Function SelectTomcatVersionPattern

src/java/containers/tomcat.go:446–470

SelectTomcatVersionPattern determines the Tomcat version pattern to use based on the detected Java version and any user-configured Tomcat version. Returns ("", nil) when Java version cannot be determined — the caller should fall back to the manifest default (matching Ruby buildpack behaviour).

(javaHome, configVersion string)

// Returns ("", nil) when Java version cannot be determined — the caller should fall back
// to the manifest default (matching Ruby buildpack behaviour).
func SelectTomcatVersionPattern(javaHome, configVersion string) (string, error) {
	if javaHome == "" {
		return "", nil
	}

	javaMajorVersion, err := common.DetermineJavaVersion(javaHome)
	if err != nil {
		if configVersion != "" {
			return configVersion, nil
		}
		return "", nil
	}

	if configVersion != "" {
		if strings.HasPrefix(configVersion, "10.") && javaMajorVersion < 11 {
			return "", fmt.Errorf("Tomcat 10.x requires Java 11+, but Java %d detected", javaMajorVersion)
		}
		return configVersion, nil
	}

	if javaMajorVersion >= 11 {
		return "10.x", nil
	}
	return "9.x", nil
}


// based on the JBP_CONFIG_TOMCAT field from manifest.