Flag Configuration

A flagd configuration is represented as a JSON object. Feature flag configurations can be found under flags and each item within flags represents a flag key (the unique identifier for a flag) and its corresponding configuration.

Sample configurations can be found at https://github.com/open-feature/flagd/tree/main/config/samples.

Flag configuration properties

State

state is required property. Validate states are "ENABLED" or "DISABLED". When the state is set to "DISABLED", flagd will behave like the flag doesn't exist.

Example:

"state": "ENABLED"

Variants

variants is a required property. It is an object containing the possible variations supported by the flag. All the values of the object must be the same type (e.g. boolean, numbers, string, JSON). The type used as the variant value will correspond directly affects how the flag is accessed. For example, to use a flag configured with boolean values the /schema.v1.Service/ResolveBoolean path should be used. If another path such as /schema.v1.Service/ResolveString is called, a type mismatch occurred and an error is returned.

Example:

"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
}

Example:

"variants": {
  "on": true,
  "off": false
}

Example of an invalid configuration:

"variants": {
  "on": true,
  "off": "false"
}

Default Variant

defaultVariant is a required property. The value must match the name of one of the variants defined above. The default variant is always used unless a targeting rule explicitly overrides it.

Example:

"variants": {
  "on": true,
  "off": false
},
"defaultVariant": "off"

Example:

"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
},
"defaultVariant": "red"

Example of an invalid configuration:

"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
},
"defaultVariant": "purple"

Targeting Rules

targeting is an optional property. A targeting rule must be valid JSON. Flagd uses a modified version of JSON Logic, as well as some custom pre-processing, to evaluate these rules. The output of the targeting rule must match the name of one of the variants defined above. If an invalid or null value is is returned by the targeting rule, the defaultVariant value is used. If no targeting rules are defined, the response reason will always be STATIC, this allows for the client side caching of these flag values, this behavior is described here.

The JSON Logic playground is a great way to experiment with new targeting rules. The following example shows how a rule could be configured to return binet when the email (which comes from evaluation context) contains @faas.com. If the email wasn't included in the evaluation context or doesn't contain @faas.com, null is returned and the defaultVariant is used instead.

Click here to see how this targeting rule would look in the JSON Logic playground.

Open the JSON Logic playground in your favorite browser

Add the follow JSON as the Rule:

{
  "if": [
    {
      "in": [
        "@faas.com",
        {
          "var": ["email"]
        }
      ]
    },
    "binet",
    null
  ]
}

Add the following JSON as the Data:
```
{
  "email": "test@faas.com"
}
```
Click Compute
confirm the output show "binet"
Optionally, experiment with different rules and data

Flag Configuration