ci: add GitHub Actions workflows and Dependabot

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/markdownlint.json

@@ -0,0 +1,6 @@
+{
+  "default": true,
+  "MD013": false,
+  "MD024": false,
+  "MD033": false
+}

.github/mlc_config.json

@@ -0,0 +1,13 @@
+{
+  "replacementPatterns": [
+    {
+      "pattern": "^/",
+      "replacement": "{{BASEURL}}/"
+    }
+  ],
+  "timeout": "20s",
+  "retryOn429": true,
+  "retryCount": 3,
+  "fallbackRetryDelay": "30s",
+  "aliveStatusCodes": [200, 206, 403]
+}

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+---
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+      fail-fast: false
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v23
+        with:
+          nix_path: nixpkgs=channel:nixpkgs-unstable
+      - uses: cachix/cachix-action@v13
+        with:
+          name: devenv
+      - name: Install devenv
+        run: nix-env -if https://github.com/cachix/devenv/tarball/latest
+      - name: Test build environment
+        run: devenv test

.github/workflows/docs.yml

@@ -0,0 +1,34 @@
+---
+name: Documentation
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: "0 8 * * 1" # Run weekly on Monday at 8:00 UTC to catch broken links
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check Markdown links
+        uses: gaurav-nelson/github-action-markdown-link-check@v1
+        with:
+          use-quiet-mode: "yes"
+          use-verbose-mode: "yes"
+          config-file: ".github/mlc_config.json"
+
+  markdown-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Lint Markdown files
+        uses: avto-dev/markdown-lint@v1
+        with:
+          config: ".github/markdownlint.json"
+          args: "*.md"

.github/workflows/format.yml

@@ -0,0 +1,25 @@
+---
+name: Format Check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v23
+        with:
+          nix_path: nixpkgs=channel:nixpkgs-unstable
+
+      - name: Check Nix formatting with nixpkgs-fmt
+        run: |
+          nix-shell -p nixpkgs-fmt --run "nixpkgs-fmt --check *.nix"
+
+      - name: Check YAML formatting
+        run: |
+          nix-shell -p yamllint --run "yamllint -c .github/yamllint.yml ."

.github/workflows/update-deps.yml

@@ -0,0 +1,26 @@
+---
+name: Update dependencies
+
+on:
+  schedule:
+    - cron: "0 0 * * 0" # Weekly on Sunday
+  workflow_dispatch: # Allow manual triggering
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v23
+        with:
+          nix_path: nixpkgs=channel:nixpkgs-unstable
+      - name: Install devenv
+        run: nix-env -if https://github.com/cachix/devenv/tarball/latest
+      - name: Update dependencies
+        run: devenv update
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v5
+        with:
+          commit-message: Update devenv dependencies
+          title: Update devenv dependencies
+          branch: update-dependencies

.github/yamllint.yml

@@ -0,0 +1,16 @@
+---
+extends: default
+
+rules:
+  # 80 chars should be enough, but don't fail if a line is longer
+  line-length:
+    max: 80
+    level: warning
+
+  # don't worry about EOL for now
+  new-line-at-end-of-file: disable
+
+ignore: |
+  .github/workflows/
+  devenv.yaml
+  devenv.lock

README.md

@@ -8,6 +8,8 @@ A minimal and reproducible development environment for Elixir and Erlang project
 - Automatic environment activation with direnv (optional but recommended)
 - Zero system-wide installations required (except Nix itself)
 - Consistent developer experience across all platforms (macOS, Linux, WSL)
+- CI integration with GitHub Actions
+- Automated dependency updates with Dependabot
 
 ## Prerequisites
 
@@ -91,6 +93,21 @@ For more information:
 - [Discussion about package versioning in Nix](https://github.com/NixOS/nixpkgs/issues/93327)
 - [NixOS search for Elixir packages](https://search.nixos.org/packages?channel=unstable&query=elixir)
 
+## CI Setup
+
+This template includes GitHub Actions workflows for continuous integration:
+
+- **CI workflow**: Automatically tests that the development environment builds correctly on every push and pull request
+  - Tests on both Ubuntu and macOS to ensure cross-platform compatibility
+- **Format checking**: Verifies that Nix and YAML files adhere to consistent formatting guidelines
+- **Documentation validation**:
+  - Checks for broken links in markdown files
+  - Validates markdown for common style and formatting issues
+- **Dependency updates**: A scheduled workflow that automatically updates Nix dependencies and creates a pull request with the changes
+- **Dependabot**: Keeps GitHub Actions dependencies up-to-date with weekly checks
+
+These workflows ensure that your development environment remains stable, well-formatted, and up-to-date with minimal manual intervention.
+
 ## Customizing
 
 ### Adding dependencies

devenv.yaml

@@ -1,3 +1,4 @@
+---
 # yaml-language-server: $schema=https://devenv.sh/devenv.schema.json
 inputs:
   nixpkgs: