Merge pull request #41617 from thaJeztah/unify_consts

opts: unify host-options, and use consts

opts/hosts_unix.go

@@ -2,7 +2,10 @@
 
 package opts // import "github.com/docker/docker/opts"
 
-import "fmt"
+const (
+	// DefaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
+	DefaultHTTPHost = "localhost"
 
-// DefaultHost constant defines the default host string used by docker on other hosts than Windows
-var DefaultHost = fmt.Sprintf("unix://%s", DefaultUnixSocket)
+	// DefaultHost constant defines the default host string used by docker on other hosts than Windows
+	DefaultHost = "unix://" + DefaultUnixSocket
+)

opts/hosts_windows.go

@@ -1,4 +1,60 @@
 package opts // import "github.com/docker/docker/opts"
 
-// DefaultHost constant defines the default host string used by docker on Windows
-var DefaultHost = "npipe://" + DefaultNamedPipe
+const (
+	// TODO Windows. Identify bug in GOLang 1.5.1+ and/or Windows Server 2016 TP5.
+	//
+	// On Windows, this mitigates a problem with the default options of running
+	// a docker client against a local docker daemon on TP5.
+	//
+	// What was found that if the default host is "localhost", even if the client
+	// (and daemon as this is local) is not physically on a network, and the DNS
+	// cache is flushed (ipconfig /flushdns), then the client will pause for
+	// exactly one second when connecting to the daemon for calls. For example
+	// using docker run windowsservercore cmd, the CLI will send a create followed
+	// by an attach. You see the delay between the attach finishing and the attach
+	// being seen by the daemon.
+	//
+	// Here's some daemon debug logs with additional debug spew put in. The
+	// AfterWriteJSON log is the very last thing the daemon does as part of the
+	// create call. The POST /attach is the second CLI call. Notice the second
+	// time gap.
+	//
+	// time="2015-11-06T13:38:37.259627400-08:00" level=debug msg="After createRootfs"
+	// time="2015-11-06T13:38:37.263626300-08:00" level=debug msg="After setHostConfig"
+	// time="2015-11-06T13:38:37.267631200-08:00" level=debug msg="before createContainerPl...."
+	// time="2015-11-06T13:38:37.271629500-08:00" level=debug msg=ToDiskLocking....
+	// time="2015-11-06T13:38:37.275643200-08:00" level=debug msg="loggin event...."
+	// time="2015-11-06T13:38:37.277627600-08:00" level=debug msg="logged event...."
+	// time="2015-11-06T13:38:37.279631800-08:00" level=debug msg="In defer func"
+	// time="2015-11-06T13:38:37.282628100-08:00" level=debug msg="After daemon.create"
+	// time="2015-11-06T13:38:37.286651700-08:00" level=debug msg="return 2"
+	// time="2015-11-06T13:38:37.289629500-08:00" level=debug msg="Returned from daemon.ContainerCreate"
+	// time="2015-11-06T13:38:37.311629100-08:00" level=debug msg="After WriteJSON"
+	// ... 1 second gap here....
+	// time="2015-11-06T13:38:38.317866200-08:00" level=debug msg="Calling POST /v1.22/containers/984758282b842f779e805664b2c95d563adc9a979c8a3973e68c807843ee4757/attach"
+	// 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"
+	//
+	// We suspect this is either a bug introduced in GOLang 1.5.1, or that a change
+	// in GOLang 1.5.1 (from 1.4.3) is exposing a bug in Windows. In theory,
+	// the Windows networking stack is supposed to resolve "localhost" internally,
+	// without hitting DNS, or even reading the hosts file (which is why localhost
+	// is commented out in the hosts file on Windows).
+	//
+	// We have validated that working around this using the actual IPv4 localhost
+	// address does not cause the delay.
+	//
+	// This does not occur with the docker client built with 1.4.3 on the same
+	// Windows build, regardless of whether the daemon is built using 1.5.1
+	// or 1.4.3. It does not occur on Linux. We also verified we see the same thing
+	// on a cross-compiled Windows binary (from Linux).
+	//
+	// Final note: This is a mitigation, not a 'real' fix. It is still susceptible
+	// to the delay if a user were to do 'docker run -H=tcp://localhost:2375...'
+	// explicitly.
+
+	// DefaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
+	DefaultHTTPHost = "127.0.0.1"
+
+	// DefaultHost constant defines the default host string used by docker on Windows
+	DefaultHost = "npipe://" + DefaultNamedPipe
+)

opts/opts_unix.go

@@ -1,6 +0,0 @@
-// +build !windows
-
-package opts // import "github.com/docker/docker/opts"
-
-// DefaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
-const DefaultHTTPHost = "localhost"

opts/opts_windows.go

@@ -1,55 +0,0 @@
-package opts // import "github.com/docker/docker/opts"
-
-// TODO Windows. Identify bug in GOLang 1.5.1+ and/or Windows Server 2016 TP5.
-//
-// On Windows, this mitigates a problem with the default options of running
-// a docker client against a local docker daemon on TP5.
-//
-// What was found that if the default host is "localhost", even if the client
-// (and daemon as this is local) is not physically on a network, and the DNS
-// cache is flushed (ipconfig /flushdns), then the client will pause for
-// exactly one second when connecting to the daemon for calls. For example
-// using docker run windowsservercore cmd, the CLI will send a create followed
-// by an attach. You see the delay between the attach finishing and the attach
-// being seen by the daemon.
-//
-// Here's some daemon debug logs with additional debug spew put in. The
-// AfterWriteJSON log is the very last thing the daemon does as part of the
-// create call. The POST /attach is the second CLI call. Notice the second
-// time gap.
-//
-// time="2015-11-06T13:38:37.259627400-08:00" level=debug msg="After createRootfs"
-// time="2015-11-06T13:38:37.263626300-08:00" level=debug msg="After setHostConfig"
-// time="2015-11-06T13:38:37.267631200-08:00" level=debug msg="before createContainerPl...."
-// time="2015-11-06T13:38:37.271629500-08:00" level=debug msg=ToDiskLocking....
-// time="2015-11-06T13:38:37.275643200-08:00" level=debug msg="loggin event...."
-// time="2015-11-06T13:38:37.277627600-08:00" level=debug msg="logged event...."
-// time="2015-11-06T13:38:37.279631800-08:00" level=debug msg="In defer func"
-// time="2015-11-06T13:38:37.282628100-08:00" level=debug msg="After daemon.create"
-// time="2015-11-06T13:38:37.286651700-08:00" level=debug msg="return 2"
-// time="2015-11-06T13:38:37.289629500-08:00" level=debug msg="Returned from daemon.ContainerCreate"
-// time="2015-11-06T13:38:37.311629100-08:00" level=debug msg="After WriteJSON"
-// ... 1 second gap here....
-// time="2015-11-06T13:38:38.317866200-08:00" level=debug msg="Calling POST /v1.22/containers/984758282b842f779e805664b2c95d563adc9a979c8a3973e68c807843ee4757/attach"
-// 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"
-//
-// We suspect this is either a bug introduced in GOLang 1.5.1, or that a change
-// in GOLang 1.5.1 (from 1.4.3) is exposing a bug in Windows. In theory,
-// the Windows networking stack is supposed to resolve "localhost" internally,
-// without hitting DNS, or even reading the hosts file (which is why localhost
-// is commented out in the hosts file on Windows).
-//
-// We have validated that working around this using the actual IPv4 localhost
-// address does not cause the delay.
-//
-// This does not occur with the docker client built with 1.4.3 on the same
-// Windows build, regardless of whether the daemon is built using 1.5.1
-// or 1.4.3. It does not occur on Linux. We also verified we see the same thing
-// on a cross-compiled Windows binary (from Linux).
-//
-// Final note: This is a mitigation, not a 'real' fix. It is still susceptible
-// to the delay if a user were to do 'docker run -H=tcp://localhost:2375...'
-// explicitly.
-
-// DefaultHTTPHost Default HTTP Host used if only port is provided to -H flag e.g. dockerd -H tcp://:8080
-const DefaultHTTPHost = "127.0.0.1"