Service Version per classloader

[tobiasstadler]

Is your feature request related to a problem?

We deploy multiple wars with different version to a JBoss EAP. Currently we can only set the service version globally for all deployments, but we would like to set the version for each deployment individualy (similar to the service name).

Describe the solution you'd like

Can we please add overrideServiceVersionForClassLoader(ClassLoader classLoader, String serviceVersion) to the Tracer class, so we can use e.g.

@WebListener
public class ElasticAPMServiceNameAndVersionContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        Tracer tracer = GlobalTracer.get();
        tracer.overrideServiceVersionForClassLoader(getClass().getClassLoader(), "...");
    }

to set the service version.

[felixbarny]

That seems linked to auto-detecting the version #1327

Have you thought about how to determine the service version of each web application? Is that part of the MANIFEST.MF? If yes, can we load that file using servletContext.getClassLoader().getResourceAsStream("META-INF/MANIFEST.MF"). How do you have to configure Maven and Gradle to set the version?

[tobiasstadler]

Yes, we will use the MANIFEST.MF.

We "instrument" the MANIFEST.MF using the maven-war-plugin:

...
<configuration>
    <archive>
        <manifest>
            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
         </manifest>
    </archive>
</configuration>
...

In the wars we will use a ServletContextListener:

@WebListener
public class ElasticAPMServiceNameAndVersionContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        Manifest manifest = new Manifest(sce.getServletContext().getResourceAsStream(JarFile.MANIFEST_NAME));
        Attributes attributes = manifest.getMainAttributes();
        String implementationTitle = attributes.getValue(Attributes.Name.IMPLEMENTATION_TITLE);
        String implementationVersion = attributes.getValue(Attributes.Name.IMPLEMENTATION_VERSION);

        Tracer tracer = GlobalTracer.get();
        tracer.overrideServiceVersionForClassLoader(getClass().getClassLoader(), implementationTitle);
        tracer.overrideServiceVersionForClassLoader(getClass().getClassLoader(), implementationVersion);
    }
}

We may use an elastic-app-agent plugin and some JBoss magic later.

[felixbarny]

It would be great to have something like that within the agent. I added some thoughts here: #1327 (comment)

[eyalkoren]

@tobiasstadler thanks for your awesome inputs! This is an important issue and it's on the long-term plans.
Do you mind if we close this issue as a duplicate of #1327 and keep the discussion going there?

[tobiasstadler]

In my opinion this issues is prerequisite for #1327. But we can continue in #1327 if you like.

[eyalkoren]

I agree on that, but I'd prefer implementing a capability along with its actual usage.
For example, I imagine overrideServiceVersionForClassLoader calls may be tightly coupled with overrideServiceNameForClassLoader, so we may not need to have these two APIs and a duplicated implementation with an additional map.