Computed metrics for HawkFX (updated)

Computed metrics are something I wanted to do for a very long time, already in RHQ, but never really got around it and sort of forgot about it again.

Lately I found a post that contained a DSL to do exactly this (actually you should read that post not because of the DSL, but because of the idea behind it).

After seeing this, I got the idea on what to do and to include this in HawkFX, my pet project, which is an explorer for Hawkular.

HawkFx with the input window for formulae, that shows a formula and also a parser error.
The orange chart shows Non-Heap used, the redish one the heap usage of a JVM.

Formulae

Formulas are in a DSL that looks a bit like UPN, e.g. as in the following (I've shortened the metric ID for readability, more on them below):

(+ metric( "MI~...Heap Used" , "max")
   metric( "MI~...NonHeap Used", "max"))

to sum up two metrics (see also screenshot below). The 'metric' element gets two parameters, the metric id and also which of the aggregates that the server sends should be taken (in this case the max value) - this comes from the fact that we request the values to be put into 120 buckets by the server.

Or if you have the total amount of memory you could also subtract the used memory to get a graph of the remaining:

(- 1000000 metric( "MI~...NonHeap Used", "max"))

You could also get the total wait time for responses at a point in time when you multiply the average wait time with the number of visitors:

(* metric("MI~..ResponseTime","avg")
   metric("MI~..NumberVisitors","sum"))

Computed total memory usage

Summing up the metrics for 'Heap Used' and 'NonHeap Used' as shown above would then give you a nice graph of the total memory consumption of a JVM:

The green chart now shows to combined memory usage of Heap and Non-Heap, which is computed from the other two series. Orange and red are as above.

On metric IDs

Metric IDs are the IDs under which a metric is stored inside of Hawkular. The example here comes from an installation of Hawkular-services in Docker. If you just feed your metrics into Hawkular metrics, the IDs will looks like the ones you are using.

ID (upper) and path fields (lower) for a selected item in the tree

I have just pushed an update to HawkFX that provides the ID and path in their own fields at the bottom of the main window, so you can copy&paste them.

Future

I will talk more about the parser in an upcoming article. For now it is a personal playground to also better understand what is doable here. If this turns out to be successful I can imagine that the DSL could directly be incorporated into Hawkular-metrics so that the rules are available to all metrics clients.

It would of course be cool to have an editor for the formulas that allows to interactively pick metric IDs etc, but I doubt that I will get to this any time soon.

Introducing HawkFX

As I said before, I started playing with JRubyFX. And for me learning something new best works with a use case, so I started creating an inventory browser for Hawkular.

Why JRubyFX?

Let's first start with "What is JRubyFX" anyway? JRubyFX is JavaFX brought to the Ruby world by the means of JRuby. This means that you can implement UIs with the help of the JavaFX framework and use its components and tools to build the UI. The difference to plain JavaFX is though that all the implementation code is written in Ruby and run by JRuby on the JVM.

I was doing a bit of JavaFX in the past and I wanted to generate a standalone inventory browser for Hawkular. Now that I have been working with Ruby lately and we already have the Hawkular client gem, I thought I'd give JRubyFX a try.

And I have to say this is pretty cool.

Some screenshots

Login screen

Main screen with inventory browser (left) and metric chart

The main screen shows a tree view on the left that displays the feeds as top level elements. Opening a feed will show recursively the resources and metrics. Clicking on a metric gets it charted on the right side.

Alert and Event list

A menu item in the main screen opens the alerts browser that allows to peek at alerts and events in the system.

Like in the main screen, there is a context menu that will allow to view the raw object as shown below:

Raw display of an event

Custom components

The time range picker on the main screen and alert screen is a custom component, that was implemented once with a .fxml file and some Ruby code:

class TimePicker < Java::javafx::scene::layout::HBox
  include JRubyFX::Controller

  fxml 'TimePicker.fxml'

  def initialize(caller, callback)
[..]
end

Including it is pretty simple too:

    box = find '#alertEventTopBox'
    box.children.add time_picker(self, :set_time_range)

In the first line we find the HBox to add the picker and then just add it to the children of the box. Done.

Running and code

HawkFX is available on my GitHub account at https://github.com/pilhuhn/hawkfx. To run the tool you need JRuby 9

If you are using rvm you can select it via

rvm use jruby-9.0.5.0

install and use bundler to install the required gems

gem install bundler bundle install

then run

jruby hawkfx.rb

Enjoy! :-)

Playing with JRubyFX

I started looking at JRubyFX as a combination of using a proven UI solution with Ruby as the programming language and I have to admit that I am impressed with how little it takes to get a UI done -- especially when it is driven by FXML.

Unfortunately the learning curve is steep, as one has to learn JavaFX and the special way JRubyFX calls the JavaFX classes and methods. And unfortunately, Google is not returning too much results here.

Anyway: this little code already creates GUI and populates a TreeView with elements it pulls from a remote server.

require 'jrubyfx'
require 'hawkular_all'

fxml_root File.dirname(__FILE__)

class HawkFx < JRubyFX::Application

  def start(stage)
    with(stage, title: 'Hello World!', width: 800, height: 600) do
      fxml HawkFxController
      show
    end

    stage.show()
  end
end

class HawkFxController
  include JRubyFX::Controller
  fxml 'fxmain.fxml'

  def login # callback from the login button
    creds = { :username => 'jdoe' ,
              :password => 'password' }
    url = 'http://localhost:8080/hawkular/inventory'
    @inventory_client = Hawkular::Inventory::InventoryClient.new(url, creds)
    @tenant = @inventory_client.get_tenant
    @FXMLtextArea.text = "Tenant: #{@tenant}"
    feeds = @inventory_client.list_feeds

    show_initial_tree(feeds)

  end

  def show_initial_tree(feeds)
    tree_root = tree_item('Feeds') do
      feeds.each do |feed|
        item = tree_item(feed) # this already adds the item to the root
      end
    end
    # bind to the view from fxml
    @FXMLtreeView.setRoot(tree_root)

    tree_root.setExpanded true
  end
end

HawkFx.launch

New experimental (ruby) script plugin for RHQ / Jopr (updated)

I've just committed an experimental 'script2' plugin to the RHQ git repository, that allows to write monitoring scripts in the Ruby programming language.

This plugin is not yet enabled in the normal build because of issues (see below) - if you want to have a look at it, go to modules/plugins/script2 and issue mvn -Pdev install.

To use the script, go to the platform and manually add a script2 resource
For the connection properties you need to specify the scripting language to use and the name of the script, which needs to exist at $AGENT/data/script2/ in the agents file system.

Your script needs to provide 3 functions: avail, metric(name) and trait(name) - here is an example to show this. By default 4 metrics named 'metric1'..'metric4' are collected as well as one trait called 'trait1'.

---

def avail
        return 1
end
 
def metric(name)
        return 4
end
 
def trait(name)
        return "Hello Ruby World: #{name}"
end

---

Unfortunately there is still one issue in the code that makes the scripting engine "forget" the script, so that after some time you'll see
exceptions like the following show up:

:1: undefined method `avail' for main:Object (NoMethodError)

If you have an idea what is going on, please tell me.


UPDATE
Thanks to Yoko Harada I was able to isolate the issue and fix it. Basically the issue is that the script was evaluated in one thread and later its methods got invoked in other threads which did not contain the evaluated script. So now I am just always re-evaluating the script before calling invokeFunction(). This is somewhat slower, but works.

It looks like if I would use the Red Bridge api directly (which is part of the JRuby 1.4 distro), there would be a better way, but the current implementation would allow for different scripting languages. Which brings me to:

Also if you want to help to get other languages implemented, contact me.

Embedding ruby in java - less than trivial so far

Currently I am trying to get puppet, a configuration management system to be executed in Jruby - and especially embedded within some java code.

Luckily there is the JSR 223 scripting available in Java6, so the start is relatively easy: get jruby from jruby.org and add it to the java programs classpath, java program code looks like this:


// Define path to jruby libraries
System.setProperty("jruby.home","/opt/local/share/java/jruby");

// Get the scripting engine
ScriptEngineManager m = new ScriptEngineManager();
ScriptEngine rubyEngine = m.getEngineByName("jruby");

// Define the puppet script to run as arguments
rubyEngine.put(ScriptEngine.ARGV,new String[]{"example.pp"});

// read the script
File f = new File("puppet.rb");
BufferedReader br = new BufferedReader(new FileReader(f));

// and execute it
rubyEngine.eval(br, context);


Simple - eh?

Unfortunately is it not that simple (yet).

Passing the argument vector to my script does not yet work in jruby 1.4 cr1 (see JRUBY-4090), so I need to do a work around of defining a script, that sets this and then calls puppet


ARGV << 'example.pp'

require 'puppet/application/puppet'

Puppet::Application[:puppet].run



Next, puppet is complaining about missing stuff like OpenSSL (which is a difficult beast in jruby, as the standard ruby implementation needs some C code, which can not directly run in jruby).

Also it is somehow complaining about yecht not being found - I still don't really grok setting and properties up things like jruby.lib, jruby.home etc.

If anyone can shed some light on it, I would appreciate it :-)