[FEATURE REQ] Make spring-cloud-azure-starter-keyvault-secrets' configuration properties more reasonable

[chenrujun]

Context

In #28128 (comment), @stliu think current property's behavior does not reasonable.

Problem

spring:
  cloud:
    azure:
      profile:
        tenant-id: ${AZURE_TENANT_ID}
      credential:
        client-id: ${AZURE_CLIENT_ID}
        client-secret: ${AZURE_CLIENT_SECRET}
      keyvault:
        secret:
          property-source-enabled: true
          endpoint: ${AZURE_KEYVAULT_ENDPOINT}

If we satisfy this requirement, some other property may confuse customer. For example: Does spring.cloud.azure.keyvault.secret.enable or spring.cloud.azure.keyvault.secret.enable can be used to disable all Key Vault property-source?

Goal

For spring-cloud-azure-starter-keyvault-secret's cofigurable properties, design each property's function, implement it, and explain it well in reference doc and changelog.

Solution

Here is a proposal about each property's function:

Yaml File Examples

spring:
  cloud:
    azure: # 1
      profile: # 2
        tenant-id: # 3
      credential: # 4
        client-id: # 5
        client-secret: # 6
      keyvault: # 7
        secret: # 8
          enabled: # 9
          property-source-enabled: # 10
          endpoint: # 11
          profile: # 12
            tenant-id: # 13
          credential: # 14
            client-id: # 15
            client-secret: # 16
          property-sources: # 17
          - name: # 18
            enabled: # 19
            endpoint: # 20
            profile: # 21
              tenant-id: # 22
            credential: # 23
              client-id: # 24
              client-secret: # 25
          - name: # 26
            enabled: # 27
            endpoint: # 28
            profile: # 29
              tenant-id: # 30
            credential: # 31
              client-id: # 32
              client-secret: # 33

Behavior Changes

# 11 ~ # 16:

1. Current behavior in version 4.0.0: this property is only used to configure a SecretClient bean, this SecretClient will not enable the feature of property-source.
2. New designed behavior: this property can be used to configure both SecretClient bean and enable the feature of property-source.

# 10:

1. Current behavior in version 4.0.0: It's used to enable/disable all property-source configured in #17 ~ #33.
2. New designed behavior: It's used to enable/disable the property-source configured in # 11 ~ # 16. Note: It has no relationship with property-source configured in #17 ~ #33.

# 9:

1. Current behavior in version 4.0.0: It's used to enable /disable the SecretClientbean configured by# 11~# 16`.
2. New designed behavior: It's used to enable / disable all features configured in #10 ~ #33.

Disable All Property-Sources:
In new design, there is no property used to disable all property-sources.

Priority of Property-Sources

1. # 11 has the highest priority.
2. For the property-sources configured in # 17, the priority is decided by the order. For example: # 18 has higher priority than # 26.

Behavior Not Changed

All other behaviors not changed. For example:

1. If # 13 is not configured, it will use # 3 instead.
2. If # 22 is not configured, it will use # 3 instead. Note: It has no relationship with #13.

[ezYakaEagle442]

@chenrujun sorry but this is still not clear, if there is spring.cloud.azure.keyvault.secret.endpoint why then shall spring.cloud.azure.keyvault.secret.property-sources[].endpoint should be filled ?

I did not have spring.cloud.azure.keyvault.secret.endpoint in my yaml config file and hit those errors :

Caused by: java.net.MalformedURLException: no protocol: ${ENDPOINT}
Caused by: java.lang.IllegalArgumentException: The Azure Key Vault url is malformed.
java.lang.IllegalStateException: Failed to configure KeyVault property source

Also why does the docs at https://learn.microsoft.com/en-us/training/modules/secure-application-secrets-use-key-vault/6-update-application-configure refers to azure.keyvault.uri ??

Azure:
    keyvault:
        enabled: true
            uri:

Why shall I start my App with JVM options below ? :
-Dazure.keyvault.uri=https://kv-XXXXXX.vault.azure.net -Xms512m -Xmx1024m -Dspring.profiles.active=mysql,key-vault,cloud

[chenrujun]

@ezYakaEagle442

Also why does the docs at https://learn.microsoft.com/en-us/training/modules/secure-application-secrets-use-key-vault/6-update-application-configure

As discussed by email, the page is out dated.

[stliu]

closing in favor of #30544