# Plugin Configuration

This document describes how to define a configuration item in the plugin and use the configuration item in the plugin. This article is only for static configuration. If you need to use the dynamic configuration item, see Dynamic Configuration.

# Function Introduction

Plugin configuration allows plugin developers to specify some variable amount of plugin deployment through the configuration file, improve the flexibility of plugin development, and configure different values for these variables in different deployment environments to adapt to different .

Note： If you modify the configuration file when the service is running, you need to restart the service to obtain the modified configuration content.

# Development Examples

This development example is based on Create first plugin document to create the project.

Add the following to the config.yaml file in the template\config directory：

template.config:
  enable-dynamic-config: false
  host: 127.0.0.1

Define a plugin configuration class under the template\template-plugin project. It needs to inherit the PluginConfig (opens new window) plugin configuration interface, and specify the ConfigTypeKey (opens new window) class to read the prefix of the configuration. Specify the name of the configuration for this variable by decorating the variable in the class with ConfigFieldKey (opens new window) (or, if not, reading the configuration with the same name as the variable).

@ConfigTypeKey(value = "template.config")
public class TemplateConfig implements PluginConfig {
    @ConfigFieldKey("enable-dynamic-config")
    private boolean enableDynamicConfig;

    private String host;

    public boolean isEnableDynamicConfig() {
        return enableDynamicConfig;
    }

    public void setEnableDynamicConfig(boolean enableDynamicConfig) {
        this.enableDynamicConfig = enableDynamicConfig;
    }

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }
}

For main method of the interceptor before method through io.sermant.core.plugin.config.PluginConfigManager (opens new window) get configuration instance, content and output configuration.

@Override
public ExecuteContext before(ExecuteContext context) throws Exception {
        TemplateConfig templateConfig = PluginConfigManager.getPluginConfig(TemplateConfig.class);
        System.out.println(templateConfig.isEnableDynamicConfig());
        System.out.println(templateConfig.getHost());
        System.out.println("Good morning!");
        return context;
}

Finally, don't forget to add the SPI profile of the plugin configuration:

  • In engineering template\template-plugin module under src\main\resources\META-INF\services directory to add io.sermant.core.plugin.config.PluginConfig configuration file.
  • Add com.huaweicloud.sermant.template.TemplateConfig to io.sermant.core.plugin.config.PluginConfig file.

After the development is completed, you can refer to the packaging construction process when creating the first plugin, execute mvn package in the project root directory, and execute cd agent/ in the root directory after completion, and run the test application with Sermant in it. Execute the command java-javaagent: sermant-agent.jar-jar Application.jar. The console output is as follows:

[xxxx-xx-xxTxx:xx:xx.xxx] [INFO] Loading god library into BootstrapClassLoader.
[xxxx-xx-xxTxx:xx:xx.xxx] [INFO] Building argument map by agent arguments.
[xxxx-xx-xxTxx:xx:xx.xxx] [INFO] Loading core library into SermantClassLoader.
[xxxx-xx-xxTxx:xx:xx.xxx] [INFO] Loading sermant agent, artifact is: default
[xxxx-xx-xxTxx:xx:xx.xxx] [INFO] Load sermant done, artifact is: default
false
127.0.0.1
Good morning!
Good afternoon!
Good night!

You can see that in the plugin, we have already obtained the configuration information that we have in the configuration file.

# API&Configuration

# API

# Get Configuration Example

Gets a configuration instance to get what was configured in the yaml file during plugin usage. The configuration instance is created when the framework is initialized, and the plugin can be used directly.

// ${plugin config class} is the Class configured by the plugin
PluginConfigManager.getPluginConfig(${plugin config class});

# Configuration

The data types now supported by the plugin configuration include:

  • Basic types and packaging types of Boolean and numerical classes
template.config:
  enable-dynamic-config: false
  num: 11
  rate: 11.11
  • String type
template.config:
  host: 127.0.0.1
  • Enumeration type
template.config:
  status: UP
  • Complex object type
template.config:
  teacher:
    name: Mr. Wang
    age: 48
  student:
    name: Xiao Li
    age: 12
  • An array of the above types
template.config:
  arrayValue:
    - January
    - February
  • The first four types form a List
template.config:
  listValue:
    - NewYork
    - 12
    - 127.0.0.1
  • The first four types form a Map
template.config:
  mapValue:
    name: Xiao Li
    age: 12

Note：

  • The priority for the configuration to take effect: Startup Parameters > Environment Variables > System Variables (-D parameter) > yaml file configuration.
  • The field names of configuration classes are typically small camel cases.You can use the ConfigFieldKey (opens new window) annotation to define aliases with underscores. Note:
    • After adding annotation, you can parse using a hyphen or small hump in yaml.
    • ConfigFieldKey (opens new window) fixing property names is not supported for complex objects involved in arrays, lists, and maps.
  • String properties inside the plug-in configuration class and complex type properties support ${} to get property values set in startup parameters, environment variables, or system variables (-D arguments). Strings in arrays, lists, and maps do not support obtaining property values by ${}.
  • If the attributes of the plugin configuration class are not defined in the yaml configuration file, the attribute values are obtained based on the priority at which the configuration takes effect. When obtaining attribute values, note:
    • Only basic data types, arrays, maps, lists, and sets are supported. Complex objects are not supported.
    • Array, list, set should be configured in yaml string format, e.g. LIST_NAME=[elem1, elem2].
    • Map must be in yaml string format, e.g. MAP_NAME={key1: value1, key2: value2}.
Last Updated: 10/18/2024, 1:29:22 AM

← Dynamic Configuration Function →