@@ -46,15 +46,18 @@ func (daemon *Daemon) setupLinkedContainers(ctr *container.Container) ([]string,

 			return nil, fmt.Errorf("container %s not attached to default bridge network", child.ID)

 		}

-		linkEnvVars := links.EnvVars(

-			bridgeSettings.IPAddress,

-			childBridgeSettings.IPAddress,

-			linkAlias,

-			child.Config.Env,

-			child.Config.ExposedPorts,

-		)

-

-		env = append(env, linkEnvVars...)

+		// Environment variables defined when using legacy links are deprecated and will be removed in a future release.

+		// Allow users to restore the old behavior through this escape hatch.

+		if os.Getenv("DOCKER_KEEP_DEPRECATED_LEGACY_LINKS_ENV_VARS") == "1" {

+			linkEnvVars := links.EnvVars(

+				bridgeSettings.IPAddress,

+				childBridgeSettings.IPAddress,

+				linkAlias,

+				child.Config.Env,

+				child.Config.ExposedPorts,

+			)

+			env = append(env, linkEnvVars...)

+		}

 	}

 	return env, nil

@@ -37,6 +37,11 @@ PY_TEST_OPTIONS="$PY_TEST_OPTIONS --deselect=tests/integration/api_image_test.py

 # TODO(laurazard): re-enable after https://github.com/docker/docker-py/pull/3290 is included in the DOCKER_PY_COMMIT release.

 PY_TEST_OPTIONS="$PY_TEST_OPTIONS --deselect=tests/integration/models_containers_test.py::ContainerTest::test_exec_run_failed"

+

+# Legacy links are deprecated since a long time, and starting with v29.0, the Engine won't set legacy links env vars

+# automatically in linking containers. Thus, this test is expected to fail — skip it. See https://github.com/moby/moby/pull/50719

+PY_TEST_OPTIONS="${PY_TEST_OPTIONS} --deselect=tests/integration/api_container_test.py::CreateContainerTest::test_create_with_links"

+

 (

 	bundle .integration-daemon-start

@@ -532,12 +532,3 @@ func (s *DockerCLIExecSuite) TestExecWindowsPathNotWiped(c *testing.T) {

 	out = strings.ToLower(strings.Trim(out, "\r\n"))

 	assert.Assert(c, is.Contains(out, `windowspowershell\v1.0`))

 }

-

-func (s *DockerCLIExecSuite) TestExecEnvLinksHost(c *testing.T) {

-	testRequires(c, DaemonIsLinux)

-	runSleepingContainer(c, "-d", "--name", "foo")

-	runSleepingContainer(c, "-d", "--link", "foo:db", "--hostname", "myhost", "--name", "bar")

-	out := cli.DockerCmd(c, "exec", "bar", "env").Stdout()

-	assert.Check(c, is.Contains(out, "HOSTNAME=myhost"))

-	assert.Check(c, is.Contains(out, "DB_NAME=/bar/db"))

-}

@@ -193,15 +193,6 @@ func (s *DockerCLILinksSuite) TestLinksUpdateOnRestart(c *testing.T) {

 	assert.Check(c, is.Equal(ip, realIP))

 }

-func (s *DockerCLILinksSuite) TestLinksEnvs(c *testing.T) {

-	testRequires(c, DaemonIsLinux)

-	cli.DockerCmd(c, "run", "-d", "-e", "e1=", "-e", "e2=v2", "-e", "e3=v3=v3", "--name=first", "busybox", "top")

-	out := cli.DockerCmd(c, "run", "--name=second", "--link=first:first", "busybox", "env").Stdout()

-	assert.Assert(c, is.Contains(out, "FIRST_ENV_e1=\n"))

-	assert.Assert(c, is.Contains(out, "FIRST_ENV_e2=v2"))

-	assert.Assert(c, is.Contains(out, "FIRST_ENV_e3=v3=v3"))

-}

-

 func (s *DockerCLILinksSuite) TestLinkShortDefinition(c *testing.T) {

 	testRequires(c, DaemonIsLinux)

 	cid := cli.DockerCmd(c, "run", "-d", "--name", "shortlinkdef", "busybox", "top").Stdout()

@@ -1894,3 +1894,60 @@ func TestDropInForwardChain(t *testing.T) {

 		}

 	})

 }

+

+// TestLegacyLinksEnvVars verify that legacy links environment variables are set in containers when the daemon is

+// started with DOCKER_KEEP_DEPRECATED_LEGACY_LINKS_ENV_VARS=1, and are skipped when the daemon is started without that

+// environment variable.

+func TestLegacyLinksEnvVars(t *testing.T) {

+	for _, tc := range []struct {

+		name          string

+		expectEnvVars bool

+	}{

+		{"with legacy links env vars", true},

+		{"without legacy links env vars", false},

+	} {

+		t.Run(tc.name, func(t *testing.T) {

+			var dEnv []string

+			if tc.expectEnvVars {

+				dEnv = []string{"DOCKER_KEEP_DEPRECATED_LEGACY_LINKS_ENV_VARS=1"}

+			}

+

+			ctx := setupTest(t)

+			d := daemon.New(t, daemon.WithEnvVars(dEnv...))

+			d.StartWithBusybox(ctx, t)

+			defer d.Stop(t)

+			c := d.NewClientT(t)

+			defer c.Close()

+

+			ctr1 := container.Run(ctx, t, c,

+				container.WithName("ctr1"),

+				container.WithCmd("httpd", "-f"))

+			defer c.ContainerRemove(ctx, ctr1, containertypes.RemoveOptions{Force: true})

+

+			exportRes := container.RunAttach(ctx, t, c,

+				container.WithName("ctr2"),

+				container.WithLinks("ctr1"),

+				container.WithCmd("/bin/sh", "-c", "export"),

+				container.WithAutoRemove)

+

+			// Check the list of environment variables set in the linking container.

+			var found bool

+			for _, l := range strings.Split(exportRes.Stdout.String(), "\n") {

+				if strings.HasPrefix(l, "export CTR1_") {

+					// Legacy links env var found, but not expected.

+					if !tc.expectEnvVars {

+						t.Fatalf("unexpected env var %q", l)

+					}

+

+					// Legacy links env var found, and expected. No need to check further.

+					found = true

+					break

+				}

+			}

+

+			if !found && tc.expectEnvVars {

+				t.Fatal("no legacy links env vars found")

+			}

+		})

+	}

+}