From 6215460613eb3bc8064ccc51a527e36ad15f8ea7 Mon Sep 17 00:00:00 2001
From: Ali Behjati <bahjatia@gmail.com>
Date: Fri, 20 Oct 2023 13:04:10 +0200
Subject: [PATCH] fix(hermes): fix metrics content-type

Openmetrics specification expects its own content-type instead of plain
text. I didn't set it before as Prometheus still accepts text format but
apparently there are some scrapers (like datadog) that decide
dynamically what format to use for parsing based on the content type and
our format follows Openmetrics specification. Prometheus should be able
to parse it but weirdly it didn't work in our situation. An example of
inconsistency is how counters are represented. In Openmetrics
specification the metric name is appended by `_total` whereas normal
prometheus just uses the metric name.
---
 hermes/Cargo.lock            | 2 +-
 hermes/Cargo.toml            | 2 +-
 hermes/src/metrics_server.rs | 9 ++++++++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/hermes/Cargo.lock b/hermes/Cargo.lock
index f6bd1272be..33b7fe9b86 100644
--- a/hermes/Cargo.lock
+++ b/hermes/Cargo.lock
@@ -1574,7 +1574,7 @@ checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
 
 [[package]]
 name = "hermes"
-version = "0.4.1"
+version = "0.4.2"
 dependencies = [
  "anyhow",
  "async-trait",
diff --git a/hermes/Cargo.toml b/hermes/Cargo.toml
index 7a2c9b9d32..629add8481 100644
--- a/hermes/Cargo.toml
+++ b/hermes/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name        = "hermes"
-version     = "0.4.1"
+version     = "0.4.2"
 description = "Hermes is an agent that provides Verified Prices from the Pythnet Pyth Oracle."
 edition     = "2021"
 
diff --git a/hermes/src/metrics_server.rs b/hermes/src/metrics_server.rs
index 213dfafffa..b9eb3e831f 100644
--- a/hermes/src/metrics_server.rs
+++ b/hermes/src/metrics_server.rs
@@ -10,6 +10,7 @@ use {
     anyhow::Result,
     axum::{
         extract::State,
+        http::header,
         response::IntoResponse,
         routing::get,
         Router,
@@ -55,5 +56,11 @@ pub async fn metrics(State(state): State<Arc<AppState>>) -> impl IntoResponse {
     // to write to the buffer.
     encode(&mut buffer, &registry).unwrap();
 
-    buffer
+    (
+        [(
+            header::CONTENT_TYPE,
+            "application/openmetrics-text; version=1.0.0; charset=utf-8",
+        )],
+        buffer,
+    )
 }