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https://github.com/mafredri/cdp

Package cdp provides type-safe bindings for the Chrome DevTools Protocol (CDP), written in the Go programming language.
https://github.com/mafredri/cdp

cdp chrome-debugging-protocol chrome-devtools-protocol debugging devtools-protocol rpc

Last synced: 19 days ago
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Package cdp provides type-safe bindings for the Chrome DevTools Protocol (CDP), written in the Go programming language.

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README 

        
# cdp



[![Build Status][travis-badge]][travis] [![Coverage Status][codecov-badge]][codecov] [![Go Report Card][goreportcard-badge]][goreportcard] [![GoDoc][godoc-badge]][godoc]



Package `cdp` provides type-safe bindings for the [Chrome DevTools Protocol][chrome-devtools-protocol] (CDP), written in the Go programming language. The bindings are generated (by [cdpgen][cdpgen]) from the latest [tip-of-tree (tot)][tip-of-tree] protocol definitions and are mainly intended for use with Google Chrome or Chromium, however, they can be used with any debug target ([Node.js][node-debugging], [Edge DevTools Protocol][edge-devtools-protocol], [Safari][ios-webkit-debug-proxy], etc.) that implement the protocol.



This package can be used for any kind of browser automation, scripting or debugging via the Chrome DevTools Protocol.



A big motivation for `cdp` is to expose the full functionality of the Chrome DevTools Protocol and provide it in a discoverable and self-documenting manner.



Providing high-level browser automation is a non-goal for this project. That being said, `cdp` hopes to improve the ergonomics of working with the protocol by providing primitives better suited for Go and automating repetitive tasks.



## Features



* Discoverable API for the Chrome DevTools Protocol (GoDoc, autocomplete friendly)

* Contexts as a first-class citizen (for timeouts and cancellation)

* Simple and synchronous event handling (no callbacks)

* Concurrently safe

* No silent or hidden errors

* Do what the user expects

* Match CDP types to Go types wherever possible

* Separation of concerns (avoid mixing CDP and RPC)



## Installation



```console

$ go get -u github.com/mafredri/cdp

```



## Documentation



See [API documentation][godoc] for package, API descriptions and examples. Examples can also be found in this repository, see the [simple][simple-example], [advanced][advanced-example], [logging][logging-example] and [incognito][incognito-example] examples.



## Usage



The main packages are `cdp` and `rpcc`, the former provides the CDP bindings and the latter handles the RPC communication with the debugging target.



To connect to a debug target, a WebSocket debugger URL is needed. For example, if Chrome is running with `--remote-debugging-port=9222` the debugger URL can be found at [localhost:9222/json](http://localhost:9222/json). The `devtool` package can also be used to query the DevTools JSON API (see example below).



Here is an example of using `cdp`:



[embedmd]:# (example_test.go)

```go

package main



import (

	"bufio"

	"context"

	"fmt"

	"io/ioutil"

	"log"

	"os"

	"time"



	"github.com/mafredri/cdp"

	"github.com/mafredri/cdp/devtool"

	"github.com/mafredri/cdp/protocol/dom"

	"github.com/mafredri/cdp/protocol/page"

	"github.com/mafredri/cdp/rpcc"

)



func main() {

	err := run(5 * time.Second)

	if err != nil {

		log.Fatal(err)

	}

}



func run(timeout time.Duration) error {

	ctx, cancel := context.WithTimeout(context.Background(), timeout)

	defer cancel()



	// Use the DevTools HTTP/JSON API to manage targets (e.g. pages, webworkers).

	devt := devtool.New("http://127.0.0.1:9222")

	pt, err := devt.Get(ctx, devtool.Page)

	if err != nil {

		pt, err = devt.Create(ctx)

		if err != nil {

			return err

		}

	}



	// Initiate a new RPC connection to the Chrome DevTools Protocol target.

	conn, err := rpcc.DialContext(ctx, pt.WebSocketDebuggerURL)

	if err != nil {

		return err

	}

	defer conn.Close() // Leaving connections open will leak memory.



	c := cdp.NewClient(conn)



	// Open a DOMContentEventFired client to buffer this event.

	domContent, err := c.Page.DOMContentEventFired(ctx)

	if err != nil {

		return err

	}

	defer domContent.Close()



	// Enable events on the Page domain, it's often preferrable to create

	// event clients before enabling events so that we don't miss any.

	if err = c.Page.Enable(ctx); err != nil {

		return err

	}



	// Create the Navigate arguments with the optional Referrer field set.

	navArgs := page.NewNavigateArgs("https://www.google.com").

		SetReferrer("https://duckduckgo.com")

	nav, err := c.Page.Navigate(ctx, navArgs)

	if err != nil {

		return err

	}



	// Wait until we have a DOMContentEventFired event.

	if _, err = domContent.Recv(); err != nil {

		return err

	}



	fmt.Printf("Page loaded with frame ID: %s\n", nav.FrameID)



	// Fetch the document root node. We can pass nil here

	// since this method only takes optional arguments.

	doc, err := c.DOM.GetDocument(ctx, nil)

	if err != nil {

		return err

	}



	// Get the outer HTML for the page.

	result, err := c.DOM.GetOuterHTML(ctx, &dom.GetOuterHTMLArgs{

		NodeID: &doc.Root.NodeID,

	})

	if err != nil {

		return err

	}



	fmt.Printf("HTML: %s\n", result.OuterHTML)



	// Capture a screenshot of the current page.

	screenshotName := "screenshot.jpg"

	screenshotArgs := page.NewCaptureScreenshotArgs().

		SetFormat("jpeg").

		SetQuality(80)

	screenshot, err := c.Page.CaptureScreenshot(ctx, screenshotArgs)

	if err != nil {

		return err

	}

	if err = ioutil.WriteFile(screenshotName, screenshot.Data, 0o644); err != nil {

		return err

	}



	fmt.Printf("Saved screenshot: %s\n", screenshotName)



	pdfName := "page.pdf"

	f, err := os.Create(pdfName)

	if err != nil {

		return err

	}



	pdfArgs := page.NewPrintToPDFArgs().

		SetTransferMode("ReturnAsStream") // Request stream.

	pdfData, err := c.Page.PrintToPDF(ctx, pdfArgs)

	if err != nil {

		return err

	}



	sr := c.NewIOStreamReader(ctx, *pdfData.Stream)

	r := bufio.NewReader(sr)



	// Write to file in ~r.Size() chunks.

	_, err = r.WriteTo(f)

	if err != nil {

		return err

	}



	err = f.Close()

	if err != nil {

		return err

	}



	fmt.Printf("Saved PDF: %s\n", pdfName)



	return nil

}

```



For more information, consult the [documentation](#documentation).



## Acknowledgements



The Go implementation of gRPC ([grpc-go](https://github.com/grpc/grpc-go)) has been a source of inspiration for some of the design decisions made in the `cdp` and `rpcc` packages. Some ideas have also been borrowed from the `net/rpc` package from the standard library.



## Resources



* [Chrome DevTools Protocol][chrome-devtools-protocol]

    * [Viewer (latest tip-of-tree)][tip-of-tree] official protocol API docs

    * [Repository (GitHub)](https://github.com/chromedevtools/devtools-protocol) please [file issues](https://github.com/ChromeDevTools/devtools-protocol/issues) at this repo if you have concerns or problems with the Chrome DevTools Protocol

    * [Mailing list](https://groups.google.com/forum/#!forum/chrome-debugging-protocol)

* [Getting Started with Headless Chrome](https://developers.google.com/web/updates/2017/04/headless-chrome)

* [Awesome chrome-devtools: Chrome DevTools Protocol](https://github.com/ChromeDevTools/awesome-chrome-devtools#chrome-devtools-protocol)

* [RemoteDebug](http://remotedebug.org/) is an initiative to bring remote debugging (e.g. CDP) to all modern browsers

    * [Protocol Compatibility Tables](https://compatibility.remotedebug.org/)



[cdpgen]: https://github.com/mafredri/cdp/tree/master/cmd/cdpgen

[simple-example]: https://github.com/mafredri/cdp/blob/master/example_test.go

[advanced-example]: https://github.com/mafredri/cdp/blob/master/example_advanced_test.go

[logging-example]: https://github.com/mafredri/cdp/blob/master/example_logging_test.go

[incognito-example]: https://github.com/mafredri/cdp/blob/master/example_incognito_test.go



[chrome-devtools-protocol]: https://chromedevtools.github.io/devtools-protocol/

[tip-of-tree]: https://chromedevtools.github.io/devtools-protocol/tot/

[node-debugging]: https://nodejs.org/en/docs/guides/debugging-getting-started/

[edge-devtools-protocol]: https://docs.microsoft.com/en-us/microsoft-edge/devtools-protocol/

[ios-webkit-debug-proxy]: https://github.com/google/ios-webkit-debug-proxy



[travis]: https://travis-ci.org/mafredri/cdp

[travis-badge]: https://travis-ci.org/mafredri/cdp.svg

[codecov]: https://codecov.io/gh/mafredri/cdp

[codecov-badge]: https://codecov.io/gh/mafredri/cdp/branch/master/graph/badge.svg

[goreportcard]: https://goreportcard.com/report/github.com/mafredri/cdp

[goreportcard-badge]: https://goreportcard.com/badge/github.com/mafredri/cdp

[godoc]: https://godoc.org/github.com/mafredri/cdp

[godoc-badge]: https://godoc.org/mafredri/cdp?status.svg