infra/modules/apim/policies/api_policy_openai.xml

<policies>
    <inbound>
        <base/>
        <set-backend-service backend-id="openai-backend" />
        <!-- Use Managed Identity to authenticate to the backend -->
        <authentication-managed-identity resource="https://cognitiveservices.azure.com" />
        <!-- Capture the value of the streaming property if it is included -->
        <choose>
            <when condition="@(context.Request.Body.As<JObject>(true)["stream"] != null && context.Request.Body.As<JObject>(true)["stream"].Type != JTokenType.Null)">
                <set-variable name="isStream" value="@{
                    var content = (context.Request.Body?.As<JObject>(true));
                    string streamValue = content["stream"].ToString();
                    return streamValue;
                }" />
            </when>
        </choose>
        <!-- Blocks streaming completions and returns 404 -->
        <choose>
            <when condition="@(context.Variables.GetValueOrDefault<string>("isStream","false").Equals("true", StringComparison.OrdinalIgnoreCase))">
                <return-response>
                    <set-status code="404" reason="BlockStreaming" />
                    <set-header name="Microsoft-Azure-Api-Management-Correlation-Id" exists-action="override">
                        <value>@{return Guid.NewGuid().ToString();}</value>
                    </set-header>
                    <set-body>Streaming chat completions are not allowed by this organization.</set-body>
                </return-response>
            </when>
        </choose>
    </inbound>
    <backend>
        <base/>
    </backend>
    <outbound>
        <base/>
        <choose>
            <when condition="@(context.Response.StatusCode == 200)">
                <log-to-eventhub logger-id="eventhub-logger">@{
                    var responseBody = context.Response.Body?.As<JObject>(true);
                    return new JObject(
                        new JProperty("timestamp", DateTime.UtcNow.ToString()),
                        new JProperty("appId", context.Request.Headers.GetValueOrDefault("Authorization",string.Empty).Split(' ').Last().AsJwt().Claims.GetValueOrDefault("appid", string.Empty)),
                        new JProperty("appSubscriptionKey", context.Request.Headers.GetValueOrDefault("Ocp-Apim-Subscription-Key",string.Empty)),
                        new JProperty("promptTokens", responseBody?["promptTokens"]?.ToString() ?? "null"),
                        new JProperty("responseTokens", responseBody?["responseTokens"]?.ToString() ?? "null"),
                        new JProperty("totalTokens", responseBody?["totalTokens"]?.ToString() ?? "null")                    
                    ).ToString();
                }
                </log-to-eventhub>
            </when>
        </choose>
    </outbound>
    <on-error>
        <base/>
    </on-error>
</policies>