Debugging Swarm

1. Open the swarm project

Load the entire Swarm project into your favorite IDE.

The default location should be $GOPATH/src/github.com/ethersphere/swarm.

2. Alter the main function

Locate the main() function, under swarm/cmd/swarm/main.go.

This function is called when starting Swarm through the swarm terminal command, therefore its arguments must be injected, like so:

func main() {
	// injection of swarm arguments
	options := []string{
		"--bzzaccount=0x2f1cd699b0bf461dcfbf0098ad8f5587b038f0f1",
		"--password=/home/usr/password.txt",
		// other CLI arguments here...
	}
	args := append(os.Args, options...)
	if err := app.Run(args); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

Each of the elements in the options array holds a swarm command option and its value, in the --option=value form.

Replace the example with your own values, and add or remove any flag as needed.

For a full list of the available command line options for swarm, see here.

3. Start debugging!

You can place a breakpoint before the app.Run(args) call is made and step over the code to see if the system is started successfully with the hard-coded arguments, or if there's an error.

Then, any other breakpoints created in the project should work if the code can reach them from the main function.

Once the breakpoints are set, run the main function with your favorite debugger.

After successfully starting up Swarm, the local web server endpoint should be accessible through your browser, by default at http://localhost:8500.