How to pass parameters in API request to back-end URL with Azure APIM? - azure

I'm trying to create a request with parameters in Azure API Management.
I have the following API(returns all invoices):
www.apibackend.com/invoice
This API can also handle parameters like this(returns invoice with ID 1):
www.apibackend.com/invoice/1
In my APIM service I've got the following code:
<policies>
<inbound>
<base />
<set-backend-service base-url="www.apibackend.com/" />
<rewrite-uri template="/invoice" />
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
With the APIM URL(for example: www.apim.com/test/GetInvoices) I can make the following request to my backend:
www.apibackend.com/invoice
This will return all the invoices, but how do I only retrieve the invoice with ID 1? If i make the request "www.apim.com/test/GetInvoices/1" I will get an error.
Hope someone can help!

In APIM change your Operation template to GetInvoices/{id} then in policies you'll be able to do:
<rewrite-uri template="/invoice/{id}" />

Related

URL Based routing on Azure

I am trying to do URL based routing for my APIs but I am not able to achieve as my API endpoints contain a wildcard in the middle of the URL, like:
/prodapi/v1.0/{appId}/level
/prodapi/v1.0/{appId}/products
appId is my customers white label ID, so it's unique for all our customers.
So far I have tried :
Azure application gateway [ But you can only handle at the end of your URL]
Azure Fron door [Have the same settings]
API management [ Not allowing me to do wildcard]
Can someone help me with any azure native or Out of the box solution.
If you want to route the traffic depending on a specific path parameter, you could use Api management service and write a inbound policy as such:
<policies>
<inbound>
<base />
<set-variable name="appId" value="#(context.Request.MatchedParameters["appId"])" />
<choose>
<when condition="#(int.Parse(context.Variables.GetValueOrDefault<string>("appId")) == 1)">
<set-backend-service base-url="https://google.com/" />
</when>
<when condition="#(int.Parse(context.Variables.GetValueOrDefault<string>("appId")) == 2)">
<set-backend-service base-url="https://twitter.com/" />
</when>
<otherwise>
<set-backend-service base-url="https://facebook.com/" />
</otherwise>
</choose>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
Replacing the backend-service with your prefer url ofc :)
API management is very powerful, so I'm sure that you'll find the solution there if this is not what you were looking for.

How do I specify a policy so that Azure API Management creates a different response cache for each combination of query parameters?

How do I specify a policy so that Azure API Management creates a different response cache for each combination of query parameters?
Suppose I have an endpoint /my-endpoint that takes 2 query parameters (item_id and language).
I want API Management to make a different cache for each combination of my query parameter values.
For example, I want the following requests to store different cache values for the responses:
/my-endpoint?item_id=4&language=en
/my-endpoint?item_id=4&language=nl
/my-endpoint?item_id=2&language=en
/my-endpoint?item_itd=2&language=nl
How do I do this?
In particular, do both of the following APIM policies (APIM Policy 1 and APIM Policy 2) work? Or is there a difference in how Azure API Management response caching works when I use a single tag with values separated by commas (see APIM Policy 1), or when I use multiple tags, each with a different value (see APIM Policy 2)?
APIM Policy 1
<policies>
<inbound>
<base />
<cache-lookup vary-by-developer="false" vary-by-developer-groups="false" allow-private-response-caching="false" must-revalidate="false" downstream-caching-type="none">
<vary-by-query-parameter>item_id;language</vary-by-query-parameter>
</cache-lookup>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
<cache-store duration="3600" />
</outbound>
<on-error>
<base />
</on-error>
</policies>
APIM Policy 2
<policies>
<inbound>
<base />
<cache-lookup vary-by-developer="false" vary-by-developer-groups="false" allow-private-response-caching="false" must-revalidate="false" downstream-caching-type="none">
<vary-by-query-parameter>item_id</vary-by-query-parameter>
<vary-by-query-parameter>language</vary-by-query-parameter>
</cache-lookup>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
<cache-store duration="3600" />
</outbound>
<on-error>
<base />
</on-error>
</policies>
If you don't get the "vary-by-query-parameter" to work, you could do something like this:
<cache-store-value key="#("my-variable-" + context.Request.MatchedParameters.GetValueOrDefault("item_id","")) + "-" + context.Request.MatchedParameters.GetValueOrDefault("language",""))" value="#(context.Response.Body.As<String>(true))" duration="3600" />
In this way you combine your parameters to get unique cache variabel names.
Given your case above you will have 4 different cache variables:
my-variable-4-en
my-variable-4-nl
my-variable-2-en
my-variable-2-nl
They will all contain different response bodies.

Azure API Management - named value at API scope

I am wondering whether it is possible to specify something like Named value but for each API separately?
So if I have, say foo-API and bar-API I can specify for each a named value-like variable, eg my-url. So now when I create a global policy
<policies>
<inbound>
<base />
<send-request mode="new">
<set-url>{{my-url}}</set-url>
<set-method>POST</set-method>
<set-body>something</set-body>
</send-request>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
but send-request will send request to the API specific URL (eg. different URL for DEV, TEST, PROD)
Not possible. Named values are a global collection, the only workaround is to name them to be descriptive enough, i.e. prefix with API id.

API Managment setting policy giving error Backend with id 'servicefabric' could not be found

I am trying to set the policy for service fabric but I get the following error
One or more fields contain incorrect values: Error in element
'set-backend-service' on line 16, column 10: Backend with id
'servicefabric' could not be found.
Where do i set the backend id
<policies>
<inbound>
<base />
<set-backend-service backend-id="servicefabric" sf-service-instance-name="fabric:/Medivet.MicroServices/Medivet.WebApi" />
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
There is still no UI to manage backends. Will have to use API: https://learn.microsoft.com/en-us/rest/api/apimanagement/2019-01-01/backend

Azure APIM as pure proxy

I am trying to deal with an Backend API(REST) with no swagger documents to be accessed through Azure APIM.
I want all the calls directed to the Backend API with me not manually creating GET/PUT/POST for all the resources. My inbound policies for all operations is below
'
<policies>
<inbound>
<set-variable name="requestPath" value="#(context.Request.Url.Path)" />
<base/>
<set-backend-service base-url="https://*****/****/" />
<rewrite-uri template="#(context.Request.Url.Path)" copy-unmatched-params="true" />
</inbound>
<backend>
<base/>
</backend>
<outbound>
<base/>
</outbound>
</policies>
`
However when hit the APIM i was given
{
"statusCode": 404,
"message": "Resource not found"
}
Any help is appreciated Thanks
The easy way to do this is to create one operation for each HTTP method you support and use /* for the template. This will match any inbound path/query and forward it to the backend.

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