Beautify error handling

Cargo.lock

@@ -450,7 +450,7 @@ dependencies = [
 
 [[package]]
 name = "nixos-exporter"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "axum",
  "reqwest",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nixos-exporter"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 
 [dependencies]

src/main.rs

@@ -1,7 +1,7 @@
 use axum::{
     extract::{State, Query},
     http::StatusCode,
-    response::{IntoResponse, Response},
+    response::IntoResponse,
     routing::get,
     Router,
 };
@@ -144,113 +144,64 @@ async fn main() {
 }
 
 fn get_current_system() -> Result<(String, String), String> {
-    let symlink = match std::fs::read_link("/run/current-system") {
+    let symlink = std::fs::read_link("/run/current-system").map_err(|err| err.to_string())?;
-        Ok(symlink) => symlink,
-        Err(err) => return Err(err.to_string()),
-    };
 
     let (hash, name) = parse_nix_store_path(symlink)?;
 
     Ok((String::from(hash), String::from(name)))
 }
 
-async fn metrics() -> Response {
+async fn metrics() -> Result<(StatusCode, impl IntoResponse), (StatusCode, impl IntoResponse)> {
-    let current_system = get_current_system();
+    let (hash, name) = get_current_system().map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, ""))?;
-    let (hash, name) = match current_system {
-        Ok((hash, name)) => (hash, name),
-        Err(err) => {
-            println!("failed: {}", err);
-            return (StatusCode::INTERNAL_SERVER_ERROR, "").into_response();
-        }
-    };
 
-    (
+    return Ok((
         StatusCode::OK,
         format!("nixos_current_system_hash{{hash=\"{}\"}} 1\nnixos_current_system_name{{name=\"{}\"}} 1\n", hash, name)
-    ).into_response()
+    ));
 }
 
-async fn check(State(app_state): State<AppState>, Query(params): Query<HashMap<String, String>>) -> Response {
+async fn check(State(app_state): State<AppState>, Query(params): Query<HashMap<String, String>>) -> Result<(StatusCode, impl IntoResponse), (StatusCode, impl IntoResponse)> {
-    let target = match params.get("target") {
+    let target = params.get("target")
-        Some(target) => target,
+        .ok_or_else(|| (StatusCode::NOT_FOUND, "specify target"))?;
-        None => {
-            return (StatusCode::NOT_FOUND, "specify target").into_response();
-        },
-    };
 
     if target.contains("\"") {
-        return (StatusCode::INTERNAL_SERVER_ERROR, "Invalid target name").into_response();
+        return Err((StatusCode::INTERNAL_SERVER_ERROR, "Invalid target name"));
     }
 
     let client = reqwest::Client::new();
 
-    let prometheus_req = match client.get(format!("{}/api/v1/query?query=nixos_current_system_hash{{{}}}", app_state.prometheus_url, app_state.prometheus_query_tag_template.clone().replace("{}", target)))
+    let prometheus_req = client.get(format!("{}/api/v1/query?query=nixos_current_system_hash{{{}}}", app_state.prometheus_url, app_state.prometheus_query_tag_template.clone().replace("{}", target)))
         .header("Accept", "application/json")
-        .send().await {
+        .send().await
-            Ok(req) => req,
+        .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Promehteus can't get reached"))?;
-            Err(_) => {
-                return (StatusCode::INTERNAL_SERVER_ERROR, "Promehteus can't get reached").into_response();
-            },
-        };
 
-
+    if prometheus_req.status() != reqwest::StatusCode::OK {
-    match prometheus_req.status() {
+       return Err((StatusCode::NOT_FOUND, "Target does not exist in Hydra"));
-        reqwest::StatusCode::OK => (),
-        _ => {
-            return (StatusCode::NOT_FOUND, "Target does not exist in Hydra").into_response();
-        },
     }
 
-    let prometheus_body = match prometheus_req.json::<serde_json::Value>().await {
+    let prometheus_body = prometheus_req.json::<serde_json::Value>().await
-        Ok(body) => body,
+        .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Invalid response from Hydra"))?;
-        Err(_) => {
-            return (StatusCode::INTERNAL_SERVER_ERROR, "Invalid response from Hydra").into_response();
-        },
-    };
 
-    let current_system_hash = match prometheus_body["data"]["result"][0]["metric"]["hash"].as_str() {
+    let current_system_hash = prometheus_body["data"]["result"][0]["metric"]["hash"].as_str()
-        Some(nix_store_path) => nix_store_path,
+        .ok_or_else(|| (StatusCode::INTERNAL_SERVER_ERROR, "No buildoutput found in Hydra"))?;
-        _ => {
-            return (StatusCode::INTERNAL_SERVER_ERROR, "No buildoutput found in Hydra").into_response();
-        },
-    };
 
-    let hydra_req = match client.get(format!("{}/job/{}/latest", app_state.hydra_url, app_state.hydra_job_template.clone().replace("{}", target)))
+    let hydra_req = client.get(format!("{}/job/{}/latest", app_state.hydra_url, app_state.hydra_job_template.clone().replace("{}", target)))
         .header("Accept", "application/json")
-        .send().await {
+        .send().await
-            Ok(req) => req,
+        .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Hydra can't get reached"))?;
-            Err(_) => {
-                return (StatusCode::INTERNAL_SERVER_ERROR, "Hydra can't get reached").into_response();
-            },
-        };
 
-    match hydra_req.status() {
+    if hydra_req.status() != reqwest::StatusCode::OK {
-        reqwest::StatusCode::OK => (),
+        return Err((StatusCode::NOT_FOUND, "Target does not exist in Hydra"));
-        _ => {
-            return (StatusCode::NOT_FOUND, "Target does not exist in Hydra").into_response();
-        },
     }
 
-    let hydra_body = match hydra_req.json::<serde_json::Value>().await {
+    let hydra_body = hydra_req.json::<serde_json::Value>().await
-        Ok(body) => body,
+        .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Invalid response from Hydra"))?;
-        Err(_) => {
-            return (StatusCode::INTERNAL_SERVER_ERROR, "Invalid response from Hydra").into_response();
-        },
-    };
 
-    let nix_store_path = match hydra_body["buildoutputs"]["out"]["path"].as_str() {
+    let nix_store_path = hydra_body["buildoutputs"]["out"]["path"].as_str()
-        Some(nix_store_path) => nix_store_path,
+        .ok_or_else(|| (StatusCode::INTERNAL_SERVER_ERROR, "No buildoutput found in Hydra"))?;
-        _ => {
-            return (StatusCode::INTERNAL_SERVER_ERROR, "No buildoutput found in Hydra").into_response();
-        },
-    };
 
-    let (hydra_system_hash, _) = match parse_nix_store_path(std::path::PathBuf::from(nix_store_path)) {
+    let (hydra_system_hash, _) = parse_nix_store_path(std::path::PathBuf::from(nix_store_path))
-        Ok((hash, name)) => (hash, name),
+        .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Invalid store path returned by Hydra"))?;
-        Err(_) => {
-            return (StatusCode::INTERNAL_SERVER_ERROR, "Invalid store path returned by Hydra").into_response();
-        },
-    };
 
     let mut status = "0";
 
@@ -258,8 +209,8 @@ async fn check(State(app_state): State<AppState>, Query(params): Query<HashMap<S
         status = "1";
     }
 
-    return (
+    return Ok((
         StatusCode::OK,
         format!("nixos_current_system_is_sync{{}} {}\n", status)
-    ).into_response();
+    ));
 }