feat(cat-gateway): CatGatewayInfo middleware (#2585)

* add CatGatewayInfo middleware

* wip

* wip

* fix

* wip

* wip

Author: Mr-Leshiy

catalyst-gateway/bin/src/build_info.rs

@@ -19,7 +19,7 @@ build time: {}
     $.timestamp
 );
 
-build_info_crate::build_info!(fn build_info);
+build_info_crate::build_info!(pub(crate) fn build_info);
 
 /// Log Build Info to our logs.
 pub(crate) fn log_build_info() {

catalyst-gateway/bin/src/service/poem_service.rs

@@ -12,7 +12,7 @@ use poem::{
 
 use super::{
     common::auth::{api_key::API_KEY_HEADER, rbac::scheme::AUTHORIZATION_HEADER},
-    utilities::middleware::db_check::DatabaseConnectionCheck,
+    utilities::middleware::{db_check::DatabaseConnectionCheck, node_info::CatGatewayInfo},
 };
 use crate::{
     metrics::init_prometheus,
@@ -50,6 +50,7 @@ fn mk_app(base_route: Option<Route>) -> impl Endpoint {
         .with(CatchPanic::new().with_handler(ServicePanicHandler))
         .with(Tracing)
         .with(DatabaseConnectionCheck)
+        .with(CatGatewayInfo)
         .with(
             SensitiveHeader::new()
                 .header(API_KEY_HEADER)

catalyst-gateway/bin/src/service/utilities/middleware/mod.rs

@@ -1,5 +1,6 @@
 //! Custom POEM Middleware for this service.
 
 pub(crate) mod db_check;
+pub(crate) mod node_info;
 pub(crate) mod schema_validation;
 pub(crate) mod tracing_mw;

catalyst-gateway/bin/src/service/utilities/middleware/node_info.rs

@@ -0,0 +1,82 @@
+//! Adds an information about the running cat-gateway instance for each response headers.
+
+use std::fmt::Write;
+
+use poem::{Endpoint, IntoResponse, Middleware, Request, Response, Result};
+
+use crate::{
+    build_info::build_info,
+    settings::{self, Settings},
+};
+
+/// A prefix for any custom header field <https://datatracker.ietf.org/doc/html/rfc6648#appendix-B>
+const CUSTOM_HEADER_PREFIX: &str = "VND.projectcatalyst.io";
+
+/// Middleware type that returns a response with 503 status code
+/// if any DB stops responding before returning the wrapped endpoint.
+pub(crate) struct CatGatewayInfo;
+
+impl<E: Endpoint> Middleware<E> for CatGatewayInfo {
+    type Output = CatGatewayInfoImpl<E>;
+
+    fn transform(&self, ep: E) -> Self::Output {
+        CatGatewayInfoImpl { ep }
+    }
+}
+
+/// The new endpoint type generated by the `CatGatewayInfo`.
+pub(crate) struct CatGatewayInfoImpl<E> {
+    /// Endpoint wrapped by the middleware.
+    ep: E,
+}
+
+impl<E: Endpoint> Endpoint for CatGatewayInfoImpl<E> {
+    type Output = Response;
+
+    async fn call(&self, req: Request) -> Result<Self::Output> {
+        let resp = self.ep.call(req).await?.into_response();
+
+        Ok(resp
+            // using a `Server` header
+            // <https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Server>
+            .with_header("Server", server_info())
+            .with_header(
+                format!("{CUSTOM_HEADER_PREFIX}.Cardano-Network"),
+                Settings::cardano_network().to_string(),
+            )
+            .into_response())
+    }
+}
+
+/// Returns a cat-gateway server info in the following format,
+/// based on the `User-Agent` <https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/User-Agent>
+/// ```
+/// cat-gateway/<service-id> commit:<git_commit>,branch:<git_branch>,tags:<git_tag1>,<git_tag2>
+/// ```
+fn server_info() -> String {
+    let cat_gateway_info = build_info();
+    let mut server_info = format!("cat-gateway/{}", settings::Settings::service_id());
+    if let Some(vc) = &cat_gateway_info.version_control {
+        if let Some(git) = vc.git() {
+            let _ = write!(&mut server_info, " commit:{}", git.commit_short_id);
+            if let Some(branch) = &git.branch {
+                let _ = write!(&mut server_info, ",branch:{branch}");
+            }
+            if !git.tags.is_empty() {
+                let _ = write!(&mut server_info, ",tags:{}", git.tags.join(","));
+            }
+        }
+    }
+    server_info
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[ignore]
+    fn server_info_test() {
+        println!("{}", server_info());
+    }
+}