Load runtime config when loading triggers in the Functions Emulator (#…

…4162)

Addresses #4158.

I've tried to find a way to add a test for this usecase, but there isn't a framework where I can easily hook in a change like this without big investments. I'm leaning towards releasing this bugfix as is, and finding a less urgent time to add regression test.

CHANGELOG.md

@@ -1 +1,2 @@
 - Fixes an issue where ext:list was not printing out information about installed Extension instances.
+- Fixes issue where Functions Emulator crashed when parsing triggers if accessing functions config values.

src/emulator/functionsEmulator.ts

@@ -451,6 +451,7 @@ export class FunctionsEmulator implements EmulatorInstance {
     if (emulatableBackend.predefinedTriggers) {
       triggerDefinitions = emulatedFunctionsByRegion(emulatableBackend.predefinedTriggers);
     } else {
+      const runtimeConfig = this.getRuntimeConfig(emulatableBackend);
       const runtimeDelegate = await getRuntimeDelegate({
         projectId: this.args.projectId,
         projectDir: this.args.projectDir,
@@ -462,7 +463,7 @@ export class FunctionsEmulator implements EmulatorInstance {
       await runtimeDelegate.build();
       logger.debug(`Analyzing ${runtimeDelegate.name} backend spec`);
       const discoveredBackend = await runtimeDelegate.discoverSpec(
-        {},
+        runtimeConfig,
         // Don't include user envs when parsing triggers.
         {
           ...this.getSystemEnvs(),
@@ -871,6 +872,17 @@ export class FunctionsEmulator implements EmulatorInstance {
     return process.execPath;
   }
 
+  getRuntimeConfig(backend: EmulatableBackend): Record<string, string> {
+    const configPath = `${backend.functionsDir}/.runtimeconfig.json`;
+    try {
+      const configContent = fs.readFileSync(configPath, "utf8");
+      return JSON.parse(configContent.toString());
+    } catch (e) {
+      // This is fine - runtime config is optional.
+    }
+    return {};
+  }
+
   getUserEnvs(backend: EmulatableBackend): Record<string, string> {
     const projectInfo = {
       functionsSource: backend.functionsDir,