Add schema directive to empty template

crates/loader/src/local.rs

@@ -91,6 +91,7 @@ impl LocalLoader {
     ) -> Result<LockedApp> {
         spin_manifest::normalize::normalize_manifest(&mut manifest, profile)?;
 
+        manifest.validate_required_fields()?;
         manifest.validate_dependencies()?;
 
         let AppManifest {

crates/manifest/src/schema/v2.rs

@@ -46,6 +46,7 @@ pub struct AppManifest {
     ///
     /// Example: `[[trigger.http]]`
     #[serde(rename = "trigger")]
+    #[serde(default)]
     #[schemars(with = "json_schema::TriggerSchema")]
     pub triggers: Map<String, Vec<Trigger>>,
     /// `[component.<id>]`
@@ -55,6 +56,15 @@ pub struct AppManifest {
 }
 
 impl AppManifest {
+    /// Ensures that required fields (where not enforced in the schema) are populated.
+    pub fn validate_required_fields(&self) -> anyhow::Result<()> {
+        if self.triggers.is_empty() {
+            anyhow::bail!("The application must have at least one trigger");
+        }
+
+        Ok(())
+    }
+
     /// This method ensures that the dependencies of each component are valid.
     pub fn validate_dependencies(&self) -> anyhow::Result<()> {
         for (component_id, component) in &self.components {

templates/http-empty/content/spin.toml

@@ -1,3 +1,5 @@
+#:schema https://schemas.spinframework.dev/spin/manifest-v2/latest.json
+
 spin_manifest_version = 2
 
 [application]

tests/integration.rs

@@ -597,8 +597,8 @@ mod integration_tests {
             },
         )?;
 
-        let expected = "Error: No triggers in app\n";
-        assert_eq!(env.runtime_mut().stderr(), expected);
+        let expected = "application must have at least one trigger";
+        assert!(env.runtime_mut().stderr().contains(expected));
 
         Ok(())
     }