Rocket NewRelic

A Rocket fairing instrumenting requests using New Relic.

Attach the fairing to your Rocket app, and any requests that include a [Transaction] in their request guard will be instrumented using the handler base path and name as the transaction name.

Usage

Important - this fairing still requires the New Relic daemon to be run alongside your app in some way, and the underlying newrelic and newrelic-sys crates have some additional build requirements. Make sure these are met when trying to use this crate.

Crucially the libnewrelic C SDK requires a few functions not provided by musl (at least qsort_r and backtrace), so this won't (currently) build against musl.

Add the crate to your Cargo.toml:

[dependencies]
rocket_newrelic = { git = "https://github.com/sd2k/rocket_newrelic" }

Then add a &Transaction request guard to any handlers you wish to instrument:

use rocket_newrelic::Transaction;

#[get("/user/me")]
pub fn get_me(_transaction: &Transaction) -> &'static str {
    "It's me!"
}

Finally, attach the fairing to your Rocket app:

use rocket_newrelic::NewRelic;

fn main() -> {
    let newrelic = NewRelic::new("MY_APP_NAME", "MY_LICENSE_KEY")
        .expect("Could not register with New Relic");
    rocket::ignite()
        .manage(newrelic)
        .mount("/root", routes![get_me])
        .launch();
}

In the above example we'd then be able to see these transactions under /root/get_me.

Advanced usage

The [Transaction] object used in the request guard provides a few methods to allow further instrumentation, such as custom attributes and transaction segments. The below example demonstrates some of this functionality; see the methods of Transaction for more details.

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate rocket;

use newrelic::{Datastore, ExternalParamsBuilder};
use rocket_contrib::json::Json;
use rocket_newrelic::{NewRelic, Transaction};
use serde_json::Value;

struct User;

// This would normally connect to a database and perhaps return some data.
fn insert_into_db(_: &Json<Value>) -> Result<User, ()> {
    Ok(User {})
}

#[post("/users", data = "<user>")]
fn create_user(transaction: &Transaction, user: Json<Value>) {
    // Add attributes to a transaction
    if let Some(Value::String(name)) = user.get("name") {
        transaction.add_attribute("user name", name);
    }
    if let Some(age) = user.get("age").and_then(|a| a.as_i64()) {
        transaction.add_attribute("user age", age);
    }

    // Executing a query in a datastore segment
    let query = "INSERT INTO users VALUES (%s, %s);";
    match transaction.datastore_segment(Datastore::Postgres, "users", "insert", query, |_| {
        insert_into_db(&user)
    }) {
        Ok(_) => println!("Created user"),
        Err(_) => println!("Could not create user"),
    }

    // Doing expensive operations in a custom segment
    let _expensive_value: Result<reqwest::blocking::Response, reqwest::Error> =
        transaction.custom_segment("process user", "process", |s| {
            // Nesting an external segment within the custom segment
            let url = "https://logging-thing";
            let external_params = ExternalParamsBuilder::new(url)
                .procedure("set")
                .library("reqwest")
                .build()
                .unwrap();
            s.external_nested(&external_params, |_| {
                reqwest::blocking::Client::new().post(url).send()
            })
        });
}

fn main() {
    let newrelic = NewRelic::from_env();
    rocket::ignite()
        .manage(newrelic)
        .mount("/", routes![create_user])
        .launch();
}

Diesel queries

With the diesel feature enabled it's possible to pass a Diesel query, along with a &Connection, into the diesel_segment_load and diesel_segment_first methods of a [Transaction]. This will log the SQL query and return either all results, or the first result, respectively.