Attached patch changes the configuration of the fencing script as follows:
By default, no arguments are passed to the script. This is different than the previous implementation, but since HA hasn't been in a release yet, I think it's fine to break this.
Instead, users are expected to use the environment to choose whatever arguments they need. Since we pass the shell command through to bash, environment variables are interpolated.
We already handled passing the configuration through. This patch also adds the ability for an HAServiceTarget to add additional key/value pairs, which are prefixed with target_ in the environment. The three passed by the Common code are $target_host, $target_port, and $target_address (which is the same as host:port).
HDFS-3084 will add the NNID and NSID to this map.
I will also file a separate JIRA to update the docs, which unfortunately live in the MapReduce project.