Merge pull request #168 from DeterminateSystems/flake-ref-output

Export the exact flakeref as an output

README.md

@@ -14,6 +14,13 @@ There are two ways to get started configuring this Action:
 
 Although the `flakehub-push` Action requires little configuration, you may benefit from assembling it with our friendly UI at [flakehub.com/new][wizard].
 
+## Integration
+
+This action sets the `flakeref` output to the exact name and version that was published.
+The flake reference can be used in subsequent steps or workflows as part of a deployment process.
+
+## More Information
+
 ### Manual configuration
 
 The example workflow configuration below pushes new tags matching the conventional format—such as `v1.0.0` or `v0.1.0-rc4`—to [Flakehub]:

src/github_actions.rs

@@ -0,0 +1,31 @@
+use tokio::io::AsyncWriteExt;
+
+#[derive(Debug, thiserror::Error)]
+pub(crate) enum Error {
+    #[error("The `GITHUB_OUTPUT` environment variable is unset.")]
+    GithubOutputUnset,
+
+    #[error("Failure opening {0:?}: {1}")]
+    OpenFile(std::ffi::OsString, std::io::Error),
+
+    #[error("Writing to {0:?}: {1}")]
+    WriteFile(std::ffi::OsString, std::io::Error),
+}
+
+pub(crate) async fn set_output<'a>(name: &'a str, value: &'a str) -> Result<(), Error> {
+    let output_path = std::env::var_os("GITHUB_OUTPUT").ok_or(Error::GithubOutputUnset)?;
+    let mut fh = tokio::fs::OpenOptions::new()
+        .create(true)
+        .read(true)
+        .write(true)
+        .truncate(false)
+        .open(&output_path)
+        .await
+        .map_err(|e| Error::OpenFile(output_path.clone(), e))?;
+
+    fh.write_all(format!("{}={}\n", name, value).as_bytes())
+        .await
+        .map_err(|e| Error::WriteFile(output_path, e))?;
+
+    Ok(())
+}

src/main.rs

@@ -17,6 +17,7 @@ mod flakehub_auth_fake;
 mod flakehub_client;
 mod git_context;
 mod github;
+mod github_actions;
 mod gitlab;
 mod push_context;
 mod release_metadata;
@@ -181,6 +182,15 @@ async fn execute() -> Result<std::process::ExitCode> {
         ctx.release_version
     );
 
+    if let Err(e) = github_actions::set_output(
+        "flakeref",
+        &format!("{}/{}", ctx.upload_name, ctx.release_version),
+    )
+    .await
+    {
+        tracing::warn!("Failed to set the `flakeref` output: {}", e);
+    }
+
     Ok(ExitCode::SUCCESS)
 }