Show github annotation on specific errors.

src/cli/mod.rs

@@ -734,6 +734,7 @@ async fn push_new_release(
         StatusCode::UNAUTHORIZED => {
             let body = &release_metadata_post_response.bytes().await?;
             let message = serde_json::from_slice::<String>(body)?;
+
             return Err(Error::Unauthorized(message))?;
         }
         _ => {

src/error.rs

@@ -1,5 +1,6 @@
 #[derive(Debug, thiserror::Error)]
 pub(crate) enum Error {
+    /// Unauthorized, with a single line message detailing the nature of the problem.
     #[error("Unauthorized: {0}")]
     Unauthorized(String),
     #[error("{upload_name}/{rolling_prefix_or_tag} already exists")]
@@ -15,4 +16,17 @@ impl Error {
             Self::Unauthorized(_) | Self::Conflict { .. } => false,
         }
     }
+
+    /// Output a Github Actions annotation command if desired.
+    // Note: These may only be one line! Any further lines will not be printed!
+    pub(crate) fn maybe_github_actions_annotation(&self) {
+        if std::env::var("GITHUB_ACTIONS").is_ok() {
+            match self {
+                Error::Unauthorized(message) => {
+                    println!("::error title=Unauthorized::{message}")
+                }
+                Error::Conflict { .. } => println!("::error title=Conflict::{self}"),
+            }
+        }
+    }
 }

src/main.rs

@@ -34,7 +34,16 @@ async fn main() -> color_eyre::Result<std::process::ExitCode> {
 
     let cli = cli::FlakeHubPushCli::parse();
     cli.instrumentation.setup()?;
-    cli.execute().await
+
+    match cli.execute().await {
+        Ok(exit) => Ok(exit),
+        Err(error) => {
+            if let Some(known_error) = error.downcast_ref::<Error>() {
+                known_error.maybe_github_actions_annotation()
+            }
+            Err(error)
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, clap::ValueEnum, serde::Serialize, serde::Deserialize)]