From 158277c5f47b9fa862375a4b4946af35fa56e995 Mon Sep 17 00:00:00 2001
From: Deep Singhvi <deep@buildwithfern.com>
Date: Thu, 4 Jul 2024 17:38:52 -0400
Subject: [PATCH] (fix): fern generate --preview doesnt check for env variables
 (#3988)

---
 .../src/createAndStartJob.ts                   |  7 +++++--
 .../src/substituteEnvVariables.ts              | 18 ++++++++++++++++--
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/packages/cli/generation/remote-generation/remote-workspace-runner/src/createAndStartJob.ts b/packages/cli/generation/remote-generation/remote-workspace-runner/src/createAndStartJob.ts
index b3ca7257fe7..63cf1331c64 100644
--- a/packages/cli/generation/remote-generation/remote-workspace-runner/src/createAndStartJob.ts
+++ b/packages/cli/generation/remote-generation/remote-workspace-runner/src/createAndStartJob.ts
@@ -93,6 +93,7 @@ async function createJob({
     whitelabel: FernFiddle.WhitelabelConfig | undefined;
     absolutePathToPreview: AbsoluteFilePath | undefined;
 }): Promise<FernFiddle.remoteGen.CreateJobResponse> {
+    const isPreview = absolutePathToPreview != null;
     const generatorConfig: FernFiddle.GeneratorConfigV2 = {
         id: generatorInvocation.name,
         version: generatorInvocation.version,
@@ -100,9 +101,11 @@ async function createJob({
         customConfig: generatorInvocation.config,
         publishMetadata: generatorInvocation.publishMetadata
     };
-    const generatorConfigsWithEnvVarSubstitutions = substituteEnvVariables(generatorConfig, context);
+    const generatorConfigsWithEnvVarSubstitutions = substituteEnvVariables(generatorConfig, context, {
+        substituteAsEmpty: isPreview
+    });
     const whitelabelWithEnvVarSubstiutions =
-        whitelabel != null ? substituteEnvVariables(whitelabel, context) : undefined;
+        whitelabel != null ? substituteEnvVariables(whitelabel, context, { substituteAsEmpty: isPreview }) : undefined;
 
     const remoteGenerationService = createFiddleService({ token: token.value });
 
diff --git a/packages/cli/generation/remote-generation/remote-workspace-runner/src/substituteEnvVariables.ts b/packages/cli/generation/remote-generation/remote-workspace-runner/src/substituteEnvVariables.ts
index 4b18e92a5dd..9071f0cd846 100644
--- a/packages/cli/generation/remote-generation/remote-workspace-runner/src/substituteEnvVariables.ts
+++ b/packages/cli/generation/remote-generation/remote-workspace-runner/src/substituteEnvVariables.ts
@@ -3,9 +3,23 @@ import { isPlainObject, mapValues } from "lodash-es";
 
 const ENV_VAR_REGEX = /\$\{(\w+)\}/g;
 
-export function substituteEnvVariables<T>(content: T, context: TaskContext): T {
+export declare namespace SubstituteEnvVariables {
+    interface Opts {
+        /* Substitues all environment variables as empty strings. */
+        substituteAsEmpty?: boolean;
+    }
+}
+
+export function substituteEnvVariables<T>(
+    content: T,
+    context: TaskContext,
+    options: SubstituteEnvVariables.Opts = {}
+): T {
     if (typeof content === "string") {
         const transformed = (content as string).replace(ENV_VAR_REGEX, (_substring, envVarName) => {
+            if (options.substituteAsEmpty) {
+                return "";
+            }
             const envVarValue = process.env[envVarName];
             if (envVarValue == null) {
                 context.failAndThrow(`Environment variable ${envVarName} is not defined.`);
@@ -20,7 +34,7 @@ export function substituteEnvVariables<T>(content: T, context: TaskContext): T {
     }
 
     const transformed = mapValues(content as unknown as object, (value: unknown) =>
-        substituteEnvVariables(value, context)
+        substituteEnvVariables(value, context, options)
     );
     return transformed as unknown as T;
 }