I want to communicate two containers in docker, I'm using netcat for the test. First I have created the Dockefile:
FROM ubuntu
WORKDIR /root
RUN apt-get update && apt-get install netcat iputils-ping -y
And added the image with:
docker build . -t ubuntu_netcat
Also I have created a new network:
docker network create --driver bridge nettest
Then I run two containers:
docker run --net=nettest --expose=8080 -it --name pc1 ubuntu_netcat
docker run --net=nettest --link=pc1 -it --name pc2 ubuntu_netcat
At first container (pc1) I listen on port 8080 with netcat command:
nc -vlk 8080
And I expect to communicate with it from the second container (pc2) executing:
nc -v pc1 8080
But I just got a connection refused:
root#c592b2015439:~# nc -v pc1 8080
pc1.nettest [172.18.0.2] 8080 (?) : Connection refused
I have been looking at the docker docs but all seems to be correct. In fact I can perform a ping between containers sucessfully, so they can reach one other, but I have something wrong with ports.
¿What am I doing wrong?
Thanks
It looks like this version of netcat on Ubuntu doesn't listen like it normally does. You have to specify -p for the port (even though the options would appear to have port as a positional option).
Your netcat listener command should be:
nc -vlkp 8080
Related
Even though internet connection is working properly, traceroute only shows node IP. Why?
Kubernetes version
1.21
Set -p 443 will result to host not to process the probe along the route. You can try kubectl run busybox --image busybox --restart Never -it --rm -- traceroute -4 -l -v -m 30 google.com. This command will show you the IP along the route; presumed your cluster has no network policy or subnet security group blocking the way.
I want nginx in a Docker container to host a simple static hello world html website. I want to simply start it with "docker run imagename". In order to do that I added the run parameters to the Dockerfile. The reason I want to do that is that I would like to host the application on Cloud Foundry in a next step. Unfortunately I get the following error when doing it like this.
Dockerfile
FROM nginx:alpine
COPY . /usr/share/nginx/html
EXPOSE 5000
CMD ["nginx -d -p 5000:5000"]
Error
Error starting userland proxy: Bind for 0.0.0.0:5000: unexpected error Permission denied.
From ::
https://docs.docker.com/engine/reference/builder/#expose
EXPOSE does not make the ports of the container accessible to the host. To do that, you must use either the -p flag to publish a range of ports or the -P flag to publish all of the exposed ports. You can expose one port number and publish it externally under another number
CMD ["nginx -d -p 5000:5000"]
You add your dockerfile
FROM nginx:alpine
its already starts nginx.
after you build from your dockerfile
you should use this on
docker run -d -p 5000:5000 <your_image>
Edit:
If you want to use docker port 80 -> machine port 5000
docker run -d -p 5000:80 <your_image>
In my local setup, I can run ...
docker run --name myapp -e HOST=$(docker-machine ip default) --user root myapp
... and then use $HOST to connect to any other container (e.g. one running mongodb).
However, in Travis, docker-machine does not exist. Thus, I cannot simply put that line in my .travis.yml.
How do I get the network IP?
The flag --link adds an entry to /etc/hosts with the ip address of the specified running container
docker run --name myapp --link mongodb:mongodb myapp
However please note that:
The default docker0 bridge network supports the use of port mapping
and docker run --link to allow communications between containers in
the docker0 network. These techniques are cumbersome to set up and
prone to error. While they are still available to you as techniques,
it is better to avoid them and define your own bridge networks
instead.
Another option is using the flag --add-host if you want to add a known ip address
docker run --name myapp --add-host mongodb:10.10.10.1 myapp
Option 2
Create a network
docker network create --subnet=172.18.0.0/16 mynet123
Run mongodb container assigning an static ip
docker run --network mynet123 --ip 172.18.0.22 -d mongodb
Add that ip to the other container
docker run --network mynet123 --add-host mongodb:172.18.0.22 -d myapp
I'm following Digital Ocean's tutorial on how to start a nginx docker container (Currently on Step 4). Currently this is their output:
$ docker run --name docker-nginx -p 80:80 -d nginx
d3ccb73a91985651ec61231bca9f9c716f0dec807e354a29eeef2144f883a01c
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b91f3ce26553 nginx "nginx -g 'daemon off" About a minute ago Up About a minute 0.0.0.0:80->80/tcp, 443/tcp docker-nginx
But when I run it, this is my output (noticed the different IP of the container):
C:\>docker run --name docker-nginx -p 80:80 -d nginx
d3ccb73a91985651ec61231bca9f9c716f0dec807e354a29eeef2144f883a01c
C:\>docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d3ccb73a9198 nginx "nginx -g 'daemon off" 14 hours ago Up 2 seconds 10.0.75.2:80->80/tcp, 443/tcp docker-nginx
Why does this happen? And how can I get the same results as Digital Ocean's? (Getting the server to start on localhost)
Edit: I'm using Docker for windows (recently released) which apparently runs native using Hyper-V. My output for docker-machine ls is this:
C:\>docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
C:\>
But when I run it, this is my output (noticed the different IP of the
container)
Since this a Windows machine, I assume that you're using Docker Toolbox Docker for Windows. 10.0.75.2 is the IP of the boot2docker virtual machine.
If you are using Windows or Mac OS, you will need some form of virtualization in
order to run Docker. The IP you just saw is the IP of that lightweight virtual machine.
And how can I get the same results as Digital Ocean's? (Getting the
server to start on localhost)
Use a Linux distribution! Also you can enable Expose container ports on localhost in Docker For Windows Settings:
Despite you created the containers in your local machine. These are actually running on a different machine (a virtual machine)
First, check what is the IP of your docker machine (the virtual machine)
$docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM
default * virtualbox Running tcp://192.168.99.100
Then run curl command (or open a browser) to view the default web site on your nginx web server inside the container
curl http://192.168.99.100:80
if you are using a virtual machine on windows:
docker-machine ip default
https://docs.docker.com/machine/concepts/
When I ran this command for the first time: docker run -d -p 80:80 --name docker-tutorial docker101tutorial
I got this error:
docker: Error response from daemon: Conflict. The container name
"/docker-tutorial" is already in use by container "LONG_CONTAINER_ID".
You have to remove (or rename) that container to be able to reuse that
name.
so, I tried to remove this container using: docker rm -f LONG_CONTAINER_ID
then I did: docker run -d -p 3080:80 --name docker-tutorial docker101tutorial
note 3080:80 instead of 80:80... Had I run this from the docker desktop, I would see this default option below:
I am trying to host a simple static site using the Docker Nginx Image from Dockerhub: https://registry.hub.docker.com/_/nginx/
A note on my setup, I am using boot2docker on OSX.
I have followed the instructions and even I cannot connect to the running container:
MacBook-Pro:LifeIT-war-games-frontend ryan$ docker build -t wargames-front-end .
Sending build context to Docker daemon 813.6 kB
Sending build context to Docker daemon
Step 0 : FROM nginx
---> 42a3cf88f3f0
Step 1 : COPY app /usr/share/nginx/html
---> Using cache
---> 61402e6eb300
Successfully built 61402e6eb300
MacBook-Pro:LifeIT-war-games-frontend ryan$ docker run --name wargames-front-end -d -p 8080:8080 wargames-front-end
9f7daa48a25bdc09e4398fed5d846dd0eb4ee234bcfe89744268bee3e5706e54
MacBook-Pro:LifeIT-war-games-frontend ryan$ curl localhost:8080
curl: (52) Empty reply from server
MacBook-Pro:LifeIT-war-games-frontend ryan$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9f7daa48a25b wargames-front-end:latest "nginx -g 'daemon of 3 minutes ago Up 3 minutes 80/tcp, 0.0.0.0:8080->8080/tcp, 443/tcp wargames-front-end
Instead of localhost, use boot2docker ip. First do boot2docker ip and use that ip:
<your-b2d-ip>:8080. Also you need to make sure you forwarded your port 8080 in VirtualBox for boot2docker.
Here is the way to connect nginx docker container service:
docker ps # confirm nginx is running, which you have done.
docker port wargames-front-end # get the ports, for example: 80/tcp, 0.0.0.0:8080->8080/tcp, 443/tcp
boot2docker ip # get the IP address, for example: 192.168.59.103
So now, you should be fine to connect to:
http://192.168.59.103:8080
https://192.168.59.103:8080
Here's how I got it to work.
docker kill wargames-front-end
docker rm wargames-front-end
docker run --name wargames-front-end -d -p 8080:80 wargames-front-end
Then I went to my virtualbox and setup these settings: