Don't use prometheus::process_collector::ProcessCollector by default

Following #491.

It can be re-enabled by:

```
cargo build --release --features prometheus/process
```

Cargo.lock

@@ -1,11 +1,5 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-[[package]]
-name = "adler"
-version = "1.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
-
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -249,15 +243,6 @@ dependencies = [
  "serde_json",
 ]
 
-[[package]]
-name = "crc32fast"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "81156fece84ab6a9f2afdb109ce3ae577e42b1228441eded99bd77f627953b1a"
-dependencies = [
- "cfg-if 1.0.0",
-]
-
 [[package]]
 name = "crossbeam-channel"
 version = "0.5.1"
@@ -389,18 +374,6 @@ dependencies = [
  "termcolor",
 ]
 
-[[package]]
-name = "flate2"
-version = "1.0.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80edafed416a46fb378521624fab1cfa2eb514784fd8921adbe8a8d8321da811"
-dependencies = [
- "cfg-if 1.0.0",
- "crc32fast",
- "libc",
- "miniz_oxide",
-]
-
 [[package]]
 name = "fmt2io"
 version = "0.1.0"
@@ -455,12 +428,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "hex"
-version = "0.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
-
 [[package]]
 name = "humantime"
 version = "1.3.0"
@@ -593,16 +560,6 @@ dependencies = [
  "autocfg 1.0.1",
 ]
 
-[[package]]
-name = "miniz_oxide"
-version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a92518e98c078586bc6c934028adcca4c92a53d6a958196de835170a01d84e4b"
-dependencies = [
- "adler",
- "autocfg 1.0.1",
-]
-
 [[package]]
 name = "nom"
 version = "5.1.2"
@@ -700,20 +657,6 @@ dependencies = [
  "unicode-xid",
 ]
 
-[[package]]
-name = "procfs"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ab8809e0c18450a2db0f236d2a44ec0b4c1412d0eb936233579f0990faa5d5cd"
-dependencies = [
- "bitflags",
- "byteorder",
- "flate2",
- "hex",
- "lazy_static",
- "libc",
-]
-
 [[package]]
 name = "prometheus"
 version = "0.12.0"
@@ -723,10 +666,8 @@ dependencies = [
  "cfg-if 1.0.0",
  "fnv",
  "lazy_static",
- "libc",
  "memchr",
  "parking_lot",
- "procfs",
  "protobuf",
  "thiserror",
 ]

Cargo.toml

@@ -28,7 +28,7 @@ dirs-next = "2.0"
 env_logger = "0.7"
 log = "0.4"
 parking_lot = "0.11"
-prometheus = { version = "0.12", features = ["process"], optional = true }
+prometheus = { version = "0.12", optional = true }
 rayon = "1.5"
 serde = "1.0"
 serde_derive = "1.0"

RELEASE-NOTES.md

@@ -1,3 +1,7 @@
+# 0.9.0 (TBD)
+
+* Don't collect process' Prometheus metrics by default (#492)
+
 # 0.9.0-rc1 (Sep 17 2021)
 
 **IMPORTANT: This release contains major changes, please read carefully!**

src/metrics.rs

@@ -1,7 +1,10 @@
 #[cfg(feature = "metrics")]
 mod metrics_impl {
     use anyhow::{Context, Result};
+
+    #[cfg(feature = "prometheus/process")]
     use prometheus::process_collector::ProcessCollector;
+
     use prometheus::{self, Encoder, HistogramOpts, HistogramVec, Registry};
     use tiny_http::{Response, Server};
 
@@ -17,6 +20,7 @@ mod metrics_impl {
         pub fn new(addr: SocketAddr) -> Result<Self> {
             let reg = Registry::new();
 
+            #[cfg(feature = "prometheus/process")]
             reg.register(Box::new(ProcessCollector::for_self()))
                 .expect("failed to register ProcessCollector");