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Azure OpenAI Semantic Search Input Binding for Azure Functions

Important

The Azure OpenAI extension for Azure Functions is currently in preview.

The Azure OpenAI semantic search input binding allows you to use semantic search on your embeddings.

For information on setup and configuration details of the Azure OpenAI extension, see Azure OpenAI extensions for Azure Functions. To learn more about semantic ranking in Azure AI Search, see Semantic ranking in Azure AI Search.

Note

References and examples are only provided for the Node.js v4 model.

Note

References and examples are only provided for the Python v2 model.

Note

While both C# process models are supported, only isolated worker model examples are provided.

Example

Go support isn't currently available for this binding.

This example shows how to perform a semantic search on a file.


[Function("PromptFile")]
public static IActionResult PromptFile(
    [HttpTrigger(AuthorizationLevel.Function, "post")] SemanticSearchRequest unused,
    [SemanticSearchInput("AISearchEndpoint", "openai-index", Query = "{prompt}", ChatModel = "%CHAT_MODEL_DEPLOYMENT_NAME%", EmbeddingsModel = "%EMBEDDING_MODEL_DEPLOYMENT_NAME%")] SemanticSearchContext result)
{
    return new ContentResult { Content = result.Response, ContentType = "text/plain" };

This example shows how to perform a semantic search on a file.

@FunctionName("PromptFile")
public HttpResponseMessage promptFile(
    @HttpTrigger(
        name = "req", 
        methods = {HttpMethod.POST},
        authLevel = AuthorizationLevel.FUNCTION)
        HttpRequestMessage<SemanticSearchRequest> request,
    @SemanticSearch(name = "search", searchConnectionName = "AISearchEndpoint", collection = "openai-index", query = "{prompt}", chatModel = "%CHAT_MODEL_DEPLOYMENT_NAME%", embeddingsModel = "%EMBEDDING_MODEL_DEPLOYMENT_NAME%", isReasoningModel = false ) String semanticSearchContext,
    final ExecutionContext context) {
        String response = new JSONObject(semanticSearchContext).getString("Response");
        return request.createResponseBuilder(HttpStatus.OK)
        .header("Content-Type", "application/json")
        .body(response)
        .build();        
}
public class SemanticSearchRequest {
    public String prompt;
    public String getPrompt() {
        return prompt;
    }
    public void setPrompt(String prompt) {
        this.prompt = prompt;
    }        
}

This example shows how to perform a semantic search on a file.

const semanticSearchInput = input.generic({
    type: "semanticSearch",
    searchConnectionName: "AISearchEndpoint",
    collection: "openai-index",
    query: "{prompt}",
    chatModel: "%CHAT_MODEL_DEPLOYMENT_NAME%",
    embeddingsModel: "%EMBEDDING_MODEL_DEPLOYMENT_NAME%"
});

app.http('PromptFile', {
    methods: ['POST'],
    authLevel: 'function',
    extraInputs: [semanticSearchInput],
    handler: async (_request, context) => {
        var responseBody = context.extraInputs.get(semanticSearchInput)

        return { status: 200, body: responseBody.Response.trim() }
    }
});

const semanticSearchInput = input.generic({
    type: "semanticSearch",
    searchConnectionName: "AISearchEndpoint",
    collection: "openai-index",
    query: "{prompt}",
    chatModel: "%CHAT_MODEL_DEPLOYMENT_NAME%",
    embeddingsModel: "%EMBEDDING_MODEL_DEPLOYMENT_NAME%"
});

app.http('PromptFile', {
    methods: ['POST'],
    authLevel: 'function',
    extraInputs: [semanticSearchInput],
    handler: async (_request, context) => {
        var responseBody: any = context.extraInputs.get(semanticSearchInput)

        return { status: 200, body: responseBody.Response.trim() }
    }
});

This example shows how to perform a semantic search on a file.

Here's the function.json file for prompting a file:

{
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "Request",
      "methods": [
        "post"
      ]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "Response"
    },
    {
      "name": "SemanticSearchInput",
      "type": "semanticSearch",
      "direction": "in",
      "searchConnectionName": "AISearchEndpoint",
      "collection": "openai-index",
      "query": "{prompt}",
      "chatModel": "%CHAT_MODEL_DEPLOYMENT_NAME%",
      "embeddingsModel": "%EMBEDDING_MODEL_DEPLOYMENT_NAME%"
    }
  ]
}

For more information about function.json file properties, see the Configuration section.

using namespace System.Net

param($Request, $TriggerMetadata, $SemanticSearchInput)

Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
        StatusCode = [HttpStatusCode]::OK
        Body       = $SemanticSearchInput.Response
    })

This example shows how to perform a semantic search on a file.

@app.function_name("PromptFile")
@app.route(methods=["POST"])
@app.semantic_search_input(
    arg_name="result",
    search_connection_name="AISearchEndpoint",
    collection="openai-index",
    query="{prompt}",
    embeddings_model="%EMBEDDING_MODEL_DEPLOYMENT_NAME%",
    chat_model="%CHAT_MODEL_DEPLOYMENT_NAME%",
)
def prompt_file(req: func.HttpRequest, result: str) -> func.HttpResponse:
    result_json = json.loads(result)
    response_json = {
        "content": result_json.get("Response"),
        "content_type": "text/plain",
    }
    return func.HttpResponse(
        json.dumps(response_json), status_code=200, mimetype="application/json"
    )

Attributes

Apply the SemanticSearchInput attribute to define a semantic search input binding, which supports these parameters:

Parameter Description
SearchConnectionName The name of an app setting or environment variable that contains the connection string value. This property supports binding expressions.
Collection The name of the collection or table or index to search. This property supports binding expressions.
Query The semantic query text to use for searching. This property supports binding expressions.
EmbeddingsModel Optional. The ID of the model to use for embeddings. The default value is text-embedding-3-small. This property supports binding expressions.
ChatModel Optional. Gets or sets the name of the Large Language Model to invoke for chat responses. The default value is gpt-3.5-turbo. This property supports binding expressions.
AIConnectionName Optional. Gets or sets the name of the configuration section for AI service connectivity settings. For Azure OpenAI: If specified, looks for "Endpoint" and "Key" values in this configuration section. If not specified or the section doesn't exist, falls back to environment variables: AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY. For user-assigned managed identity authentication, this property is required. For OpenAI service (non-Azure), set the OPENAI_API_KEY environment variable.
SystemPrompt Optional. Gets or sets the system prompt to use for prompting the large language model. The system prompt is appended with knowledge that is fetched as a result of the Query. The combined prompt is sent to the OpenAI Chat API. This property supports binding expressions.
MaxKnowledgeCount Optional. Gets or sets the number of knowledge items to inject into the SystemPrompt.
IsReasoningModel Optional. Gets or sets a value indicating whether the chat completion model is a reasoning model. This option is experimental and associated with the reasoning model until all models have parity in the expected properties, with a default value of false.

Annotations

The SemanticSearchInput annotation enables you to define a semantic search input binding, which supports these parameters:

Element Description
name Gets or sets the name of the input binding.
searchConnectionName The name of an app setting or environment variable that contains the connection string value. This property supports binding expressions.
collection The name of the collection or table or index to search. This property supports binding expressions.
query The semantic query text to use for searching. This property supports binding expressions.
embeddingsModel Optional. The ID of the model to use for embeddings. The default value is text-embedding-3-small. This property supports binding expressions.
chatModel Optional. Gets or sets the name of the Large Language Model to invoke for chat responses. The default value is gpt-3.5-turbo. This property supports binding expressions.
aiConnectionName Optional. Gets or sets the name of the configuration section for AI service connectivity settings. For Azure OpenAI: If specified, looks for "Endpoint" and "Key" values in this configuration section. If not specified or the section doesn't exist, falls back to environment variables: AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY. For user-assigned managed identity authentication, this property is required. For OpenAI service (non-Azure), set the OPENAI_API_KEY environment variable.
systemPrompt Optional. Gets or sets the system prompt to use for prompting the large language model. The system prompt is appended with knowledge that is fetched as a result of the Query. The combined prompt is sent to the OpenAI Chat API. This property supports binding expressions.
maxKnowledgeCount Optional. Gets or sets the number of knowledge items to inject into the SystemPrompt.
isReasoningModel Optional. Gets or sets a value indicating whether the chat completion model is a reasoning model. This option is experimental and associated with the reasoning model until all models have parity in the expected properties, with a default value of false.

Decorators

During the preview, define the input binding as a generic_input_binding binding of type semanticSearch, which supports these parameters:

Parameter Description
arg_name The name of the variable that represents the binding parameter.
search_connection_name The name of an app setting or environment variable that contains the connection string value. This property supports binding expressions.
collection The name of the collection or table or index to search. This property supports binding expressions.
query The semantic query text to use for searching. This property supports binding expressions.
embeddings_model Optional. The ID of the model to use for embeddings. The default value is text-embedding-3-small. This property supports binding expressions.
chat_model Optional. Gets or sets the name of the Large Language Model to invoke for chat responses. The default value is gpt-3.5-turbo. This property supports binding expressions.
ai_connection_name Optional. Gets or sets the name of the configuration section for AI service connectivity settings. For Azure OpenAI: If specified, looks for "Endpoint" and "Key" values in this configuration section. If not specified or the section doesn't exist, falls back to environment variables: AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY. For user-assigned managed identity authentication, this property is required. For OpenAI service (non-Azure), set the OPENAI_API_KEY environment variable.
system_prompt Optional. Gets or sets the system prompt to use for prompting the large language model. The system prompt is appended with knowledge that is fetched as a result of the Query. The combined prompt is sent to the OpenAI Chat API. This property supports binding expressions.
max_knowledge_count Optional. Gets or sets the number of knowledge items to inject into the SystemPrompt.
is_reasoning _model Optional. Gets or sets a value indicating whether the chat completion model is a reasoning model. This option is experimental and associated with the reasoning model until all models have parity in the expected properties, with a default value of false.

Configuration

The binding supports these configuration properties that you set in the function.json file.

Property Description
type Must be semanticSearch.
direction Must be in.
name The name of the input binding.
searchConnectionName Gets or sets the name of an app setting or environment variable that contains a connection string value. This property supports binding expressions.
collection The name of the collection or table or index to search. This property supports binding expressions.
query The semantic query text to use for searching. This property supports binding expressions.
embeddingsModel Optional. The ID of the model to use for embeddings. The default value is text-embedding-3-small. This property supports binding expressions.
chatModel Optional. Gets or sets the name of the Large Language Model to invoke for chat responses. The default value is gpt-3.5-turbo. This property supports binding expressions.
aiConnectionName Optional. Gets or sets the name of the configuration section for AI service connectivity settings. For Azure OpenAI: If specified, looks for "Endpoint" and "Key" values in this configuration section. If not specified or the section doesn't exist, falls back to environment variables: AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY. For user-assigned managed identity authentication, this property is required. For OpenAI service (non-Azure), set the OPENAI_API_KEY environment variable.
systemPrompt Optional. Gets or sets the system prompt to use for prompting the large language model. The system prompt is appended with knowledge that is fetched as a result of the Query. The combined prompt is sent to the OpenAI Chat API. This property supports binding expressions.
maxKnowledgeCount Optional. Gets or sets the number of knowledge items to inject into the SystemPrompt.
isReasoningModel Optional. Gets or sets a value indicating whether the chat completion model is a reasoning model. This option is experimental and associated with the reasoning model until all models have parity in the expected properties, with a default value of false.

Configuration

The binding supports these properties, which are defined in your code:

Property Description
searchConnectionName The name of an app setting or environment variable that contains the connection string value. This property supports binding expressions.
collection The name of the collection or table or index to search. This property supports binding expressions.
query The semantic query text to use for searching. This property supports binding expressions.
embeddingsModel Optional. The ID of the model to use for embeddings. The default value is text-embedding-3-small. This property supports binding expressions.
chatModel Optional. Gets or sets the name of the Large Language Model to invoke for chat responses. The default value is gpt-3.5-turbo. This property supports binding expressions.
aiConnectionName Optional. Gets or sets the name of the configuration section for AI service connectivity settings. For Azure OpenAI: If specified, looks for "Endpoint" and "Key" values in this configuration section. If not specified or the section doesn't exist, falls back to environment variables: AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY. For user-assigned managed identity authentication, this property is required. For OpenAI service (non-Azure), set the OPENAI_API_KEY environment variable.
systemPrompt Optional. Gets or sets the system prompt to use for prompting the large language model. The system prompt is appended with knowledge that is fetched as a result of the Query. The combined prompt is sent to the OpenAI Chat API. This property supports binding expressions.
maxKnowledgeCount Optional. Gets or sets the number of knowledge items to inject into the SystemPrompt.
isReasoningModel Optional. Gets or sets a value indicating whether the chat completion model is a reasoning model. This option is experimental and associated with the reasoning model until all models have parity in the expected properties, with a default value of false.

Usage

See the Example section for complete examples.

Connections

To use the Azure OpenAI binding extension, you need to specify a connection to an OpenAI model definition. Set the OpenAI model connection in your bindings by using one of these approaches:

  • Use the AIConnectionName binding property (preferred for Azure OpenAI).
  • Set AZURE_OPENAI_ENDPOINT and AZURE_OPENAI_KEY in app settings (for Azure OpenAI).
  • Set only Open_API_Key in app settings (for https://api.openai.com).

The way you set the connection depends on both the model API and the authentication method, as indicated by the following table:

Authentication/Model API Azure OpenAI OpenAI (https://api.openai.com)
Managed identity connection AIConnectionName Not supported
Key Vault reference AZURE_OPENAI_ENDPOINT
AZURE_OPENAI_KEY		 Open_API_Key
App Configuration reference AZURE_OPENAI_ENDPOINT
AZURE_OPENAI_KEY		 Open_API_Key
Shared secret AZURE_OPENAI_ENDPOINT
AZURE_OPENAI_KEY		 Open_API_Key

Use managed identity-based connections and the AIConnectionName property.

When you use AIConnectionName, the value of this property setting depends on the type of connection:

  • Managed identity connection: The AIConnectionName property is a <CONNECTION_NAME_PREFIX> shared by a group of settings that together define an identity-based connection to Azure OpenAI. For more information, see Define identity connections.
  • Key Vault reference: The AIConnectionName property setting returns an Azure Key Vault reference to the location where the API key is centrally maintained. For more information, see Define Key Vault connections.
  • App Configuration reference: The AIConnectionName property setting returns an Azure App Configuration reference that returns an API key or a Key Vault reference. For more information, see Azure App Configuration in the connections article.
  • API key: The AIConnectionName property setting resolves to app settings containing the endpoint and key directly. Because shared keys can be compromised, use managed identity connections when possible. For more information, see Define connections.

To learn more about bindings connections, see Manage connections in Azure Functions.

The OpenAI bindings include an AIConnectionName property that you can use to specify the <ConnectionNamePrefix> for the group of app settings that define the connection to Azure OpenAI:

Setting name Description
<CONNECTION_NAME_PREFIX>__endpoint Sets the URI endpoint of the Azure OpenAI service. This setting is always required.
<CONNECTION_NAME_PREFIX>__clientId Sets the specific user-assigned identity to use when obtaining an access token. Requires that <CONNECTION_NAME_PREFIX>__credential is set to managedidentity. The property accepts a client ID corresponding to a user-assigned identity assigned to the application. It's invalid to specify both a Resource ID and a client ID. If you don't specify this property, the system-assigned identity is used. This property is used differently in local development scenarios, when credential shouldn't be set.
<CONNECTION_NAME_PREFIX>__credential Defines how an access token is obtained for the connection. Use managedidentity for managed identity authentication. This value is only valid when a managed identity is available in the hosting environment.
<CONNECTION_NAME_PREFIX>__managedIdentityResourceId When credential is set to managedidentity, set this property to specify the resource Identifier to use when obtaining a token. The property accepts a resource identifier corresponding to the resource ID of the user-defined managed identity. It's invalid to specify both a resource ID and a client ID. If you don't specify either, the system-assigned identity is used. This property is used differently in local development scenarios, when credential shouldn't be set.
<CONNECTION_NAME_PREFIX>__key Sets the shared secret key required to access the endpoint of the Azure OpenAI service by using key-based authentication. As a security best practice, always use Microsoft Entra ID with managed identities for authentication.

Consider these managed identity connection settings when you set the AIConnectionName property to myAzureOpenAI:

  • myAzureOpenAI__endpoint=https://contoso.openai.azure.com/
  • myAzureOpenAI__credential=managedidentity
  • myAzureOpenAI__clientId=aaaaaaaa-bbbb-cccc-1111-222222222222

At runtime, the host interprets these settings as a single myAzureOpenAI setting:

"myAzureOpenAI":
{
    "endpoint": "https://contoso.openai.azure.com/",
    "credential": "managedidentity",
    "clientId": "aaaaaaaa-bbbb-cccc-1111-222222222222"
}

When you use managed identities, make sure to add your identity to the Cognitive Services OpenAI User role.

When running locally, add these settings to the local.settings.json project file. For more information, see Local development with identity-based connections.

For more information, see Work with application settings.

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