I am currently facing following problem:
I build a docker container of a node server (a simple express server which sends tracing data to Zipkin on port 9411) and want to run it along Zipkin.
So as I understood, the node server should send tracing data to Zipkin using port 9411.
If I run the server with node only (not as docker), I can run it along Zipkin and everything is working fine.
But if I got Zipkin running and than want to fire up my Docker Container, I get the error
Error starting userland proxy: listen tcp4 0.0.0.0:9411: bind: address already in use.
My understanding is that there is a conflict concerning the port 9411, since it seems to be blocked by Zipkin, but obviously, also the server in the Docker container needs to use it to communicate with Zipkin.
I would appreciate if anybody got an idea how I could solve this problem.
Greetings,
Robert
When you start a docker container, you add a port binding like this:
docker run ... -p 8000:9000
where 8000 is the port you can use on the pc to access port 9000 within the container.
Don't bind the express server to 9411 as zipkin is already using that port.
I found the solution: using the flag --network="host" does the job, -p also is not needed.
Related
There is a python application which I'm trying to run inside a docker container.
So inside the container when I'm trying to curl I can see the output but when I try to see the output on my host machine using curl it says
curl: (56) Recv failure: Connection reset by peer
and I'm not able to see any output in the browser as well
The port is exposed on 8050
host machine is centos 7
firewall and selinux are disabled
It would help if you posted the docker command / docker-compose file you use.
From what you say, it looks like you used the expose option (or, the container was made exposing that port).
I find the name "expose" a bit misleading.
Exposing a port simply means that the container listens to that port. It does not mean that this port is available ("exposed") to the host.
For that, you need to use publish (-p <host port>:<container port>).
How did you run the container ?
Connection Reset to a Docker container usually indicates that you've defined a port mapping for the container that does not point to an application.
So, if you've defined a mapping of 8050:8050, check that your process inside the docker instance is in fact running on port 8050 (netstat -an|grep LISTEN).
I have a webserver listening on some port. I dockerize this server and publish its port with the command:
docker run -p 8080:8080 image-tag
Now I write a short Java client socket connecting to localhost on this port (it is able to connect). However, when I read data from this socket via the readLine function, it always returns me null. It shouldn't. Can someone point me some direction on how to troubleshoot this? Things I have tried:
This webserver and client works fine without docker.
Using my docker installation, I'm able to pull the getting-started app and it works fine. (means there is no problem with my docker, it still can publish port)
My docker pulls only the openjdk:latest as the base image. Other than that, nothing special.
The docker is Linux Docker on Windows Host.
The port the webserver is running on is correct and the same as the published port.
I would be very happy if someone could help.
By making the server app inside container listen on address 0.0.0.0 instead of localhost, I'm able to solve the problem.
I have exposed port 80 in my application container's dockerfile.yml as well as mapping "80:80" in my docker-compose.yml but I only get a "Connection refused" after I do a "docker-compose up" and try to do a HTTP GET on port 80 on my docker-machine's IP address. My docker hub provided RethinkDB instance's admin panel gets mapped just fine through that same dockerfile.yml ("EXPOSE 8080") and docker-compose.yml (ports "8080:8080") and when I start the application on my local development machine port 80 gets exposed as expected.
What could be going wrong here? I would be very grateful for a quick insight from anyone with more docker experience!
So in my case, my service containers both bound to localhost (127.0.0.1) and therefore seemingly the exposed ports were never picked up via my docker-compose port mapping. I configured my services to bind to 0.0.0.0 respectively and now they works flawlessly. Thank you #creack for pointing me in the right direction.
In my case I was using
docker-compose run app
Apparently
docker-compose run command does not create any of the ports specified in the service configuration.
See https://docs.docker.com/compose/reference/run/
I started using
docker-compose create app
docker-compose start app
and problem solved.
In my case I found that the service I am trying to set up had all their networks as internal: true. It is strange that it didn't give me an issue when doing a docker stack deploy
I have opened up https://github.com/docker/compose/issues/6534 to ask for a proper error message so it will be obvious for other people.
If you are using the same Dockerfile, make sure you also expose the port 80 EXPOSE 80 otherwise, your compose mapping 80:80 will not work.
Also make sure that your http server listens on 0.0.0.0:80 and not localhost or a different port.
I am running 2 spring boot applications: A client and rest-api. The client communicates to the rest-api which communicates to a mongodb database. All 3 tiers are running inside docker containers.
I launch the containers normally specifying the exposed ports in the dockerfile and mapping them to a port on the host machine such as: -p 7070:7070, where 7070 is a port exposed in the Dockerfile.
When I run the applications through the java -jar [application_name.war] command, the application works fine and they all can communicate.
However, when I run the applications in a Docker container I get connection refused error, such as when the client tries to connect to the rest-api I get a connection refused error at http://localhost:7070.
But the command docker ps shows that the containers are all running and listening on the exposed and mapped ports.
I have no clue why the containers aren't recognizing that the other containers are running and listening on their ports.
Does this have anything to do with iptables?
Any help is appreciated.
Thanks
EDIT 1: The applications when ran inside containers work fine on my machine, and they don't throw any connection refused errors. The error only happens on that particular different machine.
I used container linking to solve this problem. Make sure you add --link <name>:<alias> at run-time to the container you want linked. <name> is the name of the container you want to link to and <alias> will be the host/domain of an entry in Spring's application.properties file.
Example:
spring.data.mongodb.host=mongodb if the alias supplied at run-time is 'mongodb':
--link myContainerName:mongodb
I am not sure if I understand the docker port concept. Say I have an application inside a container that listens on port 6000 for tcp connections. This container is on server A.
I want to connect to the application from another server B. But I want to start multiple instances of the same container on server A and the internal port should stay 6000. However the external port should change.
E.g
container 1 6000->9660
container 2 6000->9661
...
So from outside the application should expose 9660, 9661,... Is this possible? I tried with:
docker run -p 9660:6000 ...
however the client could not connect. Any ideas?
I forgot to
EXPOSE 6000
inside my Dockerfile. Now it works :)