Try to handle errors a bit more gracefully

In many cases where iocaine was using `unwrap()`, handle it gracefully,
and return a `Result` instead.

Signed-off-by: Gergely Nagy <me@gergo.csillger.hu>

src/app.rs

@@ -6,8 +6,9 @@
 use anyhow::Result;
 use axum::{
     extract::{Path, State},
+    http::StatusCode,
     middleware,
-    response::Html,
+    response::{Html, IntoResponse, Response},
     routing::get,
     Router,
 };
@@ -110,20 +111,49 @@ async fn poison(
     headers: axum::http::HeaderMap,
     State(iocaine): State<StatefulIocaine>,
     path: Option<Path<String>>,
-) -> Html<String> {
+) -> std::result::Result<Html<String>, AppError> {
     let default_host = axum::http::HeaderValue::from_static("<unknown>");
-    let host = headers
-        .get("host")
-        .unwrap_or(&default_host)
-        .to_str()
-        .unwrap();
+    let host = headers.get("host").unwrap_or(&default_host).to_str()?;
     let path = path.unwrap_or(Path("/".to_string()));
 
-    let garbage = AssembledStatisticalSequences::generate(&iocaine, host, &path);
+    let garbage = AssembledStatisticalSequences::generate(&iocaine, host, &path)?;
 
     if iocaine.config.metrics.enable {
         metrics::counter!("iocaine_garbage_served").increment(garbage.len() as u64);
     }
 
-    Html(garbage)
+    Ok(Html(garbage))
+}
+
+pub struct AppError(anyhow::Error);
+
+impl IntoResponse for AppError {
+    fn into_response(self) -> Response {
+        tracing::error!("Internal server error: {}", self.0);
+        (StatusCode::INTERNAL_SERVER_ERROR, "Something went wrong").into_response()
+    }
+}
+
+impl From<axum::http::header::ToStrError> for AppError {
+    fn from(e: axum::http::header::ToStrError) -> Self {
+        Self(e.into())
+    }
+}
+
+impl From<anyhow::Error> for AppError {
+    fn from(e: anyhow::Error) -> Self {
+        Self(e)
+    }
+}
+
+impl From<std::io::Error> for AppError {
+    fn from(e: std::io::Error) -> Self {
+        Self(e.into())
+    }
+}
+
+impl From<metrics_exporter_prometheus::BuildError> for AppError {
+    fn from(e: metrics_exporter_prometheus::BuildError) -> Self {
+        Self(e.into())
+    }
 }

src/assembled_statistical_sequences.rs

@@ -3,7 +3,8 @@
 //
 // SPDX-License-Identifier: MIT
 
-use handlebars::Handlebars;
+use anyhow::Result;
+use handlebars::{Handlebars, RenderErrorReason};
 use rand::{seq::IndexedRandom, Rng};
 use rust_embed::Embed;
 use serde::Serialize;
@@ -37,7 +38,7 @@ struct Page<'a> {
 pub struct AssembledStatisticalSequences;
 
 impl AssembledStatisticalSequences {
-    pub fn generate(iocaine: &Iocaine, host: &str, path: &str) -> String {
+    pub fn generate(iocaine: &Iocaine, host: &str, path: &str) -> Result<String> {
         let initial_seed = &iocaine.config.generator.initial_seed;
         let static_seed = format!("{}/{}#{}", host, path, initial_seed);
         let markov_gen = |h: &handlebars::Helper,
@@ -46,9 +47,24 @@ impl AssembledStatisticalSequences {
                           _: &mut handlebars::RenderContext,
                           out: &mut dyn handlebars::Output|
          -> handlebars::HelperResult {
-            let group = h.param(0).unwrap().value().as_str().unwrap();
-            let index = h.param(1).unwrap().value().as_i64().unwrap();
-            let words = h.param(2).unwrap().value().as_i64().unwrap();
+            let group = h
+                .param(0)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("group", 0))?
+                .value()
+                .as_str()
+                .ok_or(RenderErrorReason::InvalidParamType("string"))?;
+            let index = h
+                .param(1)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("index", 1))?
+                .value()
+                .as_i64()
+                .ok_or(RenderErrorReason::InvalidParamType("i64"))?;
+            let words = h
+                .param(2)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("words", 2))?
+                .value()
+                .as_i64()
+                .ok_or(RenderErrorReason::InvalidParamType("i64"))?;
 
             let rng = GobbledyGook::for_url(format!("{}://{}/{}", group, &static_seed, index));
             let chain = iocaine.chain.generate(rng).take(words as usize);
@@ -62,9 +78,24 @@ impl AssembledStatisticalSequences {
                         _: &mut handlebars::RenderContext,
                         out: &mut dyn handlebars::Output|
          -> handlebars::HelperResult {
-            let group = h.param(0).unwrap().value().as_str().unwrap();
-            let index = h.param(1).unwrap().value().as_i64().unwrap();
-            let count = h.param(2).unwrap().value().as_i64().unwrap();
+            let group = h
+                .param(0)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("group", 0))?
+                .value()
+                .as_str()
+                .ok_or(RenderErrorReason::InvalidParamType("string"))?;
+            let index = h
+                .param(1)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("index", 1))?
+                .value()
+                .as_i64()
+                .ok_or(RenderErrorReason::InvalidParamType("i64"))?;
+            let count = h
+                .param(2)
+                .ok_or(RenderErrorReason::ParamNotFoundForIndex("count", 2))?
+                .value()
+                .as_i64()
+                .ok_or(RenderErrorReason::InvalidParamType("i64"))?;
 
             let mut rng = GobbledyGook::for_url(format!("{}://{}/{}", group, &static_seed, index));
             let words = (1..=count)
@@ -127,12 +158,9 @@ impl AssembledStatisticalSequences {
         let mut handlebars = Handlebars::new();
         if let Some(dir) = &iocaine.config.templates.directory {
             handlebars
-                .register_templates_directory(dir, handlebars::DirectorySourceOptions::default())
-                .unwrap();
+                .register_templates_directory(dir, handlebars::DirectorySourceOptions::default())?;
         } else {
-            handlebars
-                .register_embed_templates_with_extension::<Asset>(".hbs")
-                .unwrap();
+            handlebars.register_embed_templates_with_extension::<Asset>(".hbs")?;
         }
         handlebars.register_helper("markov-gen", Box::new(markov_gen));
         handlebars.register_helper("href-gen", Box::new(href_gen));
@@ -145,10 +173,11 @@ impl AssembledStatisticalSequences {
         };
 
         let host_template = &format!("hosts/{}", host);
-        if handlebars.has_template(host_template) {
-            handlebars.render(host_template, &data).unwrap()
+        let rendered = if handlebars.has_template(host_template) {
+            handlebars.render(host_template, &data)?
         } else {
-            handlebars.render("main", &data).unwrap()
-        }
+            handlebars.render("main", &data)?
+        };
+        Ok(rendered)
     }
 }

src/tenx_programmer.rs

@@ -4,9 +4,10 @@
 // SPDX-License-Identifier: MIT
 
 use axum::{
+    body::Body,
     extract::{Request, State},
     middleware::Next,
-    response::IntoResponse,
+    response::Response,
     routing::get,
     Router,
 };
@@ -14,7 +15,7 @@ use metrics_exporter_prometheus::PrometheusBuilder;
 use std::time::{SystemTime, UNIX_EPOCH};
 
 use crate::{
-    app::{shutdown_signal, StatefulIocaine},
+    app::{shutdown_signal, AppError, StatefulIocaine},
     config::MetricsLabel,
 };
 
@@ -22,7 +23,7 @@ pub async fn track_metrics(
     State(iocaine): State<StatefulIocaine>,
     req: Request,
     next: Next,
-) -> impl IntoResponse {
+) -> Result<Response<Body>, AppError> {
     let headers = req.headers().clone();
     let response = next.run(req).await;
     let cfg = &iocaine.config.metrics;
@@ -30,7 +31,7 @@ pub async fn track_metrics(
     let mut labels = Vec::new();
     if cfg.labels.contains(&MetricsLabel::Host) {
         if let Some(host) = headers.get("host") {
-            let host = host.to_str().unwrap().to_string();
+            let host = host.to_str()?.to_string();
             labels.push(("host", host));
         }
     }
@@ -39,7 +40,7 @@ pub async fn track_metrics(
         || cfg.labels.contains(&MetricsLabel::UserAgentGroup)
     {
         if let Some(ua) = headers.get("user-agent") {
-            let user_agent = ua.to_str().unwrap().to_string();
+            let user_agent = ua.to_str()?.to_string();
 
             if cfg.labels.contains(&MetricsLabel::UserAgent) {
                 labels.push(("user-agent", user_agent.clone()));
@@ -59,12 +60,12 @@ pub async fn track_metrics(
 
     metrics::counter!("iocaine_requests_total", &labels).increment(1);
 
-    response
+    Ok(response)
 }
 
-pub async fn start_metrics_server(metrics_bind: String) -> std::result::Result<(), std::io::Error> {
+pub async fn start_metrics_server(metrics_bind: String) -> std::result::Result<(), AppError> {
     let metrics_listener = tokio::net::TcpListener::bind(metrics_bind).await?;
-    let recorder_handle = PrometheusBuilder::new().install_recorder().unwrap();
+    let recorder_handle = PrometheusBuilder::new().install_recorder()?;
     let app = Router::new().route("/metrics", get(|| async move { recorder_handle.render() }));
 
     let ts = SystemTime::now()
@@ -73,7 +74,7 @@ pub async fn start_metrics_server(metrics_bind: String) -> std::result::Result<(
     let labels = [("service", "iocaine".to_string())];
     metrics::gauge!("process_start_time_seconds", &labels).set(ts);
 
-    axum::serve(metrics_listener, app)
+    Ok(axum::serve(metrics_listener, app)
         .with_graceful_shutdown(shutdown_signal())
-        .await
+        .await?)
 }

tests/test_app.rs

@@ -34,7 +34,7 @@ fn generate(templates: &str, host: &str, url: &str) -> String {
     };
 
     let iocaine = Iocaine::new(config).unwrap();
-    AssembledStatisticalSequences::generate(&iocaine, host, url)
+    AssembledStatisticalSequences::generate(&iocaine, host, url).unwrap()
 }
 
 #[test]
@@ -95,7 +95,8 @@ fn test_templates_builtin() {
         &iocaine,
         "test.example.com",
         "/builtin-templates/",
-    );
+    )
+    .unwrap();
 
     assert!(result.contains("/builtin-templates/"));
     assert!(result.contains("a href=\"../\""));