Maximizing Your API Management with Azure: A Comprehensive Guide on Exposing, Securing, and Managing APIs using Azure API Management and Policies

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Azure API Management is a cloud-based service that enables developers to publish, secure, and manage APIs. With Azure API Management, you can create APIs that can be used by internal or external consumers, whether they are employees, partners, or customers. This article will explore how to use Azure API Management to expose and manage APIs, as well as how to use policies to add security, monitor, manage API traffic and other features to your APIs.

Exposing APIs with Azure API Management

Exposing APIs with Azure API Management is a straightforward process that can be accomplished in a few steps. Let’s walk through an example of how to expose an API using Azure API Management.

Suppose you have a backend service that retrieves data about movies, and you want to create an API that exposes this data to your users. Here’s how you can do it with Azure API Management:

1. Create a new API in Azure API Management: From the Azure portal’s dashboard, select “API Management Services” and create a new API management service. Once you have created the service, select “APIs” from the navigation menu and click “Add API.”
2. Define the backend service: In the API creation screen, you need to specify the backend service that the API will connect to. In our example, the backend service is a REST API that retrieves data about movies. You need to provide the URL of the backend service, along with any necessary headers, parameters, and authentication details.
3. Define the operations: Next, you need to define the operations that the API will expose. For example, you might create an operation that retrieves a list of movies, another operation that retrieves a specific movie by ID, and so on. For each operation, you need to specify the HTTP verb (GET, POST, PUT, DELETE, etc.), the URL path, and any necessary request and response parameters.
4. Add security policies: Once you have defined the operations, you can add security policies to protect your API from unauthorized access. For example, you might add a policy that requires API keys or OAuth2 authentication for each request.
5. Publish the API: Finally, you need to publish the API so that it can be consumed by your users. Azure API Management provides several options for publishing APIs, including a developer portal, a self-hosted gateway, and a cloud-hosted gateway.

With your API published, your users can now consume it using the API’s URL and any necessary authentication details. Azure API Management provides several tools for monitoring and managing the API traffic, including analytics dashboards, alerts, and a REST API for programmatic access.

Adding Security with Azure API Management Policies

Adding security to APIs is a critical aspect of API management, and Azure API Management provides various policies that can be used to add security to your APIs. Policies are a set of rules that define how API Management should behave with incoming requests and outgoing responses. Let’s walk through an example of how to add security with Azure API Management policies.

Suppose you have an API that retrieves data about customers, and you want to add security to protect this data from unauthorized access. Here’s how you can do it with Azure API Management policies:

I. Add a policy to require API key: In the Azure API Management portal, select the API you want to add security to and click “API policies.” Under “Inbound processing,” click “Add policy.” You can add a policy to require an API key to access the API.

<policies>
    <inbound>
        <base />
        <validate-jwt header-name="Authorization" failed-validation-httpcode="401" require-expiration-time="false" require-signed-tokens="false">
            <issuer-signing-keys>
                <key>YOUR-SIGNING-KEY</key>
            </issuer-signing-keys>
            <audiences>
                <audience>YOUR-API-ID-URI</audience>
            </audiences>
            <issuers>
                <issuer>YOUR-ISSUER-URI</issuer>
            </issuers>
            <required-claims>
                <claim name="aud" match="all">
                    <value>YOUR-API-ID-URI</value>
                </claim>
            </required-claims>
        </validate-jwt>
        <set-header name="Ocp-Apim-Subscription-Key" exists-action="delete" />
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

This policy requires that the incoming request includes a valid API key in the header named “Ocp-Apim-Subscription-Key.”

II. Add a policy to restrict access by IP address: You can also add a policy to restrict access to your API by IP address. This policy allows access to the API only from specific IP addresses.

<policies>
    <inbound>
        <base />
        <check-header name="X-Forwarded-For" failed-check-httpcode="401" ignore-case="true">
            <match regex="192\.168\.1\.[0-9]+" negate="true" />
        </check-header>
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

This policy checks the incoming request’s “X-Forwarded-For” header and only allows requests from IP addresses that match the regular expression “192.168.1.[0–9]+.”

III. Add a policy to encrypt data in transit: You can also add a policy to encrypt data in transit. This policy ensures that the communication between the client and the API is encrypted.

<policies>
    <inbound>
        <base />
        <set-header name="Strict-Transport-Security" exists-action="override">
            <value>max-age=86400; includeSubDomains</value>
        </set-header>
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
        <set-header name="Strict-Transport-Security" exists-action="override">
            <value>max-age =86400; includeSubDomains</value> 
        </set-header> 
    </outbound> 
    <on-error> 
        <base /> 
    </on-error> 
</policies>

This policy adds the “Strict-Transport-Security” header to the incoming and outgoing requests. This header instructs the client to use HTTPS to communicate with the API.

IV. Add a policy to limit the number of requests: You can also add a policy to limit the number of requests made to your API. This policy helps prevent abuse and limits the potential impact of attacks.

<policies>
    <inbound>
        <base />
        <quota calls="5" renewal-period="60" />
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

This policy limits the number of requests made to the API to 5 requests per minute. If a client makes more than 5 requests within a minute, the API Management returns an error response.

Monitoring and Managing API Traffic with Azure API Management

Monitoring and managing API traffic is an essential task for ensuring the performance and availability of your API. Azure API Management provides several tools and features to help you monitor and manage API traffic.

1. Analytics Dashboard: The Analytics Dashboard in Azure API Management provides real-time insights into API traffic, usage, and performance. It enables you to monitor the API traffic in real-time and troubleshoot any issues quickly. The Analytics Dashboard provides several charts and graphs that show the usage of APIs, response times, and error rates.
   For example, you can use the Analytics Dashboard to monitor the number of requests, the response time, and the error rate for your API. You can also filter the data by time range, API, or operation.
2. Health Check: Azure API Management provides a health check feature that monitors the availability and performance of your API. You can configure the health check feature to check the availability of the API endpoint and the response time. If the health check fails, API Management can automatically disable the API or notify you via email.
   For example, you can configure the health check feature to check the availability of your API endpoint every 5 minutes. If the API endpoint is not available or the response time is higher than a specific threshold, API Management can automatically disable the API or notify you via email.
3. Auto-scaling: Azure API Management provides an auto-scaling feature that automatically scales the API Management service based on the traffic and usage of the API. You can configure the auto-scaling feature to scale up or down the API Management service based on CPU usage, memory usage, or request rate.
   For example, you can configure the auto-scaling feature to scale up the API Management service when the request rate exceeds a specific threshold. You can also configure the auto-scaling feature to scale down the API Management service during periods of low traffic.
4. Custom Reports: Azure API Management provides a custom reports feature that enables you to create and share custom reports based on API traffic data. You can use the custom reports feature to create reports that show the usage of APIs, the response time, and the error rate.
   For example, you can use the custom reports feature to create a report that shows the usage of your API by a specific customer or a specific API operation. You can also share the report with other stakeholders or export the report to Excel or CSV format.

Conclusion

Azure API Management is a powerful service that allows you to publish, secure, and manage APIs. With Azure API Management, you can expose APIs to internal or external consumers and add security, traffic management, and other features using policies. You can also monitor and manage the API traffic using the tools provided by Azure API Management. By using Azure API Management, you can simplify the process of building and managing APIs, and focus on delivering value to your users.