PRODENG-3471: fix Windows MCR install for FIPS channels

For FIPS channels (e.g. stable-29.2.1/fips) the Windows MCR installer
repo publishes versioned artifacts (docker-29.2.1+fips.zip) but does
NOT publish docker-latest+fips.zip. Launchpad was hardcoding
DOCKER_VERSION=latest, causing install.ps1 to construct a non-existent
URL and exit 1 on all Windows nodes. Linux nodes are unaffected.

Add windowsInstallerVersion(channel string) as a package-private helper
in pkg/configurer/windows.go, alongside the existing isExitCode3010
helper. Returns 'latest' for all non-FIPS channels (preserving current
behaviour) and extracts the version from the channel string for FIPS:
  stable-29.2.1/fips   → 29.2.1
  test-29.4.1-rc3/fips → 29.4.1-rc3
  stable-29.2          → latest (unchanged)

InstallMCR uses this instead of the hardcoded 'latest'.

Signed-off-by: James Nesbitt <jnesbitt@mirantis.com>

Author: james-nesbitt

pkg/configurer/windows.go

@@ -60,7 +60,7 @@ func (c WindowsConfigurer) InstallMCRLicense(h os.Host, lic string) error {
 
 // InstallMCR install MCR on Windows.
 func (c WindowsConfigurer) InstallMCR(h os.Host, engineConfig commonconfig.MCRConfig) error {
-	version := "latest"
+	version := windowsInstallerVersion(engineConfig.Channel)
 
 	installerPath, getInstallerErr := GetInstaller(engineConfig.InstallURLWindows)
 	if getInstallerErr != nil {
@@ -124,6 +124,25 @@ func isExitCode3010(err error) bool {
 	return err != nil && strings.Contains(err.Error(), "non-zero exit code: 3010")
 }
 
+// windowsInstallerVersion returns the version token to pass as DOCKER_VERSION
+// to install.ps1. For non-FIPS channels the repo publishes only
+// docker-latest.zip so "latest" is correct. For FIPS channels (suffix /fips)
+// the repo publishes docker-<version>+fips.zip but no docker-latest+fips.zip,
+// so the version must be extracted from the channel string.
+func windowsInstallerVersion(channel string) string {
+	if !strings.HasSuffix(channel, "/fips") {
+		return "latest"
+	}
+	ch := strings.TrimSuffix(channel, "/fips")
+	parts := strings.Split(ch, "-")
+	for i, p := range parts {
+		if len(p) > 0 && p[0] >= '0' && p[0] <= '9' {
+			return strings.Join(parts[i:], "-")
+		}
+	}
+	return "latest"
+}
+
 // Reboot triggers an immediate forced restart by scheduling a SYSTEM-context
 // one-shot task that runs 'shutdown /r /f /t 5', then immediately triggering
 // and deleting it within the 5-second countdown window.

pkg/configurer/windows_test.go

@@ -0,0 +1,32 @@
+package configurer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestWindowsInstallerVersion(t *testing.T) {
+	tests := []struct {
+		channel string
+		want    string
+	}{
+		// Standard channels — always "latest"; docker-latest.zip is published
+		{"stable-29.2", "latest"},
+		{"stable-25.0", "latest"},
+		{"ee-stable-29.2", "latest"},
+		// FIPS channels — version extracted; only docker-<version>+fips.zip is published
+		{"stable-29.2.1/fips", "29.2.1"},
+		{"stable-29.4.1/fips", "29.4.1"},
+		{"test-29.4.1/fips", "29.4.1"},
+		// FIPS RC channel
+		{"test-29.4.1-rc3/fips", "29.4.1-rc3"},
+		// FIPS channel with no parseable version — falls back to latest
+		{"stable/fips", "latest"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.channel, func(t *testing.T) {
+			require.Equal(t, tt.want, windowsInstallerVersion(tt.channel), "channel=%q", tt.channel)
+		})
+	}
+}