Cloudflare SDK 1.x to 2.0 migration guide

This topic explains the changes in the Cloudflare SDK 2.0 release and how to adapt code that uses a 1.0 version of the Cloudflare SDK to use version 2.0 or later.

Version 2.0 includes several breaking changes.

Changes to package namespace

The Cloudflare SDK is now published under a new npm namespace.

$
yarn add launchdarkly-cloudflare-edge-sdk

Changes to Node.js dependencies

The Cloudflare SDK uses node:events which needs to be enabled in your Worker configuration. To do this, add the nodejs_compat flag to wrangler.toml.

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compatibility_flags = [ "nodejs_compat" ]

To learn more, read Node.js compatibility.

Changes to init function

The function signature for the init function has changed.

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const client = init(env.LD_KV, sdkKey);

To learn more, read SDK API Documentation.

Changes to polyfill requirements

The Cloudflare Edge SDK v1.x is a wrapper of the LaunchDarkly Node.js (server-side) SDK. A bundler is needed to polyfill Node.js dependencies that are not supported in the Cloudflare Worker runtime.

The Cloudflare SDK v2.0 is not a wrapper of the LaunchDarkly Node.js (server-side) SDK. It uses only Node.js dependencies which are supported in the Cloudflare Worker runtime. You no longer need to use a bundler like webpack or esbuild to polyfill unsupported Node.js dependencies.

Understanding contexts

Many LaunchDarkly customers create targeting rules for feature flags based on a variety of different information, including attributes pertaining to users, organizations, devices, and more. In previous versions of the LaunchDarkly SDK, you could define this information in a user object, using a combination of built-in and custom attributes. Now you can define this information in a more structured way, using contexts.

Each context has a required attribute called kind that you can use to categorize context instances for targeting and Experimentation. You can also add other attributes. Attributes can be strings, booleans, numbers, arrays, or JSON objects.

When you evaluate a feature flag within your application, the flag’s targeting rules use information from one or more kinds of contexts. For example, you may know:

• the username, first name, last name, and email address of a person, as part of a context with kind of “user”
• the company, department, and location of an organization, as part of a context with kind of “organization”
• the device, model, and operating system of an environment, as part of a context with kind of “device”

This new version of the LaunchDarkly SDK requires you to evaluate feature flags using an evaluation context, which is an object containing one or more contexts.

To learn more about contexts, read Contexts.

Migrating from users to contexts

The 2.0 version of this SDK lets you use contexts. When you migrate from version 1.0, replace every instance of a user with a context. If there are any instances you do not replace, the 2.0 version of the Cloudflare SDK will convert each LDUser parameter it receives to LDContext and call the LDContext-specific version of the method.

The primary differences between working with users and working with contexts include the following:

• Changes to flag evaluation: The methods for evaluating flags now require contexts, rather than users.
• Create contexts, not users: Where you previously created users, now you can create contexts.
• Changes to attributes: There are now fewer built-in attributes. You can still add as many custom attributes as you like, although the format has changed slightly. A flag’s targeting rules can now address fields within a JSON object.

Understanding changes to flag evaluation

The methods for evaluating flags and determining flag evaluation reasons have changed slightly. The 2.0 version of the SDK includes the following changes:

• The variation and variationDetail methods now take a context, rather than a user, as a parameter. To learn more, read variation and variationDetail.

• The USER_NOT_SPECIFIED evaluation error code was previously defined as, the user object or user key was not provided. It has been redefined to mean that the context was not provided or was invalid.

Here’s how to evaluate a flag using a context:

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const context = {
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   kind: 'user',
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   key: 'example-user-key',
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   name: 'Sandy'
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};
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const flagValue = await client.variation('example-flag-key', context, false);

Understanding differences between users and contexts

Where you previously created users, now you can create contexts.

Here’s how to construct a basic context, as compared with constructing a user:

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const user = {
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  key: 'example-user-key',
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}

Here’s how to construct a basic context, with a context kind of something other than “user”:

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const context = {
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  kind: 'organization',
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  key: 'example-organization-key',
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}

Here’s how to construct a multi-context, which includes multiple context kinds:

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const deviceContext = {
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  kind: 'device',
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  type: 'iPad',
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  key: 'example-device-key'
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}
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const userContext = {
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  kind: 'user',
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  key: 'example-user-key',
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  name: 'Sandy',
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  role: 'doctor'
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}
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const multiContext = {
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  kind: 'multi',
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  user: userContext,
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  device: deviceContext
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}

Understanding changes to built-in and custom attributes

This section describes the changes to built-in and custom attributes in the 2.0 version of the SDK.

Working with built-in and custom attributes

In previous SDK versions, the user object included several built-in attributes for describing the user. It also included optional custom attributes, which you could add to a custom object within the user object and then populate.

In version 2.0, the only built-in attributes are kind, key, name, and anonymous. Kind, key, and name are strings, and anonymous is a boolean.

You can define additional attributes for a context by passing in a name and value for each. Additional attributes can be any JSON type, including boolean, number, string, array, or object. In version 2.0, you do not need to add custom attributes within a custom object.

Here’s how to construct a context with additional attributes, as compared with constructing a similar user:

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const user = {
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  key: 'example-user-key',
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  firstName: 'Sandy',
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  lastName: 'Smith',
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  email: 'sandy@example.com',
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  custom: {
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    groups: ['Acme', 'Global Health Services']
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  }
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};

Referencing properties of an attribute object

In previous versions of the SDK, if you set the value of a user’s custom attribute to an object, you could not reference that object in evaluations. In version 2.0, if a context attribute’s value is a JSON object, you can reference properties of that object as the attribute in the targeting rules for a flag or segment.

Here’s how to add object attributes to a context:

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const context = {
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  kind: 'user',
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  key: 'example-user-key',
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  firstName: 'Sandy',
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  lastName: 'Smith',
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  email: 'sandy@example.com',
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  address: {
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    street: '123 Main St',
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    city: 'Springfield'
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  }
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};

In your flag or segment targeting, use / as the delimiter to refer to specific object fields. For example, you can use /address/city in your targeting. To learn more, read Target with flags.

Removing the secondary attribute

In previous versions of the SDK, you could set the value of a user’s secondary attribute, as an optional secondary key for a user. The SDK would incorporate this attribute into the variation bucket assignment hash.

In version 2.0, the secondary attribute has been removed. If you were previously using this attribute as part of distinguishing percentage rollouts, that will no longer work for your users.