Remove support for JAVA_HOME (#69149)

This commit removes support for JAVA_HOME. As we previously deprecated
usage of JAVA_HOME to override the path for the JDK, this commit follows
up by removing support for JAVA_HOME. Note that we do not treat
JAVA_HOME being set as a failure, as it is perfectly reasonable for a
user to have JAVA_HOME configured at the system level.

distribution/src/bin/elasticsearch-env

@@ -39,11 +39,6 @@ ES_CLASSPATH="$ES_HOME/lib/*"
 if [ ! -z "$ES_JAVA_HOME" ]; then
   JAVA="$ES_JAVA_HOME/bin/java"
   JAVA_TYPE="ES_JAVA_HOME"
-elif [ ! -z "$JAVA_HOME" ]; then
-  # fallback to JAVA_HOME
-  echo "warning: usage of JAVA_HOME is deprecated, use ES_JAVA_HOME" >&2
-  JAVA="$JAVA_HOME/bin/java"
-  JAVA_TYPE="JAVA_HOME"
 else
   # use the bundled JDK (default)
   if [ "$(uname -s)" = "Darwin" ]; then
@@ -66,6 +61,11 @@ if [ ! -z "$JAVA_TOOL_OPTIONS" ]; then
   unset JAVA_TOOL_OPTIONS
 fi
 
+# warn that we are not observing the value of JAVA_HOME
+if [ ! -z "$JAVA_HOME" ]; then
+  echo "warning: ignoring JAVA_HOME=$JAVA_HOME; using $JAVA_TYPE" >&2
+fi
+
 # JAVA_OPTS is not a built-in JVM mechanism but some people think it is so we
 # warn them that we are not observing the value of $JAVA_OPTS
 if [ ! -z "$JAVA_OPTS" ]; then

distribution/src/bin/elasticsearch-env.bat

@@ -35,23 +35,17 @@ if "%ES_BUNDLED_JDK%" == "false" (
 
 cd /d "%ES_HOME%"
 
-rem now set the path to java, pass "nojava" arg to skip setting JAVA_HOME and JAVA
+rem now set the path to java, pass "nojava" arg to skip setting ES_JAVA_HOME and JAVA
 if "%1" == "nojava" (
    exit /b
 )
 
 rem comparing to empty string makes this equivalent to bash -v check on env var
 rem and allows to effectively force use of the bundled jdk when launching ES
-rem by setting JAVA_HOME=
+rem by setting ES_JAVA_HOME=
 if defined ES_JAVA_HOME (
   set JAVA="%ES_JAVA_HOME%\bin\java.exe"
   set JAVA_TYPE=ES_JAVA_HOME
-) else if defined JAVA_HOME (
-  rem fallback to JAVA_HOME
-  echo "warning: usage of JAVA_HOME is deprecated, use ES_JAVA_HOME" >&2
-  set JAVA="%JAVA_HOME%\bin\java.exe"
-  set "ES_JAVA_HOME=%JAVA_HOME%"
-  set JAVA_TYPE=JAVA_HOME
 ) else (
   rem use the bundled JDK (default)
   set JAVA="%ES_HOME%\jdk\bin\java.exe"
@@ -70,6 +64,11 @@ if defined JAVA_TOOL_OPTIONS (
   set JAVA_TOOL_OPTIONS=
 )
 
+rem warn that we are not observing the value of $JAVA_HOME
+if defined JAVA_HOME (
+  echo warning: ignoring JAVA_HOME=%JAVA_HOME%; using %JAVA_TYPE% >&2
+)
+
 rem JAVA_OPTS is not a built-in JVM mechanism but some people think it is so we
 rem warn them that we are not observing the value of %JAVA_OPTS%
 if defined JAVA_OPTS (

docs/reference/migration/migrate_8_0/packaging.asciidoc

@@ -15,3 +15,17 @@ Use Java 11 or higher. Attempts to run {es} 8.0 using earlier Java versions will
 fail.
 ====
 //end::notable-breaking-changes[]
+
+//tag::notable-breaking-changes[]
+.JAVA_HOME is no longer supported.
+[%collapsible]
+====
+*Details* +
+`JAVA_HOME` is no longer supported to set the path for the JDK. Instead, use
+the bundled JDK (preferable), or set `ES_JAVA_HOME`.
+
+*Impact* +
+Use the bundled JDK (preferable), or set `ES_JAVA_HOME`. `JAVA_HOME` will be
+ignored.
+====
+//end::notable-breaking-changes[]

qa/os/src/test/java/org/elasticsearch/packaging/test/ArchiveTests.java

@@ -147,7 +147,8 @@ public void test51EsJavaHomeOverride() throws Exception {
         assertThat(FileUtils.slurpAllLogs(installation.logs, "elasticsearch.log", "*.log.gz"), containsString(systemJavaHome1));
     }
 
-    public void test51JavaHomeOverride() throws Exception {
+    public void test51JavaHomeIgnored() throws Exception {
+        assumeTrue(distribution().hasJdk);
         Platforms.onLinux(() -> {
             String systemJavaHome1 = sh.run("echo $SYSTEM_JAVA_HOME").stdout.trim();
             sh.getEnv().put("JAVA_HOME", systemJavaHome1);
@@ -163,40 +164,15 @@ public void test51JavaHomeOverride() throws Exception {
 
         final Installation.Executables bin = installation.executables();
         final Result runResult = sh.run(bin.elasticsearch.toString() + " -V");
-        assertThat(runResult.stderr, containsString("warning: usage of JAVA_HOME is deprecated, use ES_JAVA_HOME"));
+        assertThat(runResult.stderr, containsString("warning: ignoring JAVA_HOME=" + systemJavaHome + "; using bundled JDK"));
 
         startElasticsearch();
         ServerUtils.runElasticsearchTests();
         stopElasticsearch();
 
-        String systemJavaHome1 = sh.getEnv().get("JAVA_HOME");
-        assertThat(FileUtils.slurpAllLogs(installation.logs, "elasticsearch.log", "*.log.gz"), containsString(systemJavaHome1));
-    }
-
-    public void test51EsJavaHomeOverrideOverridesJavaHome() throws Exception {
-        Platforms.onLinux(() -> {
-            String systemJavaHome1 = sh.run("echo $SYSTEM_JAVA_HOME").stdout.trim();
-            sh.getEnv().put("ES_JAVA_HOME", systemJavaHome1);
-            // deliberately set to a location that does not exist, if ES_JAVA_HOME takes precedence this is ignored
-            sh.getEnv().put("JAVA_HOME", "doesnotexist");
-        });
-        Platforms.onWindows(() -> {
-            final String systemJavaHome1 = sh.run("$Env:SYSTEM_JAVA_HOME").stdout.trim();
-            sh.getEnv().put("ES_JAVA_HOME", systemJavaHome1);
-            // deliberately set to a location that does not exist, if ES_JAVA_HOME takes precedence this is ignored
-            sh.getEnv().put("JAVA_HOME", "doesnotexist");
-        });
-
-        final Installation.Executables bin = installation.executables();
-        final Result runResult = sh.run(bin.elasticsearch.toString() + " -V");
-        assertThat(runResult.stderr, not(containsString("warning: usage of JAVA_HOME is deprecated, use ES_JAVA_HOME")));
-
-        startElasticsearch();
-        ServerUtils.runElasticsearchTests();
-        stopElasticsearch();
-
-        String systemJavaHome1 = sh.getEnv().get("ES_JAVA_HOME");
-        assertThat(FileUtils.slurpAllLogs(installation.logs, "elasticsearch.log", "*.log.gz"), containsString(systemJavaHome1));
+        // if the JDK started with the bundled JDK then we know that JAVA_HOME was ignored
+        String bundledJdk = installation.bundledJdk.toString();
+        assertThat(FileUtils.slurpAllLogs(installation.logs, "elasticsearch.log", "*.log.gz"), containsString(bundledJdk));
     }
 
     public void test52BundledJdkRemoved() throws Exception {

qa/os/src/test/java/org/elasticsearch/packaging/util/Shell.java

@@ -156,7 +156,6 @@ private Result runScriptIgnoreExitCode(String[] command) {
             setWorkingDirectory(builder, workingDirectory);
         }
         builder.environment().keySet().remove("ES_JAVA_HOME"); // start with a fresh environment
-        builder.environment().keySet().remove("JAVA_HOME");
         for (Map.Entry<String, String> entry : env.entrySet()) {
             builder.environment().put(entry.getKey(), entry.getValue());
         }