feat: [torrust#508] add new binary HTTP health check

It makes a request to an HTTP endpoint to check that the service is
healthy.

Cargo.toml

@@ -1,4 +1,5 @@
 [package]
+default-run = "torrust-tracker"
 name = "torrust-tracker"
 readme = "README.md"
 

src/bin/http_health_check.rs

@@ -0,0 +1,37 @@
+//! Minimal `curl` or `wget` to be used for container health checks.
+//!
+//! It's convenient to avoid using third-party libraries because:
+//!
+//! - They are harder to maintain.
+//! - They introduce new attack vectors.
+use std::{env, process};
+
+#[tokio::main]
+async fn main() {
+    let args: Vec<String> = env::args().collect();
+    if args.len() != 2 {
+        eprintln!("Usage:   cargo run --bin health_check <HEALTH_URL>");
+        eprintln!("Example: cargo run --bin http_health_check http://localhost:1212/api/v1/stats?token=MyAccessToken");
+        std::process::exit(1);
+    }
+
+    println!("Health check ...");
+
+    let url = &args[1].clone();
+
+    match reqwest::get(url).await {
+        Ok(response) => {
+            if response.status().is_success() {
+                println!("STATUS: {}", response.status());
+                process::exit(0);
+            } else {
+                println!("Non-success status received.");
+                process::exit(1);
+            }
+        }
+        Err(err) => {
+            println!("ERROR: {err}");
+            process::exit(1);
+        }
+    }
+}