add API version in HTTP headers

mithril-aggregator/src/http_server/mod.rs

@@ -2,3 +2,5 @@ mod routes;
 mod server;
 
 pub use server::{Server, SERVER_BASE_PATH};
+
+pub const MITHRIL_API_VERSION: &str = "0.1.0";

mithril-aggregator/src/http_server/routes/router.rs

@@ -1,8 +1,9 @@
 use crate::http_server::routes::{
     certificate_routes, epoch_routes, signatures_routes, signer_routes, snapshot_routes,
 };
-use crate::http_server::SERVER_BASE_PATH;
+use crate::http_server::{MITHRIL_API_VERSION, SERVER_BASE_PATH};
 use crate::DependencyManager;
+use reqwest::header::{HeaderMap, HeaderValue};
 use std::sync::Arc;
 use warp::http::Method;
 use warp::Filter;
@@ -15,13 +16,19 @@ pub fn routes(
         .allow_any_origin()
         .allow_headers(vec!["content-type"])
         .allow_methods(vec![Method::GET, Method::POST, Method::OPTIONS]);
+    let mut headers = HeaderMap::new();
+    headers.insert(
+        "mithril-api-version",
+        HeaderValue::from_static(MITHRIL_API_VERSION),
+    );
 
     warp::any().and(warp::path(SERVER_BASE_PATH)).and(
         certificate_routes::routes(dependency_manager.clone())
             .or(snapshot_routes::routes(dependency_manager.clone()))
             .or(signer_routes::routes(dependency_manager.clone()))
             .or(signatures_routes::routes(dependency_manager.clone()))
             .or(epoch_routes::routes(dependency_manager))
-            .with(cors),
+            .with(cors)
+            .with(warp::reply::with::headers(headers)),
     )
 }