Parca UI

This is a Create React App project that utilizes Craco to modify and customize the app without 'ejecting'.

Development

The React app requires an environment variable for the API endpoint so as to talk to the Parca backend. Create a file named .env.local in packages/app/web/ to add the environment variable for the API endpoint.

REACT_APP_PUBLIC_API_ENDPOINT=http://localhost:7070

Then, start the Parca backend by running the command below. The --cors-allowed-origins='*' flag allows for enabling CORS headers on Parca.

./bin/parca --cors-allowed-origins='*'

Now the Parca backend will be running and available at localhost:7070.

Finally, run the development server for the React app:

yarn workspace @parca/web dev

Open http://localhost:3000 with your browser to see the result.

You can start editing the UI by modifying any of the components in the ui/packages/app/web directory. The app auto-updates as you edit the files.

Build

To build the UI, you can use Makefile at the root of the project to run the following commands.

Run the following command to generate a production build of the React app:

make ui/build # yarn install && yarn build

We embed the artifacts (the production build and its static assets) into the final binary distribution. See https://pkg.go.dev/embed for further details.

Run following to build the parca binary with embedded assets.

make build

Development workflow

Before make sure all the tools you need are installed. The Linux users can simply run make dev/setup.

You can set up a cluster and all else you need by simply running:

make dev/up

For a simple local development setup we use Tilt.

tilt up

UI Feature Flags

We have a feature flag system that allows you to enable or disable features for a user browser. It's a naive implementation based on browser local storage.

Usage:

import useUIFeatureFlag from '@parca/functions/useUIFeatureFlag';

const Header = () => {
  const isGreetingEnabled = useUIFeatureFlag('greeting');
  return (
    <div>
      <img src="/logo.png" alt="Logo"/>
      {isGreetingEnabled ? <h1>Hello!!!</h1> : null}
    </div>
  );
}

For easy modification of the flag states, we added a two utility query params that can be used to control the feature flag state: enable-ui-flag and disable-ui-flag.

For example, if you want to enable the greeting feature for a browser, you can load the following URL:

http://localhost:3000/?enable-ui-flag=greeting

Like wise, if you would like to disable the greeting feature for a browser, you can load the following URL:

http://localhost:3000/?disable-ui-flag=greeting

When the app loads with the above URL, the feature flags module will handle those and update the flag state accordingly. Note: These 'enable' and 'disable' params work for setting one flag value at a time (rather than for example enabling "greeting" and another feature at the same time).

If you are interested in the implementation details, you can read the source here.