This is documentation for the next version of Grafana Beyla documentation. For the latest stable release, go to the latest version.
Language specific agents
Certain programming languages that Beyla instruments are using managed runtimes with complicated threading models, such that Beyla cannot perform correct thread context propagation solely by using eBPF based techniques. In certain situations, for example Java, capturing TLS traffic is also not possible by eBPF techniques, because the Java SDK has its own TLS implementation written in Java. A lot of these programming languages start program execution with interpreters, but later perform method or execution trace compilation using Just-In-Time(JIT) compilers, which generate code in anonymous memory regions. These anonymous regions cannot be attached to with eBPF uprobes, because there is no Linux inode number associated with them. Therefore, it’s not possible to perform eBPF instrumentation on the generated code, without potentially unstable techniques of stopping the program with ptrace and remapping the anonymous regions to memory mapped files.
Because of the inherent limitation of certain programming languages and technologies, Beyla dynamically injects tiny language specific agents for certain languages, to be able to perform TLS traffic capture and context propagation. Currently, Beyla uses language agents for Java and NodeJS.
YAML section: nodejs
The NodeJS agent is used only for context propagation, since NodeJS uses libssl for TLS encryption and decryption. This agent is injected via the debugger interface. You should disable the NodeJS agent support if your program has a handler attached on SIGUSR1.
YAML section: javaagent
The Java agent is used for both context propagation and for TLS traffic capture. The dynamic injection of the agent is supported for OpenJDK Hotspot JVM (and derivatives) and for OpenJ9. Minimum Java version supported is Java 8. If the JVM is busy during the agent attach process, the attach process may take longer than 10 seconds. You can use the attach_timeout option to increase the time Beyla waits for the dynamic attach to successfully complete.
Injection of the Java agent requires that the target process has writeable file system, for example, the injection process doesn’t work for containers with read-only file systems.
