# Rocket Prometheus
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Prometheus instrumentation for Rocket applications.
## Usage
Add this crate to your `Cargo.toml`:
```toml
[dependencies]
rocket_prometheus = "0.4.0"
```
Then attach and mount a `PrometheusMetrics` instance to your Rocket app:
```rust
use rocket_prometheus::PrometheusMetrics;
fn main() {
let prometheus = PrometheusMetrics::new();
rocket::ignite()
.attach(prometheus.clone())
.mount("/metrics", prometheus)
.launch();
}
```
This will expose metrics like this at the /metrics endpoint of your application:
```shell
$ curl localhost:8000/metrics
# HELP rocket_http_requests_duration_seconds HTTP request duration in seconds for all requests
# TYPE rocket_http_requests_duration_seconds histogram
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.005"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.01"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.025"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.05"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.1"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.25"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="0.5"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="1"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="2.5"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="5"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="10"} 2
rocket_http_requests_duration_seconds_bucket{endpoint="/metrics",method="GET",status="200",le="+Inf"} 2
rocket_http_requests_duration_seconds_sum{endpoint="/metrics",method="GET",status="200"} 0.0011045669999999999
rocket_http_requests_duration_seconds_count{endpoint="/metrics",method="GET",status="200"} 2
# HELP rocket_http_requests_total Total number of HTTP requests
# TYPE rocket_http_requests_total counter
rocket_http_requests_total{endpoint="/metrics",method="GET",status="200"} 2
```
## Metrics
By default this crate tracks two metrics:
- `rocket_http_requests_total` (labels: endpoint, method, status): the
total number of HTTP requests handled by Rocket.
- `rocket_http_requests_duration_seconds` (labels: endpoint, method, status):
the request duration for all HTTP requests handled by Rocket.
The 'rocket' prefix of these metrics can be changed by setting the
`ROCKET_PROMETHEUS_NAMESPACE` environment variable.
### Custom Metrics
Further metrics can be tracked by registering them with the registry of the
PrometheusMetrics instance:
```rust
#![feature(proc_macro_hygiene, decl_macro)]
#[macro_use]
extern crate rocket;
use once_cell::sync::Lazy;
use rocket::http::RawStr;
use rocket_prometheus::{
prometheus::{opts, IntCounterVec},
PrometheusMetrics,
};
static NAME_COUNTER: Lazy<IntCounterVec> = Lazy::new(|| {
IntCounterVec::new(opts!("name_counter", "Count of names"), &["name"])
.expect("Could not create lazy IntCounterVec")
});
#[get("/hello/<name>")]
pub fn hello(name: &RawStr) -> String {
NAME_COUNTER.with_label_values(&[name]).inc();
format!("Hello, {}!", name)
}
fn main() {
let prometheus = PrometheusMetrics::new();
prometheus
.registry()
.register(Box::new(NAME_COUNTER.clone()))
.unwrap();
rocket::ignite()
.attach(prometheus.clone())
.mount("/", routes![hello])
.mount("/metrics", prometheus)
.launch();
}
```