": "5c24cf2f0a12ad855f444c30b2421d044120c66f",
+        "revCount": 614481,
         "type": "tarball",
-        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.533189%2Brev-87828a0e03d1418e848d3dd3f3014a632e4a4f64/018b0dc8-e84f-7c59-b5d6-16849c3b2074/source.tar.gz"
+        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.614481%2Brev-5c24cf2f0a12ad855f444c30b2421d044120c66f/018efa00-a443-7f41-b371-ce568b5c7e9f/source.tar.gz"
       },
       "original": {
         "type": "tarball",
-        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.1.533189.tar.gz"
+        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.1.%2A.tar.gz"
       }
     },
     "root": {

flake.nix

@@ -1,30 +1,23 @@
 {
   description = "update-flake-lock";
 
-  inputs.nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.533189.tar.gz";
+  inputs.nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*.tar.gz";
 
-  outputs =
-    { self
-    , nixpkgs
-    }:
+  outputs = { self, nixpkgs }:
     let
-      nameValuePair = name: value: { inherit name value; };
-      genAttrs = names: f: builtins.listToAttrs (map (n: nameValuePair n (f n)) names);
-
-      allSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
-      forAllSystems = f: genAttrs allSystems
-        (system: f {
-          inherit system;
-          pkgs = import nixpkgs { inherit system; };
-        });
+      supportedSystems = [ "x86_64-linux" "aarch64-darwin" "aarch64-linux" "x86_64-darwin" ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import nixpkgs { inherit system; };
+      });
     in
     {
-      devShell = forAllSystems
-        ({ system, pkgs, ... }:
-          pkgs.stdenv.mkDerivation {
-            name = "update-flake-lock-devshell";
-            buildInputs = [ pkgs.shellcheck ];
-            src = self;
-          });
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [
+            nodejs_latest
+            nodePackages_latest.pnpm
+          ];
+        };
+      });
     };
 }

package.json

@@ -0,0 +1,49 @@
+{
+  "name": "update-flake-lock",
+  "version": "1.0.0",
+  "description": "",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "type": "module",
+  "scripts": {
+    "build": "tsup",
+    "format": "prettier --write .",
+    "check-fmt": "prettier --check .",
+    "lint": "eslint src/**/*.ts --ignore-pattern *.test.ts",
+    "package": "ncc build",
+    "test": "vitest --watch false",
+    "test-dev": "vitest",
+    "all": "pnpm run format && pnpm run lint && pnpm run build && pnpm run package"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/DeterminateSystems/update-flake-lock.git"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/DeterminateSystems/update-flake-lock/issues"
+  },
+  "homepage": "https://github.com/DeterminateSystems/update-flake-lock#readme",
+  "dependencies": {
+    "@actions/core": "^1.10.1",
+    "@actions/exec": "^1.1.1",
+    "detsys-ts": "github:DeterminateSystems/detsys-ts",
+    "handlebars": "^4.7.8"
+  },
+  "devDependencies": {
+    "@trivago/prettier-plugin-sort-imports": "^4.3.0",
+    "@typescript-eslint/eslint-plugin": "^7.11.0",
+    "@vercel/ncc": "^0.38.1",
+    "eslint": "^8.57.0",
+    "eslint-import-resolver-typescript": "^3.6.1",
+    "eslint-plugin-github": "^4.10.2",
+    "eslint-plugin-import": "^2.29.1",
+    "eslint-plugin-prettier": "^5.1.3",
+    "prettier": "^3.2.5",
+    "tsup": "^8.0.2",
+    "typescript": "^5.4.5",
+    "vitest": "^1.6.0"
+  }
+}

prettier.config.cjs

@@ -0,0 +1,12 @@
+/** @type {import('prettier').Config} */
+module.exports = {
+  plugins: [require.resolve("@trivago/prettier-plugin-sort-imports")],
+  semi: true,
+  singleQuote: false,
+  tabWidth: 2,
+  trailingComma: "all",
+  useTabs: false,
+  // Import sorting
+  importOrderSeparation: true,
+  importOrderSortSpecifiers: true,
+};

src/index.ts

@@ -0,0 +1,184 @@
+import { makeNixCommandArgs } from "./nix.js";
+import { renderCommitMessage, renderPullRequestBody } from "./template.js";
+import * as actionsCore from "@actions/core";
+import * as actionsExec from "@actions/exec";
+import { DetSysAction, inputs } from "detsys-ts";
+import * as fs from "fs";
+
+const DEFAULT_FLAKE_DIR = ".";
+
+const PR_BODY_OUTPUT_KEY = "pr-body";
+
+const EVENT_EXECUTION_FAILURE = "execution_failure";
+
+class UpdateFlakeLockAction extends DetSysAction {
+  private commitMessage: string;
+  private commitMessageTemplate: string;
+  private prBody: string;
+  private prBodyTemplate: string;
+  private nixOptions: string[];
+  private flakeInputs: string[];
+  private pathToFlakeDir: string | null;
+  private flakeDirsInput: string[] | null;
+  private flakeDirs: string[];
+
+  constructor() {
+    super({
+      name: "update-flake-lock",
+      fetchStyle: "universal",
+      requireNix: "fail",
+    });
+
+    this.commitMessage = inputs.getString("commit-msg");
+    this.commitMessageTemplate = inputs.getString("commit-msg-template");
+    this.prBody = inputs.getString("pr-body");
+    this.prBodyTemplate = inputs.getString("pr-body-template");
+    this.flakeInputs = inputs.getArrayOfStrings("inputs", "space");
+    this.nixOptions = inputs.getArrayOfStrings("nix-options", "space");
+    this.pathToFlakeDir = inputs.getStringOrNull("path-to-flake-dir");
+    this.flakeDirsInput = inputs.getArrayOfStringsOrNull("flake-dirs", "space");
+
+    this.validateInputs();
+
+    if (this.flakeDirsInput !== null && this.flakeDirsInput.length > 0) {
+      this.flakeDirs = this.flakeDirsInput;
+    } else {
+      this.flakeDirs = [this.pathToFlakeDir ?? DEFAULT_FLAKE_DIR];
+    }
+  }
+
+  async main(): Promise<void> {
+    for (const directory of this.flakeDirs) {
+      await this.updateFlakeInDirectory(directory);
+    }
+
+    const prBody =
+      this.prBody !== ""
+        ? this.prBody
+        : renderPullRequestBody(this.prBodyTemplate, this.flakeDirs);
+
+    actionsCore.setOutput(PR_BODY_OUTPUT_KEY, prBody);
+  }
+
+  // No post phase
+  async post(): Promise<void> {}
+
+  private async updateFlakeInDirectory(flakeDir: string): Promise<void> {
+    this.ensureDirectoryExists(flakeDir);
+    this.ensureDirectoryIsFlake(flakeDir);
+
+    actionsCore.debug(`Running flake lock update in directory \`${flakeDir}\``);
+
+    const flakeDotLock = `${flakeDir}/flake.lock`;
+    const commitMessage =
+      this.commitMessage !== ""
+        ? this.commitMessage
+        : renderCommitMessage(
+            this.commitMessageTemplate,
+            flakeDir,
+            flakeDotLock,
+          );
+
+    // Nix command of this form:
+    // nix ${maybe nix options} flake ${"update" or "lock"} ${maybe --update-input flags} --commit-lock-file --commit-lockfile-summary ${commit message}
+    // Example commands:
+    // nix --extra-substituters https://example.com flake lock --update-input nixpkgs --commit-lock-file --commit-lockfile-summary "updated flake.lock"
+    // nix flake update --commit-lock-file --commit-lockfile-summary "updated flake.lock"
+    const nixCommandArgs: string[] = makeNixCommandArgs(
+      this.nixOptions,
+      this.flakeInputs,
+      commitMessage,
+    );
+
+    actionsCore.debug(
+      JSON.stringify({
+        directory: flakeDir,
+        options: this.nixOptions,
+        inputs: this.flakeInputs,
+        message: this.commitMessage,
+        args: nixCommandArgs,
+      }),
+    );
+
+    const execOptions: actionsExec.ExecOptions = {
+      cwd: flakeDir,
+    };
+
+    const exitCode = await actionsExec.exec("nix", nixCommandArgs, execOptions);
+
+    if (exitCode !== 0) {
+      this.recordEvent(EVENT_EXECUTION_FAILURE, {
+        exitCode,
+      });
+      actionsCore.setFailed(
+        `non-zero exit code of ${exitCode} detected while updating directory \`${flakeDir}\``,
+      );
+    } else {
+      actionsCore.info(
+        `flake.lock file in \`${flakeDir}\` was successfully updated`,
+      );
+    }
+  }
+
+  private validateInputs(): void {
+    // Ensure that either `path-to-flake-dir` or `flake-dirs` is set to a meaningful value but not both
+    if (
+      this.flakeDirsInput !== null &&
+      this.flakeDirsInput.length > 0 &&
+      this.pathToFlakeDir !== null &&
+      this.pathToFlakeDir !== ""
+    ) {
+      throw new Error(
+        "Both `path-to-flake-dir` and `flake-dirs` are set, whereas only one can be",
+      );
+    }
+
+    // Ensure that `flake-dirs` isn't an empty array if set
+    if (this.flakeDirsInput !== null && this.flakeDirsInput.length === 0) {
+      throw new Error(
+        "The `flake-dirs` input is set to an empty array; it must contain at least one directory",
+      );
+    }
+
+    // Ensure that both `flake-dirs` and `inputs` aren't set at the same time
+    if (
+      this.flakeDirsInput !== null &&
+      this.flakeDirsInput.length > 0 &&
+      this.flakeInputs.length > 0
+    ) {
+      throw new Error(
+        `You've set both \`flake-dirs\` and \`inputs\` but you can only set one`,
+      );
+    }
+  }
+
+  private ensureDirectoryExists(flakeDir: string): void {
+    actionsCore.debug(`Checking that flake directory \`${flakeDir}\` exists`);
+
+    // Ensure the directory exists
+    fs.access(flakeDir, fs.constants.F_OK, (err) => {
+      if (err !== null) {
+        throw new Error(`Directory \`${flakeDir}\` doesn't exist`);
+      } else {
+        actionsCore.debug(`Flake directory \`${flakeDir}\` exists`);
+      }
+    });
+  }
+
+  private ensureDirectoryIsFlake(flakeDir: string): void {
+    const flakeDotNix = `${flakeDir}/flake.nix`;
+    if (!fs.existsSync(flakeDotNix)) {
+      throw new Error(
+        `Directory \`${flakeDir}\` is not a valid flake as it doesn't contain a \`flake.nix\``,
+      );
+    } else {
+      actionsCore.debug(`Directory \`${flakeDir}\` is a valid flake`);
+    }
+  }
+}
+
+function main(): void {
+  new UpdateFlakeLockAction().execute();
+}
+
+main();

src/nix.ts

@@ -0,0 +1,18 @@
+// Build the Nix args out of inputs from the Actions environment
+export function makeNixCommandArgs(
+  nixOptions: string[],
+  flakeInputs: string[],
+  commitMessage: string,
+): string[] {
+  const flakeInputFlags = flakeInputs.flatMap((input) => [
+    "--update-input",
+    input,
+  ]);
+
+  const updateLockMechanism = flakeInputFlags.length === 0 ? "update" : "lock";
+
+  return nixOptions
+    .concat(["flake", updateLockMechanism])
+    .concat(flakeInputFlags)
+    .concat(["--commit-lock-file", "--commit-lockfile-summary", commitMessage]);
+}

src/template.test.ts

@@ -0,0 +1,75 @@
+import { renderCommitMessage, renderPullRequestBody } from "./template.js";
+import { template } from "handlebars";
+import { Test, describe, expect, test } from "vitest";
+
+describe("templating", () => {
+  test("commit message", () => {
+    type TestCase = {
+      template: string;
+      flakeDotLockDir: string;
+      flakeDotLock: string;
+      expected: string;
+    };
+
+    const testCases: TestCase[] = [
+      {
+        template: "Updating flake.lock in dir {{ flake_dot_lock_dir }}",
+        flakeDotLockDir: ".",
+        flakeDotLock: "./flake.lock",
+        expected: "Updating flake.lock in dir .",
+      },
+      {
+        template:
+          "Here I go doing some updating of my pristine flake.lock at {{ flake_dot_lock }}",
+        flakeDotLockDir: "subflake",
+        flakeDotLock: "subflake/flake.lock",
+        expected:
+          "Here I go doing some updating of my pristine flake.lock at subflake/flake.lock",
+      },
+      {
+        template: "This variable doesn't exist: {{ foo }}",
+        flakeDotLockDir: ".",
+        flakeDotLock: "./flake.lock",
+        expected: "This variable doesn't exist: ",
+      },
+    ];
+
+    testCases.forEach(
+      ({ template, flakeDotLockDir, flakeDotLock, expected }) => {
+        expect(
+          renderCommitMessage(template, flakeDotLockDir, flakeDotLock),
+        ).toEqual(expected);
+      },
+    );
+  });
+
+  test("pull request body", () => {
+    type TestCase = {
+      template: string;
+      dirs: string[];
+      expected: string;
+    };
+
+    const testCases: TestCase[] = [
+      {
+        template: "Updated inputs: {{ comma_separated_dirs }}",
+        dirs: ["."],
+        expected: "Updated inputs: .",
+      },
+      {
+        template: "Updated inputs: {{ space_separated_dirs }}",
+        dirs: ["subflake", "subflake2"],
+        expected: "Updated inputs: subflake subflake2",
+      },
+      {
+        template: "Updated inputs:\n{{ updated_dirs_list }}",
+        dirs: ["flake1", "flake2"],
+        expected: `Updated inputs:\n* flake1\n* flake2`,
+      },
+    ];
+
+    testCases.forEach(({ template, dirs, expected }) => {
+      expect(renderPullRequestBody(template, dirs)).toEqual(expected);
+    });
+  });
+});

src/template.ts

@@ -0,0 +1,39 @@
+import Handlebars from "handlebars";
+
+export function renderPullRequestBody(
+  template: string,
+  dirs: string[],
+): string {
+  const commaSeparated = dirs.join(", ");
+  const spaceSeparated = dirs.join(" ");
+  const dirsList = dirs.map((d: string) => `* ${d}`).join("\n");
+
+  const tpl = Handlebars.compile(template);
+
+  return tpl({
+    // eslint-disable-next-line camelcase
+    comma_separated_dirs: commaSeparated,
+    // eslint-disable-next-line camelcase
+    space_separated_dirs: spaceSeparated,
+    // eslint-disable-next-line camelcase
+    updated_dirs_list: dirsList,
+  });
+}
+
+export function renderCommitMessage(
+  template: string,
+  flakeDotLockDir: string,
+  flakeDotLock: string,
+): string {
+  return render(template, {
+    // eslint-disable-next-line camelcase
+    flake_dot_lock_dir: flakeDotLockDir,
+    // eslint-disable-next-line camelcase
+    flake_dot_lock: flakeDotLock,
+  });
+}
+
+function render(template: string, inputs: Record<string, string>): string {
+  const tpl = Handlebars.compile(template);
+  return tpl(inputs);
+}

src/update-flake-lock.test.ts

@@ -0,0 +1,74 @@
+import { makeNixCommandArgs } from "./nix.js";
+import { expect, test } from "vitest";
+
+test("Nix command arguments", () => {
+  type TestCase = {
+    inputs: {
+      nixOptions: string[];
+      flakeInputs: string[];
+      commitMessage: string;
+    };
+    expected: string[];
+  };
+
+  const testCases: TestCase[] = [
+    {
+      inputs: {
+        nixOptions: ["--log-format", "raw"],
+        flakeInputs: [],
+        commitMessage: "just testing",
+      },
+      expected: [
+        "--log-format",
+        "raw",
+        "flake",
+        "update",
+        "--commit-lock-file",
+        "--commit-lockfile-summary",
+        "just testing",
+      ],
+    },
+    {
+      inputs: {
+        nixOptions: [],
+        flakeInputs: ["nixpkgs", "rust-overlay"],
+        commitMessage: "just testing",
+      },
+      expected: [
+        "flake",
+        "lock",
+        "--update-input",
+        "nixpkgs",
+        "--update-input",
+        "rust-overlay",
+        "--commit-lock-file",
+        "--commit-lockfile-summary",
+        "just testing",
+      ],
+    },
+    {
+      inputs: {
+        nixOptions: ["--debug"],
+        flakeInputs: [],
+        commitMessage: "just testing",
+      },
+      expected: [
+        "--debug",
+        "flake",
+        "update",
+        "--commit-lock-file",
+        "--commit-lockfile-summary",
+        "just testing",
+      ],
+    },
+  ];
+
+  testCases.forEach(({ inputs, expected }) => {
+    const args = makeNixCommandArgs(
+      inputs.nixOptions,
+      inputs.flakeInputs,
+      inputs.commitMessage,
+    );
+    expect(args).toStrictEqual(expected);
+  });
+});

tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2020" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */,
+    "module": "Node16",
+    "moduleResolution": "NodeNext",
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "strict": true /* Enable all strict type-checking options. */,
+    "noImplicitAny": true /* Raise error on expressions and declarations with an implied 'any' type. */,
+    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
+    "resolveJsonModule": true,
+    "declaration": true
+  },
+  "exclude": ["node_modules", "**/*.test.ts", "dist"]
+}

tsup.config.ts

@@ -0,0 +1,16 @@
+import { name } from "./package.json";
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  name,
+  entry: ["src/index.ts"],
+  format: ["esm"],
+  target: "node20",
+  bundle: true,
+  splitting: false,
+  sourcemap: true,
+  clean: true,
+  dts: {
+    resolve: true,
+  },
+});

update-flake-lock.sh

@@ -1,23 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-if [[ -n "$PATH_TO_FLAKE_DIR" ]]; then
-  cd "$PATH_TO_FLAKE_DIR"
-fi
-
-options=()
-if [[ -n "$NIX_OPTIONS" ]]; then
-    for option in $NIX_OPTIONS; do
-        options+=("${option}")
-    done
-fi
-
-if [[ -n "$TARGETS" ]]; then
-    inputs=()
-    for input in $TARGETS; do
-        inputs+=("--update-input" "$input")
-    done
-    nix "${options[@]}" flake lock "${inputs[@]}" --commit-lock-file --commit-lockfile-summary "$COMMIT_MSG"
-else
-    nix "${options[@]}" flake update --commit-lock-file --commit-lockfile-summary "$COMMIT_MSG"
-fi