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Web server failed to start. Port 8080 was already in use. Spring Boot microservice

I am trying to call webAPI from gradle project.
My build.gradle is as following.
plugins {
id 'org.springframework.boot' version '2.1.4.RELEASE'
id 'java'
}
apply plugin: 'io.spring.dependency-management'
dependencies {
implementation 'org.springframework.boot:spring-boot-starter'
runtimeOnly 'org.springframework.boot:spring-boot-devtools'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
compile 'org.springframework.boot:spring-boot-starter-webflux'
compile 'org.projectreactor:reactor-spring:1.0.1.RELEASE'
}
If I remove following dependency
compile 'org.springframework.boot:spring-boot-starter-webflux'
It works, but if I add it back. it gives error as
Web server failed to start. Port 8080 was already in use.
So, how do I fix this, so that I can use webclient? Because application is not web application which requires port to run. it is a sort of microservice.
I just want to use WebClient of Spring Boot. How do i use it without converting my application into web application.

If on windows and your getting this every time you run the application you need to keep doing:
> netstat -ano | findstr *<port used>*
TCP 0.0.0.0:*<port used>* 0.0.0.0:0 LISTENING *<pid>*
TCP [::]:*<port used>* [::]:0 LISTENING *<pid>*
> taskkill /F /PID *<pid>*
SUCCESS: The process with PID *<pid>* has been terminated.
If netstat above includes something like this;
TCP [zzzz:e2ce:44xx:1:axx6:dxxf:xxx:xxxx]:540yy [zzzz:e2ce:44xx:1:axx6:dxxf:xxx:xxxx]:*<port used>* TIME_WAIT 0
Then you can either wait for a little while or reconfigure to use another port.
I suppose we could write some code to randomly generate and check if a port is free when the application runs. Though this will have diminishing returns as they start to get used up. On the other hand could add a resource clean up code that does what we have above once the application stops.

You can change the default port of your application in application.properties by adding the following line:
server.port = 8090

If you don't want the embedded server to start, just set the following property in you application.properties (or .yml):
spring.main.web-application-type=none
If your classpath contains the necessary bits to start a web server, Spring Boot will automatically start it. To disable this behaviour configure the WebApplicationType in your application.properties
Source: https://docs.spring.io/spring-boot/docs/current/reference/html/howto-embedded-web-servers.html
If you application really is a Web application, then you can easily change the port using the server.port property (in your application's .properties/.yaml file, as a command line argument at startup, etc).

Another way to do this is by first checking what processes are using that specific port, then killing it using its process ID:
Run lsof -i :8080
This will identify which process is listening on port 8080.
Take note of the process ID (PID) e.g. 63262
Run kill -9 <PID> e.g. kill -9 63262

Some time if you can manually kill the that port problem can solve.
Using CurrPorts software you can view what are the running all ports in your machine and you can kill that port if you want.
You can download CurrPorts from here. (download link is in bottom of the page)
============== OR ==============
Without CurrPorts you can do this using like below method also.
CMD as run as administrator
Enter netstat -a -o -n and hit enter. Now you can see like below. Port can see Local Address column after : sign.
select the process id(not port) that your port running and type taskkill /F /PID <process_id_here> command and hit enter.

You can use npm to kill the port
**npx kill-port 8080** //8080 for example
Requirement: npm
read more: https://www.npmjs.com/package/kill-port

create /resources folder inside src/main
create application.properties file inside /resources
write server.port=9090 //(use any port number of your choice)

if port:8080 already in use error occurs:
goto command prompt
.type command> .netstat -ano
.Enter->this will show all running port check port 8080
.type command> taskkill /F /PID 8080
.process will terminate.

you can set server.port= #some-available-port number in application.properties file
or run command prompt in administrator mode and run netstat -a -o -n.
Find the process id which is using port 8080.
Run taskkill /F /PID #Processid command

It's easy we have two methods to solve.
First one is to change the port number in your application.properties i.e
server.port=9999 // something like this...
and second is, to first stop the available running server and then re-run your server again.
I am sure it work :)

If you had previously started the spring boot app and forgot to stop before hitting play again then Go to windows task manager and locate the java application(Something like "OpenJDK Platform binary" and click on End Task. (Java app not eclipse). Then try running again. It worked for me.

open command prompt as administrator
step1: netstat -ano | findstr :<enter your 4 digit port number>
netstat -ano | findstr :8080
TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 6436
TCP [::]:8080 [::]:0 LISTENING 6436
step2: taskkill /PID <enter above pid number(sometimes it shown 3/4/5/6 digits)> /F
taskkill /PID 6436 /F
SUCCESS: The process with PID 6436 has been terminated.

To reset port 8080, you need to find PID (Process ID) and specify it for the command as, for example, on the screen 10512:
taskkill /F /PID 10512

You try to use an already used port.
Ports are used on the transport layer - tcp, http is application layer and uses a transport layer to send and receive requests.
Default port exposed by spring boot app is 8080. In your case you have two solutions:
change port for your application
stop the service that uses the port you want to use

to catch java.net.BindException e with message: Address already in use and to start on other available port and to use webclient with one of 2 ports.
try {
SpringApplication.run(Application.class, args);
} catch (org.springframework.boot.web.server.PortInUseException e) {
//Runtime.exec("pkil")..
//or
SpringApplication.run(Application.class, otherargs);
//SpringApplication.run(Application.class, new String[]{"--server.port=8444"});
//when invoked recursively it is a port rebalancer for port usage among port pool with server as from client for startup stage via application restarts within many busy ports which are used before or without querying.
}

The error basically means that your port 8080 is occupied. If you are getting this error then go to your project and open application.properties and add the below line and it should work fine:
server.port = 8090

Your client application also spring boot application, whats why you have two spring boot application run in 8080 port.
Change port one of them or create a standalone java application with main class, put your web client in it and run.
As http client you can use Apache Http Client.

Today I was working in Spring Boot project and I got the same error in my project. So, what I did, I clicked on stop button beside the run last tool button and run again. Then, my project started working very well.

You can also write services.msc in your search bar in windows.Then you can find Apache Tomcat and then just stop this apache. I think its gonna be work.

It is a simple answer.If you are getting this error then go to your project then
src/main/resources and open application.properties file and mention there
server.port=8045 you can give your own number here instead of 8045
thanks

Open cmd and type "netstat -ano -p tcp."
Then, look for the port number and PID.
Open up Resource Monitor and search for the PID number
Right Click and "End Process."

Restarting my machine solved the issue although I was getting below issue:
Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Failed to start bean 'webServerStartStop'; nested exception is org.springframework.boot.web.server.PortInUseException: Port 8081 is already in use

If you getting this error again and again , then make sure server.port=(your port no) is the first line in application.properties file.

The best answer to this is to always use the "Relaunch Application" button. That will stop the web server and restart the entire app on the same port as before.
It's the button with the red square and green play icon combined.
https://i.stack.imgur.com/ICGtX.png

Java/jmeter http request fails but curl works

I am trying a very basic http request with jmeter, but it seems to always get the error below. I have tried a simple get against google which is fine but the internal servers are not :
java.net.NoRouteToHostException: No route to host (Host unreachable)
I can curl the same url successfully with a 200 response, so not sure if its jmeter or java? The only thing that is unique is that our internal servers are resolving with ipv6, but I would not think that would be the problem?

Try adding the next line to system.properties file (lives in "bin" folder of your JMeter installation)
java.net.preferIPv6Addresses=true
Or pass the aforementioned property via -D command-line argument like:
jmeter -Djava.net.preferIPv6Addresses=true -n -t test.jmx -l result.jtl
References:
Java: Networking Properties
Configuring JMeter
Apache JMeter Properties Customization Guide
Overriding Properties Via The Command Line

Weblogic setting for proxy

I have a problem with configuration of proxy to connect to WebService on Weblogic 10.3.5. I cannot use System.setProperty() because it has to be per connection aproach.
Proxy which I have to use has to have "UserAgent" header.
I have tried two options:
ClientProxyFeature but it doesn't work because it generate request
to proxy without "UserAgent header".
ProxySelector: this approach work great on JUnit test but when I run
it on Weblogic I receive following error
error: java.net.SocketException: Unknown proxy type : HTTP at...
Is there any way to work this around?
Many Thanks in advance
Adam

We are able to do this with ProxySelector. The only thing which we have changed was server start parameter: -DUseSunHttpHandler=true. Now it works and send User-Agent header.

To configure WebLogic proxy file is modified setDomainEnv.cmd (Windows) that is located in the bin folder of the domain.
For example for the integrated server is here
C: \ Users \ [YOUT USER NAME] \ AppData \ Roaming \ JDeveloper \ system11.1.1.4.37.59.23 \ DefaultDomain \ bin
The following property must be placed on file with the details of your proxy
#REM Estableciendo proxi
set JAVA_OPTIONS=%JAVA_OPTIONS% -Dhttp.proxySet=true -Dhttp.proxyHost=192.168.101.11 -Dhttp.proxyPort=8080 -Dhttp.nonProxyHosts=localhost
See the next link
Proxi in WebLogic

Unable to open debugger port in IntelliJ

Unable to open debugger port in intellij.
The port number 9009 matches the one which has been set in the configuration file for the application.
<java-config debug-options="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9009" system-classpath="" native-library-path-prefix="D:\Project\lib\windows\64bit" classpath-suffix="">
<jvm-options>-XX:MaxPermSize=192m</jvm-options>
<jvm-options>-client</jvm-options>
<jvm-options>-XX:+UnlockDiagnosticVMOptions</jvm-options>
<jvm-options>-XX:+LogVMOutput</jvm-options>
<jvm-options>-XX:LogFile=${com.sun.aas.instanceRoot}/logs/jvm.log</jvm-options>
<jvm-options>-Djava.endorsed.dirs=${com.sun.aas.installRoot}/modules/endorsed${path.separator}${com.sun.aas.installRoot}/lib/endorsed</jvm-options>
<jvm-options>-Djava.security.policy=${com.sun.aas.instanceRoot}/config/server.policy</jvm-options>
<jvm-options>-Djava.security.auth.login.config=${com.sun.aas.instanceRoot}/config/login.conf</jvm-options>
<jvm-options>-Dcom.sun.enterprise.security.httpsOutboundKeyAlias=s1as</jvm-options>
<jvm-options>-Djavax.net.ssl.keyStore=${com.sun.aas.instanceRoot}/config/keystore.jks</jvm-options>
<jvm-options>-Djavax.net.ssl.trustStore=${com.sun.aas.instanceRoot}/config/cacerts.jks</jvm-options>
<jvm-options>-Djava.ext.dirs=${com.sun.aas.javaRoot}/lib/ext${path.separator}${com.sun.aas.javaRoot}/jre/lib/ext${path.separator}${com.sun.aas.instanceRoot}/lib/ext</jvm-options>
<jvm-options>-Djdbc.drivers=org.apache.derby.jdbc.ClientDriver</jvm-options>
<jvm-options>-DANTLR_USE_DIRECT_CLASS_LOADING=true</jvm-options>
<jvm-options>-Dcom.sun.enterprise.config.config_environment_factory_class=com.sun.enterprise.config.serverbeans.AppserverConfigEnvironmentFactory</jvm-options>
<jvm-options>-Dosgi.shell.telnet.port=4766</jvm-options>
<jvm-options>-Dosgi.shell.telnet.maxconn=1</jvm-options>
<jvm-options>-Dosgi.shell.telnet.ip=127.0.0.1</jvm-options>
<jvm-options>-Dfelix.fileinstall.dir=${com.sun.aas.installRoot}/modules/autostart/</jvm-options>
<jvm-options>-Dfelix.fileinstall.poll=5000</jvm-options>
<jvm-options>-Dfelix.fileinstall.debug=1</jvm-options>
<jvm-options>-Dfelix.fileinstall.bundles.new.start=true</jvm-options>
<jvm-options>-Dorg.glassfish.web.rfc2109_cookie_names_enforced=false</jvm-options>
<jvm-options>-XX:NewRatio=2</jvm-options>
<jvm-options>-Xmx2048m</jvm-options>
</java-config>
Configuration in IntelliJ:
When I try and enable the remote debugging in for this application it comes up with the following error:

You may have to change the debugger port if your port is already used by another program. To do so:
Run
Edit Configurations
Startup/Connection tab
Debug
Change the port here
Or, maybe in other versions:
Run
Edit Configurations
Remote > Remote debug in the list on the left
Configuration tab, Settings section
Port: change the port here

Add the following parameter debug-enabled="true" to this line in the glassfish configuration.
Example:
<java-config debug-options="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9009" debug-enabled="true"
system-classpath="" native-library-path-prefix="D:\Project\lib\windows\64bit" classpath-suffix="">
Start and stop the glassfish domain or service which was using this configuration.

I had the same problem and this solution also did the trick for me: Provide the IP 127.0.0.1 in the Intellij Debug configuration instead of the host name "localhost", in case you're using this hostname.

You must set CHMOD +x (execute for *.sh or *.bat files). For example, I am using macOS
cd /Users/donhuvy/Documents/tools/apache-tomcat-9.0.12/bin
sudo chmod +x *.sh
Then IntelliJ IDEA, and Apache Tomcat running or debugging just good.

In glassfish\domains\domain1\config\domain.xml set before start server
<java-config classpath-suffix="" debug-options="-agentlib:jdwp=transport=dt_socket,address=9009,server=y,suspend=n" java-home="C:\Program Files\Java\jdk1.8.0_162" debug-enabled="true" system-classpath="">
or set debug-enabled="true" server=y,suspend=n in http://localhost:4848/common/index.jsf
In current Idea 2018 - Server Run Configuration - Debug - Port - address

I'm hoping your problem has been solved by now. If not, try this... It looks like you have server=y for both your app and IDEA. IDEA should probably be server=n. Also, the (IDEA) client should have an address that includes both the host name and the port, e.g., address=127.0.0.1:9009.

This one worked for me--
If the issue still persists (in case you are not using a glassFish server), then close your JIdea and stop the server. This will disable the ports connectivity. Then start your server and JIdea, this will start fresh connectivity with the ports, resolving the issue.

For me, the problem was that catalina.sh didnt have execute permissions. The "Unable to open debugger port in intellij" message appeared in Intellij, but it sort of masked the 'could not execute catalina.sh' error that appeared in the logs immediately prior.

This error can happen Tomcat is already running. So make sure Tomcat isn't running in the background if you've asked Intellij to start it up ( default ).
Also, check the full output window for more errors. As a more useful error may have preceded this one ( as was the case with my configuration just now )

Answer is pretty simple,
I also faced the problem finally I got perfect solution.
Create Debug
Create Remote debug with following configuration
Firstly run by debug.
It gives you waitng for socket 5005
then run with remote debug

Try to connect with telnet , if it connects then it shows below:
$telnet 10.238.136.165 9999
Trying 10.238.136.165...
Connected to 10.238.136.165.
Escape character is '^]'.
Connection closed by foreign host.
If port is not available (either because someone else is already connected to it or the port is not open etc) then it shows something like it shows like below:
$telnet 10.238.136.165 9999
Trying 10.238.136.165...
telnet: connect to address 10.238.136.165: Connection refused
telnet: Unable to connect to remote host
So I think one needs to see whether:
the application is property listening to port or not
or someone else has already connected to it
Also try to connect on that m/c itself first like
$telnet localhost 9999

Set the MAVEN_OPTS. It should work !!
export MAVEN_OPTS="-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,address=4000,server=y,suspend=n"
mvn spring-boot:run -Dserver.port=8090

Run your Spring Boot application with the given command to enable debugging on port 6006 while the server is up on port 8090:
mvn spring-boot:run -Drun.jvmArguments='-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=6006' -Dserver.port=8090

Your Service/ Application might already be running. In Search enter Services and you will get list of services. Stop yours and then try again.

I had the same issue, I just have to remove the HTTP protocol from the URL. That's it.
I hope it works for you.

I once have this problem too.
My solution is to work around this problem by kill the application which is using the port.
Here is a article to teach us how to check which application is using which port, find it and kill/close it.

In my case, I was not setting the debug port while starting the application.
I am using tomcat to deploy 3 war files, and I forgot to configure the debug port.
Tomcat allows us to configure this via setenv.sh.
Here are the commands to create setenv.sh file in the bin directory of my tomcat installation and provide the debug arguments/port.
tee /usr/share/tomcat9/bin/setenv.sh << EOF
export CATALINA_OPTS="$CATALINA_OPTS -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005"
EOF
service tomcat9 restart

Merely hitting the debug icon again fixed my problem in a few seconds.

Make sure to specify an SDK and Project SDK for your app under File --> Project Structure (Project | SDKs)

Running Single instance AppScale in a virtual machine

I was trying to run AppScale in a Single-instance node installed in a Vmware box and running the appscale-tools in the same server virtual machine and got this error:
root#appscale:~appscale-tools-bin# ./appscale-run-instances --ips ips.yaml
About to start AppScale over a non-cloud environment.
Head node successfully created at 127.0.0.1. It is now starting up cassandra via the command line arguments given.
Generating certificate and private key
Starting server at 127.0.0.1
Please wait for the controller to finish pre-processing tasks.
Warning: Permanently added '127.0.0.1' (RSA) t othe list of known host.
Error: Couldn't find me in the node map
The solution I was advised was to change a code in this source:
appscale/AppController/lib/helperfunctions.rb
And look for self.local_ip() and change to:
def self.local_ip()
return "127.0.0.1"
end
But when I run
./appscale-run-instances --ips ips.yaml
I am not sure, but it just keep on saying:
"Please wait for the controller to finish pre-processing tasks." for several minutes already.
So I decided to terminate it, and here is what I get:
"...common_functions.rb:399:in 'sleep_unti_port_is_open"
In this case, it seems I need to open a port, I am running AppScale from within Ubuntu, what port should I open in my server?
Here's the complete command line:
./appscale-run-instances --ips ips.yaml
About to start AppScale over a non-cloud environment.
Head node successfully created at 127.0.0.1.
It is now starting up cassandra via the command line arguments given.
Generating certificate and private key.
Starting server at 127.0.0.1
Please wait for the controller to finish pre-processing tasks.
^C./../lib/../lib/common_functions.rb:399:in sleep': Interrupt
from ./../lib/../lib/common_functions.rb:399:in 'sleep_until_port_is_open'
from ./../lib/../lib/common_functions.rb:397:in 'loop'
from ./../lib/../lib/common_functions.rb:397:in 'sleep_until_port_is_open'
from ./../lib/../lib/common_functions.rb:1359:in 'start_appcontroller'
from /usr/lib/ruby/1.8/timeout.rb:62:in ttimeout.
from ./../lib/../lib/common_functions.rb:1351:in 'start_appcontroller'
from ./../lib/../lib/common_functions.rb:548:in 'start_head_node'
from ./../lib/appscale_tools.rb:284:in trun_instances'
from ./appscale-run-instances:14

Using the pre-build Appscale images here or following the steps listed here https://github.com/AppScale/appscale/wiki/Virtualized-Cluster will solve this problem.
Also it has the build script:
$ sudo su
# cd /root
# wget -O - http://bootstrap.appscale.com | sh