Support Kubernetes native configuration management

spring-cloud-alibaba-dependencies/pom.xml

@@ -228,6 +228,18 @@
                 <version>${revision}</version>
             </dependency>
 
+            <dependency>
+                <groupId>com.alibaba.cloud</groupId>
+                <artifactId>spring-cloud-alibaba-kubernetes-commons</artifactId>
+                <version>${revision}</version>
+            </dependency>
+
+            <dependency>
+                <groupId>com.alibaba.cloud</groupId>
+                <artifactId>spring-cloud-starter-alibaba-kubernetes-config</artifactId>
+                <version>${revision}</version>
+            </dependency>
+
             <dependency>
                 <groupId>com.alibaba.spring</groupId>
                 <artifactId>spring-context-support</artifactId>

spring-cloud-alibaba-docs/src/main/asciidoc-zh/kubernetes-config.adoc

@@ -0,0 +1,145 @@
+== Spring Cloud Alibaba Kubernetes Config
+
+link:../asciidoc/kubernetes-config.adoc[English] | link:kubernetes-config.adoc[中文]
+
+该模块的目的是利用 Kubernetes ConfigMap/Secret 作为分布式配置中心，实现无需重启应用的动态配置更新。
+
+=== 快速开始
+
+参考 link:../../../../spring-cloud-alibaba-examples/kubernetes-config-example/README-zh.md[example]，按照文档运行一下 demo，你可以的！
+
+=== 主要特性
+
+如果你有使用 `spring-cloud-starter-alibaba-nacos-config` 的经验，你会发现其用法非常相似。`spring-cloud-starter-alibaba-kubernetes-config` 提供了 `spring-cloud-starter-alibaba-nacos-config` 的所有核心功能，并提供了更容易使用的配置，更好的性能和云原生程序契合度。
+
+==== 配置动态刷新（ConfigMap/Secret）
+
+当配置更新时，不需要重新启动应用程序，应用程序可以实时地动态更新配置。
+
+NOTE: Spring Cloud 提供了在运行时动态刷新环境的能力，这主要是动态更新两类 Bean 的属性：`@ConfigurationProperties` 和 `@RefreshScope` Bean。
+
+*最佳实践：使用 `@ConfigurationProperties` 来组织你的配置！*
+
+相关配置：
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        refreshable: false # 全局默认配置，默认值为 false
+        config-maps:
+          - name: my-configmap
+            refreshable: true # my-configmap 将检测配置更改并刷新
+        secrets:
+          - name: my-secret # my-secret 不会检测配置更改和刷新
+----
+
+==== 配置优先级
+
+如果本地的 `application.yml` 和 ConfigMap/Secret 中有相同的配置，可以选择优先使用哪个配置。
+
+相关配置：
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        preference: remote # 全局默认配置，默认值为remote，表示远程配置会覆盖本地配置
+        config-maps:
+          - name: my-configmap
+            preference: local
+----
+
+==== 多种配置文件格式
+
+支持 `yaml`、`properties`、`json` 和键值对配置。
+
+NOTE: Secret 只支持键值对！
+
+Example:
+
+ConfigMap:
+
+[source,yaml]
+----
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: my-configmap
+data:
+  blacklist.yml: |
+    blacklist:
+      user-ids:
+        - 1
+        - 2
+----
+
+Secret:
+
+[source,yaml]
+----
+apiVersion: v1
+kind: Secret
+metadata:
+  name: my-secret
+stringData:
+  blacklist.user-ids[0]: 1
+  blacklist.user-ids[1]: 2
+----
+
+上面的两个配置是等价的。
+
+==== 异常操作保护
+
+如果配置被错误地删除，你不希望你的应用程序崩溃，对吗？`spring-cloud-starter-alibaba-kubernetes-config` 提供了一个机制来保护应用程序免受异常操作的影响，比如误删配置。
+
+相关配置：
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        refresh-on-deleted: false # 当检测到配置被删除时，应用程序不会触发刷新。默认值为 false。
+----
+
+如果你的配置没有跨环境同步，你在 `dev` 环境中有 `import-config` 配置，但在 `prod` 环境中没有（有可能是你忘记同步到 `prod`），你可能希望有一个机制来帮助你发现这个问题，并提供快速失败的能力来阻止应用程序启动。
+
+相关配置：
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        fail-on-missing-config: true # 如果找不到配置，应用程序将无法启动。默认值为 true。
+----
+
+=== 核心配置
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        enabled: true
+        namespace: default # 配置所在的命名空间（全局配置）。如果在 Kubernetes 集群内部，则默认为当前 pod 所在的命名空间；如果在 Kubernetes 集群之外，则默认为当前 context 的命名空间。
+        preference: remote
+        refreshable: false
+        refresh-on-delete: false
+        fail-on-missing-config: true
+        config-maps:
+          - name: my-configmap
+            preference: remote
+            refreshable: true
+        secrets:
+          - name: my-secret
+            namespace: secret-namespace
+----

spring-cloud-alibaba-docs/src/main/asciidoc/kubernetes-config.adoc

@@ -0,0 +1,146 @@
+== Spring Cloud Alibaba Kubernetes Config
+
+link:kubernetes-config.adoc[English] | link:../asciidoc-zh/kubernetes-config.adoc[中文]
+
+The purpose of this module is to use Kubernetes ConfigMap/Secret as a distributed configuration center to achieve dynamic configuration updates without restarting the application.
+
+=== Quick Start
+
+Go to the link:../../../../spring-cloud-alibaba-examples/kubernetes-config-example/README.md[example] and follow the docs to run the example.
+You got this!
+
+=== Main Features
+
+If you have experience with `spring-cloud-starter-alibaba-nacos-config`, you will find out that the usage is very similar. `spring-cloud-starter-alibaba-kubernetes-config` has provided all the core features of `spring-cloud-starter-alibaba-nacos-config`, and provides more easier-to-use configurations, better performance and more in line with cloud-native.
+
+==== Dynamic update configuration（ConfigMap/Secret）
+
+You don't need to restart the application when the configuration is updated, and the application can dynamically update the configurations.
+
+NOTE: Spring Cloud provides the capability of dynamically refreshing the Environment at runtime, which mainly dynamically updates the properties of two types of beans: `@ConfigurationProperties` and `@RefreshScope` beans.
+
+*Best Practices: use `@ConfigurationProperties` to organize your configurations!*
+
+Related configuration:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        refreshable: false # global default config, default value is false
+        config-maps:
+          - name: my-configmap
+            refreshable: true # my-configmap will detect config change and refresh
+        secrets:
+          - name: my-secret # my-secret will NOT detect config change and refresh
+----
+
+==== Configuration priority
+
+If there are same configurations in both local `application.yml` and ConfigMaps/Secret, you can choose which configuration to use first.
+
+Related configuration:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        preference: remote # Global default config, default value is remote, means remote config will override local config
+        config-maps:
+          - name: my-configmap
+            preference: local
+----
+
+==== Multiple configuration file formats
+
+Supports configuration files in `yaml`, `properties`, `json` and key-value pair.
+
+NOTE: Secret only supports key-value pair!
+
+Example:
+
+ConfigMap:
+
+[source,yaml]
+----
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: my-configmap
+data:
+  blacklist.yml: |
+    blacklist:
+      user-ids:
+        - 1
+        - 2
+----
+
+Secret:
+
+[source,yaml]
+----
+apiVersion: v1
+kind: Secret
+metadata:
+  name: my-secret
+stringData:
+  blacklist.user-ids[0]: 1
+  blacklist.user-ids[1]: 2
+----
+
+The two configurations above convey the same meaning.
+
+==== Abnormal operation protection
+
+If config was deleted by mistake, you don't want your application to crash, right? `spring-cloud-starter-alibaba-kubernetes-config` provides a mechanism to protect the application from abnormal operation, such as deleting the configuration by mistake.
+
+Related configuration:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        refresh-on-deleted: false # when detect the config was deleted, the application will not trigger a refresh. Default value is false.
+----
+
+If your configuration is not synchronized across environments, and you have the `import-config` configuration in the `dev` environment but not in the `prod` environment (it is possible that you forgot to synchronize to `prod`), you may want to have a mechanism to help you find this problem and provide fail-fast ability to prevent the application from starting.
+
+Related configuration:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        fail-on-missing-config: true # application will fail to start if the configs not found. Default value is true.
+----
+
+=== Core Configurations
+
+[source,yaml]
+----
+spring:
+  cloud:
+    k8s:
+      config:
+        enabled: true
+        namespace: default # The namespace where the configuration is located (global configuration). If inside the Kubernetes cluster, it defaults to the namespace where the current pod is located; if outside the Kubernetes cluster, it defaults to the namespace of the current context.
+        preference: remote
+        refreshable: false
+        refresh-on-delete: false
+        fail-on-missing-config: true
+        config-maps:
+          - name: my-configmap
+            preference: remote
+            refreshable: true
+        secrets:
+          - name: my-secret
+            namespace: secret-namespace
+----

spring-cloud-alibaba-examples/kubernetes-config-example/README-zh.md

@@ -0,0 +1,62 @@
+## Spring Cloud Starter Alibaba Kubernetes Config Example
+
+[English](README.md) | [中文](README-zh.md)
+
+这个例子演示了使用 `spring-cloud-starter-alibaba-kubernetes-config` 来实现一个动态黑名单功能。
+
+### 步骤
+
+1. Apply [deployments.yaml](./deployments.yaml) 文件
+
+   确保在 `kubernetes-config-example` 目录。
+
+   ```shell
+   kubectl apply -f deployments.yaml
+   ```
+
+2. 启动程序
+
+3. 访问应用
+
+   ```shell
+   curl localhost:8080/echo -H 'x-user-id:1'
+   ```
+
+   可以看到用户 `1` 已经被 block 了，可以查看 [deployments.yaml](./deployments.yaml) 得知 blocked 的用户 id。
+
+4. 修改 [deployments.yaml](./deployments.yaml) 文件中的 `blacklist` 配置。
+
+   ```yaml
+   apiVersion: v1
+   kind: ConfigMap
+   metadata:
+      name: configmap-01
+      namespace: default
+   data:
+      blacklist.yml: |
+         blacklist:
+           user-ids: 
+             - 2
+   ```
+
+   再次 apply
+
+    ```shell
+    kubectl apply -f deployments.yaml
+    ```
+
+5. 再次访问应用
+
+    ```shell
+    curl localhost:8080/echo -H 'x-user-id:1'
+    ```
+
+   可以看到用户 `1` 不再被 block，现在只有用户 `2` 被 block。
+
+6. 删除资源
+
+   确保在 `kubernetes-config-example` 目录。
+
+   ```shell
+   kubectl delete -f deployments.yaml
+   ```