Hot Deploy beta

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1. What is hot deployment

The traditional deployment process is generally submit code->pull code->package->deploy->restart project before the written code can take effect.

Hot deployment can skip this tedious process. After the developer modifies the code, there is no need to manually trigger packaging or restart the service. The application can load the new logic and run in seconds, greatly shortening the feedback cycle.

Hot deployment is based on hot reload. Hot reload only supports local environment, while hot deployment allows remote applications to be hot reloaded.

2. Enable hot deployment

TIP

Hot deployment requires a specific JDK to take effect. Please refer to JDK Installation to complete JDK initialization.

2.1 Add JVM parameters

[Java 8] Add the following JVM parameters when starting.

-XXaltjvm=dcevm -javaagent:${agentPath}/debug-tools-agent.jar=${conf}

[Java 11] Add the following JVM parameters when starting.

-javaagent:${agentPath}/debug-tools-agent.jar=${conf} --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/jdk.internal.loader=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED --add-opens java.desktop/java.beans=ALL-UNNAMED --add-opens java.desktop/com.sun.beans=ALL-UNNAMED --add-opens java.desktop/com.sun.beans.introspect=ALL-UNNAMED --add-opens java.desktop/com.sun.beans.util=ALL-UNNAMED --add-opens java.base/sun.security.action=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.net=ALL-UNNAMED

[Java 17/21] Add the following JVM parameters when starting.

-XX:+AllowEnhancedClassRedefinition -javaagent:${agentPath}/debug-tools-agent.jar=${conf} --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/jdk.internal.loader=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED --add-opens java.desktop/java.beans=ALL-UNNAMED --add-opens java.desktop/com.sun.beans=ALL-UNNAMED --add-opens java.desktop/com.sun.beans.introspect=ALL-UNNAMED --add-opens java.desktop/com.sun.beans.util=ALL-UNNAMED --add-opens java.base/sun.security.action=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.net=ALL-UNNAMED

• agentPath is the path of debug-tools-agent.jar
• conf is the configuration information passed to the agent, in the format of key1=value1,key2=value2

2.2 Optional configuration

Optional key	Meaning	Value	Example
hotswap	Whether to enable hot reload/hot deployment	true: Enable false: Disable	true
server	Whether to start the server for client connections	true: Enable false: Disable	true
tcpPort	TCP port to listen to (valid only when server=true)	Available ports	12345
httpPort	HTTP port to listen to (valid only when server=true)	Available ports	22222
printSql	Whether to print the executed SQL statement	true: Enable false: Disable	true
propertiesFilePath	External configuration file path	Configuration file address	/etc/debug-tools/conf/debug-tools-agent.properties

propertiesFilePath configuration

key	meaning	default value
hotswap	whether to enable hot reload/hot deployment (same as above)	true
server	whether to start the server for client connection (same as above)	true
tcpPort	TCP port to listen on (valid only when server=true) (same as above)	default, start from 12345 to find available ports
httpPort	HTTP port to listen on (valid only when server=true) (same as above)	default, start from 22222 to find available ports
lombokJarPath	lombok.jar path, if lombok is used during remote dynamic compilation, it needs to be specified to compile (same as above)	-
printSql	whether to print the executed SQL statement	false
includedClassLoaderPatterns	ClassLoader to initialize hot reload/hot deployment. Only one of the excludedClassLoaderPatterns can be configured at the same time	-
excludedClassLoaderPatterns	The ClassLoader to be excluded from initialization reloading/hot deployment. Only one can be configured at the same time with includedClassLoaderPatterns	-
pluginPackages	Scan plugins written on other paths, multiple paths are separated by commas	-
extraClasspath	MacOS/Linux loads extended class file path	/var/tmp/debug-tools/classes
extraClasspathWin	Windows loads extended class file path	c:/var/tmp/debug-tools/classes
watchResources	MacOS/Linux monitor resource path	/var/tmp/debug-tools/resources
watchResourcesWin	Windows monitor resource path	c:/var/tmp/debug-tools/resources
spring.basePackagePrefix	Spring base package prefix, multiple paths are separated by commas	-
disabledPlugins	Disabled plugins, multiple commas are separated	-
autoHotswap	Whether to automatically hot reload. Reloads class definitions in a running application after watching for changed class files in the ClassLoader's resources path. It uses the Java Instrumentation API to reload class bytecode.	false
autoHotswap.port	JPDA connection port, listens for changed files and performs hot reload, you need to specify the JPDA port when starting.	-

3. Connecting to a remote service

Click the toolbar on the right side of Idea to wake up the DebugTools window, and click to fill in the remote address.

Enter host, tcpPort and httpPort, and click the Save & Connent button to connect the remote application.

After successfully attaching the application, DebugTools will display the attachment status.

• R: indicates that the application is a remote application, and L indicates that it is a local application.
• Connected: the application has been successfully attached and connected to the service.
• i.g.f.d.t.t.a.DebugToolsTestApplication: the application name.
  • Specified application name if the application name is specified during attachment.
  • If the application name is not specified, the spring.application.name configuration item is used if it is a Spring application.
  • If not specified, the Main-Class in the jar at startup is used.
  • If not found, the sun.java.command in the startup command is used.

4. Using hot reload

4.1 Multiple files

Click the button to wake up the main page.

After selecting the file to be deployed

• Compiler Type: file compilation method
  • Local Intellij Idea: compile the changed files through the idea compiler
  • Remote Attach Application: remote dynamic compilation of the changed files through the attached application
• Select Type: file selection method
  • Java: changed java files
  • Resources: changed resource files (pending)
  • Vcs: select to obtain file changes through the vcs tool, and do not select to obtain file changes through the file modification time

Click the OK button and wait for the compilation to complete. After the compilation is completed, a prompt for successful compilation will pop up.

TIP

• Hot reloading of changed files through hot deployment is supported only after the application is attached
• When using remote dynamic compilation, the attached application must be started through JDK, not JRE.

4.2 Single file remote compilation

The Remote Compile 'xxx' to Hot Reload button in the right-click menu can be used to hot reload a single changed file through remote dynamic compilation.

After hot deployment is completed, a prompt will pop up indicating successful compilation.

TIP

• Hot reloading of changed files through hot deployment is only supported after the application is attached
• When using remote dynamic compilation, the attached application must be started through JDK, not JRE.