Zero-Code eBPF Instrumentation for Envoy TCP Proxy via Beyla

The article explores the integration of Beyla with Envoy to achieve zero-code instrumentation using eBPF. This method allows developers to monitor TCP proxies without altering source code or restarting processes.

Key findings include the ability to capture TCP metrics and traces automatically. However, the approach has distinct limitations regarding higher-level protocols like HTTP/2 and gRPC, which are not inspectable via this method.

The implementation relies on attaching eBPF programs to the Envoy process. This provides deep network visibility while maintaining low overhead, making it suitable for production environments.

Zero-code instrumentation refers to the ability to monitor an application without modifying its source code or requiring a restart. Traditional monitoring often requires developers to import specific libraries or SDKs, which can be difficult for legacy systems or third-party binaries like Envoy.

By leveraging eBPF (extended Berkeley Packet Filter), tools can hook into the Linux kernel to observe system calls and network activity. This allows for the extraction of telemetry data—such as request durations and byte counts—directly from the running process.

The primary advantage of this approach is agility. Operations teams can deploy observability agents to existing infrastructure immediately, bypassing the lengthy development cycles associated with code-based instrumentation.

The article demonstrates how Beyla, an eBPF-based auto-instrumentation tool, is configured to work with an Envoy TCP proxy. Beyla functions by identifying the Envoy process and attaching eBPF probes to specific network functions within the binary.

To achieve this, the tool requires specific configuration to target the correct application. For Envoy, Beyla monitors the TCP sockets to generate metrics. The process involves the following steps:

1. Locating the Envoy process ID.
2. Configuring Beyla to trace TCP connections.
3. Exporting the collected data to an observability backend.

This configuration enables the capture of detailed network traces, allowing users to visualize the flow of traffic through the proxy without touching the Envoy configuration files.

While the integration provides robust TCP observability, the article highlights significant constraints regarding protocol support. Specifically, Beyla cannot inspect the payload of HTTP/2 or gRPC traffic when running in this zero-code mode.

Because these protocols rely on binary framing layers rather than plain text, eBPF probes attached at the socket level cannot easily decode the request/response semantics. Consequently, users will see TCP connection metrics (such as handshake times and data transfer volumes) but will lack specific HTTP status codes or gRPC method names.

Despite this limitation, the tool remains highly effective for:

• Legacy applications where code modification is impossible.
• Third-party services lacking instrumentation support.
• High-performance environments requiring minimal overhead.

The use of eBPF for zero-code instrumentation represents a significant shift in how observability is achieved for infrastructure components like Envoy. By utilizing Beyla, teams can gain immediate insights into TCP traffic patterns without the operational burden of code changes.

However, the inability to decode HTTP/2 and gRPC payloads means this approach is best suited for TCP-level monitoring or scenarios where higher-level protocol details are secondary to network behavior. As the technology evolves, it is likely that support for more complex protocols will expand, further reducing the gap between managed and unmanaged observability.