Merge pull request #827 from dtolnay-contrib/uiroot

Author: shepmaster

README.md

@@ -96,13 +96,16 @@ basic HTML/CSS/JS changes, directly open in your browser the built
 
 ### Build and run the server
 
-Configure your `.env` file as described in the [ui README](./ui/README.md).
-
 ```
 cd ui
 cargo run
 ```
 
+There are some optional configuration parameters described in the
+[ui README](./ui/README.md) which you may set in a `.env` file. The server will
+run with no configuration, but in order to load and save gists a GitHub token
+must be configured.
+
 ### Build or download the containers
 ```
 cd compiler

ui/README.md

@@ -6,15 +6,15 @@ disk in this directory.
 In production, these should be set according to your deployment method
 of choice.
 
-| Key                        | Required   | Default Value     | Description                                                                                                                 |
-| -------------------------- | ---------- | ----------------- | --------------------------------------------------------------------------------------------------------------------------- |
-| `PLAYGROUND_UI_ROOT`       | **Yes**    |                   | The path to the HTML, CSS, and Javascript files; for local testing probably you'll use: `PLAYGROUND_UI_ROOT=frontend/build` |
-| `PLAYGROUND_GITHUB_TOKEN`  | No         |                   | The [GitHub API token][gist] to read and write Gists                                                                        |
-| `PLAYGROUND_UI_ADDRESS`    | No         | 127.0.0.1         | The address to listen on                                                                                                    |
-| `PLAYGROUND_UI_PORT`       | No         | 5000              | The port to listen on                                                                                                       |
-| `PLAYGROUND_METRICS_TOKEN` | No         |                   | If set, will require authentication for the metrics endpoint                                                                |
-| `PLAYGROUND_CORS_ENABLED`  | No         |                   | If set, will enable CORS support                                                                                            |
-| `TMPDIR`                   | No         | system-provided   | Where compilation artifacts will be saved. Must be accessible to Docker                                                     |
+| Key                        | Required | Default Value     | Description                                                                           |
+| -------------------------- | -------- | ----------------- | ------------------------------------------------------------------------------------- |
+| `PLAYGROUND_UI_ROOT`       | No       |                   | The path to the HTML, CSS, and Javascript files (the directory containing index.html) |
+| `PLAYGROUND_GITHUB_TOKEN`  | No       |                   | The [GitHub API token][gist] to read and write Gists                                  |
+| `PLAYGROUND_UI_ADDRESS`    | No       | 127.0.0.1         | The address to listen on                                                              |
+| `PLAYGROUND_UI_PORT`       | No       | 5000              | The port to listen on                                                                 |
+| `PLAYGROUND_METRICS_TOKEN` | No       |                   | If set, will require authentication for the metrics endpoint                          |
+| `PLAYGROUND_CORS_ENABLED`  | No       |                   | If set, will enable CORS support                                                      |
+| `TMPDIR`                   | No       | system-provided   | Where compilation artifacts will be saved. Must be accessible to Docker               |
 
 [dotenv]: https://crates.io/crates/dotenv
 [gist]: https://developer.github.com/v3/gists/#authentication

ui/src/env.rs

@@ -1,3 +1,4 @@
 pub use std::env::*;
 
 pub const PLAYGROUND_GITHUB_TOKEN: &str = "PLAYGROUND_GITHUB_TOKEN";
+pub const PLAYGROUND_UI_ROOT: &str = "PLAYGROUND_UI_ROOT";

ui/src/main.rs

@@ -1,6 +1,6 @@
 #![deny(rust_2018_idioms)]
 
-use crate::env::PLAYGROUND_GITHUB_TOKEN;
+use crate::env::{PLAYGROUND_GITHUB_TOKEN, PLAYGROUND_UI_ROOT};
 use serde::{Deserialize, Serialize};
 use snafu::prelude::*;
 use std::{
@@ -25,8 +25,8 @@ fn main() {
     let _ = dotenv::dotenv();
     openssl_probe::init_ssl_cert_env_vars();
 
-    // Enable warn-level logging by default. env_logger's default is error only.
-    let env_logger_config = env_logger::Env::default().default_filter_or("warn");
+    // Enable info-level logging by default. env_logger's default is error only.
+    let env_logger_config = env_logger::Env::default().default_filter_or("info");
     env_logger::Builder::from_env(env_logger_config).init();
 
     let config = Config::from_env();
@@ -44,9 +44,36 @@ struct Config {
 
 impl Config {
     fn from_env() -> Self {
-        let root: PathBuf = env::var_os("PLAYGROUND_UI_ROOT")
-            .expect("Must specify PLAYGROUND_UI_ROOT")
-            .into();
+        let root = if let Some(root) = env::var_os(PLAYGROUND_UI_ROOT) {
+            // Ensure it appears as an absolute path in logs to help user orient
+            // themselves about what directory the PLAYGROUND_UI_ROOT
+            // configuration is interpreted relative to.
+            let mut root = PathBuf::from(root);
+            if !root.is_absolute() {
+                if let Ok(current_dir) = env::current_dir() {
+                    root = current_dir.join(root);
+                }
+            }
+            root
+        } else {
+            // Note this is `env!` (compile time) while the above is
+            // `env::var_os` (run time). We know where the ui is expected to be
+            // relative to the source code that the server was compiled from.
+            PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+                .join("frontend")
+                .join("build")
+        };
+
+        let index_html = root.join("index.html");
+        if index_html.exists() {
+            log::info!("Serving playground frontend from {}", root.display());
+        } else {
+            log::error!(
+                "Playground ui does not exist at {}\n\
+                Playground will not work until `yarn run build` has been run or {PLAYGROUND_UI_ROOT} has been fixed",
+                index_html.display(),
+            );
+        }
 
         let address =
             env::var("PLAYGROUND_UI_ADDRESS").unwrap_or_else(|_| DEFAULT_ADDRESS.to_string());