Tunneling

Tunneling runs your app code locally on your machine via the Forge CLI and Cloudflare.

Starting

You can start a tunnel for any app that has been deployed and installed on to a site. To start a tunnel for your app, run the following command in your CLI:

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forge tunnel

You'll see output similar to this:

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Tunnel redirects requests you make to your local machine. This occurs for any Atlassian site where
your app is installed in the specific development environment. You will not see requests from other
users.

Press Ctrl+C to cancel.

=== Running forge lint...
No issues found.

=== Bundling code...
✔ Functions bundled.

Listening for requests...

Messages logged to the console will look similar to this:

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INFO 17:34:04.955 Count of objects in test array: 0

Tunneling also helps you debug your app in two ways:

• Real-time logging for your local app: By inserting console.log() statements in your code, you can see the output in the Forge CLI as the code executes.
• Fast turnaround for changes: The tunnel watches for code changes and rebuilds your app. You don’t need to deploy your app after every change, which lets you test fixes faster.

Matching your local environment to Forge runtime

Variations in your local environment can cause functions to succeed there but fail in Forge. To prevent this:

1. Ensure that your local environment uses the same version of Node.js used by deployed Forge apps (currently Node.js 18).
2. Don’t include any additional dependencies or libraries in your local environment that are not provided out-of-the-box by Node.js (or bundled directly by your app).

We are evaluating support for an optional Docker image for tunnelling, based on feedback and interest from Forge app developers.

Tunneling with UI Kit

When running forge tunnel with a UI Kit app, any changes to your source code triggers a rebundle from the Forge CLI. Once the rebundling is completed successfully, you can see your changes by refreshing the page that your app is on.

Tunneling with custom UI

When running forge tunnel with a custom UI app, the Forge CLI serves the content from the path directories specified in each resource that's defined in your manifest. This means that if your static assets require rebundling, you need to bundle them before refreshing the page that your app is on. See here for more details on resource declarations for custom UI apps.

Connecting the tunnel to your own dev server

While forge tunnel lets you avoid redeploying your custom UI app to test changes, you have to manually bundle it for each change you make. To solve having to do this, popular tools, such as create-react-app can automatically reload your app each time you change the code. These tools usually host their own server on a specific port.

For example, running npm start with create-react-app starts a server at http://localhost:3000 by default. The Forge CLI allows you to proxy tunnel requests to these servers, enabling features, such as hot-reloading while developing your custom UI apps.

To connect a server to forge tunnel, first identify the port that the server is hosted on. In the above example, the port would be 3000. Then, add the following to your manifest.yml file, under the resource your server is hosting:

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tunnel:
  port: <YOUR_PORT_HERE>

For example, a resources definition might look like this:

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resources:
  - key: main
    path: static/hello-world/build
    tunnel:
      port: 3000

Once a port has been added to a resource definition, running forge tunnel causes the Forge CLI to bypass the path directory, and instead proxy the request to http://localhost:<port>.

You can then run forge tunnel, and start your server by running npm start. You can then see the assets served by your local server by refreshing the page that your app is on. If your server supports hot-reloading, you no longer need to refresh the page to see updates when you make changes to the code.

Tunneling with non-UI functions

When running forge tunnel with non-UI functions, such as custom UI resolvers and web triggers, any changes to your source code triggers a rebundle from the Forge CLI. Once that rebundling is completed successfully, you can see your changes reflected in the next invocation of the function.

Older CLI versions using ngrok

Forge tunnel uses ngrok to tunnel invocations. As ngrok does not support anonymous users, you need to set up your credentials before using tunnel command. If you don't have an ngrok account, sign up for one.

Once you have an ngrok account:

1. Get your ngrok authtoken.
2. Create an ngrok config file. Here's an example YAML file:

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   version: 2
   log_level: debug
   region: us
   authtoken: <your-ngrok-authtoken>
   

3. Provide the path to the config file to Forge using the command forge settings set ngrok-config-path <file>.

Known limitations

• Tunneling with custom UI apps is only supported on Chrome and Firefox browsers.
• Any logging that happens while you're tunneling won’t show in forge logs. This is because your app code runs locally while tunneling. forge logs only shows information for your deployed app, not locally running code.
• If you make changes to the manifest.yml file, you must deploy the app with the latest manifest. This is needed for the tunnel to pick up the changes.
• Environment variables must be set locally, as the tunnel can't access the values set in other environments.
• Tunneling only displays output from your usage of the app, that is, your requests.
• Tunnelled app resolvers won't time out, unlike deployed apps. Instead, they will continue to run until completed. This is because developer environments have network and processing speeds that differ from Forge's runtime environment, preventing us from accurately replicating app timeouts during tunnelling. Learn more about deployed app invocation limits.
• Forge invocations have a time limit. This may cause issues in two instances:
  • If your local machine has less compute power than the remote Lambda function server, you could see local timeouts that wouldn't happen once deployed.
  • Conversely, if your local machine has more power than the remote, you could see remote timeouts that didn't happen locally.
• The forge tunnel supports Forge Cache methods, but with the following limitations:
  • TTL is ignored, so keys do not expire.
  • Forge Cache methods will store data in your local environment. This means any latency or throughput results are not indicative the Cache functions' performance in production.
  • Forge Cache tunneling will not work with apps running on the legacy runtime. We recommend migrating your app to the latest runtime version.

Troubleshooting Docker issues

Older versions of the Forge tunnel use Docker, which may cause issues.

Symlinks limitations

Docker doesn't follow symlinks when creating a container to avoid potential inconsistencies. Therefore, you can't use symlinks in your app repository.

To work around this, install Yalc locally and add dependencies via yalc add <dependency> before running forge tunnel or forge deploy.

Bundling issues

The forge tunnel command will get stuck in the Bundling Code step if you:

• are using a Mac computer with an Apple Silicon chip (for example, M1)
• have updated your Docker Desktop app recently (version 4.25+)

To work around this, disable the "Rosetta" setting on your Docker Desktop and restart your Docker daemon.

Related pages

• Debug functions using IntelliJ: This tutorial demonstrates debugging back-end Forge functions in Node.js with IntelliJ's debugger.
• Debug functions using VSCode: This tutorial demonstrates debugging back-end Forge functions in Node.js with VS Code's debugger.
• Tunnel: This reference page outlines the description, usage, and options for the forge tunnel CLI command.