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Integrating Feature Flags With Your Continuous Deployment Pipeline

Contents

Continuous deployment entails releasing small changes frequently to a production environment. It enables teams to move quickly and respond to shifting customer needs, but it also poses challenges for managing and testing new features.

Feature flags are a tool that can assist teams in overcoming these obstacles by allowing developers to enable or disable certain features in a codebase selectively.

Introduction to Feature Flags

Feature flags, also known as feature toggles, enable developers to rapidly test new features and make codebase modifications without affecting the application’s overall functionality. Feature flags have become essential for many organizations with the rise of agile development and continuous integration and deployment.

Here is how they are employed:

  • Enabling or disabling specific features for users or user groups
  • Rolling out features progressively to a subset of users before releasing them to all users
  • Conducting A/B tests to compare the effectiveness of various features
  • Permit developers to work on new features without impacting the stability of the production environment

Using feature flags enables developers to be more adaptable and responsive to fluctuating customer requirements. This way, you can quickly run tests and make modifications without undergoing an entire release cycle.

Feature flags should not be used to hide incomplete or untested code. Instead, they ought to serve as a temporary mechanism for regulating the release of new features. As a result, they make it simple to roll back or disable a feature if problems arise. (This indicates that the feature flags must be removed once the feature has been released or if they are no longer required.)

Understanding the Benefits of Integrating Feature Flags With Continuous Deployment

Feature flags are especially helpful when releasing a new feature that may significantly impact the system. By using them, you can release the new feature to a subset of users. Then you can monitor its performance, and identify and resolve any issues before releasing it to all users.

Feature flags also enable continuous experimentation and A/B testing, allowing teams to compare the performance of different feature variants. This method can help you determine which variations of a feature work best and implement features based on data-driven decisions.

The flexibility provided by feature flags allows developers to work on new features without compromising the stability of the production environment. This means that developers can work on new features concurrently without having to wait for the completion of other features before releasing them.

Setting Up Feature Flags in Your Deployment Pipeline

A configuration file can be used to define the feature flags. This method requires the creation of a configuration file, such as a JSON or YAML file, that contains a list of all the feature flags and their respective values. The application can then read this configuration file at runtime to determine which features should be enabled or disabled:

// JavaScript example
const featureConfig = '{"featureA": true,"featureB": false, "featureC": true}';
const features = JSON.parse(featureConfig);

if (features.featureA) {
  // enable feature A
} else {
  // disable feature A
}
JavaScript

Using environment variables to define the feature flags is an alternative method. Setting environment variables on the application’s server and reading them at runtime to determine which features should be enabled or disabled:

// JavaScript example
if (process.env.FEATURE_A === "true") {
  // enable feature A
} else {
  // disable feature A
}
JavaScript

Regardless of the approach chosen, it is essential to remember that feature flags must be easily configurable and centrally managed. As the application evolves, this will make updating and managing the feature flags easier.

In addition, the feature flags must be easily auditable so that you can determine when and why a feature was enabled or disabled.

Best Practices for Managing Feature Flags in Production

Managing feature flags in production necessitates striking a balance between experimenting and innovating with new features. As a result, you minimize the risk of introducing bugs or breaking changes.

Rather than using a single feature flag, using multiple feature flags to enable or disable specific feature components is preferable. This will give you finer-grained control over the feature and make it easier to undo mistakes.

// JavaScript example
const featureAPart1 = process.env.FEATURE_A_PART_1 === "true";
const featureAPart2 = process.env.FEATURE_A_PART_2 === "true";

if (featureAPart1 && featureAPart2) {
  // enable the full feature
} else {
  // disable the full feature
}
JavaScript

Feature flags should be combined with other techniques, such as A/B testing and canary releases, to reduce the risk of introducing bugs or breaking changes:

import { SplitFactory } from "@splitsoftware/splitio-browserjs";

const sdk = SplitFactory({
  /* Split SDK configuration options */
  core: {
    authorizationKey: "YOUR_API_KEY",
    // key represents your internal user id, or the account id that
    // the user belongs to.
    // This could also be a cookie you generate for anonymous users
    key: "bob@example.com",
  },
});

// And get the client instance you'll use
const client = sdk.client();

client.on(client.Event.SDK_READY, function () {
  const attributes = {
    /* User attributes */
  };
  const showFeature = client.getTreatment("new-feature", attributes);
  if (showFeature == "on") {
    // enable the new feature for a small percentage of users
  } else {
    // disable the new feature for the rest of the users
  }
});
JavaScript

Monitoring feature flag usage in production is essential to detect any issues early. Here, monitoring and alerting to detect when a feature flag is being used unintendedly:

import { SplitFactory } from "@splitsoftware/splitio-browserjs";

const sdk = SplitFactory({
  /* Split SDK configuration options */
  core: {
    authorizationKey: "YOUR_API_KEY",
    // key represents your internal user id, or the account id that
    // the user belongs to.
    // This could also be a cookie you generate for anonymous users
    key: "bob@example.com",
  },
});

// And get the client instance you'll use
const client = sdk.client();

client.once(client.Event.SDK_READY, function () {
  // the client is ready to evaluate treatments according to the latest split definitions
});

client.once(client.Event.SDK_READY_TIMED_OUT, function () {
  // this callback will be called after the set timeout period has elapsed if and only if the client
  // is not ready for that time. You can still call getTreatment()
  // but it could return CONTROL.
});

client.on(client.Event.SDK_UPDATE, function () {
  // fired each time the client state changes.
  // For example, when a Split or a Segment changes.
  console.log("The SDK has been updated!");
});

// This event fires only using the LocalStorage option and if there's Split data stored in the browser.
client.once(client.Event.SDK_READY_FROM_CACHE, function () {
  // Fired after the SDK could confirm the presence of the Split data.
  // This event fires really quickly, since there's no actual fetching of information.
  // Keep in mind that data might be stale, this is NOT a replacement of SDK_READY.
});
JavaScript

Documenting your application’s usage of feature flags is essential, so other developers can understand what each flag is used for. As the application evolves, this documentation should be kept current.

Regularly review and remove obsolete feature flags: It is essential to review and remove obsolete feature flags periodically.

If you’re not feature flagging, you should start.

Integrating feature flags into your continuous deployment pipeline can effectively manage the release of new application features. Utilize them to test new features in a controlled and secure environment, then gradually roll them out to your users. While iterating rapidly on new features, you reduce the likelihood of bugs and code breaks.

In Trunk-Based Development with CI/CD, cloud computing will continue to be essential. Teams will have access to the infrastructure and resources they need to build and deploy software fast and effectively thanks to cloud services like AWS and Azure. Also, cloud computing will make it easier for teams to grow their infrastructure, which will be crucial for managing big, complex projects.

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