Custom Plugin

Description

• Plugins are core executors of Apache ShenYu gateway. Every plugin handles matched requests when enabled.
• There are two kinds of plugins in the Apache ShenYu gateway.
  • The first type is a chain with single responsibility, and can not custom filtering of traffic.
  • The other one can do its own chain of responsibility for matched traffic.
• You could reference from shenyu-plugin module and develop plugins by yourself. Please fire pull requests of your wonderful plugins without hesitate.

Single Responsibility Plugins

• Add following dependency:

<dependency>
    <groupId>org.apache.shenyu</groupId>
    <artifactId>shenyu-plugin-api</artifactId>
    <version>${project.version}</version>
</dependency>

• Declare a new class named MyShenyuPlugin and implements org.apache.shenyu.plugin.api.ShenyuPlugin

public interface ShenyuPlugin {

    /**
     * Process the Web request and (optionally) delegate to the next
     * {@code WebFilter} through the given {@link ShenyuPluginChain}.
     *
     * @param exchange the current server exchange
     * @param chain    provides a way to delegate to the next filter
     * @return {@code Mono<Void>} to indicate when request processing is complete
     */
    Mono<Void> execute(ServerWebExchange exchange, ShenyuPluginChain chain);

    /**
     * return plugin order .
     * This attribute To determine the plugin execution order in the same type plugin.
     *
     * @return int order
     */
    int getOrder();

    /**
     * acquire plugin name.
     * this is plugin name define you must offer the right name.
     * if you impl AbstractShenyuPlugin this attribute not use.
     *
     * @return plugin name.
     */
    default String named() {
        return "";
    }

    /**
     * plugin is execute.
     * if return true this plugin can not execute.
     *
     * @param exchange the current server exchange
     * @return default false.
     */
    default Boolean skip(ServerWebExchange exchange) {
        return false;
    }
}

Detailed instruction of interface methods:

• execute() core method, you can do any task here freely.
• getOrder() get the order of current plugin.
• named() acquire the name of specific plugin that uses the Camel Case, eg: dubbo, springCloud .
• skip() determines whether this plugin should be skipped under certain conditions.
• Register plugin in Spring as a Bean, or simply apply @Component in implementation class.

    @Bean
    public ShenyuPlugin myShenyuPlugin() {
        return new MyShenyuPlugin();
    }

Matching Traffic Processing Plugin

• Introduce the following dependency:

 <dependency>
        <groupId>org.apache.shenyu</groupId>
        <artifactId>shenyu-plugin-base</artifactId>
        <version>${project.version}</version>
  </dependency>

• Add a new class CustomPlugin, inherit from org.apache.shenyu.plugin.base.AbstractShenyuPlugin

• examples down below:

/**
 * This is your custom plugin.
 * He is running in after before plugin, implement your own functionality.
 * extends AbstractShenyuPlugin so you must user shenyu-admin And add related plug-in development.
 *
 * @author xiaoyu(Myth)
 */
public class CustomPlugin extends AbstractShenyuPlugin {

    /**
     * return plugin order .
     * The same plugin he executes in the same order.
     *
     * @return int
     */
    @Override
    public int getOrder() {
        return 0;
    }

    /**
     * acquire plugin name.
     * return you custom plugin name.
     * It must be the same name as the plug-in you added in the admin background.
     *
     * @return plugin name.
     */
    @Override
    public String named() {
        return "shenYu";
    }

    /**
     * plugin is execute.
     * Do I need to skip.
     * if you need skip return true.
     *
     * @param exchange the current server exchange
     * @return default false.
     */
    @Override
    public Boolean skip(final ServerWebExchange exchange) {
        return false;
    }

    /**
     * this is Template Method child has Implement your own logic.
     *
     * @param exchange exchange the current server exchange
     * @param chain    chain the current chain
     * @param selector selector
     * @param rule     rule
     * @return {@code Mono<Void>} to indicate when request handling is complete
     */
    @Override
    protected abstract Mono<Void> doExecute(ServerWebExchange exchange, ShenyuPluginChain chain, SelectorData selector, RuleData rule) {
        LOGGER.debug(".......... function plugin start..............");
        /*
         * Processing after your selector matches the rule.
         * rule.getHandle() is you Customize the json string to be processed.
         * for this example.
         * Convert your custom json string pass to an entity class.
         */
        final String ruleHandle = rule.getHandle();

        final Test test = GsonUtils.getInstance().fromJson(ruleHandle, Test.class);

        /*
         * Then do your own business processing.
         * The last execution  chain.execute(exchange).
         * Let it continue on the chain until the end.
         */
        System.out.println(test.toString());
        return chain.execute(exchange);
    }
}

• Detailed explanation:

  • Plugins will match the selector rule for customized plugins inherit from this abstract class.

  • Firstly define a new plugin in shenyu-admin –> BasicConfig –> Plugin, please mind that your plugin name should match the named() method overridden in your class.

  • Re-login shenyu-admin, the plugin you added now showing on plugin-list page, you can choose selectors for matching.

  • There is a field named handler in rules, it is customized json string to be processed. You can process data after acquiring a ruleHandle (final String ruleHandle = rule.getHandle();) in doExecute() method.

• Register plugin in Spring as a Bean, or simply apply @Component in implementation class.

    @Bean
    public ShenyuPlugin customPlugin() {
        return new CustomPlugin();
    }

Subscribe your plugin data and do customized jobs

• Declare a new class named PluginDataHandler and implements org.apache.shenyu.plugin.base.handler.PluginDataHandler

public interface PluginDataHandler {

    /**
     * Handler plugin.
     *
     * @param pluginData the plugin data
     */
    default void handlerPlugin(PluginData pluginData) {
    }

    /**
     * Remove plugin.
     *
     * @param pluginData the plugin data
     */
    default void removePlugin(PluginData pluginData) {
    }

    /**
     * Handler selector.
     *
     * @param selectorData the selector data
     */
    default void handlerSelector(SelectorData selectorData) {
    }

    /**
     * Remove selector.
     *
     * @param selectorData the selector data
     */
    default void removeSelector(SelectorData selectorData) {
    }

    /**
     * Handler rule.
     *
     * @param ruleData the rule data
     */
    default void handlerRule(RuleData ruleData) {
    }

    /**
     * Remove rule.
     *
     * @param ruleData the rule data
     */
    default void removeRule(RuleData ruleData) {
    }

    /**
     * Plugin named string.
     *
     * @return the string
     */
    String pluginNamed();

}

• Ensure pluginNamed() is same as the plugin name you defined.
• Register defined class as a Spring Bean, or simply apply @Component in implementation class.

@Bean
public PluginDataHandler pluginDataHandler() {
  return new PluginDataHandler();
}

Dynamic loading

• When using this feature, the above extensions ShenyuPlugin, PluginDataHandler, do not need to be spring bean. You just need to build the jar package of the extension project.

• Config in Yaml：

shenyu:
  extPlugin:
    path:  //Load the extension plugin jar package path
    enabled: true //Whether to turn on 
    threads: 1  //Number of loading plug-in threads
    scheduleTime: 300  //Cycle time (in seconds)
    scheduleDelay: 30 //How long the shenyu gateway is delayed to load after it starts (in seconds)

Plugin loading path details

• This path is for the directory where the extended plugin jar package is stored。

• Used -Dplugin-ext=xxxx, Also used shenyu.extPlugin.path in yaml，If neither is configured, the ext-lib directory in the apache shenyu gateway boot path will be loaded by default.

• Priority ：-Dplugin-ext=xxxx > shenyu.extPlugin.path > ext-lib(default)