Replace Prometheus metrics with OpenTelemetry API

Push instead of Pull.

Swap the `prometheus` crate for `opentelemetry` + `opentelemetry_sdk`
Metrics instruments use the OTel Metrics API.

Remove the standalone `/metrics` Prometheus endpoint, its dedicated
listener/port, and all related code no longer needed for OTLP push.

Author: spacebear21

Cargo-minimal.lock

@@ -2498,6 +2498,35 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
 
+[[package]]
+name = "opentelemetry"
+version = "0.31.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b84bcd6ae87133e903af7ef497404dda70c60d0ea14895fc8a5e6722754fc2a0"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+ "js-sys",
+ "pin-project-lite",
+ "thiserror 2.0.17",
+ "tracing",
+]
+
+[[package]]
+name = "opentelemetry_sdk"
+version = "0.31.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e14ae4f5991976fd48df6d843de219ca6d31b01daaab2dad5af2badeded372bd"
+dependencies = [
+ "futures-channel",
+ "futures-executor",
+ "futures-util",
+ "opentelemetry",
+ "percent-encoding",
+ "rand 0.9.1",
+ "thiserror 2.0.17",
+]
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -2695,9 +2724,10 @@ dependencies = [
  "clap",
  "config",
  "ohttp-relay",
+ "opentelemetry",
+ "opentelemetry_sdk",
  "payjoin-directory",
  "payjoin-test-utils",
- "prometheus",
  "rand 0.8.5",
  "reqwest",
  "rustls 0.23.31",
@@ -2912,41 +2942,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "prometheus"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ca5326d8d0b950a9acd87e6a3f94745394f62e4dae1b1ee22b2bc0c394af43a"
-dependencies = [
- "cfg-if",
- "fnv",
- "lazy_static",
- "memchr",
- "parking_lot 0.12.3",
- "protobuf",
- "thiserror 2.0.17",
-]
-
-[[package]]
-name = "protobuf"
-version = "3.7.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d65a1d4ddae7d8b5de68153b48f6aa3bba8cb002b243dbdbc55a5afbc98f99f4"
-dependencies = [
- "once_cell",
- "protobuf-support",
- "thiserror 1.0.63",
-]
-
-[[package]]
-name = "protobuf-support"
-version = "3.7.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3e36c2f31e0a47f9280fb347ef5e461ffcd2c52dd520d8e216b52f93b0b0d7d6"
-dependencies = [
- "thiserror 1.0.63",
-]
-
 [[package]]
 name = "quinn"
 version = "0.11.8"

Cargo-recent.lock

@@ -2498,6 +2498,35 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
 
+[[package]]
+name = "opentelemetry"
+version = "0.31.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b84bcd6ae87133e903af7ef497404dda70c60d0ea14895fc8a5e6722754fc2a0"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+ "js-sys",
+ "pin-project-lite",
+ "thiserror 2.0.17",
+ "tracing",
+]
+
+[[package]]
+name = "opentelemetry_sdk"
+version = "0.31.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e14ae4f5991976fd48df6d843de219ca6d31b01daaab2dad5af2badeded372bd"
+dependencies = [
+ "futures-channel",
+ "futures-executor",
+ "futures-util",
+ "opentelemetry",
+ "percent-encoding",
+ "rand 0.9.1",
+ "thiserror 2.0.17",
+]
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -2695,9 +2724,10 @@ dependencies = [
  "clap",
  "config",
  "ohttp-relay",
+ "opentelemetry",
+ "opentelemetry_sdk",
  "payjoin-directory",
  "payjoin-test-utils",
- "prometheus",
  "rand 0.8.5",
  "reqwest",
  "rustls 0.23.31",
@@ -2912,41 +2942,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "prometheus"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ca5326d8d0b950a9acd87e6a3f94745394f62e4dae1b1ee22b2bc0c394af43a"
-dependencies = [
- "cfg-if",
- "fnv",
- "lazy_static",
- "memchr",
- "parking_lot 0.12.3",
- "protobuf",
- "thiserror 2.0.17",
-]
-
-[[package]]
-name = "protobuf"
-version = "3.7.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d65a1d4ddae7d8b5de68153b48f6aa3bba8cb002b243dbdbc55a5afbc98f99f4"
-dependencies = [
- "once_cell",
- "protobuf-support",
- "thiserror 1.0.63",
-]
-
-[[package]]
-name = "protobuf-support"
-version = "3.7.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3e36c2f31e0a47f9280fb347ef5e461ffcd2c52dd520d8e216b52f93b0b0d7d6"
-dependencies = [
- "thiserror 1.0.63",
-]
-
 [[package]]
 name = "quinn"
 version = "0.11.8"

payjoin-service/Cargo.toml

@@ -32,8 +32,9 @@ axum-server = { version = "0.8", features = [
 clap = { version = "4.5", features = ["derive", "env"] }
 config = "0.15"
 ohttp-relay = { path = "../ohttp-relay", features = ["bootstrap"] }
+opentelemetry = "0.31"
+opentelemetry_sdk = "0.31"
 payjoin-directory = { path = "../payjoin-directory" }
-prometheus = "0.14.0"
 rand = "0.8"
 rustls = { version = "0.23", default-features = false, features = [
   "ring",

payjoin-service/src/config.rs

@@ -12,23 +12,10 @@ pub struct Config {
     pub storage_dir: PathBuf,
     #[serde(deserialize_with = "deserialize_duration_secs")]
     pub timeout: Duration,
-    pub metrics: MetricsConfig,
     #[cfg(feature = "acme")]
     pub acme: Option<AcmeConfig>,
 }
 
-#[derive(Debug, Clone, Deserialize)]
-#[serde(default)]
-pub struct MetricsConfig {
-    pub listener: ListenerAddress,
-}
-
-impl Default for MetricsConfig {
-    fn default() -> Self {
-        Self { listener: "[::]:9090".parse().expect("valid default metrics listener address") }
-    }
-}
-
 #[cfg(feature = "acme")]
 #[derive(Debug, Clone, Deserialize)]
 pub struct AcmeConfig {
@@ -61,7 +48,6 @@ impl Default for Config {
             listener: "[::]:8080".parse().expect("valid default listener address"),
             storage_dir: PathBuf::from("./data"),
             timeout: Duration::from_secs(30),
-            metrics: MetricsConfig::default(),
             #[cfg(feature = "acme")]
             acme: None,
         }
@@ -77,17 +63,11 @@ where
 }
 
 impl Config {
-    pub fn new(
-        listener: ListenerAddress,
-        storage_dir: PathBuf,
-        timeout: Duration,
-        metrics_listener: ListenerAddress,
-    ) -> Self {
+    pub fn new(listener: ListenerAddress, storage_dir: PathBuf, timeout: Duration) -> Self {
         Self {
             listener,
             storage_dir,
             timeout,
-            metrics: MetricsConfig { listener: metrics_listener },
             #[cfg(feature = "acme")]
             acme: None,
         }