Java update doesn't enforce AEM restart

[jwadolowski]

Whenever Java gets updated path in AEM's config is not updated and instance won't get restarted automatically to pick that change up.

There's a several ways to fix that problem.

1. Since node['java']['java_home'] typically points to /usr/lib/jvm/java, which is a symlink to JDK home, i.e.

$ ls -l /usr/lib/jvm/java
lrwxrwxrwx 1 root root 25 Dec  2 16:01 /usr/lib/jvm/java -> /usr/lib/jvm/jdk1.8.0_112

We can expand that symlink and leverage the fact AEM gets restarted automatically whenever there's a change in that config file.

Pros:

• straightforward and simple
• better visibility - AEM config file reflects JVM version exactly (not hidden via symlink)

Cons:

• all currently running instances will be restarted upon next chef run due to config file change

2. A new mechanism can be introduced to detect JVM changes, for example by comparing data from /system/console/vmstat and java cookbook. This introduces a few challenges though, as we need to handle password updates here and consider the fact new password may not be already set at this stage.

Pros:

• AEM doesn't need to be restarted, as JAVA_HOME in config file stays as it was so far

Cons:

• complex implementation