How does Dynatrace OneAgent inject into Java

Question

Classical Dynatrace monitoring worked by using an agent for monitoring java processes. You had to add the agent to the monitored VM and it worked.

Dynatrace OneAgent does this without agents. But how does it work. There was no agent added to the Java process. All that is needed is restarting the Java process. Tried it out with Liberty Server and could find two Dynatrace threads called ruxitautosensor and ruxitsubpathsender. But i do not understand how the injection works.

Answer 1

Dynatrace OneAgent changed the "/etc/ld.so.preload" file in OS:

/$LIB/liboneagentproc.so

"/etc/ld.so.preload" and env variable "LD_PRELOAD" are used to preload specified lib when starting new process.