APIM.md

Sharing Our APIs With Others

Return to Enriching the event's payload.

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In this section, we will create an API Management (APIM) layer that will help add extra security and auditing to our Functions. To keep it simple, we will rewrite our function URLs from something like

https://streamer-utils.azurewebsites.net/api/HttpTrigger1?timestamp=1552309994&code=vWfasFDFerSFDGC1UgbfA423rfYctKHVVgdMAF2FWr7D3rfsFSdgEt343=

to something like

https://streamer.azure-api.net/utils/ConvertTimestamp?timestamp=1552309994

Section Outline

1. Creating the API Management Service
2. Importing the Functions

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Creating the API Management Service

1. Click on Create a resource and find the APIM Management service.

2. Click Create.

3. Fill in the form, giving your service a globally unique name. Select the workshop resource group and a preferred location. Upon successful validation, click Create.

Note: If you were directed here an effort to preload the service, please return to the section you were working on; the remainder of this workshop will depend on services created in prior sections.

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Importing the Functions

1. Once the API Management service has been successfully deployed, head on over to the APIs section. We will now import our functions into APIM add some usage policies. Click on + Add API, followed by Function App.

2. Click on Browse.

3. Click on the Function App option; select the app and hit Select.

4. The functions in the Function App should be listed. Select the functions you want to make available via APIM, and hit Select.

5. Expand the metadata editor by clicking Full. Add some metadata to your collection of APIs; ensure that you have a product selected before hitting Create.

6. You should see your newly created set of APIs; select the collection and click on Test. You may want to keep an extra browser tab handy as you will do a lot of back-and-forth between Design and Test sections.

7. We will now do some debugging to see what's really happening under the covers. Click on the GET API and add the timestamp parameter. Notice how the request URL updates as you add query parameters. Click Send to make the HTTP request.

8. The output is printed in the Message log. You can also view more detailed info by switching to the Trace.

9. We will now make the necessary set of changes to transform our API's URL. In our APIM designer, click on the Edit icon under the Frontend section.

10. You will be presented by a JSON document. Find the paths key, and update its value to:

    {
        "/ConvertTimestamp": {
            "get": {
                "description": "A utility to help with the conversion of Unix timestamps into human readable DateTime objects.",
                "operationId": "get-httptrigger1",
                "summary": "ConvertTimestamp",
                "parameters": [
                    {
                        "name": "timestamp",
                        "in": "query",
                        "required": true,
                        "type": "string"
                    }
                ],
                "responses": {}
            },
            "post": {
                "description": "A utility to help with the conversion of Unix timestamps into human readable DateTime objects.",
                "operationId": "post-httptrigger1",
                "summary": "ConvertTimestamp",
                "parameters": [
                    {
                        "name": "",
                        "in": "body",
                        "schema": {
                            "example": "{ \"timestamp\" : 1552309994 }"
                        }
                    }
                ],
                "consumes": [ "application/json" ],
                "responses": {}
            }
        }
    }

    

11. What did we just do in the previous step? We updated the description of each operation and provided information on expected inputs (query parameters and body). We also changed the signature of the endpoints from /HttpTrigger1 to /ConvertTimestamp; these changes should now be visible in the endpoint listing. We need to make one more change before our revised endpoints are functional. Click on + Add policy in the Inbound processing section.

12. Add the following as an inbound policy and hit Save.

    <rewrite-uri template="/HttpTrigger1" />

    

13. Head back to our Test section to test out the changes we just made. You'll notice that some information is already preloaded; this is the result of the JSON update (for the API definition) we made earlier.

14. Again, can see the output of our request here. Tou can also step into the Trace to see where the URI is being rewritten.

15. To view a policy that has rate limiting enabled, head on over to the Products section of the service and select the Starter product. Would you like to add try adding rate limiting to your service? Give it a go...

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Move on to Review and next steps.