Epic - Unify and complete configurations for all Azure Spring starters on top of Azure SDKs

[saragluna]

This epic is used to track configuration-related issues for Azure Spring starters. The goal is to make configurations exposed by all our starters consistent and complete.

Existing Problems in Azure Spring Starters:

1. Azure SDKs have their own configurations when creating the client builder; we should support all the configurations.
   • Authentication methods are not all supported. For example, the cosmos sdk supports TokenCredential and AzureKeyCredential, but the starter only supports configuring keys now.
   • We don't support configuring the proxy now. (Support configure proxy #21552)
   • We don't support configuring HTTP client options now.
   • We don't support configuring the AMQP client options now. ([FEATURE REQ] Ability to set AmqpRetryOptions in EvenHub connection #16596)
   • We don't support configuring the retry options now.
   • We don't support configuring the environment-related configurations now, e.g., the authority host. ([Spring]Support to config different Azure clouds than Azure public #21593, [BUG]azure-spring-cloud-starter-eventhubs-kafka2.4.0 example china tenant id not working #21336)
2. The configurations exposed in Azure Spring starters are not consistent, for example:
   • For the endpoint, some starters expose URI, some expose endpoint.
   • For client secret, some starters use client-key, some use client-secret. ([FEATURE REQ] Make azure-security-keyvault-jca support configuring by Spring Cloud Azure global properties. #19696)
   • Configuring the authentication methods is not consistent across starters. Some take connection-string, some take keys; we should make this configuration consistent.
3. The auto-configuration class could be as simple as possible; we should develop a common auto-configuration framework to make implementing point-1 and point-2 easy.
   • Azure SDK has a clear programmatic pattern, the azure-core + azure-identity, and all azure SDKs are built on top of them. We don't have such layers defined, and without a skeleton, the auto-configuration classes are not extendable.

Design Goal

1. The starters shouldn't block customers from configuring any SDK-supported features, e.g., authentication methods, HTTP/AMQP options.
2. Customers use a consistent way to override the opinionated auto-configuration we provide.
3. A more Spring native way to configure, for example:
   • Accept RetryTemplate as the retry in Azure SDKs.
   • Logging.
4. Support well-defined Azure environments. Some Azure services define some well-known environments, and the starters should pick them up:
   • AZURE_KEYVAULT_ENDPOINT
5. We define a common framework to support all the Azure SDK client configurations to simplify all Azure SDK clients' instantiation process.
   • Adding new service support should be as simple as implementing a bunch of interfaces.

Solution Analysis

Azure SDK client builder pattern

All azure SDKs use a builder to configure options of different kinds, HTTP, AMQP, retry, etc., and then buildClient() or buildAsyncClient().

Service Configurations
Authentication
Retry Options
HTTP | AMQP
Client Options
Configuration (Environment)

Configurations could be divide into the below categories:

Category	Description
Service Configurations	Sevice specific configurations, such as customerProvidedKey in BlobClientBuilder, consumerGroup in EventHubClientBuilder.
Authentication	Authntication methods, such as credential(TokenCredential), credential(AzureNamedKeyCredential.
Retry Options	Retry options, such as EventHubClientBuilder.retry(AmqpRetryOptions), BlobClientBuilder.retry(RequestRetryOptions), SecretClientBuilder.retryPolicy(RetryPolicy).
HTTP | AMQP	Protocal related options, such as httpClient(HttpClient), httpPipeline(HttpPipeline), ServiceBusClientBuilder.proxyOptions(ProxyOptions).
Client Options	Configuration options for clients, such as applicationId, HTTP headers, and HTTP proxy options.
Configuration (Environment)	Passing a Configuration to client builders will give them the ability to read property value from system environment or properties, such as HTTP_PROXY, HTTPS_PROXY, etc.

Azure Spring Cloud Core

• Unify Azure SDK configurations setup in all Azure Spring starters #21972
• [FEATURE REQ] Enable/disable azure-spring-boot auto configurations based on properties #23367

[saragluna]

Closing this in favor of #23402.