Move telemetry::metrics into dedicated crate (#84)

The `metrics!` macro is currently local to the telemetry module.
Furthermore, the `telemetry::metrics` module no longer has
proxy-specific logic.

This change moves the `telemetry::metrics` module into a new crate,
`linkerd2_metrics`.

This will enable unifying `telemetry::http` and `telemetry::transport`
into `http` and `transport`, respectively.

Cargo.lock

@@ -469,12 +469,23 @@ name = "linked-hash-map"
 version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "linkerd2-metrics"
+version = "0.1.0"
+dependencies = [
+ "deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "futures 0.1.23 (registry+https://github.com/rust-lang/crates.io-index)",
+ "http 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hyper 0.12.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "indexmap 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "linkerd2-proxy"
 version = "0.1.0"
 dependencies = [
  "bytes 0.4.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.23 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -488,6 +499,7 @@ dependencies = [
  "inotify 0.5.2-dev (git+https://github.com/inotify-rs/inotify)",
  "ipnet 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.40 (registry+https://github.com/rust-lang/crates.io-index)",
+ "linkerd2-metrics 0.1.0",
  "linkerd2-proxy-api 0.1.1 (git+https://github.com/linkerd/linkerd2-proxy-api?tag=v0.1.1)",
  "linkerd2-proxy-router 0.1.0",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -2,6 +2,7 @@
 members = [
     ".",
     "futures-mpsc-lossy",
+    "metrics",
     "router",
 ]
 
@@ -18,12 +19,12 @@ flaky_tests = []
 
 [dependencies]
 futures-mpsc-lossy    = { path = "./futures-mpsc-lossy" }
+linkerd2-metrics      = { path = "./metrics" }
 linkerd2-proxy-router = { path = "./router" }
 
 linkerd2-proxy-api = { git = "https://github.com/linkerd/linkerd2-proxy-api", tag = "v0.1.1", version = "0.1.1" }
 
 bytes = "0.4"
-deflate = {version = "0.7.18", features = ["gzip"] }
 env_logger = { version = "0.5", default-features = false }
 futures = "0.1"
 futures-watch = { git = "https://github.com/carllerche/better-future" }
@@ -77,6 +78,7 @@ procinfo = "0.4.2"
 [dev-dependencies]
 net2 = "0.2"
 quickcheck = { version = "0.6", default-features = false }
+linkerd2-metrics = { path = "./metrics", features = ["test_util"] }
 linkerd2-proxy-api = { git = "https://github.com/linkerd/linkerd2-proxy-api", tag = "v0.1.1", version = "0.1.1", features = ["arbitrary"] }
 flate2 = { version = "1.0.1", default-features = false, features = ["rust_backend"] }
 # `tokio-io` is needed for TCP tests, because `tokio::io` doesn't re-export

Dockerfile

@@ -19,17 +19,19 @@ WORKDIR /usr/src/linkerd2-proxy
 #
 # Mock out all local code and fetch external dependencies to ensure that
 # external sources are primarily cached on Cargo.lock.
-RUN for d in . futures-mpsc-lossy router ; \
+RUN for d in . futures-mpsc-lossy router metrics ; \
     do mkdir -p "${d}/src" && touch "${d}/src/lib.rs" ; \
     done
 COPY Cargo.toml Cargo.lock          ./
 COPY futures-mpsc-lossy/Cargo.toml  futures-mpsc-lossy/Cargo.toml
 COPY router/Cargo.toml              router/Cargo.toml
+COPY metrics/Cargo.toml             metrics/Cargo.toml
 RUN cargo fetch --locked
 
 # Build libraries, leaving the proxy mocked out.
 COPY futures-mpsc-lossy futures-mpsc-lossy
 COPY router router
+COPY metrics metrics
 ARG PROXY_UNOPTIMIZED
 RUN if [ -n "$PROXY_UNOPTIMIZED" ]; \
     then cargo build --frozen ; \

metrics/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "linkerd2-metrics"
+version = "0.1.0"
+authors = ["Oliver Gould <ver@buoyant.io>"]
+publish = false
+
+[features]
+default = []
+test_util = []
+
+[dependencies]
+deflate = { version = "0.7.18", features = ["gzip"] }
+futures = "0.1"
+http = "0.1"
+hyper = "0.12.3"
+indexmap = "1.0"
+log = "0.4"

metrics/src/histogram.rs

@@ -85,11 +85,11 @@ impl<V: Into<u64>> Histogram<V> {
         self.buckets[idx].incr();
         self.sum += value;
     }
+}
 
-    // ===== Test-only methods to help with assertions about histograms. =====
-
+#[cfg(any(test, feature = "test_util"))]
+impl<V: Into<u64>> Histogram<V> {
     /// Assert the bucket containing `le` has a count of at least `at_least`.
-    #[cfg(test)]
     pub fn assert_bucket_at_least(&self, le: u64, at_least: u64) {
         for (&bucket, &count) in self {
             if bucket >= le {
@@ -104,7 +104,6 @@ impl<V: Into<u64>> Histogram<V> {
     }
 
     /// Assert the bucket containing `le` has a count of exactly `exactly`.
-    #[cfg(test)]
     pub fn assert_bucket_exactly(&self, le: u64, exactly: u64) -> &Self {
         for (&bucket, &count) in self {
             if bucket >= le {
@@ -122,7 +121,6 @@ impl<V: Into<u64>> Histogram<V> {
 
     /// Assert all buckets less than the one containing `value` have
     /// counts of exactly `exactly`.
-    #[cfg(test)]
     pub fn assert_lt_exactly(&self, value: u64, exactly: u64) -> &Self {
         for (i, &bucket) in self.bounds.0.iter().enumerate() {
             let ceiling = match bucket {
@@ -148,7 +146,6 @@ impl<V: Into<u64>> Histogram<V> {
 
     /// Assert all buckets greater than the one containing `value` have
     /// counts of exactly `exactly`.
-    #[cfg(test)]
     pub fn assert_gt_exactly(&self, value: u64, exactly: u64) -> &Self {
         // We set this to true after we've iterated past the first bucket
         // whose upper bound is >= `value`.

metrics/src/lib.rs

@@ -0,0 +1,39 @@
+//! Utilties for exposing metrics to Prometheus.
+
+extern crate deflate;
+extern crate indexmap;
+extern crate futures;
+extern crate http;
+extern crate hyper;
+#[macro_use]
+extern crate log;
+
+mod counter;
+mod gauge;
+mod histogram;
+pub mod latency;
+mod prom;
+mod scopes;
+mod serve;
+
+pub use self::counter::Counter;
+pub use self::gauge::Gauge;
+pub use self::histogram::Histogram;
+pub use self::prom::{FmtMetrics, FmtLabels, FmtMetric, Metric};
+pub use self::scopes::Scopes;
+pub use self::serve::Serve;
+
+#[macro_export]
+macro_rules! metrics {
+    { $( $name:ident : $kind:ty { $help:expr } ),+ } => {
+        $(
+            #[allow(non_upper_case_globals)]
+            const $name: ::linkerd2_metrics::Metric<'static, $kind> =
+                ::linkerd2_metrics::Metric {
+                    name: stringify!($name),
+                    help: $help,
+                    _p: ::std::marker::PhantomData,
+                };
+        )+
+    }
+}

src/lib.rs

@@ -3,9 +3,7 @@
 #![deny(warnings)]
 
 extern crate bytes;
-extern crate linkerd2_proxy_api;
 extern crate env_logger;
-extern crate deflate;
 #[macro_use]
 extern crate futures;
 extern crate futures_mpsc_lossy;
@@ -47,12 +45,16 @@ extern crate tower_h2;
 extern crate tower_h2_balance;
 extern crate tower_reconnect;
 extern crate tower_service;
-extern crate linkerd2_proxy_router;
 extern crate tower_util;
 extern crate tower_in_flight_limit;
 extern crate trust_dns_resolver;
 extern crate try_lock;
 
+#[macro_use]
+extern crate linkerd2_metrics;
+extern crate linkerd2_proxy_api;
+extern crate linkerd2_proxy_router;
+
 use futures::*;
 
 use std::error::Error;

src/telemetry/metrics/mod.rs

@@ -1,16 +0,0 @@
-//! Utilties for exposing metrics to Prometheus.
-
-mod counter;
-mod gauge;
-mod histogram;
-pub mod latency;
-mod prom;
-mod scopes;
-mod serve;
-
-pub use self::counter::Counter;
-pub use self::gauge::Gauge;
-pub use self::histogram::Histogram;
-pub use self::prom::{FmtMetrics, FmtLabels, FmtMetric, Metric};
-pub use self::scopes::Scopes;
-pub use self::serve::Serve;

src/telemetry/mod.rs

@@ -1,23 +1,10 @@
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, SystemTime};
 
-macro_rules! metrics {
-    { $( $name:ident : $kind:ty { $help:expr } ),+ } => {
-        $(
-            #[allow(non_upper_case_globals)]
-            const $name: ::telemetry::metrics::Metric<'static, $kind> =
-                ::telemetry::metrics::Metric {
-                    name: stringify!($name),
-                    help: $help,
-                    _p: ::std::marker::PhantomData,
-                };
-        )+
-    }
-}
+use linkerd2_metrics as metrics;
 
 mod errno;
 pub mod http;
-mod metrics;
 mod process;
 mod report;
 pub mod tap;