Intellij, Postman and curl - not recognize localhost on port 8080

Question

I have a simple rest server in Scala. Run this project via intellij on localhost:8080. I tried to send POST or GET request into this server via postman and curl, but it cannot connect with it, don't know why. I pinged localhost and it answer, but localhost:8080 where the app runs only loading and nothing more. I run intellij and start my server (scala, cats, Blaze). Everything works correctly yesterday, but today it's not. I looked into intellij logs, and they look like good:

2019-04-21 19:29:08,912 [14101080]   INFO - ij.compiler.impl.CompileDriver - COMPILATION STARTED (BUILD PROCESS) 
2019-04-21 19:29:08,919 [14101087]   INFO - j.compiler.server.BuildManager - Using preloaded build process to compile /home/project 
2019-04-21 19:29:11,565 [14103733]   INFO - lij.compiler.impl.CompilerUtil -    COMPILATION FINISHED (BUILD PROCESS); Errors: 0; warnings: 0 took 2662 ms: 0 min 2sec 
2019-04-21 19:29:11,565 [14103733]   INFO - s.CompilerReferenceServiceBase - backward reference index reader doesn't exist 
2019-04-21 19:29:12,358 [14104526]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stdout]: Build process started. Classpath: /home/intellij/idea-IU-183.5912.21/lib/jps-launcher.jar:/usr/lib/jvm/java-1.11.0-openjdk-amd64/lib/tools.jar:/home/intellij/idea-IU-183.5912.21/lib/optimizedFileManager.jar 
2019-04-21 19:29:12,419 [14104587]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". 
2019-04-21 19:29:12,419 [14104587]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: SLF4J: Defaulting to no-operation (NOP) logger implementation 
2019-04-21 19:29:12,419 [14104587]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details. 
2019-04-21 19:29:14,496 [14106664]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: WARNING: An illegal reflective access operation has occurred 
2019-04-21 19:29:14,496 [14106664]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: WARNING: Illegal reflective access by com.google.protobuf.UnsafeUtil (file:/home/intellij/idea-IU-183.5912.21/lib/protobuf-java-3.4.0.jar) to field java.nio.Buffer.address 
2019-04-21 19:29:14,496 [14106664]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: WARNING: Please consider reporting this to the maintainers of com.google.protobuf.UnsafeUtil 
2019-04-21 19:29:14,496 [14106664]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations 
2019-04-21 19:29:14,496 [14106664]   INFO - j.compiler.server.BuildManager - BUILDER_PROCESS [stderr]: WARNING: All illegal access operations will be denied in a future release 

Everything builds well. I don't know where the problem could be. I also tried to turn on proxy in postman but it did not help. Cleared also cache in intellij, nothing help. I'm using newest Ubuntu. Does anyone had same problem and know how to solve it? Maybe it is a stupid question but I really don't have any idea what could happend.

EDIT I ckecked if something else using port 8080 with this command: netstat -tulpn | grep 8080, but I only got one result:

tcp6 0 0 127.0.0.1:8080 :::*LISTEN 18125/java. It looks like only my running app is using this port.

Answer 1

That is correct. Only your server should be using that port. Nothing else is attempting to connect to it.

Try: telnet 127.0.0.1 8080. If you get back

Trying 127.0.0.1...
Connected to 127.0.0.1.

(which you should, given the output of netstat) then the port is open. What your code is doing with it is beyond the scope of this forum; try a scala forum maybe?