+++
title = "Config Center"
weight = 1
+++

## Motivation

- Centralized configuration: more and more running examples have made it hard to manage separate configurations and asynchronized configurations can cause serious problems. Concentrating them in the configuration center can make the management more effective.

- Dynamic configuration: distribution after configuration modification is another important capability of configuration center. It can support dynamic switch between data sources and rule configurations.

## Structure in Configuration Center

Under defined namespace, configuration center stores data sources, rule configurations, authentication configuration, and properties in YAML. Modifying nodes can dynamically refresh configurations.

```
namespace
    ├──authentication                            # Authentication configuration
    ├──props                                     # Properties configuration
    ├──schemas                                   # Schema configuration
    ├      ├──${schema_1}                        # Schema name 1
    ├      ├      ├──datasource                  # Datasource configuration
    ├      ├      ├──rule                        # Rule configuration
    ├      ├      ├──table                       # Table configuration
    ├      ├──${schema_2}                        # Schema name 2
    ├      ├      ├──datasource                  # Datasource configuration
    ├      ├      ├──rule                        # Rule configuration
    ├      ├      ├──table                       # Table configuration
```

### /authentication

Authentication configuration. Can configure username and password for ShardingSphere-Proxy.

```yaml
username: root
password: root
```

### /props

Properties configuration. Please refer to [Configuration Manual](/en/user-manual/shardingsphere-jdbc/configuration/) for more details.

```yaml
executor-size: 20
sql-show: true
```

### /schemas/${schemeName}/datasource

A collection of multiple database connection pools, whose properties (e.g. DBCP, C3P0, Druid and HikariCP) are configured by users themselves.

```yaml
dataSources:
  ds_0: 
    dataSourceClassName: com.zaxxer.hikari.HikariDataSource
    props:
      url: jdbc:mysql://127.0.0.1:3306/demo_ds_0?serverTimezone=UTC&useSSL=false
      password: null
      maxPoolSize: 50
      maintenanceIntervalMilliseconds: 30000
      connectionTimeoutMilliseconds: 30000
      idleTimeoutMilliseconds: 60000
      minPoolSize: 1
      username: root
      maxLifetimeMilliseconds: 1800000
  ds_1: 
    dataSourceClassName: com.zaxxer.hikari.HikariDataSource
    props:
      url: jdbc:mysql://127.0.0.1:3306/demo_ds_1?serverTimezone=UTC&useSSL=false
      password: null
      maxPoolSize: 50
      maintenanceIntervalMilliseconds: 30000
      connectionTimeoutMilliseconds: 30000
      idleTimeoutMilliseconds: 60000
      minPoolSize: 1
      username: root
      maxLifetimeMilliseconds: 1800000
```

### /schemas/${schemeName}/rule

Rule configurations, including sharding, replica query, data encryption, shadow DB configurations.

```yaml
rules:
- !SHARDING
  xxx
  
- !REPLICA_QUERY
  xxx
  
- !ENCRYPT
  xxx
```

### /schemas/${schemeName}/table

Dynamic modification of metadata content is not supported currently.

```yaml
tables:                                       # Tables
  t_order:                                    # table_name
    columns:                                  # Columns
      id:                                     # column_name
        caseSensitive: false
        dataType: 0
        generated: false
        name: id
        primaryKey: trues
      order_id:
        caseSensitive: false
        dataType: 0
        generated: false
        name: order_id
        primaryKey: false
    indexs:                                   # Indexes
      t_user_order_id_index:                  # index_name
        name: t_user_order_id_index
  t_order_item:
    columns:
      order_id:
        caseSensitive: false
        dataType: 0
        generated: false
        name: order_id
        primaryKey: false
  addressingDataSources:                      # Actual data source names
    - ds_0
    - ds_1
```

## Dynamic Effectiveness

Modification, deletion and insertion of relevant configurations in the config center will immediately take effect in the producing environment.