Merge pull request #5129 from vieux/host_resolv

allow /etc/hosts /etc/resolv.conf and /etc/hostname to be changed

daemon/container.go

@@ -849,18 +849,16 @@ func (container *Container) setupContainerDns() error {
 		daemon = container.daemon
 	)
 
-	if config.NetworkMode == "host" {
-		container.ResolvConfPath = "/etc/resolv.conf"
-		return nil
-	}
-
 	resolvConf, err := resolvconf.Get()
 	if err != nil {
 		return err
 	}
+	container.ResolvConfPath, err = container.getRootResourcePath("resolv.conf")
+	if err != nil {
+		return err
+	}
 
-	// If custom dns exists, then create a resolv.conf for the container
-	if len(config.Dns) > 0 || len(daemon.config.Dns) > 0 || len(config.DnsSearch) > 0 || len(daemon.config.DnsSearch) > 0 {
+	if config.NetworkMode != "host" && (len(config.Dns) > 0 || len(daemon.config.Dns) > 0 || len(config.DnsSearch) > 0 || len(daemon.config.DnsSearch) > 0) {
 		var (
 			dns       = resolvconf.GetNameservers(resolvConf)
 			dnsSearch = resolvconf.GetSearchDomains(resolvConf)
@@ -875,18 +873,9 @@ func (container *Container) setupContainerDns() error {
 		} else if len(daemon.config.DnsSearch) > 0 {
 			dnsSearch = daemon.config.DnsSearch
 		}
-
-		resolvConfPath, err := container.getRootResourcePath("resolv.conf")
-		if err != nil {
-			return err
-		}
-		container.ResolvConfPath = resolvConfPath
-
 		return resolvconf.Build(container.ResolvConfPath, dns, dnsSearch)
-	} else {
-		container.ResolvConfPath = "/etc/resolv.conf"
 	}
-	return nil
+	return ioutil.WriteFile(container.ResolvConfPath, resolvConf, 0644)
 }
 
 func (container *Container) initializeNetworking() error {

daemon/volumes.go

@@ -50,15 +50,15 @@ func prepareVolumesForContainer(container *Container) error {
 
 func setupMountsForContainer(container *Container) error {
 	mounts := []execdriver.Mount{
-		{container.ResolvConfPath, "/etc/resolv.conf", false, true},
+		{container.ResolvConfPath, "/etc/resolv.conf", true, true},
 	}
 
 	if container.HostnamePath != "" {
-		mounts = append(mounts, execdriver.Mount{container.HostnamePath, "/etc/hostname", false, true})
+		mounts = append(mounts, execdriver.Mount{container.HostnamePath, "/etc/hostname", true, true})
 	}
 
 	if container.HostsPath != "" {
-		mounts = append(mounts, execdriver.Mount{container.HostsPath, "/etc/hosts", false, true})
+		mounts = append(mounts, execdriver.Mount{container.HostsPath, "/etc/hosts", true, true})
 	}
 
 	// Mount user specified volumes

docs/sources/articles/networking.md

@@ -731,3 +731,14 @@ usual containers.  But unless you have very specific networking needs
 that drive you to such a solution, it is probably far preferable to use
 `--icc=false` to lock down inter-container communication, as we explored
 earlier.
+
+## Editing networking config files
+
+Starting with Docker v.1.2.0, you can now edit `/etc/hosts`, `/etc/hostname`
+and `/etc/resolve.conf` in a running container. This is useful if you need
+to install bind or other services that might override one of those files.
+
+Note, however, that changes to these files will not be saved by
+`docker commit`, nor will they be saved during `docker run`.
+That means they won't be saved in the image, nor will they persist when a
+container is restarted; they will only "stick" in a running container.

integration-cli/docker_cli_run_test.go

@@ -1549,3 +1549,84 @@ func TestRunExitOnStdinClose(t *testing.T) {
 	}
 	logDone("run - exit on stdin closing")
 }
+
+// Test for #2267
+func TestWriteHostsFileAndNotCommit(t *testing.T) {
+	name := "writehosts"
+	cmd := exec.Command(dockerBinary, "run", "--name", name, "busybox", "sh", "-c", "echo test2267 >> /etc/hosts && cat /etc/hosts")
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if !strings.Contains(out, "test2267") {
+		t.Fatal("/etc/hosts should contain 'test2267'")
+	}
+
+	cmd = exec.Command(dockerBinary, "diff", name)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if len(strings.Trim(out, "\r\n")) != 0 {
+		t.Fatal("diff should be empty")
+	}
+
+	logDone("run - write to /etc/hosts and not commited")
+}
+
+// Test for #2267
+func TestWriteHostnameFileAndNotCommit(t *testing.T) {
+	name := "writehostname"
+	cmd := exec.Command(dockerBinary, "run", "--name", name, "busybox", "sh", "-c", "echo test2267 >> /etc/hostname && cat /etc/hostname")
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if !strings.Contains(out, "test2267") {
+		t.Fatal("/etc/hostname should contain 'test2267'")
+	}
+
+	cmd = exec.Command(dockerBinary, "diff", name)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if len(strings.Trim(out, "\r\n")) != 0 {
+		t.Fatal("diff should be empty")
+	}
+
+	logDone("run - write to /etc/hostname and not commited")
+}
+
+// Test for #2267
+func TestWriteResolvFileAndNotCommit(t *testing.T) {
+	name := "writeresolv"
+	cmd := exec.Command(dockerBinary, "run", "--name", name, "busybox", "sh", "-c", "echo test2267 >> /etc/resolv.conf && cat /etc/resolv.conf")
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if !strings.Contains(out, "test2267") {
+		t.Fatal("/etc/resolv.conf should contain 'test2267'")
+	}
+
+	cmd = exec.Command(dockerBinary, "diff", name)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatal(err, out)
+	}
+	if len(strings.Trim(out, "\r\n")) != 0 {
+		t.Fatal("diff should be empty")
+	}
+
+	logDone("run - write to /etc/resolv.conf and not commited")
+}