DEV Community

realNameHidden
realNameHidden

Posted on

Environment vs. Proxy Variables in Apigee X

#api #beginners #google #tutorial

Introduction

Imagine you’re building a fleet of smart delivery vans. Each van needs a GPS destination (where it’s going right now) and access to a Company Fuel Card (which works across the whole fleet). If you hard-code the fuel card PIN into every single van's dashboard, you’ll have a nightmare on your hands the moment that PIN needs to change. You’d have to stop every van, open the dashboard, and manually update it.

This is exactly why we use variables in Apigee X.

In the world of API management, Apigee X acts as the brain of your API traffic. But as your system grows, you’ll find yourself needing to store data—like backend URLs, secret keys, or timeout settings. The big question for beginners is always: Should I store this at the Environment level or the Proxy level?

In this post, we’re going to break down these two types of variables so you can manage your API proxies like a pro, keeping your code clean and your security tight.

Core Concepts: Understanding the Scope

In Apigee X, "scope" is just a fancy word for "Who can see this variable?"

1. Proxy-Level Variables: The "Local" Knowledge

A proxy-level variable is like a sticky note inside a specific van. It only exists for that specific API Proxy.

  • Analogy: A variable called target.url inside a "Weather-API" proxy is only relevant to that weather service. The "Payments-API" doesn't need to know about it.
  • Why use them? They are perfect for logic that is unique to one specific API flow, such as temporary data processing or specific transformation logic.

2. Environment-Level Variables: The "Global" Settings

An environment-level variable (often managed via Key Value Maps or Target Servers) is like a broadcast message sent to the entire fleet.

  • Analogy: Your "Development" environment has a different backend URL than your "Production" environment. Instead of changing the code, you tell Apigee: "Whenever any proxy in 'Prod' asks for Base_URL, give them api.company.com."
  • Why use them? They are essential for API security and traffic management, allowing you to change configurations across hundreds of proxies instantly without redeploying code.

Step-by-Step Guide: Implementing Variables

Let’s look at a practical example. We want to store a Backend API Key. We shouldn't hard-code this in the proxy because if the key rotates, we’d have to redeploy the proxy.

Method A: Environment-Level (Using Key Value Maps - KVM)

This is the best practice for sensitive or shared data.

  1. In the Apigee UI, go to Admin > Environments > Key Value Maps.
  2. Create a KVM named SharedSettings.
  3. Add a Key: backend_auth_key | Value: your-secret-123.

To use it in your Proxy, add a KeyValueMapOperations policy:

<KeyValueMapOperations name="Get-Shared-Secret" mapIdentifier="SharedSettings">
    <Get assignTo="private.secret_key">
        <Key>
            <Parameter>backend_auth_key</Parameter>
        </Key>
    </Get>
    <Scope>environment</Scope>
</KeyValueMapOperations>
Enter fullscreen mode Exit fullscreen mode

Method B: Proxy-Level (Using AssignMessage)

Use this for data that only matters right now for this specific call.

To create a variable on the fly within your Proxy flow:

<AssignMessage name="Set-Local-Variable">
    <AssignVariable>
        <Name>proxy.local.request_id</Name>
        <Value>12345</Value> 
    </AssignVariable>
    <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
</AssignMessage>
Enter fullscreen mode Exit fullscreen mode

Best Practices for Apigee X Variables

  1. Never Hard-code sensitive data: Use Environment-level KVMs (encrypted) for API keys, passwords, and private tokens. This is a pillar of API security.
  2. Use Target Servers for Backend URLs: Instead of a proxy variable for your URL, use a Target Server at the Environment level. This allows for easier API traffic management and load balancing.
  3. Prefix Your Variables: To keep things organized, use prefixes like local.var_name for proxies and env.var_name for shared settings.
  4. Avoid "Variable Bloat": Don't create variables you don't need. Every variable consumes a tiny bit of memory during the API runtime.

Common Mistake: Beginners often hard-code the backend URL inside the Proxy's TargetEndpoint. When they move from "Test" to "Prod," the API breaks because it's still pointing to the test server! Always use Environment-level Target Servers.

Conclusion

Understanding the difference between environment-level and proxy-level variables is the "Aha!" moment for many API developers.

  • Proxy-level is for internal, specific logic.
  • Environment-level is for shared, configuration, and security-sensitive data.

By mastering this distinction, you make your APIs more modular, secure, and significantly easier to maintain.

Ready to try it out? Log into your Apigee X console today and try moving one hard-coded URL into a Target Server. You'll thank yourself the next time you have to update your backend!

Call to Action

Did this clear up the confusion, or do you have a specific use case that’s tripping you up? Drop a comment below! For more deep dives into Apigee X and modern API management strategies, be sure to subscribe to the newsletter or follow me for weekly updates.

Learn More:

Top comments (0)