feat: add AppConfig as a parameter provider

docs/utilities/parameters.md

@@ -4,9 +4,13 @@ description: Utility
 ---
 
 
-The parameters utility provides a way to retrieve parameter values from
-[AWS Systems Manager Parameter Store](https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html) or
-[AWS Secrets Manager](https://aws.amazon.com/secrets-manager/). It also provides a base class to create your parameter provider implementation.
+The parameters utility provides a way to retrieve parameter values from:
+
+ - [AWS Systems Manager Parameter Store](https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html)
+ - [AWS Secrets Manager](https://aws.amazon.com/secrets-manager/)
+ - [AWS AppConfig](https://aws.amazon.com/systems-manager/features/appconfig/)
+
+It also provides a base class to create your parameter provider implementation.
 
 **Key features**
 
@@ -40,11 +44,12 @@ To install this utility, add the following dependency to your project.
 
 This utility requires additional permissions to work as expected. See the table below:
 
-Provider | Function/Method | IAM Permission
-------------------------------------------------- | ------------------------------------------------- | ---------------------------------------------------------------------------------
-SSM Parameter Store | `SSMProvider.get(String)` `SSMProvider.get(String, Class)`  | `ssm:GetParameter`
-SSM Parameter Store | `SSMProvider.getMultiple(String)` | `ssm:GetParametersByPath`
-Secrets Manager | `SecretsProvider.get(String)` `SecretsProvider.get(String, Class)` | `secretsmanager:GetSecretValue`
+| Provider            | Function/Method                                                        | IAM Permission                                                              |
+|---------------------|------------------------------------------------------------------------|-----------------------------------------------------------------------------|
+| SSM Parameter Store | `SSMProvider.get(String)` `SSMProvider.get(String, Class)`             | `ssm:GetParameter`                                                          |
+| SSM Parameter Store | `SSMProvider.getMultiple(String)`                                      | `ssm:GetParametersByPath`                                                   |
+| Secrets Manager     | `SecretsProvider.get(String)` `SecretsProvider.get(String, Class)`     | `secretsmanager:GetSecretValue`                                             |
+| AppConfig           | `AppConfigProvider.get(String)` `AppConfigProvider.get(String, Class)` | `appconfig:GetLatestConfiguration` & `appconfig:StartConfigurationSession`  |
 
 ## SSM Parameter Store
 
@@ -99,10 +104,10 @@ in order to get data from other regions or use specific credentials.
 
 The AWS Systems Manager Parameter Store provider supports two additional arguments for the `get()` and `getMultiple()` methods:
 
-| Option     | Default | Description |
-|---------------|---------|-------------|
-| **withDecryption()**   | `False` | Will automatically decrypt the parameter. |
-| **recursive()** | `False`  | For `getMultiple()` only, will fetch all parameter values recursively based on a path prefix. |
+| Option               | Default | Description                                                                                   |
+|----------------------|---------|-----------------------------------------------------------------------------------------------|
+| **withDecryption()** | `False` | Will automatically decrypt the parameter.                                                     |
+| **recursive()**      | `False` | For `getMultiple()` only, will fetch all parameter values recursively based on a path prefix. |
 
 **Example:**
 
@@ -166,6 +171,46 @@ in order to get data from other regions or use specific credentials.
     }
     ```
 
+## AppConfig
+
+!!! info
+    See how to create configuration in AppConfig in the [documentation](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-working.html).
+
+=== "AppConfigProvider"
+
+    ```java hl_lines="5 9-10"
+    import software.amazon.lambda.powertools.parameters.AppConfigProvider;
+    import software.amazon.lambda.powertools.parameters.ParamManager;
+
+    public class AppWithConfig implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
+        // Get an instance of the AppConfig Provider
+        AppConfigProvider appConfigProvider = ParamManager.getAppConfigProvider();
+
+        // Retrieve some configuration
+        // The key must be in form /application/environment/configuration and match your AppConfig setup
+        String value = appConfigProvider.get("/app/prod/config");
+
+    }
+    ```
+
+=== "AppConfigProvider with a custom client"
+
+    ```java hl_lines="5 8 11"
+    import software.amazon.lambda.powertools.parameters.AppConfigProvider;
+    import software.amazon.lambda.powertools.parameters.ParamManager;
+
+    public class AppWithConfig implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
+        AppConfigDataClient client = AppConfigDataClient.builder().region(Region.EU_CENTRAL_1).build();
+
+        // Get an instance of the AppConfig Provider
+        AppConfigProvider appConfigProvider = ParamManager.getAppConfigProvider(client);
+
+        // Retrieve a single secret
+        String value = appConfigProvider.get("/app/prod/config");
+
+    }
+    ```
+
 ## Advanced configuration
 
 ### Caching

powertools-parameters/pom.xml

@@ -69,6 +69,20 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>software.amazon.awssdk</groupId>
+            <artifactId>appconfigdata</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>software.amazon.awssdk</groupId>
+                    <artifactId>apache-client</artifactId>
+                </exclusion>
+                <exclusion>
+                    <groupId>software.amazon.awssdk</groupId>
+                    <artifactId>netty-nio-client</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
         <dependency>
             <groupId>software.amazon.awssdk</groupId>
             <artifactId>url-connection-client</artifactId>
@@ -118,6 +132,34 @@
             <artifactId>aspectjweaver</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit-pioneer</groupId>
+            <artifactId>junit-pioneer</artifactId>
+            <version>1.6.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
-
+    <profiles>
+        <profile>
+            <id>jdk16</id>
+            <activation>
+                <jdk>[16,)</jdk>
+            </activation>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <version>3.0.0-M5</version>
+                        <configuration>
+                            <argLine>
+                                --add-opens java.base/java.util=ALL-UNNAMED
+                                --add-opens java.base/java.lang=ALL-UNNAMED
+                            </argLine>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
 </project>

powertools-parameters/src/main/java/software/amazon/lambda/powertools/parameters/AppConfigProvider.java

@@ -0,0 +1,171 @@
+package software.amazon.lambda.powertools.parameters;
+
+import software.amazon.awssdk.auth.credentials.EnvironmentVariableCredentialsProvider;
+import software.amazon.awssdk.core.SdkSystemSetting;
+import software.amazon.awssdk.http.urlconnection.UrlConnectionHttpClient;
+import software.amazon.awssdk.regions.Region;
+import software.amazon.awssdk.services.appconfigdata.AppConfigDataClient;
+import software.amazon.awssdk.services.appconfigdata.model.GetLatestConfigurationRequest;
+import software.amazon.awssdk.services.appconfigdata.model.GetLatestConfigurationResponse;
+import software.amazon.awssdk.services.appconfigdata.model.StartConfigurationSessionRequest;
+import software.amazon.awssdk.services.appconfigdata.model.StartConfigurationSessionResponse;
+import software.amazon.lambda.powertools.parameters.cache.CacheManager;
+import software.amazon.lambda.powertools.parameters.transform.TransformationManager;
+import software.amazon.lambda.powertools.parameters.transform.Transformer;
+
+import java.time.temporal.ChronoUnit;
+import java.util.Map;
+
+public class AppConfigProvider extends BaseProvider {
+
+    private AppConfigDataClient client;
+
+    AppConfigProvider(CacheManager cacheManager) {
+        this(cacheManager, defaultClient());
+    }
+
+    AppConfigProvider(CacheManager cacheManager, AppConfigDataClient client) {
+        super(cacheManager);
+        this.client = client;
+    }
+
+    /**
+     * Create a builder that can be used to configure and create a {@link AppConfigProvider}.
+     *
+     * @return a new instance of {@link Builder}
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    @Override
+    protected String getValue(String key) {
+        String[] profile = key.split("/");
+        if (profile.length < 3) {
+            throw new IllegalArgumentException("Your key is incorrect, please specify an 'application', an 'environment' and the 'configuration' separated with '/', eg. '/myapp/prod/myvar'");
+        }
+        int index = key.startsWith("/") ? 1 : 0;
+        String application = profile[index];
+        String environment = profile[index + 1];
+        String configuration = profile[index + 2];
+
+        return getValueWithClient(application, environment, configuration);
+    }
+
+    private String getValueWithClient(String application, String environment, String configuration) {
+        StartConfigurationSessionResponse sessionResponse = client.startConfigurationSession(StartConfigurationSessionRequest.builder()
+                .applicationIdentifier(application)
+                .environmentIdentifier(environment)
+                .configurationProfileIdentifier(configuration)
+                .build());
+        GetLatestConfigurationResponse configurationResponse = client.getLatestConfiguration(GetLatestConfigurationRequest.builder()
+                .configurationToken(sessionResponse.initialConfigurationToken())
+                .build());
+        return configurationResponse.configuration().asUtf8String();
+    }
+
+    /**
+     * @throws UnsupportedOperationException as it is not possible to get multiple values simultaneously from App Config
+     */
+    @Override
+    protected Map<String, String> getMultipleValues(String path) {
+        throw new UnsupportedOperationException("Impossible to get multiple values from AWS Secrets Manager");
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public AppConfigProvider defaultMaxAge(int maxAge, ChronoUnit unit) {
+        super.defaultMaxAge(maxAge, unit);
+        return this;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public AppConfigProvider withMaxAge(int maxAge, ChronoUnit unit) {
+        super.withMaxAge(maxAge, unit);
+        return this;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public AppConfigProvider withTransformation(Class<? extends Transformer> transformerClass) {
+        super.withTransformation(transformerClass);
+        return this;
+    }
+
+    private static AppConfigDataClient defaultClient() {
+        return AppConfigDataClient.builder()
+                .httpClientBuilder(UrlConnectionHttpClient.builder())
+                .credentialsProvider(EnvironmentVariableCredentialsProvider.create())
+                .region(Region.of(System.getenv(SdkSystemSetting.AWS_REGION.environmentVariable())))
+                .build();
+    }
+
+    static class Builder {
+
+        private AppConfigDataClient client;
+        private CacheManager cacheManager;
+        private TransformationManager transformationManager;
+
+        /**
+         * Create a {@link AppConfigProvider} instance.
+         *
+         * @return a {@link AppConfigProvider}
+         */
+        public AppConfigProvider build() {
+            if (cacheManager == null) {
+                throw new IllegalStateException("No CacheManager provided, please provide one");
+            }
+            AppConfigProvider provider;
+            if (client != null) {
+                provider = new AppConfigProvider(cacheManager, client);
+            } else {
+                provider = new AppConfigProvider(cacheManager);
+            }
+            if (transformationManager != null) {
+                provider.setTransformationManager(transformationManager);
+            }
+            return provider;
+        }
+
+        /**
+         * Set custom {@link AppConfigDataClient} to pass to the {@link AppConfigProvider}. <br/>
+         * Use it if you want to customize the region or any other part of the client.
+         *
+         * @param client Custom client
+         * @return the builder to chain calls (eg. <pre>builder.withClient().build()</pre>)
+         */
+        public Builder withClient(AppConfigDataClient client) {
+            this.client = client;
+            return this;
+        }
+
+        /**
+         * <b>Mandatory</b>. Provide a CacheManager to the {@link AppConfigProvider}
+         *
+         * @param cacheManager the manager that will handle the cache of parameters
+         * @return the builder to chain calls (eg. <pre>builder.withCacheManager().build()</pre>)
+         */
+        public Builder withCacheManager(CacheManager cacheManager) {
+            this.cacheManager = cacheManager;
+            return this;
+        }
+
+        /**
+         * Provide a transformationManager to the {@link AppConfigProvider}
+         *
+         * @param transformationManager the manager that will handle transformation of parameters
+         * @return the builder to chain calls (eg. <pre>builder.withTransformationManager().build()</pre>)
+         */
+        public Builder withTransformationManager(TransformationManager transformationManager) {
+            this.transformationManager = transformationManager;
+            return this;
+        }
+    }
+}

powertools-parameters/src/main/java/software/amazon/lambda/powertools/parameters/ParamManager.java

@@ -13,6 +13,7 @@
  */
 package software.amazon.lambda.powertools.parameters;
 
+import software.amazon.awssdk.services.appconfigdata.AppConfigDataClient;
 import software.amazon.awssdk.services.secretsmanager.SecretsManagerClient;
 import software.amazon.awssdk.services.ssm.SsmClient;
 import software.amazon.lambda.powertools.parameters.cache.CacheManager;
@@ -36,7 +37,7 @@ public final class ParamManager {
 
     /**
      * Get a concrete implementation of {@link BaseProvider}.<br/>
-     * You can specify {@link SecretsProvider} or {@link SSMProvider} or create your custom provider
+     * You can specify {@link SecretsProvider} or {@link SSMProvider} or {@link AppConfigProvider} or create your custom provider
      * by extending {@link BaseProvider} if you need to integrate with a different parameter store.
      * @return a {@link SecretsProvider}
      */
@@ -65,6 +66,15 @@ public static SSMProvider getSsmProvider() {
         return getProvider(SSMProvider.class);
     }
 
+    /**
+     * Get a {@link AppConfigProvider} with default {@link AppConfigDataClient}.<br/>
+     * If you need to customize the region, or other part of the client, use {@link ParamManager#getAppConfigProvider(AppConfigDataClient)} instead.
+     * @return a {@link AppConfigProvider}
+     */
+    public static AppConfigProvider getAppConfigProvider() {
+        return getProvider(AppConfigProvider.class);
+    }
+
     /**
      * Get a {@link SecretsProvider} with your custom {@link SecretsManagerClient}.<br/>
      * Use this to configure region or other part of the client. Use {@link ParamManager#getSsmProvider()} if you don't need this customization.
@@ -91,6 +101,19 @@ public static SSMProvider getSsmProvider(SsmClient client) {
                 .build());
     }
 
+    /**
+     * Get a {@link AppConfigProvider} with your custom {@link AppConfigDataClient}.<br/>
+     * Use this to configure region or other part of the client. Use {@link ParamManager#getAppConfigProvider()} if you don't need this customization.
+     * @return a {@link AppConfigProvider}
+     */
+    public static AppConfigProvider getAppConfigProvider(AppConfigDataClient client) {
+        return (AppConfigProvider) providers.computeIfAbsent(AppConfigProvider.class, (k) -> AppConfigProvider.builder()
+                .withClient(client)
+                .withCacheManager(cacheManager)
+                .withTransformationManager(transformationManager)
+                .build());
+    }
+
     public static CacheManager getCacheManager() {
         return cacheManager;
     }