chore: add devcontainer contributor workflow [DX-822]

.devcontainer/Dockerfile

@@ -0,0 +1,4 @@
+ARG RUBY_VERSION=3.4
+FROM mcr.microsoft.com/devcontainers/ruby:1-${RUBY_VERSION}-bookworm
+
+RUN gem install bundler:2.3.26 --no-document

.devcontainer/devcontainer.json

@@ -0,0 +1,24 @@
+{
+  "name": "contentful.rb",
+  "build": {
+    "dockerfile": "Dockerfile",
+    "context": "..",
+    "args": {
+      "RUBY_VERSION": "${localEnv:RUBY_VERSION:3.4}"
+    }
+  },
+  "containerEnv": {
+    "BUNDLE_APP_CONFIG": "/home/vscode/.bundle",
+    "BUNDLE_PATH": "/home/vscode/.bundle/vendor"
+  },
+  "workspaceFolder": "/workspaces/${localWorkspaceFolderBasename}",
+  "remoteUser": "vscode",
+  "postCreateCommand": "bundle _2.3.26_ install",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "Shopify.ruby-lsp"
+      ]
+    }
+  }
+}

.github/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+permissions:
+  contents: read
+
+jobs:
+  test-and-lint:
+    name: Test and lint (Ruby ${{ matrix.ruby-version }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby-version: ["3.2", "3.3", "3.4"]
+    steps:
+      - uses: actions/checkout@v5
+
+      - name: Install devcontainer CLI
+        run: npm install -g @devcontainers/cli@0
+
+      - name: Run tests and lint checks in dev container
+        env:
+          RUBY_VERSION: ${{ matrix.ruby-version }}
+        run: |
+          devcontainer up --workspace-folder .
+          devcontainer exec --workspace-folder . bash -lc "bundle _2.3.26_ exec rake rspec_rubocop"

CONTRIBUTING.md

@@ -0,0 +1,39 @@
+# Contributing
+
+Thanks for helping improve `contentful.rb`.
+
+## Development with Dev Containers
+
+This repository includes a `.devcontainer` configuration for a reproducible local setup. GitHub Actions uses the same devcontainer configuration for CI.
+
+### Visual Studio Code
+
+Open the repository in Visual Studio Code, install the Dev Containers extension if needed, then run `Dev Containers: Reopen in Container`. Wait for the container build and post-create setup to finish.
+
+### Terminal or other editors
+
+Install Docker and the Dev Container CLI (`npm install -g @devcontainers/cli`). From the repository root, run:
+
+```bash
+devcontainer up --workspace-folder .
+devcontainer exec --workspace-folder . bash
+```
+
+### Verify the environment
+
+```bash
+bundle exec rake rspec_rubocop
+```
+
+## Other Useful Commands
+
+```bash
+bundle exec rake spec
+bundle exec rake rubocop
+```
+
+## Pull Requests
+
+1. Fork the repository and create a branch for your change.
+2. Run the relevant checks from the dev container.
+3. Open a pull request with a short summary of the change and any follow-up context.

README.md

@@ -21,8 +21,8 @@
     <img src="https://img.shields.io/badge/license-MIT-brightgreen.svg" alt="MIT License" />
   </a>
   &nbsp;
-  <a href="https://app.circleci.com/pipelines/github/contentful/contentful.rb?branch=master">
-    <img src="https://circleci.com/gh/contentful/contentful.rb/tree/master.svg?style=svg" alt="CircleCI">
+  <a href="https://github.com/contentful/contentful.rb/actions/workflows/ci.yml">
+    <img src="https://github.com/contentful/contentful.rb/actions/workflows/ci.yml/badge.svg" alt="CI">
   </a>
 </p>
 
@@ -758,6 +758,14 @@ For more information on the internal changes present in the 2.x release, please
 
 We appreciate any help on our repositories. For more details about how to contribute see our [CONTRIBUTING.md](CONTRIBUTING.md) document.
 
+For a reproducible local setup, open this repository in its included dev container. The container installs the project dependencies automatically when it is created.
+
+After the container is ready, run:
+
+```bash
+bundle exec rake rspec_rubocop
+```
+
 ## License
 
 This repository is published under the [MIT](LICENSE.txt) license.