dexmar has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks!

I have a Centos 8 VM running on my local machine with a fresh install of Chrome 87.0.4270.0 and WWW::Mechanize::Chrome installed to version 0.60. In trying the dump-links.pl sample project I get this error: 

Can't connect without knowing the port?! 0 at /usr/local/share/perl5/C
+hrome/DevToolsProtocol.pm line 316.

[download]

I tried setting the port as per the docs: 

my $mech = WWW::Mechanize::Chrome->new(port => 9222);

[download]
Same error. I followed this earlier post as well but no luck: https://www.perlmonks.org/?node_id=1203079

From the $TRACE it appears the port is not being set: 

2020/09/26 13:02:28 Spawning $VAR1 = [
          '/usr/bin/google-chrome',
          '--remote-debugging-port=0',
          '--enable-automation',
          '--no-first-run',
          '--mute-audio',
          '--no-zygote',
          '--no-sandbox',
          '--safebrowsing-disable-auto-update',
          '--disable-background-networking',
          '--disable-breakpad',
          '--disable-client-side-phishing-detection',
          '--disable-component-update',
          '--disable-hang-monitor',
          '--disable-prompt-on-repost',
          '--disable-sync',
          '--disable-translate',
          '--disable-web-resources',
          '--disable-default-apps',
          '--disable-infobars',
          '--disable-popup-blocking',
          '--disable-gpu',
          '--disable-save-password-bubble',
          'about:blank'
        ];
2020/09/26 13:02:28 Spawned child as 7191
Can't connect without knowing the port?! 0 at /usr/local/share/perl5/C
+hrome/DevToolsProtocol.pm line 316.

[download]
Any thoughts on this would be much appreciated!! Thanks! Ed

Replies are listed 'Best First'.
Re: WWW::Mechanize::Chrome Can't Connect without knowing the port?!
by Corion (Patriarch) on Sep 26, 2020 at 20:40 UTC

    Oops! This seems to be a regression that nobody found yet!

    As a workaround, you can use

    WWW_MECHANIZE_CHROME_CONNECTION_STYLE=pipe perl -Ilib -MWWW::Mechanize
+::Chrome -wle 'my $mech = WWW::Mechanize::Chrome::->new()'

    [download]

    ... or, for a script

    #!perl
use strict;
use WWW::Mechanize::Chrome;
$ENV{WWW_MECHANIZE_CHROME_CONNECTION_STYLE}='pipe';
my $mech = WWW::Mechanize::Chrome::->new();
...

    [download]
[reply]
[d/l]
[select]

      Thank you for the quick reply!!!

      Does that only work headless? When I insert that code into dump-links.pl I get this:

      2020/09/26 14:01:35 Spawning $VAR1 = [
          '/usr/bin/google-chrome',
          '--remote-debugging-pipe',
          '--enable-automation',
          '--no-first-run',
          '--mute-audio',
          '--no-zygote',
          '--no-sandbox',
          '--safebrowsing-disable-auto-update',
          '--disable-background-networking',
          '--disable-breakpad',
          '--disable-client-side-phishing-detection',
          '--disable-component-update',
          '--disable-hang-monitor',
          '--disable-prompt-on-repost',
          '--disable-sync',
          '--disable-translate',
          '--disable-web-resources',
          '--disable-default-apps',
          '--disable-infobars',
          '--disable-popup-blocking',
          '--disable-gpu',
          '--disable-save-password-bubble',
          'about:blank'
        ];
2020/09/26 14:01:35 Spawned child as 3455
[3455:3455:0926/140135.852054:ERROR:browser_main_loop.cc(1434)] Unable
+ to open X display.
2020/09/26 14:01:35 Sent message $VAR1 = '{"id":1,"method":"Target.get
+Targets","params":{}}';
$VAR1 = [
          bless( {
                   'read_len' => 8192,
                   'reader' => '_sysread',
                   'cb_r' => sub { "DUMMY" },
                   'want_readready' => 1,
                   'close_on_read_eof' => 1,
                   'handle_closing' => undef,
                   'write_handle' => \*{'WWW::Mechanize::Chrome::$pare
+nt{...}'},
                   'want_writeready' => 1,
                   'read_handle' => \*{'WWW::Mechanize::Chrome::$paren
+t{...}'},
                   'want' => 9,
                   'on_read' => sub { "DUMMY" },
                   'write_eof' => 1,
                   'writequeue' => [
                                     bless( [
                                              '{"id":1,"method":"Targe
+t.getTargets","params":{}}',
                                              8192,
                                              undef,
                                              undef,
                                              undef,
                                              0
                                            ], 'IO::Async::Stream::Wri
+ter' )
                                   ],
                   'write_len' => 8192,
                   'writeable' => 1,
                   'readqueue' => [],
                   'writer' => '_syswrite',
                   'cb_w' => sub { "DUMMY" },
                   'on_write_error' => sub { "DUMMY" },
                   'IO_Async_Notifier__loop' => bless( {
                                                         'os' => {},
                                                         'deferrals' =
+> [],
                                                         'sigattaches'
+ => {},
                                                         'timequeue' =
+> undef,
                                                         'pollevents' 
+=> {
                                                                      
+     '7' => 16,
                                                                      
+     '6' => 12
                                                                      
+   },
                                                         'notifiers' =
+> {
                                                                      
+    '94094341331112' => $VAR1->[0]
                                                                      
+  },
                                                         'childwatches
+' => {},
                                                         'pollmask' =>
+ {
                                                                      
+   '6' => 4,
                                                                      
+   '7' => 1
                                                                      
+ },
                                                         'childmanager
+' => undef,
                                                         'threadwatche
+s' => {},
                                                         'iowatches' =
+> {
                                                                      
+    '6' => [
                                                                      
+             $VAR1->[0]{'write_handle'},
                                                                      
+             undef,
                                                                      
+             $VAR1->[0]{'cb_w'}
                                                                      
+           ],
                                                                      
+    '7' => [
                                                                      
+             $VAR1->[0]{'read_handle'},
                                                                      
+             $VAR1->[0]{'cb_r'}
                                                                      
+           ]
                                                                      
+  },
                                                         'poll' => und
+ef,
                                                         'old_timer' =
+> ''
                                                       }, 'IO::Async::
+Loop::Poll' ),
                   'readbuff' => ''
                 }, 'IO::Async::Stream' ),
          'Broken pipe'
        ];

      [download]
[reply]
[d/l]
        [3455:3455:0926/140135.852054:ERROR:browser_main_loop.cc(1434)] Unable
+ to open X display.

        [download]

        So maybe your Chrome process can't connect to your display server. This would explain why it works headless but not when trying with a display. I don't know why Chrome can't connect to a display - are you launching the process as a different user or in a shell without the DISPLAY variable set?

[reply]
[d/l]

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