github.com/pwn-term/docker@v0.0.0-20210616085119-6e977cce2565/cli/opts/hosts_windows.go (about)

     1  // +build windows
     2  
     3  package opts
     4  
     5  // defaultHost constant defines the default host string used by docker on Windows
     6  const defaultHost = "npipe://" + defaultNamedPipe
     7  
     8  // TODO Windows. Identify bug in GOLang 1.5.1+ and/or Windows Server 2016 TP5.
     9  // @jhowardmsft, @swernli.
    10  //
    11  // On Windows, this mitigates a problem with the default options of running
    12  // a docker client against a local docker daemon on TP5.
    13  //
    14  // What was found that if the default host is "localhost", even if the client
    15  // (and daemon as this is local) is not physically on a network, and the DNS
    16  // cache is flushed (ipconfig /flushdns), then the client will pause for
    17  // exactly one second when connecting to the daemon for calls. For example
    18  // using docker run windowsservercore cmd, the CLI will send a create followed
    19  // by an attach. You see the delay between the attach finishing and the attach
    20  // being seen by the daemon.
    21  //
    22  // Here's some daemon debug logs with additional debug spew put in. The
    23  // AfterWriteJSON log is the very last thing the daemon does as part of the
    24  // create call. The POST /attach is the second CLI call. Notice the second
    25  // time gap.
    26  //
    27  // time="2015-11-06T13:38:37.259627400-08:00" level=debug msg="After createRootfs"
    28  // time="2015-11-06T13:38:37.263626300-08:00" level=debug msg="After setHostConfig"
    29  // time="2015-11-06T13:38:37.267631200-08:00" level=debug msg="before createContainerPl...."
    30  // time="2015-11-06T13:38:37.271629500-08:00" level=debug msg=ToDiskLocking....
    31  // time="2015-11-06T13:38:37.275643200-08:00" level=debug msg="loggin event...."
    32  // time="2015-11-06T13:38:37.277627600-08:00" level=debug msg="logged event...."
    33  // time="2015-11-06T13:38:37.279631800-08:00" level=debug msg="In defer func"
    34  // time="2015-11-06T13:38:37.282628100-08:00" level=debug msg="After daemon.create"
    35  // time="2015-11-06T13:38:37.286651700-08:00" level=debug msg="return 2"
    36  // time="2015-11-06T13:38:37.289629500-08:00" level=debug msg="Returned from daemon.ContainerCreate"
    37  // time="2015-11-06T13:38:37.311629100-08:00" level=debug msg="After WriteJSON"
    38  // ... 1 second gap here....
    39  // time="2015-11-06T13:38:38.317866200-08:00" level=debug msg="Calling POST /v1.22/containers/984758282b842f779e805664b2c95d563adc9a979c8a3973e68c807843ee4757/attach"
    40  // time="2015-11-06T13:38:38.326882500-08:00" level=info msg="POST /v1.22/containers/984758282b842f779e805664b2c95d563adc9a979c8a3973e68c807843ee4757/attach?stderr=1&stdin=1&stdout=1&stream=1"
    41  //
    42  // We suspect this is either a bug introduced in GOLang 1.5.1, or that a change
    43  // in GOLang 1.5.1 (from 1.4.3) is exposing a bug in Windows. In theory,
    44  // the Windows networking stack is supposed to resolve "localhost" internally,
    45  // without hitting DNS, or even reading the hosts file (which is why localhost
    46  // is commented out in the hosts file on Windows).
    47  //
    48  // We have validated that working around this using the actual IPv4 localhost
    49  // address does not cause the delay.
    50  //
    51  // This does not occur with the docker client built with 1.4.3 on the same
    52  // Windows build, regardless of whether the daemon is built using 1.5.1
    53  // or 1.4.3. It does not occur on Linux. We also verified we see the same thing
    54  // on a cross-compiled Windows binary (from Linux).
    55  //
    56  // Final note: This is a mitigation, not a 'real' fix. It is still susceptible
    57  // to the delay if a user were to do 'docker run -H=tcp://localhost:2375...'
    58  // explicitly.
    59  
    60  // defaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
    61  const defaultHTTPHost = "127.0.0.1"