[LEP-4968] fix(release): support Ubuntu 26.04 install artifact fallback (#1243)

Signed-off-by: Gyuho Lee <gyuhol@nvidia.com>

Author: gyuho

install.sh

@@ -144,12 +144,31 @@ main() {
   fi
 
   if [ "$OS_NAME" = "ubuntu" ]; then
+    # Ubuntu artifact compatibility:
+    # GPUd uses github.com/mattn/go-sqlite3 with CGO enabled, but does not build
+    # with the "libsqlite3" build tag. That means go-sqlite3 compiles its bundled
+    # SQLite amalgamation into the gpud binary instead of dynamically linking
+    # against Ubuntu's /usr/lib/.../libsqlite3.so. The distro-specific runtime
+    # compatibility risk is therefore the C runtime ABI, not the host SQLite
+    # package version.
+    #
+    # glibc preserves runtime backward compatibility for older linked symbols:
+    # a binary built against an older glibc baseline can run on newer Ubuntu
+    # releases, while the reverse is not guaranteed. The Ubuntu 24.04 artifact
+    # is safe for Ubuntu 26.04 because it does not require Ubuntu 26.04-only
+    # glibc symbols or any Ubuntu-provided SQLite shared library. Keep 22.04 on
+    # its own artifact, and map newer supported LTS releases to the newest
+    # existing Ubuntu artifact until we intentionally raise the glibc baseline or
+    # add a real distro-specific dynamic dependency.
     case "$OS_VERSION" in
-      22.04|24.04)
+      22.04)
         OS_DISTRO="_${OS_NAME}${OS_VERSION}"
         ;;
+      24.04|26.04)
+        OS_DISTRO="_${OS_NAME}24.04"
+        ;;
       *)
-        echo "GPUd $APP_VERSION supports Ubuntu 22.04 and 24.04. Current version $OS_VERSION is not supported."
+        echo "GPUd $APP_VERSION supports Ubuntu 22.04, 24.04, and 26.04. Current version $OS_VERSION is not supported."
         exit 1
         ;;
     esac

pkg/update/mock_system_test.go

@@ -48,6 +48,24 @@ func TestDetectUbuntuVersion_Ubuntu2404(t *testing.T) {
 	})
 }
 
+// TestDetectUbuntuVersion_Ubuntu2604UsesUbuntu2404Artifact tests Ubuntu 26.04
+// detection intentionally reuses the Ubuntu 24.04 artifact.
+func TestDetectUbuntuVersion_Ubuntu2604UsesUbuntu2404Artifact(t *testing.T) {
+	mockey.PatchConvey("detect ubuntu 26.04", t, func() {
+		cmdCallCount := 0
+		mockey.Mock((*exec.Cmd).Output).To(func(cmd *exec.Cmd) ([]byte, error) {
+			cmdCallCount++
+			if cmdCallCount == 1 {
+				return []byte("Ubuntu\n"), nil
+			}
+			return []byte("26.04\n"), nil
+		}).Build()
+
+		result := detectUbuntuVersion()
+		assert.Equal(t, "ubuntu24.04", result)
+	})
+}
+
 // TestDetectUbuntuVersion_NotUbuntu tests when OS is not Ubuntu.
 func TestDetectUbuntuVersion_NotUbuntu(t *testing.T) {
 	mockey.PatchConvey("not ubuntu", t, func() {

pkg/update/system.go

@@ -23,9 +23,13 @@ func detectUbuntuVersion() string {
 		return ""
 	}
 	version := strings.TrimSpace(string(outputBytes))
-	if version == "22.04" || version == "24.04" {
+	if version == "22.04" {
 		return "ubuntu" + version
 	}
+	if version == "24.04" || version == "26.04" {
+		// Keep self-update artifact selection aligned with install.sh.
+		return "ubuntu24.04"
+	}
 	return ""
 }