Test for updating hosts files via links.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)

integration-cli/docker_cli_links_test.go

@@ -6,6 +6,7 @@ import (
 	"os/exec"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/docker/docker/pkg/iptables"
 )
@@ -177,3 +178,39 @@ func TestLinksNotStartedParentNotFail(t *testing.T) {
 	}
 	logDone("link - container start not failing on updating stopped parent links")
 }
+
+func TestLinksHostsFilesInject(t *testing.T) {
+	defer deleteAllContainers()
+
+	out, _, err := runCommandWithOutput(exec.Command(dockerBinary, "run", "-itd", "--name", "one", "busybox", "top"))
+	if err != nil {
+		t.Fatal(err, out)
+	}
+
+	idOne := strings.TrimSpace(out)
+
+	out, _, err = runCommandWithOutput(exec.Command(dockerBinary, "run", "-itd", "--name", "two", "--link", "one:onetwo", "busybox", "top"))
+	if err != nil {
+		t.Fatal(err, out)
+	}
+
+	idTwo := strings.TrimSpace(out)
+
+	time.Sleep(1 * time.Second)
+
+	contentOne, err := readContainerFile(idOne, "hosts")
+	if err != nil {
+		t.Fatal(err, string(contentOne))
+	}
+
+	contentTwo, err := readContainerFile(idTwo, "hosts")
+	if err != nil {
+		t.Fatal(err, string(contentTwo))
+	}
+
+	if !strings.Contains(string(contentTwo), "onetwo") {
+		t.Fatal("Host is not present in updated hosts file", string(contentTwo))
+	}
+
+	logDone("link - ensure containers hosts files are updated with the link alias.")
+}

integration-cli/docker_utils.go

@@ -736,10 +736,11 @@ func containerStorageFile(containerId, basename string) string {
 	return filepath.Join("/var/lib/docker/containers", containerId, basename)
 }
 
+// docker commands that use this function must be run with the '-d' switch.
 func runCommandAndReadContainerFile(filename string, cmd *exec.Cmd) ([]byte, error) {
 	out, _, err := runCommandWithOutput(cmd)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%v: %q", err, out)
 	}
 
 	time.Sleep(1 * time.Second)