Add notifications for target maintainers (#10)

This adds a feature where maintainers can add themselves to an array in the source to receive notifications whenever the target fails.

The way this works is via GitHub, I created a new repository https://github.com/Noratrieb/does-it-build-notifications where an app will create issues that ping the respective users. This is the easiest option for me and also fits nicely into people's workflows on GitHub.

Whenever a target fails, an issue is created for it. This issue is kept open (with a new comment every day that it continues to fail), and then closed when the target builds again.

src/main.rs

@@ -1,6 +1,7 @@
 mod build;
 mod db;
 mod nightlies;
+mod notification;
 mod web;
 
 use color_eyre::{eyre::WrapErr, Result};
@@ -12,6 +13,10 @@ const VERSION_SHORT: &str = env!("GIT_COMMIT_SHORT");
 
 #[tokio::main]
 async fn main() -> Result<()> {
+    main_inner().await
+}
+
+async fn main_inner() -> Result<()> {
     tracing_subscriber::fmt()
         .with_env_filter(EnvFilter::try_from_default_env().unwrap_or(EnvFilter::new("info")))
         .init();
@@ -22,7 +27,33 @@ async fn main() -> Result<()> {
         .await
         .wrap_err("running migrations")?;
 
-    let builder = build::background_builder(db.clone());
+    let send_pings = std::env::var("GITHUB_SEND_PINGS")
+        .map(|_| true)
+        .unwrap_or(false);
+    let github_owner = std::env::var("GITHUB_OWNER").wrap_err("missing GITHUB_OWNER env var")?;
+    let github_repo = std::env::var("GITHUB_REPO").wrap_err("missing GITHUB_REPO env var")?;
+    let app_id = std::env::var("GITHUB_APP_ID")
+        .wrap_err("missing GITHUB_APP_ID env var")?
+        .parse::<u64>()
+        .wrap_err("invalid GITHUB_APP_ID")?;
+    let key = std::env::var("GITHUB_APP_PRIVATE_KEY")
+        .wrap_err("missing GITHUB_APP_PRIVATE_KEY env var")?;
+    let key = jsonwebtoken::EncodingKey::from_rsa_pem(key.as_bytes()).unwrap();
+
+    let github_client = octocrab::Octocrab::builder()
+        .app(app_id.into(), key)
+        .build()
+        .wrap_err("failed to create client")?;
+
+    let github_client = notification::GitHubClient::new(
+        send_pings,
+        github_client,
+        github_owner.clone(),
+        github_repo.clone(),
+    )
+    .await?;
+
+    let builder = build::background_builder(db.clone(), github_client);
     let server = web::webserver(db);
 
     tokio::select! {