Beautify error handling

Cargo.lock

@@ -450,7 +450,7 @@ dependencies = [
 
 [[package]]
 name = "nixos-exporter"
-version = "0.3.0"
+version = "0.1.0"
 dependencies = [
  "axum",
  "reqwest",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nixos-exporter"
-version = "0.3.0"
+version = "0.2.0"
 edition = "2021"
 
 [dependencies]

flake.nix

@@ -10,7 +10,7 @@
     in {
       nixos-exporter = pkgs.rustPlatform.buildRustPackage rec {
         pname = "nixos-exporter";
-        version = "0.3.0";
+        version = "0.1.0";
 
         src = ./.;
 

src/main.rs

@@ -59,12 +59,12 @@ impl AppState{
 }
 
 fn parse_nix_store_path(path: std::path::PathBuf) -> Result<(String, String), String> {
-    let (hash, name) = path.iter().nth(3)
-        .ok_or_else(|| String::from("Can't read store path name"))?
+    let (hash, name) = path.file_name()
+        .ok_or_else(String::default)?
         .to_str()
-        .ok_or_else(|| String::from("Failed converting store path name to string"))?
+        .ok_or_else(String::default)?
         .split_once("-")
-        .ok_or_else(|| String::from("Failed splitting store path name for hash and name"))?;
+        .ok_or_else(String::default)?;
     return Ok((hash.to_string(), name.to_string()));
 }
 
@@ -143,33 +143,20 @@ async fn main() {
         .unwrap();
 }
 
-fn parse_symlink(path: String) -> Result<(String, String), String> {
-    let symlink = std::fs::read_link(path).map_err(|err| err.to_string())?;
+fn get_current_system() -> Result<(String, String), String> {
+    let symlink = std::fs::read_link("/run/current-system").map_err(|err| err.to_string())?;
 
     let (hash, name) = parse_nix_store_path(symlink)?;
 
     Ok((String::from(hash), String::from(name)))
 }
 
-fn gen_prometheus_metric(path: String, infix: String) -> Result<String, String> {
-    let (hash, name) = parse_symlink(path).map_err(|err| err)?;
-
-    return Ok(format!("nixos_{}_hash{{hash=\"{}\"}} 1\nnixos_{}_name{{name=\"{}\"}} 1\n", infix, hash, infix, name));
-}
-
 async fn metrics() -> Result<(StatusCode, impl IntoResponse), (StatusCode, impl IntoResponse)> {
-    let mut out = String::new();
-    out.push_str(&gen_prometheus_metric(String::from("/run/current-system"), String::from("current_system"))
-        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err))?);
-    out.push_str(&gen_prometheus_metric(String::from("/run/current-system/kernel"), String::from("current_system_kernel"))
-        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err))?);
-    out.push_str(&gen_prometheus_metric(String::from("/run/booted-system"), String::from("booted_system"))
-        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err))?);
-    out.push_str(&gen_prometheus_metric(String::from("/run/booted-system/kernel"), String::from("booted_system_kernel"))
-        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err))?);
+    let (hash, name) = get_current_system().map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, ""))?;
+
     return Ok((
         StatusCode::OK,
-        out,
+        format!("nixos_current_system_hash{{hash=\"{}\"}} 1\nnixos_current_system_name{{name=\"{}\"}} 1\n", hash, name)
     ));
 }
 
@@ -183,7 +170,7 @@ async fn check(State(app_state): State<AppState>, Query(params): Query<HashMap<S
 
     let client = reqwest::Client::new();
 
-    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)))
+    let prometheus_req = client.get(format!("{}/api/v1/query?query=nixos_nixos_current_system_hash{{{}}}", app_state.prometheus_url, app_state.prometheus_query_tag_template.clone().replace("{}", target)))
         .header("Accept", "application/json")
         .send().await
         .map_err(|_err| (StatusCode::INTERNAL_SERVER_ERROR, "Promehteus can't get reached"))?;
@@ -224,6 +211,6 @@ async fn check(State(app_state): State<AppState>, Query(params): Query<HashMap<S
 
     return Ok((
         StatusCode::OK,
-        format!("nixos_current_system_is_sync{{}} {}\n", status)
+        format!("nixos_current_system_valid{{{}}} {}\n", app_state.prometheus_query_tag_template.clone().replace("{}", target), status)
     ));
 }