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Once you have your application integrated with the Flipt backend, it’s time to create some flags to evaluate. This document will walk you through creating your first flag, segment, set of rules and finally using the debug console to evaluate everything.

For more information on any of the concepts described here, please see the Concepts documentation.


Before getting started, make sure the Flipt server is up and running on your host on your chosen ports. See Installation for more.

In this example we’ll use the default location of http://localhost:8080.

Flags and Variants

First we’ll create a flag and variants that we will use to evaluate against.

Create a Flag

A flag is the basic entity in Flipt. Flags can represent features in your applications that you want to enable/disable for your users.

To create a flag:

  1. Open the UI at http://localhost:8080.
  2. Click New Flag.
  3. Populate the details of the flag as shown.
  4. Click Enabled so the flag will be enabled once created.
  5. Click Create.

"Create Flag"

You should see the message Flag created!.

Create Variants

Variants allow you to return different values for your flags based on rules that you define.

To create a variant:

  1. On the Flag Details page for the new flag you created, click New Variant.
  2. Populate the details of the variant as shown.
  3. Click Add Variant.
  4. Create one more variant populating the information as you wish.

"Create Variant"

You should see the message Variant added!.

Click Flags in the navigation menu and you should now see your newly created flag in the list.

Segments and Constraints

Next we’ll create a segment with a constraint that will be used to determine the reach of your flag.

Create a Segment

Segments are used to split your user base into subsets.

To create a segment:

  1. From the main page click Segments.
  2. Click New Segment.
  3. Populate the details of the segment as shown.
  4. Click Create.

"Create Segment"

You should see the message Segment created!.

Create a Constraint

Constraints are used to target a specific segment.

Constraints are not required to match a segment. A segment with no constraints will match every request by default.

To create a constraint:

  1. On the Segment Details page for the new segment you created, click New Constraint.
  2. Populate the details of the constraint as shown.
  3. Click Add Constraint.

"Create Constraint"

You should see the message Constraint added!.

Click Segments in the navigation menu and you should now see your newly created segment in the list.

Rules and Distributions

Finally we’ll create a rule and set of distributions for your flag and variants. Rules and distributions allow you to define which variant gets returned when you evaluate a specific flag that falls into a given segment.

To create a rule and distribution:

  1. Go back to the flag you created at the beginning.
  2. Click Targeting.
  3. Click New Rule.
  4. Under Segment: choose the segment you created earlier.
  5. Under Then serve: choose A Percentage Rollout.
  6. You should see your two variants that you created earlier, with a percentage of 50% each next to them.
  7. Click Add Rule.

"Create Rule"

You should see the message Rule added!. You just created your first rule and distribution.

A distribution is a way of assigning a percentage for which entities evaluated get a specific variant. The higher the percentage assigned, the more likely it is that any entity will get that specific variant.

You could just as easily have picked a single variant instead of A Percentage Rollout when setting up your rule. This would effectively mean you have a single distribution, a variant with 100% chance of being returned.

Evaluation and Debug console

After creating the above flag, segment and targeting rule, you’re now ready to test how this would work in your application.

Fortunately the Flipt UI contains a Debug Console to allow you to experiment with different evaluation requests to see how they would be evaluated.

The main ideas behind how evaluation works is described in more detail in the Concepts documentation.

To test evaluation:

  1. Navigate to the Targeting section for your flag that you created above.
  2. Scroll down to the Debug Console section and click into the left pane where you will see a JSON payload. This represents the body of the request that will be evaluated.
  3. Notice the flagKey matches the key field of your flag.
  4. Notice that entityId is pre-populated with a random UUID. This represents the ID that you would use to uniquely identify entities (ex: users) that you want to test against your flags.
  5. Note that the context object is pre-populated as well. This corresponds to the properties that will be evaluated to determine if your request matches any constraints of your segments.
  6. Update the context object as shown.
  7. Click Debug.
  8. Note the Response pane to the right has been populated with the evaluation response from the server, informing you that this request would match your segment that you created earlier, and return one of the variants defined.
  9. Experiment with different values for the context and entityId fields.

"Debug Console"

You can click Reset to populate a new example request in the Request pane. This will also generate a fresh UUID for the entityId field.

That’s it! You’re now ready to integrate Flipt into your application and start defining your own flags and segments that will enable you to seamlessly rollout new features to your users while reducing risk.