Add availability constants for network and port drivers in help text

Signed-off-by: fahed dorgaa <[email protected]>

Author: fahedouch

cmd/rootlesskit/main.go

@@ -83,6 +83,33 @@ Examples:
 Note: RootlessKit requires /etc/subuid and /etc/subgid to be configured by the real root user.
 See https://rootlesscontaine.rs/getting-started/common/ .
 `
+	// Build the list of available network drivers for help text
+	// Only compiled-in drivers will be shown here, so omitted drivers don't appear in --help.
+	drivers := []string{"host", "none", "pasta(experimental)"}
+	if slirp4netns.Available {
+		drivers = append(drivers, "slirp4netns")
+	}
+	if vpnkit.Available {
+		drivers = append(drivers, "vpnkit")
+	}
+	if lxcusernic.Available {
+		drivers = append(drivers, "lxc-user-nic(experimental)")
+	}
+	if gvisortapvsock.Available {
+		drivers = append(drivers, "gvisor-tap-vsock(experimental)")
+	}
+	netDriversHelp := strings.Join(drivers, ", ")
+
+	// Build the list of available port drivers for help text
+	portDrivers := []string{"none", "implicit (for pasta)", "builtin"}
+	if slirp4netns_port.Available {
+		portDrivers = append(portDrivers, "slirp4netns")
+	}
+	if gvisortapvsock_port.Available {
+		portDrivers = append(portDrivers, "gvisor-tap-vsock(experimental)")
+	}
+	portDriversHelp := strings.Join(portDrivers, ", ")
+
 	app.Flags = []cli.Flag{
 		Categorize(&cli.BoolFlag{
 			Name:        "debug",
@@ -99,7 +126,7 @@ See https://rootlesscontaine.rs/getting-started/common/ .
 		}, CategoryState),
 		Categorize(&cli.StringFlag{
 			Name:  "net",
-			Usage: "network driver [host, none, pasta(experimental), slirp4netns, vpnkit, lxc-user-nic(experimental), gvisor-tap-vsock(experimental)]",
+			Usage: fmt.Sprintf("network driver [%s]", netDriversHelp),
 			Value: "host",
 		}, CategoryNetwork),
 		Categorize(&cli.StringFlag{
@@ -169,7 +196,7 @@ See https://rootlesscontaine.rs/getting-started/common/ .
 		}, CategoryMount),
 		Categorize(&cli.StringFlag{
 			Name:  "port-driver",
-			Usage: "port driver for non-host network. [none, implicit (for pasta), builtin, slirp4netns, gvisor-tap-vsock]",
+			Usage: fmt.Sprintf("port driver for non-host network. [%s]", portDriversHelp),
 			Value: "none",
 		}, CategoryPort),
 		Categorize(&cli.StringSliceFlag{

docs/network.md

@@ -271,25 +271,13 @@ The child command can enter `$ROOTLESSKIT_STATE_DIR/netns` by itself to create n
 
 ## Build tags to omit drivers
 
-To exclude specific drivers at compilation time, use Go build tags:
+Build-time driver selection is documented in BUILDING.md.
 
-- Tag no_vpnkit: omits the VPNKit network driver implementation.
-- Tag no_gvisortapvsock: omits the gvisor-tap-vsock network driver implementation and its port driver.
-- Tag no_slirp4netns: omits the slirp4netns network driver implementation and its port driver.
-- Tag no_lxcusernic: omits the lxc-user-nic network driver implementation.
-
-Examples:
+Example:
 
 - Build without VPNKit support:
   go build -tags no_vpnkit ./cmd/rootlesskit
 
-- Build without gvisor-tap-vsock support (also disables the gvisor-tap-vsock port driver):
-  go build -tags no_gvisortapvsock ./cmd/rootlesskit
-
-- Build without slirp4netns support (also disables the slirp4netns port driver):
-  go build -tags no_slirp4netns ./cmd/rootlesskit
-
-- Build without lxc-user-nic support:
-  go build -tags no_lxcusernic ./cmd/rootlesskit
+Note: CI should test all supported combinations of these build tags.
 
 If a disabled driver is selected at runtime (e.g., --net=vpnkit when built with -tags no_vpnkit), RootlessKit returns an error indicating that the driver was disabled at build time.

docs/port.md

@@ -59,3 +59,14 @@ To specify IPv6 explicitly, use `tcp6`, e.g., `[::]:8080:80/tcp6`.
 
 The `tcp4` and `tcp6` forms were introduced in RootlessKit v0.14.0.
 The `tcp6` is currently supported only for `builtin` port driver.
+
+## Build tags to omit port drivers
+
+Build-time driver selection is documented in BUILDING.md.
+
+Example:
+
+- Building with `-tags no_slirp4netns` disables both the slirp4netns network driver and its port driver.
+- Building with `-tags no_gvisortapvsock` disables both the gvisor-tap-vsock network driver and its port driver.
+
+Note: CI should test supported combinations of these build tags.

pkg/network/gvisortapvsock/gvisortapvsock.go

@@ -35,6 +35,8 @@ const (
 	DriverName = "gvisor-tap-vsock"
 	// Default buffer size for packet reading/writing
 	defaultBufferSize = 65536
+	// Available indicates whether this driver is compiled in (used for generating help text)
+	Available = true
 )
 
 // NewParentDriver instantiates a new parent driver

pkg/network/gvisortapvsock/gvisortapvsock_disabled.go

@@ -43,3 +43,6 @@ func (d *disabledChild) ChildDriverInfo() (*network.ChildDriverInfo, error) {
 func (d *disabledChild) ConfigureNetworkChild(netmsg *messages.ParentInitNetworkDriverCompleted, detachedNetNSPath string) (string, error) {
 	return "", errors.New("gvisor-tap-vsock network driver disabled by build tag no_gvisortapvsock")
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = false

pkg/network/lxcusernic/lxcusernic.go

@@ -217,3 +217,6 @@ func dhcpRenewRoutine(c *client4.Client, dev string, initialIP net.IP, lease tim
 		lease = p.IPAddressLeaseTime(lease)
 	}
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = true

pkg/network/lxcusernic/lxcusernic_disabled.go

@@ -41,3 +41,6 @@ func (d *disabledChild) ChildDriverInfo() (*network.ChildDriverInfo, error) {
 func (d *disabledChild) ConfigureNetworkChild(netmsg *messages.ParentInitNetworkDriverCompleted, detachedNetNSPath string) (string, error) {
 	return "", errors.New("lxc-user-nic network driver disabled by build tag no_lxcusernic")
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = false

pkg/network/slirp4netns/slirp4netns.go

@@ -356,3 +356,6 @@ func (d *childDriver) ConfigureNetworkChild(netmsg *messages.ParentInitNetworkDr
 	// and they are up to the child.
 	return tap, nil
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = true

pkg/network/slirp4netns/slirp4netns_disabled.go

@@ -43,3 +43,6 @@ func (d *disabledChild) ChildDriverInfo() (*network.ChildDriverInfo, error) {
 func (d *disabledChild) ConfigureNetworkChild(netmsg *messages.ParentInitNetworkDriverCompleted, detachedNetNSPath string) (string, error) {
 	return "", errors.New("slirp4netns network driver disabled by build tag no_slirp4netns")
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = false

pkg/network/vpnkit/vpnkit.go

@@ -291,3 +291,6 @@ func vif2tap(w io.Writer, vif *vmnet.Vif) {
 		}
 	}
 }
+
+// Available indicates whether this driver is compiled in (used for generating help text)
+const Available = true