Exception on reloading remote spring boot application with Intellij IDEA

Question

I'm trying to setup remote spring-boot environment using spring devtools, docker and IntelliJ. All started with this article. Unfortunately it randomly fails with an exception. Below the configuration:

Dockerfile

FROM        java:8

EXPOSE      8888

WORKDIR     /app

ADD         build.gradle    /app/build.gradle
ADD         gradlew         /app/gradlew
ADD         gradle          /app/gradle

ADD         src             /app/src

RUN         ["chmod", "+x", "/app/gradlew"]

docker-compose.yml

backend:
  build: .
  env_file: environment
  ports:
    - "8888:8888"
  volumes:
    - ./.gradle-docker:/root/.gradle
  command: "/app/gradlew clean bootRun"
  links:
    - db

db:
  image:  postgres:9.5.3
  env_file: environment
  ports:
    - "5454:5432"

The whole application is started from command line with: docker-compose build and docker-compose up commands.

In IntelliJ I've prepared the following java application configuration:

where docker:8888 is the IP of the docker-machine and port that is used by spring application. After the configuration is run is the following output:

/\\ / ___'_ __ _ _(_)_ __  __ _          ___               _      \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` |        | _ \___ _ __  ___| |_ ___ \ \ \ \
\\/  ___)| |_)| | | | | || (_| []::::::[]   / -_) '  \/ _ \  _/ -_) ) ) ) )
 '  |____| .__|_| |_|_| |_\__, |        |_|_\___|_|_|_\___/\__\___|/ / / /
=========|_|==============|___/===================================/_/_/_/
:: Spring Boot Remote ::  (v1.3.5.RELEASE)

2016-07-06 12:48:51.997  INFO 17731 --- [           main] o.s.b.devtools.RemoteSpringApplication   : Starting RemoteSpringApplication v1.3.5.RELEASE on opal-mac.local with PID 17731 (/Users/opal/.gradle/caches/modules-2/files-2.1/org.springframework.boot/spring-boot-devtools/1.3.5.RELEASE/ab035bdc1e6297ff4c8676edd93ed307b11353c2/spring-boot-devtools-1.3.5.RELEASE.jar started by opal in /Users/opal/projects/backend)
2016-07-06 12:48:52.013  INFO 17731 --- [           main] o.s.b.devtools.RemoteSpringApplication   : No active profile set, falling back to default profiles: default
2016-07-06 12:48:52.106  INFO 17731 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@441772e: startup date [Wed Jul 06 12:48:52 CEST 2016]; root of context hierarchy
2016-07-06 12:48:54.016  WARN 17731 --- [           main] o.s.b.d.r.c.RemoteClientConfiguration    : The connection to http://docker:8888 is insecure. You should use a URL starting with 'https://'.
2016-07-06 12:48:54.419  WARN 17731 --- [           main] o.s.b.d.a.OptionalLiveReloadServer       : Unable to start LiveReload server
2016-07-06 12:48:54.499  INFO 17731 --- [           main] o.s.b.devtools.RemoteSpringApplication   : Started RemoteSpringApplication in 3.793 seconds (JVM running for 5.004)

Unfortunately after some change is made to the code, the following exception occurs:

2016-07-06 12:49:29.141  INFO 17731 --- [   File Watcher] o.s.b.d.r.c.ClassPathChangeUploader      : Uploaded 1 class resource
2016-07-06 12:49:31.056  INFO 17731 --- [   File Watcher] o.s.b.d.r.c.ClassPathChangeUploader      : Uploaded 1 class resource
Exception in thread "File Watcher" java.lang.IllegalStateException: java.net.ConnectException: Connection refused
    at org.springframework.boot.devtools.remote.client.ClassPathChangeUploader.onApplicationEvent(ClassPathChangeUploader.java:107)
    at org.springframework.boot.devtools.remote.client.ClassPathChangeUploader.onApplicationEvent(ClassPathChangeUploader.java:56)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:166)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:138)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:381)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:335)
    at org.springframework.boot.devtools.classpath.ClassPathFileChangeListener.publishEvent(ClassPathFileChangeListener.java:68)
    at org.springframework.boot.devtools.classpath.ClassPathFileChangeListener.onChange(ClassPathFileChangeListener.java:64)
    at org.springframework.boot.devtools.filewatch.FileSystemWatcher.fireListeners(FileSystemWatcher.java:230)
    at org.springframework.boot.devtools.filewatch.FileSystemWatcher.updateSnapshots(FileSystemWatcher.java:223)
    at org.springframework.boot.devtools.filewatch.FileSystemWatcher.scan(FileSystemWatcher.java:183)
    at org.springframework.boot.devtools.filewatch.FileSystemWatcher.access$100(FileSystemWatcher.java:41)
    at org.springframework.boot.devtools.filewatch.FileSystemWatcher$1.run(FileSystemWatcher.java:150)
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
    at sun.net.www.http.HttpClient.<init>(HttpClient.java:211)
    at sun.net.www.http.HttpClient.New(HttpClient.java:308)
    at sun.net.www.http.HttpClient.New(HttpClient.java:326)
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1169)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1105)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:999)
    at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:933)
    at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:80)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
    at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:93)
    at org.springframework.boot.devtools.remote.client.HttpHeaderInterceptor.intercept(HttpHeaderInterceptor.java:57)
    at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:85)
    at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:69)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
    at org.springframework.boot.devtools.remote.client.ClassPathChangeUploader.onApplicationEvent(ClassPathChangeUploader.java:102)
    ... 12 more

In docker and IntelliJ:

2016-07-06 12:49:29.141  INFO 17731 --- [   File Watcher] o.s.b.d.r.c.ClassPathChangeUploader      : Uploaded 1 class resource

logs I see that the context is reloaded. What may be the problem?

Answer 1

There's a bug in Spring boot's DevTools which means that if you make a change to your application while the restart that was triggered by the previous change is still in progress, the attempt to upload the changes will fail. I think we probably need to update DevTools to retry the upload attempt.

In the meantime, the only "solution" is to stop and restart your RemoteSpringApplication whenever you see the failure due to java.net.ConnectException: Connection refused.