feat(fetch-engine): only print error message for nixos if applicable

Previously on nixos, an error message regarding not available
precompiled engine files was always printed. With this change, the error
message is only shown if the engine files were not configured correctly
via environment variables.

Fixes: #17900

packages/fetch-engine/src/download.ts

@@ -13,7 +13,7 @@ import { BinaryType } from './BinaryType'
 import { chmodPlusX } from './chmodPlusX'
 import { cleanupCache } from './cleanupCache'
 import { downloadZip } from './downloadZip'
-import { getBinaryEnvVarPath } from './env'
+import { allEngineEnvVarsSet, getBinaryEnvVarPath } from './env'
 import { getHash } from './getHash'
 import { getBar } from './log'
 import { getCacheDir, getDownloadUrl, overwriteFile } from './utils'
@@ -70,8 +70,12 @@ export async function download(options: DownloadOptions): Promise<BinaryPaths> {
   const platform = await getPlatform()
   const os = await getos()
 
-  if (os.targetDistro && ['nixos'].includes(os.targetDistro)) {
-    console.error(`${yellow('Warning')} Precompiled engine files are not available for ${os.targetDistro}.`)
+  if (os.targetDistro && ['nixos'].includes(os.targetDistro) && !allEngineEnvVarsSet(Object.keys(options.binaries))) {
+    console.error(
+      `${yellow('Warning')} Precompiled engine files are not available for ${
+        os.targetDistro
+      }, please provide the paths via environment variables, see https://www.prisma.io/docs/concepts/components/prisma-engines#using-custom-engine-libraries-or-binaries.`,
+    )
   } else if (['freebsd11', 'freebsd12', 'freebsd13', 'openbsd', 'netbsd'].includes(platform)) {
     console.error(
       `${yellow(

packages/fetch-engine/src/env.ts

@@ -70,3 +70,13 @@ function getEnvVarToUse(binaryType: BinaryType): string {
 
   return envVar
 }
+
+export function allEngineEnvVarsSet(binaries: string[]): boolean {
+  for (const binaryType of binaries) {
+    if (!getBinaryEnvVarPath(binaryType as BinaryType)) {
+      return false
+    }
+  }
+
+  return true
+}