Description

The example showcases how to run a p2p network with libp2p and collect metrics using libp2p-metrics as well as span data via opentelemetry. It sets up multiple nodes in the network and measures various metrics, such as libp2p_ping, to evaluate the network's performance.

Usage

To run the example, follow these steps:

Run the following command to start the first node:
```
cargo run
```
Open a second terminal and run the following command to start a second node:
```
cargo run -- <listen-addr-of-first-node>
```
Replace <listen-addr-of-first-node> with the listen address of the first node reported in the first terminal. Look for the line that says NewListenAddr to find the address.
Open a third terminal and run the following command to retrieve the metrics from either the first or second node:
```
curl localhost:<metrics-port-of-first-or-second-node>/metrics
```
Replace <metrics-port-of-first-or-second-node> with the listen port of the metrics server of either the first or second node. Look for the line that says tide::server Server listening on to find the port.

After executing the command, you should see a long list of metrics printed to the terminal. Make sure to check the libp2p_ping metrics, which should have a value greater than zero (>0).

Opentelemetry

To see the span data collected as part of the Swarms activity, start up an opentelemetry collector:

docker compose up

Then, configure tracing to output spans:

export RUST_LOG=info,[ConnectionHandler::poll]=trace,[NetworkBehaviour::poll]=trace

Next, (re)-start the two example for it to connect to the OTEL collector. Finally, open the Jaeger UI in a browser and explore the spans: http://localhost:16686.

Filtering spans

For a precise documentation, please see the following documentation in tracing: https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives.

rust-libp2p consistently applies spans to the following functions:

ConnectionHandler::poll implementations
NetworkBehaviour::poll implementations

The above spans are all called exactly that: ConnectionHandler::poll and NetworkBehaviour::poll. You can activate all of them by setting:

RUST_LOG=[ConnectionHandler::poll]=trace

If you just wanted to see the spans of the libp2p_ping crate, you can filter like this:

RUST_LOG=libp2p_ping[ConnectionHandler::poll]=trace

Conclusion

This example demonstrates how to utilize the libp2p-metrics crate to collect and analyze metrics in a libp2p network. By running multiple nodes and examining the metrics, users can gain insights into the network's performance and behavior.