fix(configurer): fall back to ip(8) when hostname lacks --all-ip-addresses

LinuxConfigurer.LocalAddresses() ran 'hostname --all-ip-addresses'
unconditionally. SLES 12 SP5's hostname (net-tools, ~2018) does not
support this GNU extension and exits status 4, which ValidateHosts
surfaces as a hard failure before any MCR/MKE install work starts.

Fall back to parsing 'ip -4 -o addr show scope global' when the
hostname command fails. Also switch strings.Split -> strings.Fields
on the hostname path so a trailing space no longer produces an empty
address element.

Re-add the WrkSles12 worker to TestLegacyCluster now that the
Validate Hosts blocker is fixed.

PRODENG-3588

Author: james-nesbitt

pkg/configurer/linux.go

@@ -130,14 +130,41 @@ func (c LinuxConfigurer) CheckPrivilege(_ os.Host) error {
 	return nil
 }
 
-// LocalAddresses returns a list of local addresses.
+// LocalAddresses returns a list of local IP addresses for the host.
+//
+// It first tries "hostname --all-ip-addresses" (GNU net-tools). Older toolchains
+// such as SLES 12 SP5 ship a hostname(1) that does not support this flag and
+// exit with status 4. In that case it falls back to parsing "ip -4 -o addr show
+// scope global", which is available on all supported Linux platforms.
 func (c LinuxConfigurer) LocalAddresses(h os.Host) ([]string, error) {
 	output, err := h.ExecOutput("hostname --all-ip-addresses")
+	if err == nil {
+		// hostname emits addresses separated by spaces with a trailing space;
+		// use Fields so the trailing space does not produce an empty element.
+		return strings.Fields(output), nil
+	}
+
+	// Fallback: "ip -4 -o addr show scope global" produces one line per
+	// address in the form:
+	//   2: eth0    inet 10.0.0.5/24 brd 10.0.0.255 scope global eth0\
+	// Field index 3 is "addr/prefix".
+	output, err = h.ExecOutput("ip -4 -o addr show scope global")
 	if err != nil {
 		return nil, fmt.Errorf("failed to get local addresses: %w", err)
 	}
 
-	return strings.Split(output, " "), nil
+	var addrs []string
+	for _, line := range strings.Split(strings.TrimSpace(output), "\n") {
+		fields := strings.Fields(line)
+		if len(fields) < 4 {
+			continue
+		}
+		addr, _, _ := strings.Cut(fields[3], "/")
+		if iputil.IsValidAddress(addr) {
+			addrs = append(addrs, addr)
+		}
+	}
+	return addrs, nil
 }
 
 type reconnectable interface {

pkg/configurer/linux_test.go

@@ -0,0 +1,113 @@
+package configurer
+
+import (
+	"fmt"
+	"io"
+	"io/fs"
+	"testing"
+
+	"github.com/k0sproject/rig/exec"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// mockHost stubs os.Host for unit-testing configurer methods that run remote
+// commands. Command responses are keyed by the full command string; a missing
+// key returns an error to simulate command-not-found / non-zero exit.
+type mockHost struct {
+	outputs map[string]string
+	errors  map[string]error
+}
+
+func (m *mockHost) String() string { return "mockHost" }
+
+func (m *mockHost) ExecOutput(cmd string, _ ...exec.Option) (string, error) {
+	if err, ok := m.errors[cmd]; ok {
+		return "", err
+	}
+	if out, ok := m.outputs[cmd]; ok {
+		return out, nil
+	}
+	return "", fmt.Errorf("unexpected command: %q", cmd)
+}
+
+func (m *mockHost) Exec(cmd string, opts ...exec.Option) error {
+	_, err := m.ExecOutput(cmd, opts...)
+	return err
+}
+
+func (m *mockHost) ExecOutputf(cmd string, argsOrOpts ...any) (string, error) {
+	// Separate format args from exec.Option values.
+	var args []any
+	var opts []exec.Option
+	for _, a := range argsOrOpts {
+		if o, ok := a.(exec.Option); ok {
+			opts = append(opts, o)
+		} else {
+			args = append(args, a)
+		}
+	}
+	return m.ExecOutput(fmt.Sprintf(cmd, args...), opts...)
+}
+
+func (m *mockHost) Execf(cmd string, argsOrOpts ...any) error {
+	_, err := m.ExecOutputf(cmd, argsOrOpts...)
+	return err
+}
+
+func (m *mockHost) Upload(_ string, _ string, _ fs.FileMode, _ ...exec.Option) error {
+	return nil
+}
+
+func (m *mockHost) ExecStreams(_ string, _ io.ReadCloser, _ io.Writer, _ io.Writer, _ ...exec.Option) (exec.Waiter, error) {
+	return nil, nil
+}
+
+func (m *mockHost) Sudo(cmd string) (string, error) {
+	return cmd, nil
+}
+
+// TestLocalAddresses_Hostname verifies the happy path: hostname --all-ip-addresses
+// returns a space-separated list (with trailing space, as real hostname emits).
+func TestLocalAddresses_Hostname(t *testing.T) {
+	h := &mockHost{
+		outputs: map[string]string{
+			"hostname --all-ip-addresses": "10.0.0.5 172.31.0.10 ",
+		},
+	}
+	addrs, err := LinuxConfigurer{}.LocalAddresses(h)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"10.0.0.5", "172.31.0.10"}, addrs)
+}
+
+// TestLocalAddresses_IPFallback verifies the SLES 12 SP5 scenario: hostname
+// --all-ip-addresses fails (exit 4), so LocalAddresses falls back to
+// "ip -4 -o addr show scope global" and parses the addr/prefix fields.
+func TestLocalAddresses_IPFallback(t *testing.T) {
+	ipOutput := "2: eth0    inet 10.0.0.5/24 brd 10.0.0.255 scope global eth0\\\n" +
+		"3: eth1    inet 172.31.0.10/20 brd 172.31.15.255 scope global eth1\\\n"
+	h := &mockHost{
+		outputs: map[string]string{
+			"ip -4 -o addr show scope global": ipOutput,
+		},
+		errors: map[string]error{
+			"hostname --all-ip-addresses": fmt.Errorf("exit status 4"),
+		},
+	}
+	addrs, err := LinuxConfigurer{}.LocalAddresses(h)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"10.0.0.5", "172.31.0.10"}, addrs)
+}
+
+// TestLocalAddresses_BothFail verifies that an error is returned when both
+// commands are unavailable (neither hostname nor ip work).
+func TestLocalAddresses_BothFail(t *testing.T) {
+	h := &mockHost{
+		errors: map[string]error{
+			"hostname --all-ip-addresses":     fmt.Errorf("exit status 4"),
+			"ip -4 -o addr show scope global": fmt.Errorf("exit status 127"),
+		},
+	}
+	_, err := LinuxConfigurer{}.LocalAddresses(h)
+	assert.Error(t, err)
+}

test/smoke/smoke_test.go

@@ -112,7 +112,7 @@ func runSmokeTest(t *testing.T, cfg smokeConfig) {
 		"nodegroups":        cfg.Nodegroups,
 		"ssh_key_algorithm": cfg.SSHKeyAlgorithm,
 		"extra_tags": map[string]string{
-			"launchpad-smoke-test": "true",
+			"launchpad-smoke-test":      "true",
 			"launchpad-smoke-test-name": cfg.Name,
 		},
 	}
@@ -191,8 +191,8 @@ func TestModernCluster(t *testing.T) {
 	})
 }
 
-// TestLegacyCluster exercises rhel8/rocky8/ubuntu22 managers and workers
-// with MCR stable-25.0 and MKE 3.8.8.
+// TestLegacyCluster exercises rhel8/rocky8/ubuntu22 managers and
+// rhel8/rocky8/ubuntu22/sles12 workers with MCR stable-25.0 and MKE 3.8.8.
 func TestLegacyCluster(t *testing.T) {
 	runSmokeTest(t, smokeConfig{
 		Name:            "legacy",
@@ -207,6 +207,7 @@ func TestLegacyCluster(t *testing.T) {
 			"WrkRhel8":     test.Platforms["Rhel8"].GetWorker(),
 			"WrkRocky8":    test.Platforms["Rocky8"].GetWorker(),
 			"WrkUbuntu22":  test.Platforms["Ubuntu22"].GetWorker(),
+			"WrkSles12":    test.Platforms["Sles12"].GetWorker(),
 		},
 	})
 }
@@ -243,7 +244,7 @@ func TestFIPSCluster(t *testing.T) {
 		SSHKeyAlgorithm: "rsa",
 		Nodegroups: map[string]interface{}{
 			"MngrUbuntu22FIPS": test.Platforms["Ubuntu22FIPS"].GetManager(),
-			"WrkWin2025":   test.Platforms["Windows2025"].GetWorker(),
+			"WrkWin2025":       test.Platforms["Windows2025"].GetWorker(),
 		},
 	})
 }