---
title: Integrating a Feature Flag Server-Side using an Origin Experiment
description: In this article, we'll guide you through integrating a server-side feature flag using a cookie to control the flag state. This setup is particularly useful for testing new features in a production environment with minimal risk.
---
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# Integrating a Feature Flag Server-Side using an Origin Experiment
## In this article, we'll guide you through integrating a server-side feature flag using a cookie to control the flag state. This setup is particularly useful for testing new features in a production environment with minimal risk.
### Step 1: Creating the Origin Experiment in SiteSpect
Origin Experiments allow you to test variations directly from your server-side code by leveraging cookies, headers, or URL parameters. Here's how to set up an experiment using a cookie as the flag:
1. **Create a New Campaign**:
- Go to the **Campaigns** menu and select **New Campaign**.
- Choose **A/B Campaign** since we're working with a binary feature flag (enabled/disabled).
2. **Define the Campaign**:
- Enter a descriptive name for your campaign that indicates it's using a feature flag.
- In the **General** section, define the percentage of users that should be exposed to this campaign, and select a [campaign set](https://doc.sitespect.com/knowledge/campaign-sets-vizualisation?hsLang=en).
- Write a [hypothesis](https://doc.sitespect.com/knowledge/hypothesis?hsLang=en) that describes what you believe your Campaign accomplishes.
3. **Set up the Origin Variation**:
- Go to the **Variations** tab, click **New**, and select **Origin Factor**.
- Configure the variation to modify a request header or cookie. For a cookie-based feature flag, set the cookie name and values corresponding to your variations (e.g., "feature\_enabled" with values "true" and "false").
4. **Create Variations**:
- In the **Variations** section, under Variation Group 1 \> Variation 1, select **Type \> [Origin](https://doc.sitespect.com/knowledge/origin-experiments?hsLang=en).**
- Configure the variation to modify a request header or cookie. For a cookie-based feature flag, set the cookie name and values corresponding to your variations (e.g., "feature\_enabled" with values "true" and "false").
- The Original variation group represents the default or off-state.
- The Variation Group represents the enabled state.
- For the enabled state, set the cookie value to "true", and for the disabled state, set it to "false".
- Rename the variation groups for easy-to-understand feature names and states.
- Define [**Triggers**](https://doc.sitespect.com/knowledge/defining-triggers?hsLang=en) as needed, to set specific rules for when the flag should be set.
5. **Select Metrics**:
- Go to the **Metrics** section to what actions or behaviors you will measure to evaluate the impact of the feature flag.
6. **Define Audiences** (if applicable):
- If the feature should only be tested on a specific subset of users, configure your audiences under the **Audiences** tab.
7. **Save the Campaign**:
- Once all settings are configured, save the campaign.
For more details on creating and managing origin experiments in SiteSpect, you can visit the documentation [here](https://doc.sitespect.com/knowledge/creating-an-origin-experiment?hsLang=en).
### Step 2: Integrating Feature Flag Logic in Your Code Base
To utilize the feature flag within your server-side application, you need to check the value of the cookie.
Here are basic code snippet examples to demonstrate this.
#### Python
Using Flask, a popular web framework in Python, here's how you might check the cookie value:
```
from flask import request, Flask
app = Flask(__name__)
@app.route('/')
def home():
feature_flag = request.cookies.get('feature_enabled', 'false')
if feature_flag.lower() == 'true':
return "Feature is enabled."
else:
return "Feature is disabled."
if __name__ == '__main__':
app.run(debug=True)
```
#### Node.js
In Node.js, using the Express framework and the `cookie-parser` middleware to handle cookies:
```
const express = require('express');
const cookieParser = require('cookie-parser');
const app = express();
app.use(cookieParser());
app.get('/', (req, res) => {
const featureEnabled = req.cookies.feature_enabled === 'true';
if (featureEnabled) {
res.send('Feature is enabled.');
} else {
res.send('Feature is disabled.');
}
});
app.listen(3000, () => console.log('Server running on port 3000'));
```
#### PHP
In PHP, you can access cookies directly through the `$_COOKIE` superglobal array:
```
function isFeatureEnabled() {
return isset($_COOKIE['feature_enabled']) && $_COOKIE['feature_enabled'] === 'true';
}
// Example usage
if (isFeatureEnabled()) {
echo "Feature is enabled.";
} else {
echo "Feature is disabled.";
}
```
#### Java
In Java, particularly within a servlet, you would check the cookie value like this:
```
import javax.servlet.ServletException;
import javax.servlet.http.*;
public class FeatureFlagServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Cookie[] cookies = request.getCookies();
boolean featureEnabled = false;
if (cookies != null) {
for (Cookie cookie : cookies) {
if ("feature_enabled".equals(cookie.getName()) && "true".equals(cookie.getValue())) {
featureEnabled = true;
break;
}
}
}
response.setContentType("text/html");
response.getWriter().print(featureEnabled ? "Feature is enabled." : "Feature is disabled.");
}
}
```
These snippets provide the basic functionality required to integrate a feature flag based on a cookie in various programming environments. Adjust the code as necessary to fit into your specific application structure and coding standards.
### Step 3: Activate the Campaign and Start Serving Your Feature
When ready, set the campaign status to **Active - Running** or [schedule a start and end time](https://doc.sitespect.com/knowledge/specifying-a-date-range?hsLang=en).
The campaign will start setting the feature flag according to the traffic percentage, campaign set, audiences, and triggers defined.
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