56 lines
3.3 KiB
Go
56 lines
3.3 KiB
Go
package opts
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// TODO Windows. Identify bug in GOLang 1.5.1+ and/or Windows Server 2016 TP5.
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// @jhowardmsft, @swernli.
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//
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// On Windows, this mitigates a problem with the default options of running
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// a docker client against a local docker daemon on TP5.
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//
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// What was found that if the default host is "localhost", even if the client
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// (and daemon as this is local) is not physically on a network, and the DNS
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// cache is flushed (ipconfig /flushdns), then the client will pause for
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// exactly one second when connecting to the daemon for calls. For example
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// using docker run windowsservercore cmd, the CLI will send a create followed
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// by an attach. You see the delay between the attach finishing and the attach
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// being seen by the daemon.
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//
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// Here's some daemon debug logs with additional debug spew put in. The
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// AfterWriteJSON log is the very last thing the daemon does as part of the
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// create call. The POST /attach is the second CLI call. Notice the second
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// time gap.
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//
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// time="2015-11-06T13:38:37.259627400-08:00" level=debug msg="After createRootfs"
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// time="2015-11-06T13:38:37.263626300-08:00" level=debug msg="After setHostConfig"
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// time="2015-11-06T13:38:37.267631200-08:00" level=debug msg="before createContainerPl...."
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// time="2015-11-06T13:38:37.271629500-08:00" level=debug msg=ToDiskLocking....
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// time="2015-11-06T13:38:37.275643200-08:00" level=debug msg="loggin event...."
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// time="2015-11-06T13:38:37.277627600-08:00" level=debug msg="logged event...."
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// time="2015-11-06T13:38:37.279631800-08:00" level=debug msg="In defer func"
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// time="2015-11-06T13:38:37.282628100-08:00" level=debug msg="After daemon.create"
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// time="2015-11-06T13:38:37.286651700-08:00" level=debug msg="return 2"
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// time="2015-11-06T13:38:37.289629500-08:00" level=debug msg="Returned from daemon.ContainerCreate"
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// time="2015-11-06T13:38:37.311629100-08:00" level=debug msg="After WriteJSON"
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// ... 1 second gap here....
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// time="2015-11-06T13:38:38.317866200-08:00" level=debug msg="Calling POST /v1.22/containers/984758282b842f779e805664b2c95d563adc9a979c8a3973e68c807843ee4757/attach"
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// 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"
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//
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// We suspect this is either a bug introduced in GOLang 1.5.1, or that a change
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// in GOLang 1.5.1 (from 1.4.3) is exposing a bug in Windows. In theory,
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// the Windows networking stack is supposed to resolve "localhost" internally,
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// without hitting DNS, or even reading the hosts file (which is why localhost
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// is commented out in the hosts file on Windows).
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//
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// We have validated that working around this using the actual IPv4 localhost
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// address does not cause the delay.
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//
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// This does not occur with the docker client built with 1.4.3 on the same
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// Windows build, regardless of whether the daemon is built using 1.5.1
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// or 1.4.3. It does not occur on Linux. We also verified we see the same thing
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// on a cross-compiled Windows binary (from Linux).
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//
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// Final note: This is a mitigation, not a 'real' fix. It is still susceptible
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// to the delay if a user were to do 'docker run -H=tcp://localhost:2375...'
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// explicitly.
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// DefaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
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const DefaultHTTPHost = "127.0.0.1"
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