From e41794f885e380adea6c5ae4ea187a93e13835ff Mon Sep 17 00:00:00 2001
From: Bruno de Queiroz <bruno.queiroz@zalando.de>
Date: Thu, 19 Sep 2024 15:33:13 +0200
Subject: [PATCH] feat: exposing openApi 3 servers to allow multiple hosts

---
 packages/cli/src/swagger/specGenerator3.ts | 10 +++-------
 packages/runtime/src/config.ts             |  7 +++++++
 tests/unit/swagger/schemaDetails3.spec.ts  | 14 +++++++++++++-
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/packages/cli/src/swagger/specGenerator3.ts b/packages/cli/src/swagger/specGenerator3.ts
index cc17ee02d..f23c9bce7 100644
--- a/packages/cli/src/swagger/specGenerator3.ts
+++ b/packages/cli/src/swagger/specGenerator3.ts
@@ -67,7 +67,6 @@ export class SpecGenerator3 extends SpecGenerator {
     if (this.config.license) {
       info.license = { name: this.config.license };
     }
-
     if (this.config.contact) {
       info.contact = this.config.contact;
     }
@@ -144,12 +143,9 @@ export class SpecGenerator3 extends SpecGenerator {
   private buildServers() {
     const basePath = normalisePath(this.config.basePath as string, '/', undefined, false);
     const scheme = this.config.schemes ? this.config.schemes[0] : 'https';
-    const url = this.config.host ? `${scheme}://${this.config.host}${basePath}` : basePath;
-    return [
-      {
-        url,
-      } as Swagger.Server,
-    ];
+    const hosts = this.config.servers ? this.config.servers : this.config.host ? [this.config.host!] : undefined;
+    const convertHost = (host: string) => ({ url: `${scheme}://${host}${basePath}` });
+    return (hosts?.map(convertHost) || [{ url: basePath }]) as Swagger.Server[];
   }
 
   private buildSchema() {
diff --git a/packages/runtime/src/config.ts b/packages/runtime/src/config.ts
index eeac0f12c..9e908fea9 100644
--- a/packages/runtime/src/config.ts
+++ b/packages/runtime/src/config.ts
@@ -73,6 +73,13 @@ export interface SpecConfig {
    */
   host?: string;
 
+  /**
+   * API servers, expressTemplate.g. [production.api.com, staging.api.com]
+   *
+   * Only available with the specVersion 3
+   */
+  servers?: string[];
+
   /**
    * Base-name of swagger.json or swagger.yaml.
    *
diff --git a/tests/unit/swagger/schemaDetails3.spec.ts b/tests/unit/swagger/schemaDetails3.spec.ts
index f954e6187..21dc43f3b 100644
--- a/tests/unit/swagger/schemaDetails3.spec.ts
+++ b/tests/unit/swagger/schemaDetails3.spec.ts
@@ -14,6 +14,9 @@ describe('Definition generation for OpenAPI 3.0.0', () => {
   const metadataPost = new MetadataGenerator('./fixtures/controllers/postController.ts').Generate();
 
   const defaultOptions: ExtendedSpecConfig = getDefaultExtendedOptions();
+  const optionsWithServers = Object.assign<object, ExtendedSpecConfig, Partial<ExtendedSpecConfig>>({}, defaultOptions, {
+    servers: ['localhost:3000', 'staging.api.com'],
+  });
   const optionsWithNoAdditional = Object.assign<object, ExtendedSpecConfig, Partial<ExtendedSpecConfig>>({}, defaultOptions, {
     noImplicitAdditionalProperties: 'silently-remove-extras',
   });
@@ -29,13 +32,17 @@ describe('Definition generation for OpenAPI 3.0.0', () => {
     /**
      * If you want to add another spec here go for it. The reason why we use a string literal is so that tests below won't have "magic string" errors when expected test results differ based on the name of the spec you're testing.
      */
-    specName: 'specDefault' | 'specWithNoImplicitExtras' | 'specWithXEnumVarnames' | 'specWithOperationIdTemplate';
+    specName: 'specDefault' | 'specWithServers' | 'specWithNoImplicitExtras' | 'specWithXEnumVarnames' | 'specWithOperationIdTemplate';
   }
 
   const specDefault: SpecAndName = {
     spec: new SpecGenerator3(metadataGet, defaultOptions).GetSpec(),
     specName: 'specDefault',
   };
+  const specWithServers: SpecAndName = {
+    spec: new SpecGenerator3(metadataGet, optionsWithServers).GetSpec(),
+    specName: 'specWithServers',
+  };
   const specWithNoImplicitExtras: SpecAndName = {
     spec: new SpecGenerator3(metadataGet, optionsWithNoAdditional).GetSpec(),
     specName: 'specWithNoImplicitExtras',
@@ -85,6 +92,11 @@ describe('Definition generation for OpenAPI 3.0.0', () => {
       expect(specDefault.spec.servers[0].url).to.match(/localhost:3000/);
     });
 
+    it('should replace the parent hosts element', () => {
+      expect(specWithServers.spec.servers[0].url).to.match(/localhost:3000/);
+      expect(specWithServers.spec.servers[1].url).to.match(/staging\.api\.com/);
+    });
+
     it('should replace the parent basePath element', () => {
       expect(specDefault.spec).to.not.have.property('basePath');
       expect(specDefault.spec.servers[0].url).to.match(/\/v1/);