Tab management questions

[jotto]

Can you verify the following?

• CDP.List, CDP.New, CDP.Activate, CDP.Close use the HTTP transport
  • although on headless Chrome, CDP.New() fails for me with: Error: Could not create new page
• CDP() returns a websocket connection to the currently active tab
• CDP().Target.createTarget({url: 'about:blank'}) creates a new tab, and returns { targetId: 'some-hash' }
  • but I can't connect to that new tab with CDP({tab: {targetId: 'some-hash}}), I have to query all the tabs to get the webSocketDebuggerUrl URL of that matching targetId/id first?
• can I maintain websocket connections to multiple tabs doing something like: CDP.List().then(tabs => Promise.all(tabs.map(tab => CDP({ tab }))))

[cyrus-and]

CDP.List, CDP.New, CDP.Activate, CDP.Close use the HTTP transport

That's correct.

although, CDP.New() fails for me with: Error: Could not create new page

Well, this should not happen can you provide a minimal script reproducing this, along with Chrome and Node.js versions.

CDP() returns a websocket connection to the currently active tab

In abstract terms, yes, it actually return an instance of the CDP class.

CDP().Target.createTarget({url: 'about:blank'}) creates a new tab, and returns { targetId: 'some-hash' }

Proper syntax is: CDP((client) => { client.Target.createTarget({url: 'about:blank'}) }); but yes.

but I can't connect to that new tab with CDP({tab: {targetId: 'some-hash}}), I have to query all the tabs to get the webSocketDebuggerUrl URL of that matching targetId/id first?

You can't connect in that way because there's no documented way to build a WebSocket URL out of the target id, you can either:

• build the WebSocket URL manually ws://localhost:9222/devtools/page/${targetId} but I cannot guarantee that it will always work;

• or, basically do what you said with:

  CDP({tab: tabs => tabs.findIndex(tab => tab.id == targetId)}, (client) => { /*...*/ });

can I maintain websocket connections to multiple tabs doing something like: CDP.List().then(tabs => Promise.all(tabs.map(tab => CDP({ tab }))))

Absolutely, as long as, at any given time, there's at most one CDP instance for each tab.

[jotto]

Well, this should not happen can you provide a minimal script reproducing this, along with Chrome and Node.js versions.

const CDP = require('chrome-remote-interface');
CDP.New().then(console.log).catch(console.error)

Error: Could not create new page
    at IncomingMessage.<anonymous> (./node_modules/chrome-remote-interface/lib/external-request.js:14:26)
    at emitNone (events.js:91:20)
    at IncomingMessage.emit (events.js:185:7)
    at endReadableNT (_stream_readable.js:974:12)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickDomainCallback (internal/process/next_tick.js:122:9)

• chrome: headless, via Docker. Chrome versions I tried: 58.0.2992.2, or 57.0.2952.2
  • https://hub.docker.com/r/yukinying/chrome-headless/
• node: 7.4.0
• chrome-remote-interface: 0.17.1

[cyrus-and]

I suspect that headless Chrome cannot create new tabs via the HTTP endpoint, can you test the following?

curl http://localhost:9222/json/new

You can even navigate that URL by any other means.

Possibly compare with a regular (non-headless) Chrome version.

[jotto]

curl http://localhost:9222/json/new

Could not create new page

must be headless then. I also checked the non-headless and it works fine. Sorry for false alarm.

[cyrus-and]

No worries! Good to know, it might be worth it to file an issue to Chromium about that, I can't see no reason why /json/list is available via HTTP whereas /json/new is not...

[cyrus-and]

Good to know, it might be worth it to file an issue to Chromium about that, I can't see no reason why /json/list is available via HTTP whereas /json/new is not...

FYI https://bugs.chromium.org/p/chromium/issues/detail?id=696198

[jotto]

Thank you for filing and thank you for maintaining this great project!

[jotto]

Add the Proj-Headless label: https://bugs.chromium.org/p/chromium/issues/list?q=label:Proj-Headless

[cyrus-and]

I don't think I'm allowed to add labels to that issues.

[jameshartig]

Yeah label creation is tricket with monorail. If you file the bug via: https://bugs.chromium.org/p/chromium/issues/entry?labels=Proj-Headless then it'll tag it.

Additionally the headless-dev mailing list has been super helpful so feel free to post it there if you need it tagged.

[VoidMonk]

although on headless Chrome, CDP.New() fails for me with: Error: Could not create new page

This must have broken recently, because I remember reading about and testing CDP.New() working fine with headless shell.

Meanwhile, is there any other way to open/manage tabs, or load isolated pages, with a single running instance of Chrome headless?