is it possible to use chromedp for node js debugging?

[poonai]

I want to hit nodejs debugger api using chromedp.

Is it possible to use chromedp since nodejs also exposing chrome dev tool protocol
https://nodejs.org/api/debugger.html#debugger_advanced_usage

[ZekeLu]

No, chromedp does not work with Node.js debugger.

First, Node.js uses URL like ws://127.0.0.1:9229/48a5b28a-550c-471b-b5e1-d13dd7165df9, which is considered as invalid because it does not contain /devtools/browser/. chromedp will try to detect the URL from http://127.0.0.1:9229/json/version, but the response is something like this:

{
  "Browser": "node.js/v14.17.6",
  "Protocol-Version": "1.1"
}

Which does not contain the expected WebSocket URL.

This logic was introduced by chromedp@v.0.7.3. See #817. I have tried chromedp@v.0.7.2, but it still does not work.

Try 1 with chromedp@v.0.7.2:

package main

import (
	"context"
	"log"

	"github.com/chromedp/chromedp"
)

func main() {
	actx, cancel := chromedp.NewRemoteAllocator(context.Background(),
		"ws://127.0.0.1:9229/21e0413d-d55b-44dc-a96e-a3197f9d16c8",
	)
	defer cancel()

	ctx, cancel := chromedp.NewContext(actx, chromedp.WithDebugf(log.Printf))
	defer cancel()

	if err := chromedp.Run(ctx); err != nil {
		log.Fatal(err)
	}
}

Output:

2021/09/18 23:39:19 -> {"id":1,"method":"Target.createTarget","params":{"url":"about:blank"}}
2021/09/18 23:39:19 <- {"error":{"code":-32601,"message":"'Target.createTarget' wasn't found"},"id":1}
2021/09/18 23:39:19 'Target.createTarget' wasn't found (-32601)

Try 2 with chromedp@v.0.7.2:

package main

import (
	"context"
	"log"

	"github.com/chromedp/chromedp"
)

func main() {
	actx, cancel := chromedp.NewRemoteAllocator(context.Background(),
		"ws://127.0.0.1:9229/21e0413d-d55b-44dc-a96e-a3197f9d16c8",
	)
	defer cancel()

	ctx, cancel := chromedp.NewContext(actx, chromedp.WithDebugf(log.Printf))
	defer cancel()

	targets, err := chromedp.Targets(ctx)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("%+v", targets)
}

Output:

2021/09/18 23:38:17 -> {"id":1,"method":"Target.getTargets"}
2021/09/18 23:38:17 <- {"error":{"code":-32601,"message":"'Target.getTargets' wasn't found"},"id":1}
2021/09/18 23:38:17 'Target.getTargets' wasn't found (-32601)

[poonai]

Ahh, Thanks for the detailed answer. I guess, I just have to write my own client.

It's awesome that you folks separated generated types from https://github.com/chromedp/cdproto chromedp. It'll be even more easy to write the client.

[ZekeLu]

Try 3 with chromedp@v.0.7.2:

It seems that we can work with the debugger domain like this. I'm not sure whether this is what you want, but it will give you some clues.

package main

import (
	"context"
	"log"

	"github.com/chromedp/cdproto/cdp"
	"github.com/chromedp/cdproto/debugger"
	"github.com/chromedp/chromedp"
)

func main() {
	actx, cancel := chromedp.NewRemoteAllocator(context.Background(),
		"ws://127.0.0.1:9229/21e0413d-d55b-44dc-a96e-a3197f9d16c8",
	)
	defer cancel()

	ctx, cancel := chromedp.NewContext(actx, chromedp.WithDebugf(log.Printf))
	defer cancel()

	if err := run(ctx,
		chromedp.ActionFunc(func(ctx context.Context) error {
			_, err := debugger.Enable().Do(ctx)
			return err
		}),
		debugger.SetBreakpointsActive(false),
	); err != nil {
		log.Fatal(err)
	}
}

func run(ctx context.Context, actions ...chromedp.Action) error {
	// to make sure chromedp.initContextBrowser is called
	if err := chromedp.Run(ctx); err != nil && err.Error() != "'Target.createTarget' wasn't found (-32601)" {
		return err
	}
	c := chromedp.FromContext(ctx)
	// to run actions with the Browser executor
	// chromedp.Run will run actions with the Target executor
	return chromedp.Tasks(actions).Do(cdp.WithExecutor(ctx, c.Browser))
}

[poonai]

I tried with it. But I got error

2021/09/20 13:17:29 could not dial "ws://127.0.0.1:9229/a8fa298b-20eb-418f-bd73-0a06a45fa4a6": handshake error: bad HTTP protocol version

Btw, does chromedp handles event from the remote server eg event https://chromedevtools.github.io/devtools-protocol/tot/Debugger/#event-breakpointResolved

[ZekeLu]

For event handling, please see https://pkg.go.dev/github.com/chromedp/chromedp#ListenBrowser and https://pkg.go.dev/github.com/chromedp/chromedp#ListenTarget.

For the bad HTTP protocol version issue, can you describe the steps (including the version of the Node.js) to reproduce it?

[ZekeLu]

Closing due to lack of activity.