Add trivial logging

Cargo.toml

@@ -16,6 +16,7 @@ categories = ["command-line-utilities", "science"]
 actix-web = "1.0.8"
 actix-service = "0.4"
 actix-cors = "0.1"
+env_logger = "0.7"
 image = "0.19"
 n5 = "0.4"
 ndarray = "0.12"

README.md

@@ -49,6 +49,16 @@ h2n5 -h
 | FLOAT32|                | PNG        | JPEG PNG   |
 | FLOAT64|                |            | PNG        |
 
+### Logging
+
+Logs are output to stderr using standard Rust `log` and `env_logger` in the `actix_web` scope. By default only major errors at the `WARN` level or above are shown. For example, to show all requests:
+
+```
+RUST_LOG=actix_web=info h2n5
+```
+
+For more information, see the [`env_logger`](https://docs.rs/env_logger) and [`actix_web` logging middleware](https://actix.rs/docs/errors/) documentation.
+
 ## License
 
 Licensed under either of

src/main.rs

@@ -495,6 +495,7 @@ mod actix_middleware_kludge {
 fn main() -> std::io::Result<()> {
 
     let opt = Options::from_args();
+    env_logger::init();
 
     let mut server = HttpServer::new(
         || {
@@ -504,6 +505,7 @@ fn main() -> std::io::Result<()> {
             let cors = opt.cors.clone();
             App::new()
                 .data(opt)
+                .wrap(actix_web::middleware::Logger::default())
                 .service(
                     web::resource("/tile/{spec:.*}")
                         .route(web::get().to(tile))