OpenAI connector: send default model for "other" openAI provider (ela…

…stic#204934)

## Summary

Part of elastic#204116

When model is not present in the payload, use the default model as
specified in the connector configuration.

We were already doing that for OpenAI-OpenAI, but not for
"Other"-OpenAI.

### Some section because I downloaded ollama just for that issue

<img width="950" alt="Screenshot 2024-12-19 at 13 53 48"
src="https://github.com/user-attachments/assets/4a6e4b35-a0c5-46e5-9372-677e99d070f8"
/>

<img width="769" alt="Screenshot 2024-12-19 at 13 54 54"
src="https://github.com/user-attachments/assets/a0a5a12a-ea1e-42b7-8fa1-6531bef5ae6c"
/>

x-pack/plugins/stack_connectors/server/connector_types/openai/lib/other_openai_utils.test.ts

@@ -112,5 +112,42 @@ describe('Other (OpenAI Compatible Service) Utils', () => {
       const sanitizedBodyString = getRequestWithStreamOption(bodyString, false);
       expect(sanitizedBodyString).toEqual(bodyString);
     });
+
+    it('sets model parameter if specified and not present in the body', () => {
+      const body = {
+        messages: [
+          {
+            role: 'user',
+            content: 'This is a test',
+          },
+        ],
+      };
+
+      const sanitizedBodyString = getRequestWithStreamOption(JSON.stringify(body), true, 'llama-3');
+      expect(JSON.parse(sanitizedBodyString)).toEqual({
+        messages: [{ content: 'This is a test', role: 'user' }],
+        model: 'llama-3',
+        stream: true,
+      });
+    });
+
+    it('does not overrides model parameter if present in the body', () => {
+      const body = {
+        model: 'mistral',
+        messages: [
+          {
+            role: 'user',
+            content: 'This is a test',
+          },
+        ],
+      };
+
+      const sanitizedBodyString = getRequestWithStreamOption(JSON.stringify(body), true, 'llama-3');
+      expect(JSON.parse(sanitizedBodyString)).toEqual({
+        messages: [{ content: 'This is a test', role: 'user' }],
+        model: 'mistral',
+        stream: true,
+      });
+    });
   });
 });

x-pack/plugins/stack_connectors/server/connector_types/openai/lib/other_openai_utils.ts

@@ -23,13 +23,19 @@ export const sanitizeRequest = (body: string): string => {
  * The stream parameter is accepted in the ChatCompletion
  * API and the Completion API only
  */
-export const getRequestWithStreamOption = (body: string, stream: boolean): string => {
+export const getRequestWithStreamOption = (
+  body: string,
+  stream: boolean,
+  defaultModel?: string
+): string => {
   try {
     const jsonBody = JSON.parse(body);
     if (jsonBody) {
       jsonBody.stream = stream;
     }
-
+    if (defaultModel && !jsonBody.model) {
+      jsonBody.model = defaultModel;
+    }
     return JSON.stringify(jsonBody);
   } catch (err) {
     // swallow the error

x-pack/plugins/stack_connectors/server/connector_types/openai/lib/utils.test.ts

@@ -111,9 +111,19 @@ describe('Utils', () => {
     });
 
     it('calls other_openai_utils getRequestWithStreamOption when provider is Other OpenAi', () => {
-      getRequestWithStreamOption(OpenAiProviderType.Other, OPENAI_CHAT_URL, bodyString, true);
+      getRequestWithStreamOption(
+        OpenAiProviderType.Other,
+        OPENAI_CHAT_URL,
+        bodyString,
+        true,
+        'default-model'
+      );
 
-      expect(mockOtherOpenAiGetRequestWithStreamOption).toHaveBeenCalledWith(bodyString, true);
+      expect(mockOtherOpenAiGetRequestWithStreamOption).toHaveBeenCalledWith(
+        bodyString,
+        true,
+        'default-model'
+      );
       expect(mockOpenAiGetRequestWithStreamOption).not.toHaveBeenCalled();
       expect(mockAzureAiGetRequestWithStreamOption).not.toHaveBeenCalled();
     });

x-pack/plugins/stack_connectors/server/connector_types/openai/lib/utils.ts

@@ -75,7 +75,7 @@ export function getRequestWithStreamOption(
     case OpenAiProviderType.AzureAi:
       return azureAiGetRequestWithStreamOption(url, body, stream);
     case OpenAiProviderType.Other:
-      return otherOpenAiGetRequestWithStreamOption(body, stream);
+      return otherOpenAiGetRequestWithStreamOption(body, stream, defaultModel);
     default:
       return body;
   }