Azure API 管理速率限制(按 Json 请求正文)

Question

我想根据请求正文中的 mailTo 属性对 Lime 进行评级。

这是 APIM 政策

<rate-limit-by-key calls="5" 
    renewal-period="10" 
    counter-key="@(context.Request.Body.As<JObject>()["mailTo"].ToString())" />

这是请求正文

{
  "mailTo": "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="224f5b474f434b4e62454f434b4e0c414d4f" rel="noreferrer noopener nofollow">[email protected]</a>"
}

这对于直接调用后端来说工作正常，但在调用 APIM 时出现以下错误

{
    "errors": {
        "": [
            "A non-empty request body is required."
        ]
    },
    "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
    "title": "One or more validation errors occurred.",
    "status": 400,
    "traceId": "00-......-3be881755d918044-00"
}`

<rate-limit-by-key calls="5" 
    renewal-period="10" 
    counter-key="@(context.Request.Body.As<JObject>()["mailTo"].ToString())" />

Answer 1

我想该政策中有更多逻辑。

这个简单的策略不会产生上述错误:

<policies>
    <inbound>
        <base />
        <rate-limit-by-key calls="5" renewal-period="10" counter-key="@(context.Request.Body.As<JObject>()["mailTo"].ToString())" />
        <return-response>
            <set-status code="200" reason="Ok" />
            <set-body>{    
    "message": "It's fine!"           
}</set-body>
        </return-response>
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

但我猜想请求正文在策略中至少使用了两次。 因此您必须设置参数 preserveContent至true :

context.Request.Body.As<JObject>(true)["mailTo"].ToString()

https://learn.microsoft.com/en-us/azure/api-management/api-management-policy-expressions

To avoid that and have the method operate on a copy of the body stream, set the preserveContent parameter to true

两次使用请求的策略:

<policies>
    <inbound>
        <base />
        <rate-limit-by-key calls="5" renewal-period="10" counter-key="@(context.Request.Body.As<JObject>(true)["mailTo"].ToString())" />
        <set-variable name="email" value="@(context.Request.Body.As<JObject>(true)["mailTo"]?.ToString().ToLower())" />
        <return-response>
            <set-body template="none">@{
                var jsonResponse = new JObject(); 
                jsonResponse.Add(new JProperty("message", (string)context.Variables["email"])); 
                return jsonResponse.ToString(); 
            }</set-body>
        </return-response>
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>