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80 lines
2.8 KiB
Markdown
80 lines
2.8 KiB
Markdown
---
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id: custom_activation_strategy
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title: Custom Activation Strategy
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---
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Even though Unleash comes with a few powerful [activation strategies](activation-strategies.md) there might be scenarios where you would like to extend Unleash with your own custom strategies.
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### Example: TimeStamp Strategy
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In this example we want to define an activation strategy offers a scheduled release of a feature toggle. This means that we want the feature toggle to be activated after a given date and time.
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#### Define custom strategy
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First we need to "define" our new strategy. To add a new "Strategy", open the Strategies tab from the sidebar.
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We name our strategy `TimeStamp` and add one required parameter of type string, which we call `enableAfter`.
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#### Use custom strategy
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After we have created the strategy definition, we can now decide to use that activation strategy for our feature toggle.
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In the example we want to use our custom strategy for the feature toggle named `demo.TimeStampRollout`.
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#### Client implementation
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All official client SDK's for Unleash provides abstractions for you to implement support for custom strategies.
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> Before you have provided support for the custom strategy; the client will return false, because it does not understand the activation strategy.
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In Node.js the implementation for the `TimeStampStrategy` would be:
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```javascript
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class TimeStampStrategy extends Strategy {
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constructor() {
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super('TimeStamp');
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}
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isEnabled(parameters, context) {
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Date.parse(parameters.enableAfter) < Date.now();
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}
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}
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```
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In the example implementation we make use of the library called moment to parse the timestamp and verify that current time is after the specified `enabledAfter` parameter.
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All parameter injected to the strategy are handled as `string` objects. This means that the strategies needs to parse it to a more suitable format. In this example we just parse it directly to a `Date` type and do the comparison directly. You might want to also consider timezone in a real implementation.
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We also have to remember to register the custom strategy when initializing the Unleash client. Full working code example:
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```javascript
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const { Strategy, initialize, isEnabled } = require('unleash-client');
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class TimeStampStrategy extends Strategy {
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constructor() {
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super('TimeStamp');
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}
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isEnabled(parameters, context) {
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return Date.parse(parameters.enableAfter) < Date.now();
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}
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}
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const instance = initialize({
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url: 'http://unleash.herokuapp.com/api/',
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appName: 'unleash-demo',
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instanceId: '1',
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strategies: [new TimeStampStrategy()],
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});
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instance.on('ready', () => {
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setInterval(() => {
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console.log(isEnabled('demo.TimeStampRollout'));
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}, 1000);
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});
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```
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