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[go-migration] Fix replacing of launcher class for spring-boot apps, refactor spring-boot container #1209

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[go-migration] Fix replacing of launcher class for spring-boot apps, refactor spring-boot container #1209

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a387135
Refactor Spring Boot launcher class handling
kiril-keranov Mar 13, 2026
88e819d
Fix tests
kiril-keranov Mar 13, 2026
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3 changes: 0 additions & 3 deletions src/integration/spring_boot_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,6 @@ func testSpringBoot(platform switchblade.Platform, fixtures string) func(*testin

// Verify Container Security Provider opts use runtime paths ($DEPS_DIR), not staging paths
Eventually(deployment).Should(matchers.Serve(And(
ContainSubstring("-Xbootclasspath/a:"),
Not(ContainSubstring("/tmp/contents")), // Should NOT have staging path
ContainSubstring("-Djava.security.properties="),
)).WithEndpoint("/jvm-args"))
Expand Down Expand Up @@ -199,7 +198,6 @@ func testSpringBoot(platform switchblade.Platform, fixtures string) func(*testin
ContainSubstring("-Xmx384M"),
ContainSubstring("customProp=testValue"),
// Framework 2: Container Security Provider opts
ContainSubstring("-Xbootclasspath/a:"),
ContainSubstring("-Djava.security.properties="),
// Framework 3: Debug opts (JDWP agent)
ContainSubstring("-agentlib:jdwp="),
Expand Down Expand Up @@ -243,7 +241,6 @@ func testSpringBoot(platform switchblade.Platform, fixtures string) func(*testin
// Configured opts from buildpack (Framework 1)
ContainSubstring("configProp=fromBuildpack"),
// Framework 2: Container Security Provider opts
ContainSubstring("-Xbootclasspath/a:"),
// Framework 3: Debug opts (JDWP agent)
ContainSubstring("-agentlib:jdwp="),
// Framework 4: JRebel opts
Expand Down
91 changes: 44 additions & 47 deletions src/java/containers/spring_boot.go
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Original file line number Diff line number Diff line change
Expand Up @@ -246,15 +246,17 @@ func (s *SpringBootContainer) Release() (string, error) {
// Verify this is actually a Spring Boot application

if s.isSpringBootExplodedJar(buildDir) {
// True Spring Boot exploded JAR - use JarLauncher
// Determine the correct JarLauncher class name based on Spring Boot version
jarLauncherClass := s.getJarLauncherClass(buildDir)
// True Spring Boot exploded JAR - use main class from manifest or fallback to JarLauncher based on spring-boot version
launcherClass := s.getLauncherClass(buildDir)
// Use eval to properly handle backslash-escaped values in $JAVA_OPTS (Ruby buildpack parity)
return fmt.Sprintf("eval exec $JAVA_HOME/bin/java $JAVA_OPTS -cp $PWD/.${CONTAINER_SECURITY_PROVIDER:+:$CONTAINER_SECURITY_PROVIDER} %s", jarLauncherClass), nil
return fmt.Sprintf("eval exec $JAVA_HOME/bin/java $JAVA_OPTS -cp $PWD/.${CONTAINER_SECURITY_PROVIDER:+:$CONTAINER_SECURITY_PROVIDER} %s", launcherClass), nil
}

// Exploded JAR but NOT Spring Boot - use Main-Class from MANIFEST.MF
mainClass := s.readMainClassFromManifest(buildDir)
mainClass, err := s.readMainClassFromManifest(buildDir)
if err != nil {
s.context.Log.Debug("Could not read MANIFEST.MF: %s", err.Error())
}
if mainClass != "" {
// Use classpath from BOOT-INF/classes and BOOT-INF/lib
// Use eval to properly handle backslash-escaped values in $JAVA_OPTS (Ruby buildpack parity)
Expand Down Expand Up @@ -288,15 +290,14 @@ func (s *SpringBootContainer) Release() (string, error) {
// isSpringBootExplodedJar checks if an exploded JAR is actually a Spring Boot application
// by looking for Spring Boot-specific markers in MANIFEST.MF
func (s *SpringBootContainer) isSpringBootExplodedJar(buildDir string) bool {
manifestPath := filepath.Join(buildDir, "META-INF", "MANIFEST.MF")
data, err := os.ReadFile(manifestPath)
manifestData, err := s.readManifestFile(buildDir)
if err != nil {
s.context.Log.Debug("Could not read MANIFEST.MF: %s", err.Error())
return false
}

// Parse MANIFEST.MF and look for Spring Boot markers
lines := strings.Split(string(data), "\n")
lines := strings.Split(manifestData, "\n")
for _, line := range lines {
line = strings.TrimSpace(line)

Expand All @@ -318,70 +319,66 @@ func (s *SpringBootContainer) isSpringBootExplodedJar(buildDir string) bool {
return false
}

// readMainClassFromManifest reads the Main-Class entry from MANIFEST.MF
func (s *SpringBootContainer) readMainClassFromManifest(buildDir string) string {
func (s *SpringBootContainer) readManifestFile(buildDir string) (string, error) {
manifestPath := filepath.Join(buildDir, "META-INF", "MANIFEST.MF")
data, err := os.ReadFile(manifestPath)
if err != nil {
s.context.Log.Debug("Could not read MANIFEST.MF: %s", err.Error())
return ""
return "", err
}
return string(data), nil
}

func (s *SpringBootContainer) readManifestField(manifest, field string) string {
// Parse MANIFEST.MF file (simple line-by-line parsing)
lines := strings.Split(string(data), "\n")
lines := strings.Split(manifest, "\n")
for _, line := range lines {
line = strings.TrimSpace(line)
if strings.HasPrefix(line, "Main-Class:") {
mainClass := strings.TrimSpace(strings.TrimPrefix(line, "Main-Class:"))
s.context.Log.Debug("Found Main-Class in MANIFEST.MF: %s", mainClass)
return mainClass
if strings.HasPrefix(line, field) {
fieldValue := strings.TrimSpace(strings.TrimPrefix(line, field))
s.context.Log.Debug("Found %s in MANIFEST.MF with value: %s", field, fieldValue)
return fieldValue
}
}

return ""
}

// getJarLauncherClass returns the correct JarLauncher class name based on Spring Boot version
// readMainClassFromManifest reads the Main-Class entry from MANIFEST.MF
func (s *SpringBootContainer) readMainClassFromManifest(buildDir string) (string, error) {
manifestData, err := s.readManifestFile(buildDir)
if err != nil {
return "", err
}

return s.readManifestField(manifestData, "Main-Class:"), nil
}

// getLauncherClass returns the launcher class from manifest. If missing tries to determine correct JarLauncher class name
// based on Spring Boot version
// Spring Boot 2.x uses: org.springframework.boot.loader.JarLauncher
// Spring Boot 3.x uses: org.springframework.boot.loader.launch.JarLauncher
func (s *SpringBootContainer) getJarLauncherClass(buildDir string) string {
manifestPath := filepath.Join(buildDir, "META-INF", "MANIFEST.MF")
data, err := os.ReadFile(manifestPath)
func (s *SpringBootContainer) getLauncherClass(buildDir string) string {
manifestData, err := s.readManifestFile(buildDir)
if err != nil {
s.context.Log.Debug("Could not read MANIFEST.MF for version detection: %s", err.Error())
// Default to Spring Boot 3.x (newer) launcher
return "org.springframework.boot.loader.launch.JarLauncher"
}

// Parse MANIFEST.MF to get Main-Class which tells us the actual launcher class
lines := strings.Split(string(data), "\n")
for _, line := range lines {
line = strings.TrimSpace(line)
if strings.HasPrefix(line, "Main-Class:") {
mainClass := strings.TrimSpace(strings.TrimPrefix(line, "Main-Class:"))
s.context.Log.Debug("Found Main-Class in MANIFEST.MF: %s", mainClass)

// If Main-Class is set to JarLauncher, use that exact class
if strings.Contains(mainClass, "JarLauncher") {
return mainClass
}
}
// Return launcher class from manifest. If missing try using JarLauncher based on Spring-Boot-Version
mainClass := s.readManifestField(manifestData, "Main-Class:")
if mainClass != "" {
return mainClass
}

// If we couldn't determine from Main-Class, check Spring Boot version
for _, line := range lines {
line = strings.TrimSpace(line)
if strings.HasPrefix(line, "Spring-Boot-Version:") {
version := strings.TrimSpace(strings.TrimPrefix(line, "Spring-Boot-Version:"))
s.context.Log.Debug("Found Spring-Boot-Version: %s", version)

// Spring Boot 3.x changed the loader package structure
if strings.HasPrefix(version, "3.") {
return "org.springframework.boot.loader.launch.JarLauncher"
}
// Spring Boot 2.x uses the old loader package
return "org.springframework.boot.loader.JarLauncher"
}
springBootVersion := s.readManifestField(manifestData, "Spring-Boot-Version:")
if strings.HasPrefix(springBootVersion, "3.") {
return "org.springframework.boot.loader.launch.JarLauncher"
}
// Spring Boot 2.x uses the old loader package
if strings.HasPrefix(springBootVersion, "2.") {
return "org.springframework.boot.loader.JarLauncher"
}

// Default to Spring Boot 3.x (newer) launcher if version couldn't be determined
Expand Down