Epimetheus
An easy-to-use prometheus-compatible metrics library.
Epimetheus is probably the easiest way to get your Rust application
serving metrics. Just scatter your code with instrumentation and call
spawn_http_server()
in main()
.
Watch your hashmaps grow!
metric!.set;
metric!.set;
Monitor the latency of your functions!
let start = now;
my_function;
metric!.add;
metric!.add;
Track the status codes of your responses!
let resp = compute_response;
metric!.add;
Ok
Then connect to port 9898 to see what's happening:
$ curl localhost:9898
my_data_cap 1024
my_data_len 764
my_function_duration_count 6032
my_function_duration_sum 8.32
responses{code="200 OK"} 5443
responses{code="404 Not Found"} 587
responses{code="500 Internal Server Error"} 2
Features
- Multi-threaded OK! Everyone shares the same set of metrics.
- The format is prometheus-compatible. Point prometheus' watchful eye at your program and get nice graphs.
- Updating metrics is fast (...mostly. See below.)
- The port number can be customised via the
RUST_METRICS_PORT
environment variable. - The code is very readable - around 100 sloc. Take a look!
- Public domain.
Performance
- Updating an unlabelled metric (like
my_data_len
above) is fast (~500ns uncontended, ~5us contended). - Updating a labelled metric (like
responses
above) is slower (~1us uncontended, ~10us contended). - The HTTP server is extremely dumb and can only handle one client at a time; typically this doesn't matter.
Other stuff
Epimetheus is the brother of Prometheus, hence the crate's name.
Contributing
Please send bug reports to ~asayers/public-inbox@lists.sr.ht.
Please send patches to ~asayers/public-inbox@lists.sr.ht, and include the following text:
I dedicate any and all copyright interest in this software to the public domain. I make this dedication for the benefit of the public at large and to the detriment of my heirs and successors. I intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.