New global option interface_name in containers.conf

Add a new containers.conf attribute to define how to set interface name inside containers.

Relates to: containers/podman#21313

Signed-off-by: Vikas Goel <[email protected]>

docs/containers.conf.5.md

@@ -227,6 +227,13 @@ Path to the container-init binary, which forwards signals and reaps processes
 within containers. Note that the container-init binary will only be used when
 the `--init` for podman-create and podman-run is set.
 
+**interface_name**=""
+
+Default way to set interface names inside containers. Defaults to legacy pattern
+of ethX, where X is an integer, when left undefined.
+Options are:
+  `device`   Uses the network_interface name from the network config as interface name. Falls back to the ethX pattern if the network_interface is not set.
+
 **ipcns**="shareable"
 
 Default way to to create a IPC namespace for the container.

pkg/config/config.go

@@ -154,6 +154,13 @@ type ContainersConfig struct {
 	// Deprecated: Do not use this field directly use conf.FindInitBinary() instead.
 	InitPath string `toml:"init_path,omitempty"`
 
+	// InterfaceName tells container runtimes how to set interface names
+	// inside containers.
+	// The only valid value at the moment is "device" that indicates the
+	// interface name should be set as the network_interface name from
+	// the network config.
+	InterfaceName string `toml:"interface_name,omitempty"`
+
 	// IPCNS way to create a ipc namespace for the container
 	IPCNS string `toml:"ipcns,omitempty"`
 
@@ -814,6 +821,10 @@ func (c *ContainersConfig) Validate() error {
 		return err
 	}
 
+	if err := c.validateInterfaceName(); err != nil {
+		return err
+	}
+
 	if err := c.validateTZ(); err != nil {
 		return err
 	}

pkg/config/config_local.go

@@ -42,6 +42,14 @@ func (c *ContainersConfig) validateDevices() error {
 	return nil
 }
 
+func (c *ContainersConfig) validateInterfaceName() error {
+	if c.InterfaceName == "device" || c.InterfaceName == "" {
+		return nil
+	}
+
+	return fmt.Errorf("invalid interface_name option %s", c.InterfaceName)
+}
+
 func (c *ContainersConfig) validateUlimits() error {
 	for _, u := range c.DefaultUlimits.Get() {
 		ul, err := units.ParseUlimit(u)

pkg/config/config_local_test.go

@@ -234,6 +234,51 @@ var _ = Describe("Config Local", func() {
 		gomega.Expect(err).NotTo(gomega.BeNil())
 	})
 
+	It("should fail on invalid interface_name", func() {
+		defConf, err := defaultConfig()
+		gomega.Expect(err).To(gomega.BeNil())
+		gomega.Expect(defConf).NotTo(gomega.BeNil())
+
+		// Given
+		defConf.Containers.InterfaceName = "random"
+
+		// When
+		err = defConf.Containers.Validate()
+
+		// Then
+		gomega.Expect(err).NotTo(gomega.BeNil())
+	})
+
+	It("should succeed on good interface_name", func() {
+		defConf, err := defaultConfig()
+		gomega.Expect(err).To(gomega.BeNil())
+		gomega.Expect(defConf).NotTo(gomega.BeNil())
+
+		// Given
+		defConf.Containers.InterfaceName = "device"
+
+		// When
+		err = defConf.Containers.Validate()
+
+		// Then
+		gomega.Expect(err).To(gomega.BeNil())
+	})
+
+	It("should succeed on default interface_name", func() {
+		defConf, err := defaultConfig()
+		gomega.Expect(err).To(gomega.BeNil())
+		gomega.Expect(defConf).NotTo(gomega.BeNil())
+
+		// Given
+		defConf.Containers.InterfaceName = ""
+
+		// When
+		err = defConf.Containers.Validate()
+
+		// Then
+		gomega.Expect(err).To(gomega.BeNil())
+	})
+
 	It("should fail on bad timezone", func() {
 		defConf, err := defaultConfig()
 		gomega.Expect(err).To(gomega.BeNil())

pkg/config/config_remote.go

@@ -20,6 +20,10 @@ func (c *ContainersConfig) validateDevices() error {
 	return nil
 }
 
+func (c *ContainersConfig) validateInterfaceName() error {
+	return nil
+}
+
 func (c *ContainersConfig) validateUlimits() error {
 	return nil
 }

pkg/config/config_test.go

@@ -28,6 +28,7 @@ var _ = Describe("Config", func() {
 			gomega.Expect(err).To(gomega.BeNil())
 			gomega.Expect(defaultConfig.Containers.ApparmorProfile).To(gomega.Equal(apparmor.Profile))
 			gomega.Expect(defaultConfig.Containers.BaseHostsFile).To(gomega.Equal(""))
+			gomega.Expect(defaultConfig.Containers.InterfaceName).To(gomega.Equal(""))
 			gomega.Expect(defaultConfig.Containers.PidsLimit).To(gomega.BeEquivalentTo(2048))
 			gomega.Expect(defaultConfig.Containers.Privileged).To(gomega.BeFalse())
 			gomega.Expect(defaultConfig.Containers.ReadOnly).To(gomega.BeFalse())

pkg/config/containers.conf

@@ -164,6 +164,13 @@ default_sysctls = [
 #
 #ipcns = "shareable"
 
+# Default way to set an interface name inside container. Defaults to legacy
+# pattern of ethX, where X is a integer, when left undefined.
+# Options are:
+#  "device"   Uses the network_interface name from the network config as interface name.
+#             Falls back to the ethX pattern if the network_interface is not set.
+#interface_name = ""
+
 # keyring tells the container engine whether to create
 # a kernel keyring for use within the container.
 #

pkg/config/testdata/containers_comment.conf

@@ -86,6 +86,9 @@
 # Run an init inside the container that forwards signals and reaps processes.
 # init = false
 
+# Pattern of interface name inside container.
+# interface_name = ""
+
 
 # The network table containers settings pertaining to the management of
 # CNI plugins.

pkg/config/testdata/containers_default.conf

@@ -66,6 +66,9 @@ env = [
 # Run an init inside the container that forwards signals and reaps processes.
 init = false
 
+# Set interface name inside container in legacy way, ethX.
+interface_name = ""
+
 host_containers_internal_ip = "1.2.3.4"
 
 # proxy environment variables are passed into the container