Add optional GZIP compression to proxy /metrics endpoint (#665)

Closes #598.

According to the Prometheus documentation, metrics export endpoints should support serving metrics compressed using GZIP. I've modified the proxy's `/metrics` endpoint to serve metrics compressed with GZIP when an `Accept-Encoding: gzip` request header is sent.

I've also added a new unit test that attempts to get the proxy's metrics endpoint as GZIP, and asserts that the metrics are decompressed successfully.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Cargo.lock

@@ -9,6 +9,11 @@ dependencies = [
  "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "adler32"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "aho-corasick"
 version = "0.6.4"
@@ -62,6 +67,11 @@ name = "bitflags"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "build_const"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "byteorder"
 version = "1.2.1"
@@ -112,8 +122,10 @@ dependencies = [
  "conduit-proxy-controller-grpc 0.3.0",
  "conduit-proxy-router 0.3.0",
  "convert 0.3.0",
+ "deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "domain 0.2.3 (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 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures-mpsc-lossy 0.3.0",
  "futures-watch 0.1.0 (git+https://github.com/carllerche/better-future.git)",
@@ -177,6 +189,24 @@ dependencies = [
 name = "convert"
 version = "0.3.0"
 
+[[package]]
+name = "crc"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "build_const 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "deflate"
+version = "0.7.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "adler32 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "byteorder 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "gzip-header 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "domain"
 version = "0.2.3"
@@ -193,6 +223,14 @@ name = "either"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "enum_primitive"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-traits 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.5.3"
@@ -217,6 +255,15 @@ name = "fixedbitset"
 version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "flate2"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "miniz_oxide_c_api 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.6"
@@ -266,6 +313,15 @@ dependencies = [
  "futures 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "gzip-header"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "crc 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "enum_primitive 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "h2"
 version = "0.1.5"
@@ -409,6 +465,26 @@ dependencies = [
  "unicase 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "miniz_oxide"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "adler32 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "miniz_oxide_c_api"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crc 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "miniz_oxide 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "mio"
 version = "0.6.14"
@@ -502,6 +578,14 @@ dependencies = [
  "num-traits 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "num-traits"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-traits 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.0"
@@ -1015,29 +1099,36 @@ dependencies = [
 
 [metadata]
 "checksum abstract-ns 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8964f1b6e32687dfe6377ca7dd801b2646a01dfcdb44a25b521d4af29faaa38c"
+"checksum adler32 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6cbd0b9af8587c72beadc9f72d35b9fbb070982c9e6203e46e93f10df25f8f45"
 "checksum aho-corasick 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d6531d44de723825aa81398a6415283229725a00fa30713812ab9323faa82fc4"
 "checksum atty 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "8352656fd42c30a0c3c89d26dea01e3b77c0ab2af18230835c15e2e13cd51859"
 "checksum backtrace 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ebbbf59b1c43eefa8c3ede390fcc36820b4999f7914104015be25025e0d62af2"
 "checksum backtrace-sys 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "44585761d6161b0f57afc49482ab6bd067e4edef48c12a152c237eb0203f7661"
 "checksum base64 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "229d032f1a99302697f10b27167ae6d03d49d032e6a8e2550e8d3fc13356d2b4"
 "checksum bitflags 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b3c30d3802dfb7281680d6285f2ccdaa8c2d8fee41f93805dba5c4cf50dc23cf"
+"checksum build_const 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e90dc84f5e62d2ebe7676b83c22d33b6db8bd27340fb6ffbff0a364efa0cb9c9"
 "checksum byteorder 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "652805b7e73fada9d85e9a6682a4abd490cb52d96aeecc12e33a0de34dfd0d23"
 "checksum bytes 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "1b7db437d718977f6dc9b2e3fd6fc343c02ac6b899b73fdd2179163447bd9ce9"
 "checksum cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "deaf9ec656256bb25b404c51ef50097207b9cbb29c933d31f92cae5a8a0ffee0"
 "checksum cfg-if 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d4c819a1287eb618df47cc647173c5c4c66ba19d888a6e50d605672aed3140de"
 "checksum chrono 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7c20ebe0b2b08b0aeddba49c609fe7957ba2e33449882cb186a180bc60682fa9"
 "checksum codegen 0.1.0 (git+https://github.com/carllerche/codegen)" = "<none>"
+"checksum crc 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bd5d02c0aac6bd68393ed69e00bbc2457f3e89075c6349db7189618dc4ddc1d7"
+"checksum deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)" = "32c8120d981901a9970a3a1c97cf8b630e0fa8c3ca31e75b6fd6fd5f9f427b31"
 "checksum domain 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ed223144c5eaf3fc1406b4ccc7f360564218df8eec11cbfa03282d405a751f64"
 "checksum either 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "740178ddf48b1a9e878e6d6509a1442a2d42fd2928aae8e7a6f8a36fb01981b3"
+"checksum enum_primitive 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "be4551092f4d519593039259a9ed8daedf0da12e5109c5280338073eaeb81180"
 "checksum env_logger 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "f15f0b172cb4f52ed5dbf47f774a387cd2315d1bf7894ab5af9b083ae27efa5a"
 "checksum failure 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "934799b6c1de475a012a02dab0ace1ace43789ee4b99bcfbf1a2e3e8ced5de82"
 "checksum fixedbitset 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "85cb8fec437468d86dc7c83ca7cfc933341d561873275f22dd5eedefa63a6478"
+"checksum flate2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "9fac2277e84e5e858483756647a9d0aa8d9a2b7cba517fd84325a0aaa69a0909"
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2e9763c69ebaae630ba35f74888db465e49e259ba1bc0eda7d06f4a067615d82"
 "checksum fuchsia-zircon-sys 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3dcaa9ae7725d12cdb85b3ad99a434db70b468c09ded17e012d86b5c1010f7a7"
 "checksum futures 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)" = "0bab5b5e94f5c31fc764ba5dd9ad16568aae5d4825538c01d6bca680c9bf94a7"
 "checksum futures-cpupool 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "ab90cde24b3319636588d0c35fe03b1333857621051837ed769faefb4c2162e4"
 "checksum futures-watch 0.1.0 (git+https://github.com/carllerche/better-future.git)" = "<none>"
+"checksum gzip-header 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0a9fcfe1c9ee125342355b2467bc29b9dfcb2124fcae27edb9cee6f4cc5ecd40"
 "checksum h2 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "065fb096fc65bbfb9c765d48c9f3f1a21cdb25ba0d3f82105b38f30ddffa2f7e"
 "checksum heck 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ea04fa3ead4e05e51a7c806fc07271fdbde4e246a6c6d1efd52e72230b771b82"
 "checksum http 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "75df369fd52c60635208a4d3e694777c099569b3dcf4844df8f652dc004644ab"
@@ -1055,6 +1146,8 @@ dependencies = [
 "checksum log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "89f010e843f2b1a31dbd316b3b8d443758bc634bed37aabade59c686d644e0a2"
 "checksum memchr 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "796fba70e76612589ed2ce7f45282f5af869e0fdd7cc6199fa1aa1f1d591ba9d"
 "checksum mime 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e2e00e17be181010a91dbfefb01660b17311059dc8c7f48b9017677721e732bd"
+"checksum miniz_oxide 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "aaa2d3ad070f428fffbd7d3ca2ea20bb0d8cffe9024405c44e1840bc1418b398"
+"checksum miniz_oxide_c_api 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "92d98fdbd6145645828069b37ea92ca3de225e000d80702da25c20d3584b38a5"
 "checksum mio 0.6.14 (registry+https://github.com/rust-lang/crates.io-index)" = "6d771e3ef92d58a8da8df7d6976bfca9371ed1de6619d9d5a5ce5b1f29b85bfe"
 "checksum mio-uds 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "1731a873077147b626d89cc6c2a0db6288d607496c5d10c0cfcf3adc697ec673"
 "checksum miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
@@ -1064,6 +1157,7 @@ dependencies = [
 "checksum num 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "4703ad64153382334aa8db57c637364c322d3372e097840c72000dabdcf6156e"
 "checksum num-integer 0.1.36 (registry+https://github.com/rust-lang/crates.io-index)" = "f8d26da319fb45674985c78f1d1caf99aa4941f785d384a2ae36d0740bc3e2fe"
 "checksum num-iter 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)" = "4b226df12c5a59b63569dd57fafb926d91b385dfce33d8074a412411b689d593"
+"checksum num-traits 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "92e5113e9fd4cc14ded8e499429f396a20f98c772a47cc8622a736e1ec843c31"
 "checksum num-traits 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e7de20f146db9d920c45ee8ed8f71681fd9ade71909b48c3acbd766aa504cf10"
 "checksum num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c51a3322e4bca9d212ad9a158a02abc6934d005490c054a2778df73a70aa0a30"
 "checksum percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "31010dd2e1ac33d5b46a5b413495239882813e0369f8ed8a5e266f173602f831"

proxy/Cargo.toml

@@ -17,6 +17,7 @@ conduit-proxy-router            = { path = "./router" }
 
 bytes = "0.4"
 domain = "0.2.3"
+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.git" }
@@ -59,3 +60,4 @@ libc = "0.2"
 quickcheck = { version = "0.6", default-features = false }
 conduit-proxy-controller-grpc = { path = "./controller-grpc" , features = ["arbitrary"] }
 regex = "0.2"
+flate2 = { version = "1.0.1", default-features = false, features = ["rust_backend"] }

proxy/src/lib.rs

@@ -8,6 +8,7 @@ extern crate conduit_proxy_controller_grpc;
 extern crate convert;
 extern crate domain;
 extern crate env_logger;
+extern crate deflate;
 #[macro_use]
 extern crate futures;
 extern crate futures_mpsc_lossy;

proxy/src/telemetry/metrics/mod.rs

@@ -27,19 +27,22 @@
 //! to worry about missing commas, double commas, or trailing commas at the
 //! end of the label set (all of which will make Prometheus angry).
 use std::default::Default;
-use std::{fmt, ops, time};
+use std::{fmt, time};
 use std::hash::Hash;
 use std::num::Wrapping;
 use std::sync::{Arc, Mutex};
+use std::io::Write;
+use std::ops;
 
+use deflate::CompressionOptions;
+use deflate::write::GzEncoder;
 use futures::future::{self, FutureResult};
-use hyper;
+use hyper::{self, Body, StatusCode};
-use hyper::header::{ContentLength, ContentType};
+use hyper::header::{AcceptEncoding, ContentEncoding, ContentType, Encoding, QualityItem};
-use hyper::StatusCode;
 use hyper::server::{
-    Service as HyperService,
+    Response as HyperResponse,
     Request as HyperRequest,
-    Response as HyperResponse
+    Service as HyperService,
 };
 use indexmap::{IndexMap};
 
@@ -631,9 +634,23 @@ impl Aggregate {
 
 impl Serve {
     fn new(metrics: &Arc<Mutex<Metrics>>) -> Self {
-        Serve { metrics: metrics.clone() }
+        Serve {
+            metrics: metrics.clone(),
         }
     }
+}
+
+fn is_gzip(req: &HyperRequest) -> bool {
+    if let Some(accept_encodings) = req
+        .headers()
+        .get::<AcceptEncoding>()
+    {
+        return accept_encodings
+            .iter()
+            .any(|&QualityItem { ref item, .. }| item == &Encoding::Gzip)
+    }
+    false
+}
 
 impl HyperService for Serve {
     type Request = HyperRequest;
@@ -647,14 +664,30 @@ impl HyperService for Serve {
                 .with_status(StatusCode::NotFound));
         }
 
-        let body = {
         let metrics = self.metrics.lock()
             .expect("metrics lock poisoned");
-            format!("{}", *metrics)
+
-        };
+        let resp = if is_gzip(&req) {
-        future::ok(HyperResponse::new()
+            trace!("gzipping metrics");
-            .with_header(ContentLength(body.len() as u64))
+            let mut writer = GzEncoder::new(Vec::<u8>::new(), CompressionOptions::fast());
+            write!(&mut writer, "{}", *metrics)
+                .and_then(|_| writer.finish())
+                .map(|body| {
+                    HyperResponse::new()
+                        .with_header(ContentEncoding(vec![Encoding::Gzip]))
                         .with_header(ContentType::plaintext())
-            .with_body(body))
+                        .with_body(Body::from(body))
+                })
+        } else {
+            let mut writer = Vec::<u8>::new();
+            write!(&mut writer, "{}", *metrics)
+                .map(|_| {
+                    HyperResponse::new()
+                        .with_header(ContentType::plaintext())
+                        .with_body(Body::from(writer))
+                })
+        };
+
+        future::result(resp.map_err(hyper::Error::Io))
     }
 }

proxy/tests/support/mod.rs

@@ -5,7 +5,7 @@
 // Note, lints like `unused_variable` should not be ignored.
 #![allow(dead_code)]
 
-extern crate bytes;
+pub extern crate bytes;
 pub extern crate conduit_proxy_controller_grpc;
 extern crate conduit_proxy;
 pub extern crate convert;

proxy/tests/telemetry.rs

@@ -2,10 +2,13 @@
 #[macro_use]
 extern crate log;
 extern crate regex;
+extern crate flate2;
 
 #[macro_use]
 mod support;
 use self::support::*;
+use support::bytes::IntoBuf;
+use std::io::Read;
 
 macro_rules! assert_contains {
     ($scrape:expr, $contains:expr) => {
@@ -1089,3 +1092,70 @@ mod transport {
             "tcp_connections_open{direction=\"outbound\"} 0");
     }
 }
+
+// https://github.com/runconduit/conduit/issues/613
+#[test]
+#[cfg_attr(not(feature = "flaky_tests"), ignore)]
+fn metrics_compression() {
+    let _ = env_logger::try_init();
+
+    let Fixture { client, metrics, proxy: _proxy } = Fixture::inbound();
+
+    let do_scrape = |encoding: &str| {
+        let resp = metrics.request(
+            metrics.request_builder("/metrics")
+                .method("GET")
+                .header("Accept-Encoding", encoding)
+        );
+
+        {
+            // create a new scope so we can release our borrow on `resp` before
+            // getting the body
+            let content_encoding = resp.headers()
+                .get("content-encoding")
+                .as_ref()
+                .map(|val| val
+                    .to_str()
+                    .expect("content-encoding value should be ascii")
+                );
+            assert_eq!(content_encoding, Some("gzip"),
+                "unexpected Content-Encoding {:?} (requested Accept-Encoding: {})", content_encoding, encoding);
+        }
+
+        let body = resp.into_body()
+            .concat2()
+            .wait()
+            .expect("response body concat");
+        let mut decoder = flate2::read::GzDecoder::new(body.into_buf());
+        let mut scrape = String::new();
+        decoder.read_to_string(&mut scrape)
+            .expect(&format!(
+                "decode gzip (requested Accept-Encoding: {})",
+                encoding
+            ));
+        scrape
+    };
+
+    let encodings = &[
+        "gzip",
+        "deflate, gzip",
+        "gzip,deflate",
+        "brotli,gzip,deflate"
+    ];
+
+    info!("client.get(/)");
+    assert_eq!(client.get("/"), "hello");
+
+    for &encoding in encodings {
+        assert_contains!(do_scrape(encoding),
+            "request_duration_ms_count{authority=\"tele.test.svc.cluster.local\",direction=\"inbound\"} 1");
+    }
+
+    info!("client.get(/)");
+    assert_eq!(client.get("/"), "hello");
+
+    for &encoding in encodings {
+        assert_contains!(do_scrape(encoding),
+            "request_duration_ms_count{authority=\"tele.test.svc.cluster.local\",direction=\"inbound\"} 2");
+    }
+}