add https support in Prometheus gateway (#392)

metrics-exporter-prometheus/Cargo.toml

@@ -20,7 +20,7 @@ keywords = ["metrics", "telemetry", "prometheus"]
 default = ["http-listener", "push-gateway"]
 async-runtime = ["tokio", "hyper"]
 http-listener = ["async-runtime", "hyper/server", "ipnet"]
-push-gateway = ["async-runtime", "hyper/client", "tracing"]
+push-gateway = ["async-runtime", "hyper/client", "hyper-tls", "tracing"]
 
 [dependencies]
 metrics = { version = "^0.21", path = "../metrics" }
@@ -35,6 +35,7 @@ hyper = { version = "0.14", default-features = false, features = ["tcp", "http1"
 ipnet = { version = "2", optional = true }
 tokio = { version = "1", features = ["rt", "net", "time"], optional = true }
 tracing = { version = "0.1.26", optional = true }
+hyper-tls = { version = "0.5.0", optional = true }
 
 [dev-dependencies]
 tracing = "0.1"

metrics-exporter-prometheus/src/builder.rs

@@ -29,6 +29,7 @@ use hyper::{
     http::HeaderValue,
     Method, Request, Uri,
 };
+use hyper_tls::HttpsConnector;
 
 use indexmap::IndexMap;
 #[cfg(feature = "http-listener")]
@@ -460,7 +461,8 @@ impl PrometheusBuilder {
             #[cfg(feature = "push-gateway")]
             ExporterConfig::PushGateway { endpoint, interval, username, password } => {
                 let exporter = async move {
-                    let client = Client::new();
+                    let https = HttpsConnector::new();
+                    let client = Client::builder().build::<_, hyper::Body>(https);
                     let auth = username.as_ref().map(|name| basic_auth(name, password.as_deref()));
 
                     loop {