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.
Related
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.
I'm just starting up with Docker and the first example that I was trying to run already fails:
docker container run -p 80:80 nginx
The command successfully fetches the nginx/latest image from the Docker Hub registry and runs the new container, there is no indication in CMD of anything going wrong. When I browse to localhost:80 I get 503 (Service Unavailable). I'm doing this test on Windows 7.
I tried the same command on another computer (this time on macOS) and it worked as expected, no issues.
What might be a problem? I found some issues on SO similar to mine, but they were connected with the usage of nginx-proxy, which I don't use and don't even know what it is. I'm trying to run a normal http server.
//EDIT
When I try to bind my container to a different port, for example:
docker container run -p 4201:80 nginx
I get ERR_CONNECTION_REFUSED in Chrome, so basically connection can't be established, because destination does not exist. Why is that?
The reason why it didn't work is that on Windows, Docker publishes results on different IP than localhost. This IP given is at the top in Docker client console.
I'm trying to launch a docker container that is running a tornado app in python 3.
It serves a few API calls and is writing data to a rethinkdb service on the system. RethinkDB does not run inside a container.
The system it runs on is ubuntu 16.04.
Whenever I tried to launch the docker with docker-compose, it would crash saying the connection to localhost:28015 was refused.
I went researching the problem and realized that docker has its own network and that external connections must be configured prior to launching the container.
I used this command from a a question I found to make it work:
docker run -it --name "$container_name" -d -h "$host_name" -p 9080:9080 -p 1522:1522 "$image_name"
I've changed the container name, host name, ports and image name to fit my own application.
Now, the docker is not crashing, but I have two problems:
I can't reach it from a browser by pointing to https://localhost/login
I lose the docker-compose usage. This is problematic if we want to add more services that talk to each other in the future.
So, how do I launch a docker that can talk to my rethinkdb database without putting that DB into a container?
Please, let me know if you need more information to answer this question.
I'd appreciate your guidance in this.
The end result is that the docker will serve requests coming over https.
for exmaple I have an end-point called /getURL.
The request includes a token verified in the DB. The URL is like this:
https://some-domain.com/getURL
after verification with the DB it will send back a relevant response.
the docker needs to be able to talk on 443 and also on 28015 with the rethinkdb service.
(Since 443 and https include the use of certificates, I'd appreciate a solution that handles this on regular http with some random port too and I'll take it from there)
Thanks!
P.S. The service works when I launch it without a docker on pycharm it's the docker configuration I have problems with.
I found a solution.
I needed to add this so that the container can connect to both the database and the rethinkdb:
--network="host"
Since this solution works for me right now, but it isn't the best solution, I won't mark this as the answer for now.
I am using VS2017 docker support. VS created DockerFile for me and when I build docker-compose file, it creates the container and runs the app on 172.x.x.x IP address. But I want to run my application on localhost.
I did many things but nothing worked. Followed the docker docs as a starter and building microsoft sample app . The second link is working perfectly but I get HTTP Error 404 when tried the first link approach.
Any help is appreciated.
Most likely a different application already runs at port 80. You'll have to forward your web site to a different port, eg:
docker run -d -p 5000:80 --name myapp myasp
And point your browser to http://localhost:5000.
When you start a container you specify which inner ports will be exposed as ports on the host through the -p option. -p 80:80 exposes the inner port 80 used by web sites to the host's port 80.
Docker won't complain though if another application already listens at port 80, like IIS, another web application or any tool with a web interface that runs on 80 by default.
The solution is to:
Make sure nothing else runs on port 80 or
Forward to a different port.
Forwarding to a different port is a lot easier.
To ensure that you can connect to a port, use the telnet command, eg :
telnet localhost 5000
If you get a blank window immediatelly, it means a server is up and running on this port. If you get a message and timeout after a while, it means nobody is running. You anc use this both to check for free ports and ensure you can connect to your container web app.
PS I run into this just a week ago, as I was trying to set up a SQL Server container for tests. I run 1 default and 2 named instances already, and docker didn't complain at all when I tried to create the container. Took me a while to realize what was wrong.
In order to access the example posted on Docker Docs, that you pointed out as not working, follow the below steps,
1 - List all the running docker containers
docker ps -a
After you run this command you should be able to view all your docker containers that are currently running and you should see a container with the name webserver listed there, if you have followed the docker docs example correctly.
2 - Get the IP address where your webserver container is running. To do that run the following command.
docker inspect -f "{{ .NetworkSettings.Networks.nat.IPAddress }}" webserver
You should now get the IP address which the webserver container is running, hope you are familiar with this step as it was even available within the building Microsoft sample app example that you attached with the question.
Access the IP address you get once running the above command and you should see the desired output.
Answering to your first question (accessing docker container with localhost in docker for windows), in Windows host you cannot access the container with localhost due to a limitation in the default NAT network stack. A more detailed explanation for this issue can be obtained by visiting this link. Seems like the docker documentation is not yet updated but this issue only exists in Windows hosts.
There is an issue reported for this as well - Follow this link to see that.
Hope this helps you out.
EDIT
The solution for this issue seems to be coming in a future Windows release. Yet that release comes out this limitation is available in Windows host. Follow this link -> https://github.com/MicrosoftDocs/Virtualization-Documentation/issues/181
For those who encountering this issue in 2022, changing localhost to 127.0.0.1 solved an issue for me.
There is other problem too
You must have correct order with parameters
This is WRONG
docker run container:latest -p 5001:80
This sequence start container but parameter -p is ignore, therefore container have no ports mapping
This is good
docker run -p 5001:80 container:latest
Pretty new to docker, but I just created an image and it seems to start up fine until it attempts to connect to a remote SQL server. That is, a SQL server that is on it's own VM and is normally accessible via a host (e.g. mydatabase.mydomain.com). This problem doesn't present when it's run out of visual studio; the database is fine and it is reachable.
I suspect that it has something with docker networking. I tried exposing 1433 with no luck. I've also tried running it with --net=host also no luck. The errors are being output by NServiceBus where it's trying to communiciate with AzureServiceBus as well as SQL Server stating that the server was not responding or is unreachable.
The Dockerfile
FROM microsoft/windowsservercore
WORKDIR /command
EXPOSE 8002
EXPOSE 1433
COPY . /command
ENTRYPOINT ["NServiceBus.Host.exe"]
Any ideas or insight would be good.
It can be a firewall issue on SQL Server host.
Here is an article on how to host a multi container application on a windows container.