Hermes is a GossipSub listener and tracer. It subscribes to all relevant pubsub topics
and traces all protocol interactions. As of 2024-03-27, Hermes supports the Ethereum
network.
go install github.com/probe-lab/hermes@latestCheck out the repository:
git clone git@github.com:probe-lab/hermes.gitStart Hermes by running
go run ./cmd/hermes # requires Go >=1.22This should print this help text
NAME:
hermes - a gossipsub listener
USAGE:
hermes [global options] command [command options]
COMMANDS:
eth, ethereum Listen to gossipsub topics of the Ethereum network
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--help, -h show help
Kinesis Configuration:
--kinesis.region value The region of the AWS Kinesis Data Stream [$HERMES_KINESIS_REGION]
--kinesis.stream value The name of the AWS Kinesis Data Stream [$HERMES_KINESIS_DATA_STREAM]
Logging Configuration:
--log.format value Sets the format to output the log statements in: text, json, hlog, tint (default: "hlog") [$HERMES_LOG_FORMAT]
--log.level value Sets an explicity logging level: debug, info, warn, error. Takes precedence over the verbose flag. (default: "info") [$HERMES_LOG_LEVEL]
--log.nocolor Whether to prevent the logger from outputting colored log statements (default: false) [$HERMES_LOG_NO_COLOR]
--log.source Compute the source code position of a log statement and add a SourceKey attribute to the output. Only text and json formats. (default: false) [$HERMES_LOG_SOURCE]
--verbose, -v Set logging level more verbose to include debug level logs (default: false) [$HERMES_VERBOSE]
Telemetry Configuration:
--metrics Whether to expose metrics information (default: false) [$HERMES_METRICS_ENABLED]
--metrics.addr value Which network interface should the metrics endpoint bind to. (default: "localhost") [$HERMES_METRICS_ADDR]
--metrics.port value On which port should the metrics endpoint listen (default: 6060) [$HERMES_METRICS_PORT]
--tracing Whether to emit trace data (default: false) [$HERMES_TRACING_ENABLED]
--tracing.addr value Where to publish the traces to. (default: "localhost") [$HERMES_TRACING_ADDR]
--tracing.port value On which port does the traces collector listen (default: 4317) [$HERMES_TRACING_PORT]
We use dot notation to namespace command line arguments instead of hyphens because the CLI library allows
to configuration parameters from a file which will then resolve the command line parameters. For example,
the CLI flag --log.format could be read from a yaml file that looks like this:
log:
format: jsonHowever, Hermes currently doesn't support loading CLI arguments from a file ¯_(ツ)_/¯.
Depending on the network you want to trace Hermes requires auxiliary infrastructure.
As of 2024-03-27, Hermes supports these networks:
Hermes currently only supports emitting events to AWS Kinesis. We're using our own producer library to do that.
In order to hook up Hermes with AWS Kinesis you need to provide the following command line flags:
--kinesis.region=us-east-1# us-east-1 is the default--kinesis.stream=$YOUR_DATA_STREAM_NAME
If the name is set, Hermes will start pumping events to that stream.
It's important to note that the events will not be strictly ordered. They will only follow a lose ordering. The reasons are 1) potential retries of event submissions and 2) record aggregation. Depending on the configured number of submission retries the events should be ordered within each 30s time window.
In order to run Hermes in the Ethereum network you are required to run a Prysm beacon node. Hermes requires Prysm over other implementations because as far as I know it's the only implementation that allows dynamic registration of trusted peers. For example, Lighthouse requires the list of trusted peers at boot time.
Further, Hermes requires beacon node in general because it delegates certain requests to it. In the case of the Ethereum network Hermes forwards all requests for the following protocols:
/eth2/beacon_chain/req/beacon_blocks_by_range/2/ssz_snappy/eth2/beacon_chain/req/beacon_blocks_by_root/2/ssz_snappy/eth2/beacon_chain/req/blob_sidecars_by_range/1/ssz_snappy/eth2/beacon_chain/req/blob_sidecars_by_root/1/ssz_snappy
These request handlers require knowledge of the chain state wherefore Hermes cannot handle them itself. Still, they are required to be a good citizen of the network and not get pruned by other peers.
To run Hermes for the Ethereum network you would need to point it to the beacon node by providing the
--prysm.host=1.2.3.4--prysm.port.http=3500# 3500 is the default--prysm.port.grpc=4000# 4000 is the default
command line flags to the hermes ethereum subcommand. Check out the help page via hermes ethereum --help for configuration options of the libp2p host or devp2p local node (e.g., listen addrs/ports).
Hermes' Ethereum Help Page
NAME:
hermes eth - Listen to gossipsub topics of the Ethereum network
USAGE:
hermes eth command [command options]
COMMANDS:
ids generates peer identities in csv format
chains List all supported chains
help, h Shows a list of commands or help for one command
OPTIONS:
--key value, -k value The private key for the hermes libp2p/ethereum node in hex format. [$HERMES_ETH_KEY]
--chain value The beacon chain to participate in. (default: "mainnet") [$HERMES_ETH_CHAIN]
--attnets value, -a value The attestation network digest. (default: "ffffffffffffffff") [$HERMES_ETH_ATTNETS]
--dial.concurrency value The maximum number of parallel workers dialing other peers in the network (default: 16) [$HERMES_ETH_DIAL_CONCURRENCY]
--dial.timeout value The request timeout when contacting other network participants (default: 5s) [$HERMES_ETH_DIAL_TIMEOUT]
--devp2p.host value Which network interface should devp2p (discv5) bind to. (default: "127.0.0.1") [$HERMES_ETH_DEVP2P_HOST]
--devp2p.port value On which port should devp2p (disv5) listen (default: random) [$HERMES_ETH_DEVP2P_PORT]
--libp2p.host value Which network interface should libp2p bind to. (default: "127.0.0.1") [$HERMES_ETH_LIBP2P_HOST]
--libp2p.port value On which port should libp2p (disv5) listen (default: random) [$HERMES_ETH_LIBP2P_PORT]
--prysm.host value The host ip/name where Prysm's (beacon) API is accessible [$HERMES_ETH_PRYSM_HOST]
--prysm.port.http value The port on which Prysm's beacon nodes' Query HTTP API is listening on (default: 3500) [$HERMES_ETH_PRYSM_PORT_HTTP]
--prysm.port.grpc value The port on which Prysm's gRPC API is listening on (default: 4000) [$HERMES_ETH_PRYSM_PORT_GRPC]
--max-peers value The maximum number of peers we want to be connected with (default: 30) [$HERMES_ETH_MAX_PEERS]
--help, -h show help
When you provide the --metrics command line flag Hermes will expose a Prometheus HTTP endpoint at localhost:6060. Host and port are configurable via --metrics.addr and --metrics.port.
Run an OpenTelemetry Collector compatible trace collector like Jaeger:
docker run --name jaeger \
-e COLLECTOR_OTLP_ENABLED=true \
-p 16686:16686 \
-p 4317:4317 \
--rm jaegertracing/all-in-one:1.54You can find the UI at http://localhost:16686. Port 4317 is used by Hermes to export traces to.
Run Hermes with the --tracing flag. To change the address of the trace collector, you can also specify --tracing.addr and --tracing.port.
Contributions are welcome!
Please take a look at the issues.