[Hawkular-dev] agent running as a VM javaagent - non-EAP based solution

[Thomas Heute]

Adding Thomas, as this could be interesting for Fuse on Karaf if we proceed
with this javaagent.

On Wed, Mar 8, 2017 at 6:08 PM, John Mazzitelli <mazz at redhat.com> wrote:

> Right now, the Hawkular WildFly Agent runs as a WildFly subsystem
> extension - which means it must run in EAP.
>
> To avoid this requirement, I refactored the agent code [1] so it can be
> run using a standard VM javaagent (using the VM argument -javaagent).
>
> This means the agent need not run as a subsystem extension, in fact, it
> can run in any VM (non-EAP/WildFly based). Just pass in the -javaagent
> command line argument to your VM and you got an agent. You have a Karaf
> container in a JVM exposing metrics via JMX? You can use this. You got a
> vert.x server in a JVM exposing metrics via JMX? You can use this.
>
> This new agent's config file is a single YAML file that mimics virtually
> the same settings as you see today in the agent's <subsystem> XML in
> standalone.xml.
>
> Like the EAP-based agent, this new agent can still:
>
> * collect DMR metrics and inventory from any EAP 6.4, EAP 7.x, or WildFly
> 10+ servers - local or remote.
> * collect JMX metrics and inventory from any remote Jolokia endpoint or
> local JMX MBeanServer
> * receive websocket messages from a Hawkular Server (if running in full
> Hawkular mode)
> * run in metrics-only mode where it only stores data to Hawkular-Metrics
> and does not connect via websocket to the server nor stores inventory to
> H-Inventory
> * Talk to the Hawkular Server and remote DMR/JMX endpoints via SSL/https
> using defined security-realms/keystores
>
> Unlike the EAP-based agent, this new agent:
>
> * does NOT have a CLI (jboss-cli.sh is the EAP-based agent's CLI)
> * does NOT have a built-in configuration persistent mechanicm (EAP-based
> agents can persist their config changes to standalone.xml when those
> changes are made via the WildFly management interface - because the
> javaagent is completely independent, it has nothing like this for its YAML
> config).
> * does NOT integrate with the lifecycle of any EAP/WildFly running in the
> same VM (in other words, if you ask to "reload" the EAP server, the
> javaagent knows nothing about that and won't also itself reload. Remember,
> this javaagent is now completely independent of any co-located EAP/WildFly
> server).
>
> In addition, if your JVM is installed in OpenShift, you can get the nice
> option of putting the javaagent's YAML config in a config map and mount it
> so your javaagent can access it. This means you can edit your javaagent
> YAML directly in the OpenShift UI :)
>
> I still need to see how well this supports the disabling/enabling of
> metrics on the fly from the websocket commands (e.g. I will need to add the
> ability to change the YAML config to persist the settings, that is not done
> yet - the EAP-based agent got this support for free - its config changes go
> into standalone.xml).
>
> Other than persisting changes to the YAML file, I believe this javaagent
> will work essentially the same as the current agent (indeed, the core agent
> engine is identical - its the same code). Just have to make sure the
> websocket commands can work considering there is a YAML config backing the
> settings and not standalone.xml.
>
> I need people's feedback on this. Thoughts? If you want to try it, you can
> build it from my PR right now using the README [2] and the instructions [3].
>
> --John Mazz
>
> [1] https://github.com/hawkular/hawkular-agent/pull/302
>
> [2] https://github.com/jmazzitelli/hawkular-agent/
> blob/refactor-core/hawkular-javaagent/README.adoc
>
> [3] Instructions to build using the PR and test it by collecting EAP
> metrics:
>
> 1) Build it:
>
>    $ git clone git at github.com:hawkular/hawkular-agent.git
>    $ cd hawkular-agent
>    $ git checkout -b jmazzitelli-refactor-core master
>    $ git pull https://github.com/jmazzitelli/hawkular-agent.git
> refactor-core
>    $ mvn clean install
>
> 2) Install it - assuming you have a base EAP 6.4 or 7.x or WildFly 10+
> installed at <eap.dir>
>
> 2a) Change this line in <eap.dir>/bin/standalone.conf:
>
>    JBOSS_MODULES_SYSTEM_PKGS="org.jboss.byteman"
>
> to this:
>
>    JBOSS_MODULES_SYSTEM_PKGS="org.jboss.byteman,org.jboss.logmanager"
>
> 2b) Inside that same <eap.dir>/bin/standalone.conf you add this line in the
>     appropriate place (you know where, just under where it sets JAVA_OPTS):
>
>    JAVA_OPTS="$JAVA_OPTS -Djava.util.logging.manager=org.jboss.logmanager.LogManager
> -javaagent:$JBOSS_HOME/bin/hawkular-javaagent-*.jar=
> config=$JBOSS_HOME/standalone/configuration/real-config*.yaml,delay=10"
>
> 2c) Copy the binary/config files you built to that EAP / WildFly install:
>
>    cp hawkular-agent/hawkular-javaagent/target/hawkular-
> javaagent-*-jar-with-dependencies.jar <eap.dir>/bin
>
>    if EAP 7.x/WildFly 10+:
>
>    cp hawkular-agent/hawkular-javaagent/src/test/resources/real-config.yaml
> <eap.dir>/standalone/configuration
>
>    if EAP 6.4:
>
>    cp hawkular-agent/hawkular-javaagent/src/test/resources/real-config-eap6.yaml
> <eap.dir>/standalone/configuration
>
>
>
>
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>
>
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