Workers – Develop locally with Containers and the Cloudflare Vite plugin

You can now configure and run Containers alongside your Worker during local development when using the Cloudflare Vite plugin. Previously, you could only develop locally when using Wrangler as your local development server.

Configuration

You can simply configure your Worker and your Container(s) in your Wrangler configuration file:

• wrangler.jsonc

  {
    "name": "container-starter",
    "main": "src/index.js",
    "containers": [
      {
        "class_name": "MyContainer",
        "image": "./Dockerfile",
        "instances": 5
      }
    ],
    "durable_objects": {
      "bindings": [
        {
          "class_name": "MyContainer",
          "name": "MY_CONTAINER"
        }
      ]
    },
    "migrations": [
      {
        "new_sqlite_classes": [
          "MyContainer"
        ],
        "tag": "v1"
      }
    ],
  }

• wrangler.toml

  name = "container-starter"
  main = "src/index.js"
  
  [[containers]]
  class_name = "MyContainer"
  image = "./Dockerfile"
  instances = 5
  
  [[durable_objects.bindings]]
  class_name = "MyContainer"
  name = "MY_CONTAINER"
  
  [[migrations]]
  new_sqlite_classes = [ "MyContainer" ]
  tag = "v1"

Worker Code

Once your Worker and Containers are configured, you can access the Container instances from your Worker code:

import { Container, getContainer } from "@cloudflare/containers";

export class MyContainer extends Container {
  defaultPort = 4000; // Port the container is listening on
  sleepAfter = "10m"; // Stop the instance if requests not sent for 10 minutes
}

async fetch(request, env) {
  const { "session-id": sessionId } = await request.json();
  // Get the container instance for the given session ID
  const containerInstance = getContainer(env.MY_CONTAINER, sessionId)
  // Pass the request to the container instance on its default port
  return containerInstance.fetch(request);
}

Local development

To develop your Worker locally, start a local dev server by running

vite dev

in your terminal.

Resources

Learn more about Cloudflare Containers or the Cloudflare Vite plugin in our developer docs.