Support batch secrets retrieval in Parameters module

[jeromevdl]

Is your feature request related to a problem? Please describe.
N/A

Describe the solution you'd like
Add support for https://aws.amazon.com/about-aws/whats-new/2023/11/aws-secrets-manager-batch-retrieval-secrets/ in Parameters module.

[scottgerring]

This can be done in the v2 branch once #1403 is merged. It will be a good first issue at that point.

[jreijn]

@scottgerring @jeromevdl I would like to pick this up if possible. It seems #1403 has been merged, so good to go?

[jreijn]

I took a look at the code base and started with some minor improvements. I noticed that the getValue and the existing getMultipleValues exists, however the later on is now based on path now. I'm thinking of renaming the getMultipleValues to getMultipleValuesByPath and introduce a new method on the BaseProvider called getMultipleValuesByKey(List keys). That way we can support both use cases.
For the new method, I'll see if I can implement a solution in all the providers.

[scottgerring]

Hey @jreijn happy for you to pick this up - I will assign it to you.
I'll take some time tomorrow morning to look at the current ...multipleValues interface and write back!

[scottgerring]

v2 getMultipleValues impls

1. AppConfigProvider - unsupported

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

Lines 113 to 117 in 3963d6d

	protected Map<String, String> getMultipleValues(String path) {
	// Retrieving multiple values is not supported with the AppConfig provider.
	throw new RuntimeException(
	"Retrieving multiple parameter values is not supported with the AWS App Config Provider");
	}

2. DynamoDbProvider

Retrieves all values that share the same partition key.

powertools-lambda-java/powertools-parameters/powertools-parameters-dynamodb/src/main/java/software/amazon/lambda/powertools/parameters/dynamodb/DynamoDbProvider.java

Lines 93 to 99 in 3963d6d

	protected Map<String, String> getMultipleValues(String path) {
	QueryResponse resp = client.query(QueryRequest.builder()
	.tableName(tableName)
	.keyConditionExpression("id = :v_id")
	.expressionAttributeValues(Collections.singletonMap(":v_id", AttributeValue.fromS(path)))
	.build());

3. SSMProvider

Retrieves either everything at the given level of the /parameter/hierarchy, or everything at the given level plus /parameter/hierarchy/nested/levels when using withRecursive.

powertools-lambda-java/powertools-parameters/powertools-parameters-ssm/src/main/java/software/amazon/lambda/powertools/parameters/ssm/SSMProvider.java

Lines 160 to 166 in 3963d6d

	private Map<String, String> getMultipleBis(String path, String nextToken) {
	GetParametersByPathRequest request = GetParametersByPathRequest.builder()
	.path(path)
	.withDecryption(decrypt)
	.recursive(recursive)
	.nextToken(nextToken)
	.build();

Both the existing implementations - DDB and SSM provider - already vary a little - SSM is path-based, DDB is more like, common key. I'm a bit hesitant to change the existing method name because 1/ its not path-based in both cases and 2/ it's a breaking change against v1 which wouldn't add much. What do you think?

Maybe rather than changing the existing interface, we could add getMultipleValuesByKey(keys) on the BaseProvider, provide a default impl that simply maps getValue over the keys, and then override in SSMProvider ?

Thoughts @jreijn / @jeromevdl ?

[jreijn]

@scottgerring sounds reasonable. I also noticed that lambda powertools in other languages do something similar. I'll make some small commits while I go along, so I can get some feedback along the way.