Add package pre-install check for java binary

The package installation relies on java being in the path. If java is
not in the path, the tests fail at post-install time. This commit adds a
pre-install check to validate that java exists, and if it fails, the
package is never installed, and thus keeps a system clean, rather than
aborting at post-install and leaving behind a mess.

Closes elastic#29665

distribution/packages/src/common/scripts/preinst

@@ -9,6 +9,18 @@
 #       $1=1       : indicates an new install
 #       $1=2       : indicates an upgrade
 
+# Check for these at preinst time due to failures in postinst if they do not exist
+if [ -x "$JAVA_HOME/bin/java" ]; then
+    JAVA="$JAVA_HOME/bin/java"
+else
+    JAVA=`which java`
+fi
+
+if [ ! -x "$JAVA" ]; then
+    echo "Could not find any executable java binary. Please install java in your PATH or set JAVA_HOME"
+    exit 1
+fi
+
 case "$1" in
 
     # Debian ####################################################

qa/vagrant/src/test/resources/packaging/tests/30_deb_package.bats

@@ -72,6 +72,14 @@ setup() {
     [ "$status" -eq 1 ]
 }
 
+@test "[DEB] temporarily remove java and ensure the install fails" {
+    move_java
+    run dpkg -i elasticsearch-oss-$(cat version).deb
+    output=$status
+    unmove_java
+    [ "$output" -eq 1 ]
+}
+
 @test "[DEB] install package" {
     dpkg -i elasticsearch-oss-$(cat version).deb
 }

qa/vagrant/src/test/resources/packaging/tests/40_rpm_package.bats

@@ -71,6 +71,14 @@ setup() {
     [ "$status" -eq 1 ]
 }
 
+@test "[RPM] temporarily remove java and ensure the install fails" {
+    move_java
+    run rpm -i elasticsearch-oss-$(cat version).rpm
+    output=$status
+    unmove_java
+    [ "$output" -eq 1 ]
+}
+
 @test "[RPM] install package" {
     rpm -i elasticsearch-oss-$(cat version).rpm
 }

qa/vagrant/src/test/resources/packaging/utils/utils.bash

@@ -68,8 +68,11 @@ if [ ! -x "`which unzip 2>/dev/null`" ]; then
 fi
 
 if [ ! -x "`which java 2>/dev/null`" ]; then
-    echo "'java' command is mandatory to run the tests"
-    exit 1
+    # there are some tests that move java temporarily
+    if [ ! -x "`command -v java.bak 2>/dev/null`" ]; then
+        echo "'java' command is mandatory to run the tests"
+        exit 1
+    fi
 fi
 
 # Returns 0 if the 'dpkg' command is available
@@ -578,3 +581,17 @@ file_privileges_for_user_from_umask() {
 
     echo $((0777 & ~$(sudo -E -u $user sh -c umask) & ~0111))
 }
+
+# move java to simulate it not being in the path
+move_java() {
+    which_java=`command -v java`
+    assert_file_exist $which_java
+    mv $which_java ${which_java}.bak
+}
+
+# move java back to its original location
+unmove_java() {
+    which_java=`command -v java.bak`
+    assert_file_exist $which_java
+    mv $which_java `dirname $which_java`/java
+}