Feature flag samples for AWS AppConfig Agent local development mode

This section includes feature flag samples you can use with AWS AppConfig Agent in local development mode. Local development mode expects feature flag data in the data's retrieval-time format. Retrieval-time format is the format returned when the flag is retrieved from the GetLatestConfiguration API, which only contains the flag's value. Retrieval-time format doesn't include a flag's complete definition (as passed to the CreateHostedConfigurationVersion API). The complete definition for a flag also contains information such as attribute names and values, constraints, and the flag's enabled state.

Basic feature flag samples

Use the following basic feature flag samples with AWS AppConfig Agent in local development mode.

Sample 1: A single flag representing a UI refresh.

{
    "ui_refresh": {
        "enabled": true,
        "new_styleguide_colors": true
    }
}

Sample 2: Multiple flags representing operational feature flags.

{
   "background_worker": {
        "enabled": true,
        "num_threads": 4,
        "queue_name": "MyWorkQueue"
   },
   "emergency_shutoff_switch": {
        "enabled": false
   },
   "logger_settings": {
        "enabled": true,
        "level": "INFO"
   }
}

Multi-variant feature flag samples

The retrieval-time format of a feature flag configuration that contains at least one multi-variant feature flag is represented as Amazon Ion data instead of JSON data. In this format, multi-variant flags are represented as an annotated list, and basic flags are represented as an annotated string. The list elements of a multi-variant flag are either a tuple (a list with a length of two), which represents a single variant, or a string, which represents the default variant. Within a variant tuple, the first element is an s-expression that represents the variant's rule, and the second element is a string that represents the variant's content.

In order for the agent to properly interpret these files, your local feature flag files must use the following extension: .application%ion%type=AWS.AppConfig.FeatureFlags. For example, Local:MyFeatureFlags:SampleMV1.application%ion%type=AWS.AppConfig.FeatureFlags.

Sample 1: A multi-variant flag representing a tiered release of a new feature.

'tiered_release'::[
  [
    (or (and (eq $group "Tier1") (split by::$userId pct::1 seed::"2025.01.01")) (and (eq $group "Tier2") (split by::$userId pct::7 seed::"2025.01.01"))),
    '''{"_variant": "ShowFeature", "enabled": true}'''
  ],
  '''{"_variant": "HideFeature", "enabled": false}'''
]

Sample 2: Multiple flags representing different UX displays based on the user’s ID. The first two flags are multi-variant and the final flag is basic.

'colorway'::[
  [
    (contains $userId "beta"),
    '''{"_variant": "BetaTesters", "enabled": true, "background": "blue", "foreground": "red"}''',
  ],
  [
    (split by::$userId pct::10),
    '''{"_variant": "SplitRollOutRedAndBlue", "enabled": true, "background": "blue", "foreground": "red"}''',
  ],
  '''{"_variant": "default", "enabled": true, "background": "green", "foreground": "green"}''',
]

'simple_feature'::[
  [
    (contains $userId "beta"),
    '''{"_variant": "BetaTesters", "enabled": true}'''
  ],
  '''{"_variant": "default", "enabled": false}'''
]

'button_color'::'''{"enabled": true, "color": "orange"}'''