From 7636195380b5db3b70d3b6eaf75ffc56c9f690de Mon Sep 17 00:00:00 2001
From: bahdotsh <appu.yess@gmail.com>
Date: Wed, 13 Aug 2025 13:21:58 +0530
Subject: [PATCH] fix: Support array format for runs-on field in GitHub Actions
 workflows

- Add custom deserializer for runs-on field to handle both string and array formats
- Update Job struct to use Vec<String> instead of String for runs-on field
- Modify executor to extract first element from runs-on array for runner selection
- Add test workflow to verify both string and array formats work correctly
- Maintain backwards compatibility with existing string-based workflows

Fixes issue where workflows with runs-on: [self-hosted, ubuntu, small] format
would fail with 'invalid type: sequence, expected a string' error.

This change aligns with GitHub Actions specification which supports:
- String format: runs-on: ubuntu-latest
- Array format: runs-on: [self-hosted, ubuntu, small]
---
 crates/executor/src/engine.rs          |  8 ++++++--
 crates/parser/src/gitlab.rs            |  2 +-
 crates/parser/src/workflow.rs          | 24 ++++++++++++++++++++++--
 tests/workflows/runs-on-array-test.yml | 18 ++++++++++++++++++
 4 files changed, 47 insertions(+), 5 deletions(-)
 create mode 100644 tests/workflows/runs-on-array-test.yml

diff --git a/crates/executor/src/engine.rs b/crates/executor/src/engine.rs
index e7a5866..1e1435f 100644
--- a/crates/executor/src/engine.rs
+++ b/crates/executor/src/engine.rs
@@ -1762,9 +1762,13 @@ fn get_runner_image(runs_on: &str) -> String {
     .to_string()
 }
 
-fn get_runner_image_from_opt(runs_on: &Option<String>) -> String {
+fn get_runner_image_from_opt(runs_on: &Option<Vec<String>>) -> String {
     let default = "ubuntu-latest";
-    let ro = runs_on.as_deref().unwrap_or(default);
+    let ro = runs_on
+        .as_ref()
+        .and_then(|vec| vec.first())
+        .map(|s| s.as_str())
+        .unwrap_or(default);
     get_runner_image(ro)
 }
 
diff --git a/crates/parser/src/gitlab.rs b/crates/parser/src/gitlab.rs
index a2f8fb1..7bd238c 100644
--- a/crates/parser/src/gitlab.rs
+++ b/crates/parser/src/gitlab.rs
@@ -130,7 +130,7 @@ pub fn convert_to_workflow_format(pipeline: &Pipeline) -> workflow::WorkflowDefi
 
         // Create a new job
         let mut job = workflow::Job {
-            runs_on: Some("ubuntu-latest".to_string()), // Default runner
+            runs_on: Some(vec!["ubuntu-latest".to_string()]), // Default runner
             needs: None,
             steps: Vec::new(),
             env: HashMap::new(),
diff --git a/crates/parser/src/workflow.rs b/crates/parser/src/workflow.rs
index bbb4a86..58a29cb 100644
--- a/crates/parser/src/workflow.rs
+++ b/crates/parser/src/workflow.rs
@@ -26,6 +26,26 @@ where
     }
 }
 
+// Custom deserializer for runs-on field that handles both string and array formats
+fn deserialize_runs_on<'de, D>(deserializer: D) -> Result<Option<Vec<String>>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum StringOrVec {
+        String(String),
+        Vec(Vec<String>),
+    }
+
+    let value = Option::<StringOrVec>::deserialize(deserializer)?;
+    match value {
+        Some(StringOrVec::String(s)) => Ok(Some(vec![s])),
+        Some(StringOrVec::Vec(v)) => Ok(Some(v)),
+        None => Ok(None),
+    }
+}
+
 #[derive(Debug, Deserialize, Serialize)]
 pub struct WorkflowDefinition {
     pub name: String,
@@ -38,8 +58,8 @@ pub struct WorkflowDefinition {
 
 #[derive(Debug, Deserialize, Serialize)]
 pub struct Job {
-    #[serde(rename = "runs-on")]
-    pub runs_on: Option<String>,
+    #[serde(rename = "runs-on", default, deserialize_with = "deserialize_runs_on")]
+    pub runs_on: Option<Vec<String>>,
     #[serde(default, deserialize_with = "deserialize_needs")]
     pub needs: Option<Vec<String>>,
     #[serde(default)]
diff --git a/tests/workflows/runs-on-array-test.yml b/tests/workflows/runs-on-array-test.yml
new file mode 100644
index 0000000..c3e6e26
--- /dev/null
+++ b/tests/workflows/runs-on-array-test.yml
@@ -0,0 +1,18 @@
+name: Test Runs-On Array Format
+
+on: [push]
+
+jobs:
+  test-array-runs-on:
+    timeout-minutes: 15
+    runs-on: [self-hosted, ubuntu, small]
+    steps:
+      - name: Test step
+        run: echo "Testing array format for runs-on"
+
+  test-string-runs-on:
+    timeout-minutes: 15
+    runs-on: ubuntu-latest
+    steps:
+      - name: Test step
+        run: echo "Testing string format for runs-on"