[Apiman-user] API policy response data handler
Eric Wittmann
eric.wittmann at redhat.com
Fri Feb 3 16:31:56 EST 2017
So I think at least one aspect of this is solvable. You can modify the
request metric data directly in a custom policy. You can access and modify
the request metric like this:
{code}
protected void doApply(ApiResponse response, IPolicyContext context, C
config, IPolicyChain<ApiResponse> chain) {
RequestMetric metric = context.getAttribute("apiman.request-metric",
null);
metric.setFailure(true);
metric.setFailureCode(12345);
metric.setFailureReason("Backend API failed for a reason!"";
chain.doApply(response);
}
{code}
That will allow you to make sure the metrics information is correct for
your use-case. The policy context (and thus the request metric object) is
also available to data policies:
https://github.com/apiman/apiman/blob/master/gateway/engine/core/src/main/java/io/apiman/gateway/engine/policy/IDataPolicy.java#L53-L54
Does that make sense? Is there more to your use-case?
-Eric
On Fri, Feb 3, 2017 at 6:48 AM, Marc Savy <marc.savy at redhat.com> wrote:
> Aha, you're specifically talking about the apiman UI - I had thought from
> the context that you were using an external tool like Grafana.
>
> I'll let Eric respond as he implemented that code.
>
> On 3 February 2017 at 11:38, Balu S <sbalu27 at gmail.com> wrote:
>
>> sorry, I don't understand what you wrote.
>>
>> I would like Apiman metrics to consider the HTTP response (>=400) as
>> failure/error (whatever that is appropriate) and indicate in below charts.
>>
>>
>>
>> [image: Inline image 1]
>>
>> On Fri, Feb 3, 2017 at 12:21 PM, Marc Savy <marc.savy at redhat.com> wrote:
>>
>>> I think I understand what you're asking.
>>>
>>> IIRC:
>>>
>>> Error = an exception occurred within the gateway (e.g. could not connect
>>> to backend).
>>> Failure = a policy failure occurred.
>>>
>>>
>>> If you're wanting to look at http exception codes, just look at the
>>> 'responseCode' field in the ES Metrics.
>>>
>>> If you're wanting a "failed/not failed" determination then perhaps just
>>> execute `responseCode/100 == 2` in your analysis? Or is this not possible
>>> in your use-case?
>>>
>>> On 3 February 2017 at 10:45, Balu S <sbalu27 at gmail.com> wrote:
>>>
>>>> Its the default one ES.
>>>>
>>>> # ---------------------------------------------------------------------
>>>> # Elasticsearch Metrics Settings
>>>> # ---------------------------------------------------------------------
>>>>
>>>> apiman-gateway.metrics=io.apiman.gateway.engine.es.ESMetrics
>>>> apiman-gateway.metrics.client.type=jest
>>>> apiman-gateway.metrics.client.protocol=${apiman.es.protocol}
>>>> apiman-gateway.metrics.client.host=${apiman.es.host}
>>>> apiman-gateway.metrics.client.port=${apiman.es.port}
>>>> apiman-gateway.metrics.client.username=${apiman.es.username}
>>>> apiman-gateway.metrics.client.password=${apiman.es.password}
>>>> apiman-gateway.metrics.client.timeout=${apiman.es.timeout}
>>>> apiman-gateway.metrics.client.initialize=true
>>>>
>>>> On Fri, Feb 3, 2017 at 11:40 AM, Marc Savy <marc.savy at redhat.com>
>>>> wrote:
>>>>
>>>>> Which metrics implementation are you using? The data you're talking
>>>>> about should be in there; if it's not then there's a problem.
>>>>>
>>>>>
>>>>> On 3 February 2017 at 09:50, Balu S <sbalu27 at gmail.com> wrote:
>>>>>
>>>>>> Thanks for your inputs.
>>>>>>
>>>>>> Yes, I mean HTTP error codes (non-200) that are returned to client.
>>>>>> For example, when a request is missing query parameters and the API
>>>>>> responds with a "Bad request" (400) along with error XML. Here the error
>>>>>> code is set at HTTP level only and Apiman metrics should consider it as bad
>>>>>> response (in my opinion). Neither I do not see the Apiman source
>>>>>> (HttpApiConnection) interpreting the HTTP response using the HTTP code. But
>>>>>> with the custom policy, If I check for non-200 code and handle as failure,
>>>>>> then metrics shows them as error.
>>>>>>
>>>>>> To clarify on my implementation with custom policy, I'm not trying to
>>>>>> change the HTTP error code based on the response, rather we are unpacking
>>>>>> the error response body and packing in different XML format as done by
>>>>>> Apiman. Is this not a valid scenario ? I think there could other scenarios
>>>>>> where one want to alter the response body. I agree there will be additional
>>>>>> cost to performance and memory, but can it be not done one demand basis
>>>>>> like how one can implement IDataPolicy to parse the response only if he
>>>>>> needs to.
>>>>>>
>>>>>> Thanks
>>>>>> Balu
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Feb 2, 2017 at 10:31 PM, Eric Wittmann <
>>>>>> eric.wittmann at redhat.com> wrote:
>>>>>>
>>>>>>> The bottom line here is that you cannot return a Policy Failure (or
>>>>>>> customize it) based on information in the response body. The response is
>>>>>>> streamed from the back-end to the client, and at the time streaming begins,
>>>>>>> the response code and HTTP headers have already been sent.
>>>>>>>
>>>>>>> It sounds to me like you're asking for a feature where you can parse
>>>>>>> the response body *before* the policy's "apply" method is invoked. We have
>>>>>>> such a feature for requests, but not for responses. I suspect core changes
>>>>>>> to apiman would be required to enable that. It seems like a reasonable
>>>>>>> request to me, as long as users of the feature understand the performance
>>>>>>> and memory requirements of enabling it.
>>>>>>>
>>>>>>> -Eric
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Feb 2, 2017 at 1:03 PM, Marc Savy <marc.savy at redhat.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> NB: This is distinct from the body you're setting which contains a
>>>>>>>> JSON/XML payload containing the error code. It's in the HTTP protocol
>>>>>>>> itself.
>>>>>>>>
>>>>>>>> On 2 February 2017 at 18:02, Marc Savy <marc.savy at redhat.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> That sounds like metrics are going wrong, or perhaps you're
>>>>>>>>> misinterpreting it (adding Eric).
>>>>>>>>>
>>>>>>>>> When you say your API returns an error, does it still return an
>>>>>>>>> appropriate non-200 error code at the HTTP level? For instance, 500 or
>>>>>>>>> similar? That's very important.
>>>>>>>>>
>>>>>>>>> There's a difference between an error and a failure - have you
>>>>>>>>> checked both of those fields to see whether they contain the information
>>>>>>>>> you're expecting to see.
>>>>>>>>>
>>>>>>>>> Certainly in my experience we *do* collect the metrics you're
>>>>>>>>> talking about, unless I'm misunderstanding you.
>>>>>>>>>
>>>>>>>>> On 2 February 2017 at 17:40, Balu S <sbalu27 at gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Hi Marc,
>>>>>>>>>>
>>>>>>>>>> I shall explain my use case. From our API call, we return error
>>>>>>>>>> response (in XML or JSON) for 401, 500 and so on. However, Apiman metrics
>>>>>>>>>> seems to just consider them as good response (it is, as Apiman received the
>>>>>>>>>> response back) and show as successful response. So I have made custom
>>>>>>>>>> policy to intercept the response to know if it is failure and trigger the
>>>>>>>>>> Policy Failure. This is fairly simple and straight forward as the response
>>>>>>>>>> code will just do the purpose. But I want also to add some additional
>>>>>>>>>> information about the failure to Policy Failure. This additional
>>>>>>>>>> information is in the original error response which will be lost once
>>>>>>>>>> doFailure() happens. And no we don't want to those additional information
>>>>>>>>>> in some HTTP headers to pass around. Hence I implemented responseHandler()
>>>>>>>>>> to handle the response buffer and like you pointed out, it seems to be too
>>>>>>>>>> late to meddle the response.
>>>>>>>>>>
>>>>>>>>>> So ideally, there are possible 2 solution
>>>>>>>>>>
>>>>>>>>>> - Apiman metrics can interpret the response as unsuccessful
>>>>>>>>>> for such error response from API call.
>>>>>>>>>> - Handle the response buffer data before the write() call to
>>>>>>>>>> response outputstream.
>>>>>>>>>>
>>>>>>>>>> Do you see any alternative solution?
>>>>>>>>>>
>>>>>>>>>> Thanks
>>>>>>>>>> Balu
>>>>>>>>>>
>>>>>>>>>> On Thu, Feb 2, 2017 at 6:15 PM, Marc Savy <marc.savy at redhat.com>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> Perhaps URLRewritingPolicy https://github.com/apiman/apim
>>>>>>>>>>> an/blob/master/gateway/engine/policies/src/main/java/io/apim
>>>>>>>>>>> an/gateway/engine/policies/URLRewritingPolicy.java be an
>>>>>>>>>>> informative place to start?
>>>>>>>>>>>
>>>>>>>>>>> - Apiman streams data, so the client may be receiving data
>>>>>>>>>>> already by the time you've determined you want to cancel (the connection is
>>>>>>>>>>> already established; headers have been sent) - it's often too late to
>>>>>>>>>>> gracefully cancel. You could try throwing an exception and seeing what
>>>>>>>>>>> happens (not recommended practice!).
>>>>>>>>>>>
>>>>>>>>>>> If that doesn't work, perhaps you can explain your use-case more
>>>>>>>>>>> clearly and explicitly so we can see what the alternatives are?
>>>>>>>>>>>
>>>>>>>>>>> - Policies are *static* instances, if you are assigning that
>>>>>>>>>>> buffer to the object then it's as if you were writing "static Buffer
>>>>>>>>>>> buffer" and different requests will all share that variable (and thus swap
>>>>>>>>>>> it out repeatedly!).
>>>>>>>>>>>
>>>>>>>>>>> Regards,
>>>>>>>>>>> Marc
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 2 February 2017 at 16:56, Balu S <sbalu27 at gmail.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Hello,
>>>>>>>>>>>> I'm trying to parse the response using responseDataHandler() in
>>>>>>>>>>>> the custom policy. In cases, if the response from API is of certain
>>>>>>>>>>>> content, I would like the Apiman to consider as failure. But I don't find a
>>>>>>>>>>>> way to throw policy failure from responseDataHandler(). And I cannot
>>>>>>>>>>>> achieve this in doApply() as the ApiResponse object does not have "content"
>>>>>>>>>>>> to parse.
>>>>>>>>>>>>
>>>>>>>>>>>> Also, what I found is write(chunk) in the AbstractStream is
>>>>>>>>>>>> called after doApply, so I cannot set any attributes in it to fetch it in
>>>>>>>>>>>> doApply() and trigger doFailure().
>>>>>>>>>>>>
>>>>>>>>>>>> For example, in below call, how to throw as policy failure
>>>>>>>>>>>> after parsing the contents ? Or how can I access response content even
>>>>>>>>>>>> before write() method.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> *URLRewritingPolicy.java*
>>>>>>>>>>>>
>>>>>>>>>>>> @Override
>>>>>>>>>>>> protected IReadWriteStream<ApiResponse>
>>>>>>>>>>>> responseDataHandler(ApiResponse response,
>>>>>>>>>>>> IPolicyContext context, URLRewritingConfig
>>>>>>>>>>>> policyConfiguration) {
>>>>>>>>>>>> if (policyConfiguration.isProcessResponseBody()) {
>>>>>>>>>>>> return new URLRewritingStream(context.get
>>>>>>>>>>>> Component(IBufferFactoryComponent.class), response,
>>>>>>>>>>>> policyConfiguration.getFromRegex(),
>>>>>>>>>>>> policyConfiguration.getToReplacement());
>>>>>>>>>>>> } else {
>>>>>>>>>>>> return null;
>>>>>>>>>>>> }
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> *URLRewritingStream.java*
>>>>>>>>>>>>
>>>>>>>>>>>> /**
>>>>>>>>>>>> * @see io.apiman.gateway.engine.io.Ab
>>>>>>>>>>>> stractStream#write(io.apiman.gateway.engine.io.IApimanBuffer)
>>>>>>>>>>>> */
>>>>>>>>>>>> @Override
>>>>>>>>>>>> public void write(IApimanBuffer chunk) {
>>>>>>>>>>>> if (buffer == null) {
>>>>>>>>>>>> buffer = bufferFactory.cloneBuffer(chunk);
>>>>>>>>>>>> } else {
>>>>>>>>>>>> buffer.append(chunk);
>>>>>>>>>>>> }
>>>>>>>>>>>> atEnd = false;
>>>>>>>>>>>> processBuffer();
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Best regards
>>>>>>>>>>>> Balu
>>>>>>>>>>>>
>>>>>>>>>>>> _______________________________________________
>>>>>>>>>>>> Apiman-user mailing list
>>>>>>>>>>>> Apiman-user at lists.jboss.org
>>>>>>>>>>>> https://lists.jboss.org/mailman/listinfo/apiman-user
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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