IBM Cloud App Configuration SDK is used to perform feature flag and property evaluation based on the configuration on IBM Cloud App Configuration service.
IBM Cloud App Configuration is a centralized feature management and configuration service on IBM Cloud for use with web and mobile applications, microservices, and distributed environments.
Instrument your applications with App Configuration Java SDK, and use the App Configuration dashboard, CLI or API to define feature flags or properties, organized into collections and targeted to segments. Toggle feature flag states in the cloud to activate or deactivate features in your application or environment, when required. You can also manage the properties for distributed applications centrally.
<dependency>
<groupId>com.ibm.cloud</groupId>
<artifactId>appconfiguration-java-sdk</artifactId>
<version>0.3.6</version>
</dependency>
implementation group: 'com.ibm.cloud', name: 'appconfiguration-java-sdk', version: '0.3.6'
import com.ibm.cloud.appconfiguration.sdk.AppConfiguration;
String region = AppConfiguration.REGION_US_SOUTH;
String guid = "guid";
String apikey = "apikey";
String collectionId = "airlines-webapp";
String environmentId = "dev";
AppConfiguration appConfigClient = AppConfiguration.getInstance();
appConfigClient.init(region, guid, apikey);
appConfigClient.setContext(collectionId, environmentId);
đź”´ Important đź”´
The init()
and setContext()
are the initialisation methods and should be invoked only once using
appConfigClient. The appConfigClient, once initialised, can be obtained across classes.
using AppConfiguration.getInstance()
. See this example below.
- region : Region name where the service instance is created. Use
AppConfiguration.REGION_US_SOUTH
for DallasAppConfiguration.REGION_EU_GB
for LondonAppConfiguration.REGION_AU_SYD
for SydneyAppConfiguration.REGION_US_EAST
for Washington DCAppConfiguration.REGION_EU_DE
for Frankfurt
- guid : GUID of the App Configuration service. Get it from the service instance credentials section of the dashboard
- apikey : ApiKey of the App Configuration service. Get it from the service instance credentials section of the dashboard
- collectionId : Id of the collection created in App Configuration service instance under the Collections section.
- environmentId : Id of the environment created in App Configuration service instance under the Environments section.
Set the SDK to connect to App Configuration service by using a private endpoint that is accessible only through the IBM Cloud private network.
appConfigClient.usePrivateEndpoint(true);
This must be done before calling the init
function on the SDK.
In order for your application and SDK to continue its operations even during the unlikely scenario of App Configuration service across your application restarts, you can configure the SDK to work using a persistent cache. The SDK uses the persistent cache to store the App Configuration data that will be available across your application restarts.
// 1. default (without persistent cache)
appConfigClient.setContext(collectionId, environmentId);
// 2. optional (with persistent cache)
ConfigurationOptions configOptions = new ConfigurationOptions();
configOptions.setPersistentCacheDirectory("/var/lib/docker/volumes/");
appConfigClient.setContext(collectionId, environmentId, configOptions);
- persistentCacheDirectory: Absolute path to a directory which has read & write permission for the user. The SDK will create a file - appconfiguration.json in the specified directory, and it will be used as the persistent cache to store the App Configuration service information.
When persistent cache is enabled, the SDK will keep the last known good configuration at the persistent cache. In the case of App Configuration server being unreachable, the latest configurations at the persistent cache is loaded to the application to continue working.
Please ensure that the cache file is not lost or deleted in any case. For example, consider the case when a kubernetes pod is restarted and the cache file (appconfiguration.json) was stored in ephemeral volume of the pod. As pod gets restarted, kubernetes destroys the ephermal volume in the pod, as a result the cache file gets deleted. So, make sure that the cache file created by the SDK is always stored in persistent volume by providing the correct absolute path of the persistent directory.
The SDK is also designed to serve configurations, and perform feature flag & property evaluations without being connected to App Configuration service.
ConfigurationOptions configOptions = new ConfigurationOptions();
configOptions.setBootstrapFile("saflights/flights.json");
configOptions.setLiveConfigUpdateEnabled(false);
appConfigClient.setContext(collectionId, environmentId, configOptions);
- bootstrapFile: Absolute path of the JSON file, which contains configuration details. Make sure to provide a proper JSON file. You can generate this file using
ibmcloud ac config
command of the IBM Cloud App Configuration CLI. - liveConfigUpdateEnabled: Live configuration update from the server. Set this value to
false
if the new configuration values must not be fetched from the server. By default, this value is set totrue
.
Feature feature = appConfigClient.getFeature("online-check-in");
if (feature != null) {
System.out.println("Feature Name : " + feature.getFeatureName());
System.out.println("Feature Id : " + feature.getFeatureId());
System.out.println("Feature Type : " + feature.getFeatureDataType());
System.out.println("Is feature enabled? : " + feature.isEnabled());
}
HashMap<String, Feature> features = appConfigClient.getFeatures();
Use the feature.getCurrentValue(entityId, entityAttributes) method to evaluate the value of the feature flag. This method returns one of the Enabled/Disabled/Overridden value based on the evaluation.
String entityId = "john_doe";
JSONObject entityAttributes = new JSONObject();
entityAttributes.put("city", "Bangalore");
entityAttributes.put("country", "India");
String value = (String) feature.getCurrentValue(entityId, entityAttributes);
- entityId: Id of the Entity. This will be a string identifier related to the Entity against which the feature is evaluated. For example, an entity might be an instance of an app that runs on a mobile device, a microservice that runs on the cloud, or a component of infrastructure that runs that microservice. For any entity to interact with App Configuration, it must provide a unique entity ID.
- entityAttributes: A JSON object consisting of the attribute name and their values that defines the specified entity. This is an optional parameter if the feature flag is not configured with any targeting definition. If the targeting is configured, then entityAttributes should be provided for the rule evaluation. An attribute is a parameter that is used to define a segment. The SDK uses the attribute values to determine if the specified entity satisfies the targeting rules, and returns the appropriate feature flag value.
Property property = appConfigClient.getProperty("check-in-charges");
if (property != null) {
System.out.println("Property Name : " + property.getPropertyName());
System.out.println("Property Id : " + property.getPropertyId());
System.out.println("Property Type : " + property.getPropertyDataType());
}
HashMap<String, Property> property = appConfigClient.getProperties();
Use the property.getCurrentValue(entityId, entityAttributes) method to evaluate the value of the property. This method returns the default property value or its overridden value based on the evaluation.
String entityId = "john_doe";
JSONObject entityAttributes = new JSONObject();
entityAttributes.put("city", "Bangalore");
entityAttributes.put("country", "India");
String value = (String) property.getCurrentValue(entityId, entityAttributes);
- entityId: Id of the Entity. This will be a string identifier related to the Entity against which the property is evaluated. For example, an entity might be an instance of an app that runs on a mobile device, a microservice that runs on the cloud, or a component of infrastructure that runs that microservice. For any entity to interact with App Configuration, it must provide a unique entity ID.
- entityAttributes: A JSON object consisting of the attribute name and their values that defines the specified entity. This is an optional parameter if the property is not configured with any targeting definition. If the targeting is configured, then entityAttributes should be provided for the rule evaluation. An attribute is a parameter that is used to define a segment. The SDK uses the attribute values to determine if the specified entity satisfies the targeting rules, and returns the appropriate property value.
Once the SDK is initialized, the appConfigClient can be obtained across other classes as shown below:
// **other classes**
import com.ibm.cloud.appconfiguration.sdk.AppConfiguration;
AppConfiguration appConfigClient = AppConfiguration.getInstance();
Feature feature = appConfigClient.getFeature("string-feature");
boolean enabled = feature.isEnabled();
String featureValue = (String) feature.getCurrentValue(entityId, entityAttributes);
App Configuration service allows to configure the feature flag and properties in the following data types : Boolean, Numeric, String. The String data type can be of the format of a TEXT string , JSON or YAML. The SDK processes each format accordingly as shown in the below table.
View Table
Feature or Property value | DataType | DataFormat | Type of data returned by GetCurrentValue() |
Example output |
---|---|---|---|---|
true |
BOOLEAN | not applicable | java.lang.Boolean |
true |
25 |
NUMERIC | not applicable | java.lang.Integer |
25 |
"a string text" | STRING | TEXT | java.lang.String |
a string text |
{ |
STRING | JSON | org.json.JSONObject |
{"firefox": {"name": "Firefox", "pref_url": "about:config"}} |
men: |
STRING | YAML | java.lang.String |
"men:\n - John Smith\n - Bill Jones\nwomen:\n - Mary Smith\n - Susan Williams" |
Feature flag
Feature feature = appConfigClient.getFeature("json-feature");
if (feature != null) {
feature.getFeatureDataType(); // STRING
feature.getFeatureDataFormat(); // JSON
feature.getCurrentValue(entityId, entityAttributes); // JSONObject or JSONArray is returned
}
// Example Below
// input json :- [{"role": "developer", "description": "do coding"},{"role": "tester", "description": "do testing"}]
// expected output :- "do coding"
JSONArray tar_val = (JSONArray) feature.get_current_value(entityId, entityAttributes);
String expected_output = (String) ((JSONObject) tar_val.get(0)).get('description');
// input json :- {"role": "tester", "description": "do testing"}
// expected output :- "tester"
JSONObject tar_val = (JSONObject) feature.get_current_value(entityId, entityAttributes);
String expected_output = (String) tar_val.get('role');
Feature feature = appConfigClient.getFeature("yaml-feature");
if (feature != null) {
feature.getFeatureDataType(); // STRING
feature.getFeatureDataFormat(); // YAML
feature.getCurrentValue(entityId, entityAttributes); // Yaml String is returned
}
Property
Property property = appConfigClient.getProperty("json-property");
if (property != null) {
property.getPropertyDataType(); // STRING
property.getPropertyDataFormat(); // JSON
property.getCurrentValue(entityId, entityAttributes); // JSONObject or JSONArray is returned
}
// Example Below
// input json :- [{"role": "developer", "description": "do coding"},{"role": "tester", "description": "do testing"}]
// expected output :- "do coding"
JSONArray tar_val = (JSONArray) property.get_current_value(entityId, entityAttributes);
String expected_output = (String) ((JSONObject) tar_val.get(0)).get('description');
// input json :- {"role": "tester", "description": "do testing"}
// expected output :- "tester"
JSONObject tar_val = (JSONObject) property.get_current_value(entityId, entityAttributes);
String expected_output = (String) tar_val.get('role');
Property property = appConfigClient.getProperty("yaml-property");
if (property != null) {
property.getPropertyDataType(); // STRING
property.getPropertyDataFormat(); // YAML
property.getCurrentValue(entityId, entityAttributes); // Yaml String is returned
}
The SDK provides mechanism to notify you in real-time when feature flag's or property's configuration changes. You can subscribe to configuration changes using the same appConfigClient.
appConfigClient.registerConfigurationUpdateListener(new ConfigurationUpdateListener() {
@Override
public void onConfigurationUpdate() {
System.out.println("Received updated configurations");
// **add your code**
// To find the effect of any configuration changes, you can call the feature or property related methods
// Feature feature = appConfigClient.getFeature("numeric-feature");
// Integer newValue = (Integer) feature.getCurrentValue(entityId, entityAttributes);
}
});
appConfigClient.fetchConfigurations();
appConfigClient.enableDebug(true);
This project is released under the Apache 2.0 license. The license's full text can be found in LICENSE