Add dataSource & dataSourceManagement Readme

Signed-off-by: Kristen Tian <tyarong@amazon.com>

src/plugins/data_source/README.md

@@ -1,9 +1,73 @@
-# data_source
+# DataSource Plugin
 
 An OpenSearch Dashboards plugin
 
-This plugin introduces OpenSearch data source into OpenSearch Dashboards, and provides related functions to connect to OpenSearch data sources.
+This plugin introduces multiple OpenSearch data sources into OpenSearch Dashboards, and provides related functions to connect to OpenSearch data sources.
 
+## Configuration
+Update the following flags in the opensearch_dashboards.yml file to apply changes.
+
+1. The dataSource plugin is by default disabled, to enable it:
+`data_source.enabled=true`
+
+2. The audit trail is by default enabled for logging the accessing to data source, to disable it:
+`data_source.audit.eanbled = false`
+
+ - Current auditor configuration:
+```
+data_source.audit.appender.kind: 'file'
+data_source.audit.appender.layout.kind: 'pattern'
+data_source.audit.appender.path: '/tmp/opensearch-dashboards-data-source-audit.log'
+```
+
+3. The encryption realted config are default to:
+```
+data_source.encryption.wrappingKeyName: 'changeme'
+data_source.encryption.wrappingKeyNamespace: 'changeme'
+data_source.encryption.wrappingKey: [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
+```
+Note that if any of the encryption keyring config value changed (wrappingKeyName/wrappingKeyNamespace/wrappingKey), all current encrypted credientails cannot be decrypted; Therefore, credentials of previously created data sources must be updated to continue use.
+
+How to generate random wrapping key for testing?  
+Consider use an online generator or implementing customized logic. 
+
+## Public
+The public plugin is been used to control the enablement/disablement of the multidata source related feature in other plugin's public side. e.g. data_source_management, index_pattern_management
+
+- Add as a required dependency for whole plugin on/off switch
+- Add as opitional dependency for partial flow changes control
+
+## Server
+The provided data source client is integrated with default search strategy in data plugin. When data source id presented in IOpenSearchSearchRequest, data source client will be used.
+
+### Data Source Service
+The data source service will provide a data source client given a data source id and optional client configurations. 
+
+Currently supported client config is:
+- `data_source.clientPool.size`
+
+Data source service uses LRU cache to cache the root client to improve client pool usage.
+#### Example usage:
+In the RequestHandler, get data source client as such:
+```ts
+client: OpenSearchClient = await context.dataSource.opensearch.getClient(dataSourceId);
+
+//Support for legacy client
+apiCaller: LegacyAPICaller = context.dataSource.opensearch.legacy.getClient(dataSourceId).callAPI;
+```
+
+### Data Source Client Wrapper
+The data source saved object client wrapper overrides the write related action for data source object in order to perform validation and encryption actions of the authentication information inside data source.
+
+### Cryptograph Client
+The research issue regarding the solution selection: [#1756](https://github.com/opensearch-project/OpenSearch-Dashboards/issues/1756)
+#### Example usage:
+```ts
+//Encrypt
+const encryptedPassword = await this.cryptographyClient.encryptAndEncode(password);
+//Decrypt
+const decodedPassword = await this.cryptographyClient.decodeAndDecrypt(password);
+```
 ---
 
 ## Development

src/plugins/data_source_management/README.md

@@ -1,6 +1,19 @@
-# dataSourceManagement
+# DataSourceManagement Plugin
 
-An OpenSearch Dashboards plugin
+An OpenSearch Dashboards plugin for managing creation, update, list actions for data sources.
+
+## Creation
+Required inputs:
+
+- Title: title of the data source, no duplicted titles are allowed.
+- Description: description of the data source.
+- Endpoint URL: the connection endpoint of the data source.
+- Authentication: authentication information for the data source, currently two types of authentication are supported:
+  - No auth: no authentication information needed.
+  - Basic auth: user name & password.
+
+## Update
+Endpoint URL is immutable. If need to update endpoint, please go ahead and create a new data source.
 
 ---