Avoid to run on JDK < 21

.buildkite/linux_jdk_matrix_pipeline.yml

@@ -68,16 +68,8 @@ steps:
             value: "adoptiumjdk_11"
           - label: "OpenJDK 21"
             value: "openjdk_21"
-          - label: "OpenJDK 17"
-            value: "openjdk_17"
-          - label: "OpenJDK 11"
-            value: "openjdk_11"
           - label: "Zulu 21"
             value: "zulu_21"
-          - label: "Zulu 17"
-            value: "zulu_17"
-          - label: "Zulu 11"
-            value: "zulu_11"
 
   - wait: ~
     if: build.source != "schedule" && build.source != "trigger_job"

.buildkite/windows_jdk_matrix_pipeline.yml

@@ -33,22 +33,10 @@ steps:
         options:
           - label: "Adoptium JDK 21 (Eclipse Temurin)"
             value: "adoptiumjdk_21"
-          - label: "Adoptium JDK 17 (Eclipse Temurin)"
-            value: "adoptiumjdk_17"
-          - label: "Adoptium JDK 11 (Eclipse Temurin)"
-            value: "adoptiumjdk_11"
           - label: "OpenJDK 21"
             value: "openjdk_21"
-          - label: "OpenJDK 17"
-            value: "openjdk_17"
-          - label: "OpenJDK 11"
-            value: "openjdk_11"
           - label: "Zulu 21"
             value: "zulu_21"
-          - label: "Zulu 17"
-            value: "zulu_17"
-          - label: "Zulu 11"
-            value: "zulu_11"
 
   - wait: ~
     if: build.source != "schedule" && build.source != "trigger_job"

config/jvm.options

@@ -87,4 +87,9 @@
 #
 # Sets the maximum nesting depth. The depth is a count of objects and arrays that have not
 # been closed, `{` and `[` respectively.
-#-Dlogstash.jackson.stream-read-constraints.max-nesting-depth=1000
+#-Dlogstash.jackson.stream-read-constraints.max-nesting-depth=1000
+
+# Bypass JDK version check
+#
+# Setting this to true permit to run Logstash with an unsupported JDK version.
+#-Dlogstash.jdk.force=true

logstash-core/lib/logstash/runner.rb

@@ -331,15 +331,24 @@ def execute
       deprecation_logger.deprecated msg
     end
 
+    jvmArgs = ManagementFactory.getRuntimeMXBean().getInputArguments()
     if JavaVersion::CURRENT < JavaVersion::JAVA_11
       logger.warn I18n.t("logstash.runner.java.version",
                                              :java_home => java.lang.System.getProperty("java.home"))
     elsif JavaVersion::CURRENT < JavaVersion::JAVA_17
       deprecation_logger.deprecated I18n.t("logstash.runner.java.version_17_minimum",
                                            :java_home => java.lang.System.getProperty("java.home"))
     elsif JavaVersion::CURRENT < JavaVersion::JAVA_21
-      deprecation_logger.deprecated I18n.t("logstash.runner.java.version_21_minimum",
-                                           :java_home => java.lang.System.getProperty("java.home"))
+      if force_jdk_check(jvmArgs)
+        logger.warn I18n.t("logstash.runner.java.version_below_21_force",
+                           :java_home => java.lang.System.getProperty("java.home"),
+                           :java_version => JavaVersion::CURRENT)
+      else
+        logger.error I18n.t("logstash.runner.java.version_21_minimum",
+                            :java_home => java.lang.System.getProperty("java.home"), 
+                            :java_version => JavaVersion::CURRENT)
+        return 1
+      end
     end
 
     logger.warn I18n.t("logstash.runner.java.home") if ENV["JAVA_HOME"]
@@ -350,7 +359,6 @@ def execute
     end
 
     logger.info("Starting Logstash", "logstash.version" => LOGSTASH_VERSION, "jruby.version" => RUBY_DESCRIPTION)
-    jvmArgs = ManagementFactory.getRuntimeMXBean().getInputArguments()
     logger.info "JVM bootstrap flags: #{jvmArgs}"
 
     # Add local modules to the registry before everything else
@@ -650,4 +658,8 @@ def configure_pipeline_buffer_type
     end
   end
 
+  def force_jdk_check(jvm_args_list)
+    jvm_args_list.include? "-Dlogstash.jdk.force=true"
+  end
+  private :force_jdk_check
 end

logstash-core/locales/en.yml

@@ -453,8 +453,15 @@ en:
           The bundled JDK has been verified to work with each specific version of Logstash, and generally provides best performance and reliability.
           If you have compelling reasons for using your own JDK (organizational-specific compliance requirements, for example), the version you supply with LS_JAVA_HOME must meet the minimum requirements.
         version_21_minimum: >-
-          Java 17 is deprecated and in a future release the minimum required version of Java will be Java 21;
-          your Java version from `%{java_home}` does not meet this requirement.
+          Starting from Logstash 8.19.19 the minimum required version of Java is 21;
+          your Java version from `%{java_home}` is `%{java_version}` and does not meet this requirement.
+          Running Logstash with the bundled JDK is recommended.
+          The bundled JDK has been verified to work with each specific version of Logstash, and generally provides best performance and reliability.
+          If you have compelling reasons for using your own JDK (organizational-specific compliance requirements, for example), the version you supply with LS_JAVA_HOME must meet the minimum requirements.
+        version_below_21_force: >-
+          Starting from Logstash 8.19.19 the minimum required version of Java is 21;
+          your Java version from `%{java_home}` is `%{java_version}` and does not meet this requirement.
+          You have selected to force the execution with unsupported Java version, and could generate unexpected malfunctions.
           Running Logstash with the bundled JDK is recommended.
           The bundled JDK has been verified to work with each specific version of Logstash, and generally provides best performance and reliability.
           If you have compelling reasons for using your own JDK (organizational-specific compliance requirements, for example), the version you supply with LS_JAVA_HOME must meet the minimum requirements.

logstash-core/src/main/java/org/logstash/util/JavaVersion.java

@@ -22,6 +22,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Collectors;
 
 /**
  * Helper class to compare current version of JVM with a target version.
@@ -84,4 +85,9 @@ private static int compare(final JavaVersion leftVersion, final JavaVersion righ
     public int compareTo(JavaVersion other) {
         return compare(this, other);
     }
+
+    @Override
+    public String toString() {
+        return version.stream().map(Object::toString).collect(Collectors.joining("."));
+    }
 }