I use a docker container to interact with my kubernetes cluster. I run kubectl from inside the container. All works fine except when I want to port forward. I can use kubectl port forward to forward from the pod to my container. But then I won't be able to access the site from my laptop browser. I can only curl from inside the container.
Is there any way at all I can access the site from my browser. docker host networking mode isn't supported on Macs and I use a Mac. Any suggestions?
I have this scenario you may adapt for your need :
On my laptop, I run :
docker run -it --rm -p 2222:2222 ubuntu bash
From inside container, I run :
kubectl port-forward --address 0.0.0.0 pod/my-pod-7f66c99ddd-6c429 2222:22
Now this is the diagram for port-forwarding :
2222 2222 2222 22
laptop -------------------> docker-container------------------->k8s-pod
Now, in another terminal on my laptop, I can do
ssh -p 2222 user-on-pod#laptop-hostname
to arrive at pod
Related
I got a container that has openssh installed and can be connnected via the command
ssh 172.17.0.2.
Now I want to get a port (say 32769) on the host side, and map the port 22 (of docker container) to it, the reason for doing that is I want to get the ssh 127.0.0.1 -p 32769 works on localhost, I got the errors as : ssh_exchange_identification: read: Connection reset by peer . The port mapping is showing normally on docker engine: 0.0.0.0:32769->22/tcp.
Can somebody help me with that? Much appreciated!
Check that the SSH daemon is running in your container first (through a docker exec or docker attach session):
service ssh status
# or
service sshd status
Make sure you have the right IP address
sudo docker inspect -f "{{ .NetworkSettings.IPAddress }}" Container_Name
Use the right SSH URL:
ssh root#172.17.0.2
See more in "How to SSH into a Running Docker Container and Run Commands" from Sofija Simic.
Using a docker run -p 32769:22 is in your case a good idea.
The OP mentions in the discussion an issue with docker proxy:
The docker-proxy was not getting eth0 of the container as -container-ip.
Here is what I've got
/usr/bin/docker-proxy -proto tcp -host-ip 0.0.0.0 -host-port 32785 \
-container-ip 172.21.1.2 -container-port 22
I have a remote ubuntu machine with docker installed and a container is running on that, i want to access it from my windows machine through a browser, i can connect to the ubuntu remote machine from my windows machine through putty, is there any way, i would be able to achieve this, any helps or leads in this case will be highly appreciated?
When you start the container, you'll need to publish the port that you want to connect to using the -p flag. Here's an example from the Docker documentation that publishes port 80 in the container to port 80 on the host (you can map to a different port if you'd like):
$ docker run -d -p 80:80 my_image service nginx start
See https://docs.docker.com/engine/reference/run/#expose-incoming-ports
Say, if I use this command inside a docker container.
/opt/lampp/bin/mysql -h localhost -u root -pThePassword
What would the localhost here refer to? The host machine's IP or the docker container's own IP?
From inside a container, localhost always refers to the current container. It never refers to another container, and it never refers to anything else running on your physical system that's not in the same container. It's not usually useful to make outbound connections to localhost or configure localhost as your database host.
From a shell on your host system, localhost could refer to daemons running on your system outside Docker, or to ports you've published with docker run -p options.
From a different system, localhost refers to the system it's called from.
In terms of IP addresses, localhost is always 127.0.0.1, and that IP address is special and is always localhost and behaves the same way as above.
If you want to make a connection to a container...
...from another container, the best way is to make sure they're on the same Docker network (you started them from the same Docker Compose YAML file; you did a docker network create and then did docker run --net ... on the same network) and use Docker's internal DNS service to refer to them by the container's --name or its name in the Docker Compose YAML file and the port number inside the container. Even if the target has a published port with a docker run -p option or Docker Compose ports: setting, use the second (container-internal) port number.
...from outside Docker space, make sure you started the container with a docker run -p or Docker Compose ports: option, and connect to the host's IP address or DNS name using the first port number from that option.
...from a terminal window or browser on the same physical host, not in a container, in this case and in this case only, localhost will work consistently.
Except:
If you started a container with --net host, localhost refers to the physical host, and you're in the "terminal window on the same physical host" scenario.
If you've gone out of your way to have multiple servers in the same container, you can use localhost to communicate between them.
If you're running in Kubernetes, and you have multiple containers in the same pod, you can use localhost to communicate between them. Between pods, you should set up a service in front of each pod/deployment, and use DNS names of the form service-name.namespace-name.svc.cluster.local.
Definitely, It will be your container, if you are running command in container.
/opt/lampp/bin/mysql -h localhost -u root -pThePassword
If you run this command inside container then it will try to connect mysql running inside container.
I have a cloud pc with static external ip, f.e. 162.243.100.100
Inside I installed docker with nginx, and mapped 80 port like this
docker run -it -p 80:80 nginx
I'm able to access nginx demo page from curl 162.243.100.100 from host machine.
I'm able to access nginx demo page from curl localhost from inside said container.
But I want to have able to access ngninx demo page from command curl 162.243.100.100 from inside said nginx containeer.
Seem this not follow port mapping, and just give me timeout error.
I thin I need to do something with network settings, but not know what.
The short answer is "don't do that."
The default iptables rules and routing tables from Docker aren't setup to route traffic from a container out to the host and back into the container through the docker-proxy. Considering how much this is an anti-pattern, I don't expect it to be a priority to change this behavior. It's much easier to work with the tool and use docker networks and the container name when talking from container to container.
Create a network and start your container in that network:
docker network create --subnet 172.16.0.0/16 dockernet
docker run -it -p 80:80 --net=dockernet nginx
I have a daemon on my host running on some port (i.e. 8008) and my code normally interacts with the daemon by contacting localhost:8008 for instance.
I've now containerized my code but not yet the daemon.
How can I forward the localhost:8008 on my container to localhost:8008 on the host running the container (and therefore the daemon as well).
The following is netstat -tlnp on my host. I'd like the container to forward localhost:2009 to localhost:2009 on the host
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:2009 0.0.0.0:* LISTEN 22547/ssh
tcp6 0 0 :::22 :::* LISTEN -
tcp6 0 0 ::1:2009 :::* LISTEN 22547/ssh
So the way you need to think about this is that Docker containers have their own network stack (unless you explicitly tell it to share the host's stack with --net=host). This means ports need to be exposed both inside the docker container and also on the outside (documentation), when linked with host ports. The ports exposed on the container need to be bound to the host ports explicitly (with -p xxxx:yyyy in your docker run command) or implicitly (using EXPOSE in your Dockerfile and using -P on the command line), like it says here. If your Dockerfile does not contain EXPOSE 8008, or you do not specify --expose 8008 in your docker run command, your container can't talk to the outside world, even if you then use -p 8008:8008 in your docker run command!
So to get tcp/8008 on the host linked with tcp/8008 on the container, you need EXPOSE 8008 inside your Dockerfile (and then docker build your container) OR --expose 8008 in your docker run command. In addition, you need to either use -P to implicitly or -p 8008:8008 to explicitly link that exposed container port to the host port. An example docker run command to do this might look like:
docker run -it --expose 8008 -p 8008:8008 myContainer
It's handy to remember that in the -p 8008:8008 command line option, the order for this operation is -p HOST_PORT:CONTAINER_PORT. Also, don't forget that you won't be able to SSH into your container from another machine on the internet unless you also have this port unblocked in iptables on the host. I always end up forgetting about that and waste half an hour before I remember I forgot to iptables -A INPUT ... for that specific tcp port on the host machine. But you should be able to SSH from your host into the container without the iptables rule, since it uses loopback for local connections. Good luck!
TL;DR: You can use the special hostname host.docker.internal instead of localhost anywhere inside the container that you want to access localhost on the host. Note that:
macOS and Windows versions of Docker Desktop have this feature enabled by default.
Linux hosts (using Docker v 20.10 and above - since December 14th 2020) require you to add --add-host=host.docker.internal:host-gateway to your Docker command to enable the feature.
Docker Compose on Linux requires you to add the following lines to the container definition:
extra_hosts:
- "host.docker.internal:host-gateway"
Full answer: Is the host running MacOS or Windows? Buried in the documentation for Docker Desktop is the fact that there is no docker0 bridge on MacOS and there is no docker0 bridge on Windows. Apparently that's the cause of this. In both cases the workaround (given right after, in a subsection titled "Use cases and workarounds") is to use the special hostname host.docker.internal in placed of localhost anywhere inside the container that you want to access localhost on the host.
If the host is Linux, there are some Linux-only techniques for achieving this. However, host.docker.internal is also useable with a Linux host, but it has to be enabled first. See the Linux part of the TL;DR, above, for instructions.
By this method, in OP's case host.docker.internal:8008 should be used instead of localhost:8008. Note that this is a code or configuration change of the application code running inside the container. There is no need to mention the port in the container configuration. Do not try to use -p or --expose in the docker run commandline. Not only is it not necessary, but your container will fail to start if the host application you want the container to connect to is already listening on that port.
After checked the answers and did some investigation, I believe there are 2 ways of doing that and these 2 only work in Linux environment.
The first is in this post How to access host port from docker container
The second should be set your --network=host when you docker run or docker container create. In this case, your docker will use the same network interface you use in Mac.
However, both ways above cannot be used in Mac, so I think it is not possible to forward from the container to host in Mac environment. Correct me if I am wrong.
I'm not sure if you can do that just with docker's settings.
If my under standing is correct, expose port is not what you looking for.
Instead, establish ssh port forwarding from container to host mightbe the answer.
You can easily use -p 127.0.0.1:8008:8008 and forward the container's port 8008 to localhost's port 8008. An example docker command would be:
docker run -it -p 127.0.0.1:8008:8008 <image name>
If you're doing this on your local machine, you can simple specify the network type as host when starting your container (--network host), which will make your host machine share network with your docker container.
eg:
Start your container:
docker run -it --rm --network host <container>
On your host machine, Run:
python3 -m http.server 8822
Now from your container run:
curl 127.0.0.1:8822
If all went well you'll see traffic on your host terminal.
Serving HTTP on 0.0.0.0 port 8822 (http://0.0.0.0:8822/) ...
127.0.0.1 - - [24/Jan/2023 22:37:01] "GET / HTTP/1.1" 200 -
docker run -d --name <NAME OF YOUR CONTAINER> -p 8008:8008 <YOUR IMAGE>
That will publish port 8008 in your container to 8008 on your host.