Docker commands that I have used to spin the consul container-
Created static Ip for container 1 = docker network create --subnet=172.18.0.0/16 C1
Run a consul container to that Ip:
docker run -d --net C1 --ip 172.18.0.10 -p 48301:8301/tcp -p 48400:8400/tcp -p 48600:8600/tcp -p 48300:8300/tcp -p 48302:8302/tcp -p 48302:8302/udp -p 48500:8500/tcp -p 48600:8600/udp -p 48301:8301/udp --name=test1 consul agent -client=172.18.0.10 -bind=172.18.0.10 -server -bootstrap -ui
Similarly created static Ip for containter 2 - docker network create --subnet=172.19.0.0/16 C2
docker run -d --net C2 --ip 172.19.0.10 -p 58301:8301/tcp -p 58400:8400/tcp -p 58600:8600/tcp -p 58300:8300/tcp -p 58302:8302/tcp -p 58302:8302/udp -p 58500:8500/tcp -p 58600:8600/udp -p 58301:8301/udp --name=test2 consul agent -client=172.19.0.10 -bind=172.19.0.10 -server -bootstrap -ui -join 192.168.99.100:48301
The consul container test2 at IP 172.19.0.10:8301 is not able to gossip with the 172.18.0.10:8301. I get the No Acknowledgement received message.
I also tried the --link to link both containers. But that didn't work.
Can anyone let me know if I am doing everything correct?
When you create a user-defined network on the docker daemon, there are some properties of these networks that you have to be aware of.
Each container in the network can immediately communicate with other containers in the network. Though, the network itself isolates the containers from external networks. Docker documentation
That effectively says what you are experiencing. The containers can not talk to each other because they are isolated from each other (reside in different networks).
To the point of --link, it is not supported in user-defined networks.
Within a user-defined bridge network, linking is not supported. Docker documentation
The solution would be to simply put both containers in the same network. I don't see an apparent need to use two different networks from your description. Just use a different --ip for the second one.
Related
I have 3 docker applications(containers) in which one container is communicating with other 2 containers. If I run that containers using below command, container 3 is able to access the container 1 and container 2.
docker run -d --network="host" --env-file container1.txt -p 8001:8080 img1:latest
docker run -d --network="host" --env-file container2.txt -p 8080:8080 img2:latest
docker run -d --network="host" --env-file container3.txt -p 8000:8080 img3:latest
But this is working only with host network if I remove this --network="host" option then I am not able to access this application outside(on web browser). In order to access it outside i need to make the host port and container ports same as below.
docker run -d --env-file container1.txt -p 8001:8001 img1:latest
docker run -d --env-file container2.txt -p 8080:8080 img2:latest
docker run -d --env-file container3.txt -p 8000:8000 img3:latest
With this above commands i am able to access my application on web browser but container 3 is not able to communicate with container 1. here container 3 can access the container 2 because there i am exposing 8080 host + container port. But i can't expose again 8080 host port for container 3.
How to resolve this issue??
At last my goal is this application should be accessible on browser without using host network, it should use the bridge network . And container 3 needs to communicate with container 1 & 2.
On user-defined networks, containers can not only communicate by IP address but can also resolve a container name to an IP address. This capability is called automatic service discovery.
Read this for more details on Docker container networking.
You can perform the following steps to achieve the desired result.
Create a private bridge network.
docker network create --driver bridge privet-net
Now start your application containers along with the --network private-net added to your docker run command.
docker run -d --env-file container1.txt -p 8001:8001 --network private-net img1:latest
docker run -d --env-file container2.txt -p 8080:8080 --network private-net img2:latest
docker run -d --env-file container3.txt -p 8000:8000 --network private-net img3:latest
With this way, all the three containers will be able to communicate with each other and also to the internet.
In this case when you are using --network=host, then you are telling docker to not isolate the network rather to use the host's network. So all the containers are on the same network, hence can communicate with each other without any issues. However when you remove --newtork=host, then docker will isolate the network as well there by restricting container 3 to communicate with container 1.
You will need some sort of orchestration service like docker compose, docker swarm etc.
I've got two Docker containers that need to have a websocket connection between the two.
I run one container like this:
docker run --name comm -p 8080:8080 comm_module:latest
to expose port 8080 to the host. Then I try to run the second container like this:
docker run --name test -p 8080:8080 datalogger:latest
However, I get the error below:
docker: Error response from daemon: driver failed programming external
connectivity on endpoint test
(f06588ee059e2c4be981e3676d7e05b374b42a8491f9f45be27da55248189556):
Bind for 0.0.0.0:8080 failed: port is already allocated. ERRO[0000]
error waiting for container: context canceled
I'm not sure what to do. Should I connect these to a network? How do I run these containers?
you can't bind the same host port twice in the same time you may change one of the ports on one container:
docker run --name comm -p 8080:8080 comm_module:latest
docker run --name test -p 8081:8080 datalogger:latest
you may check the configuration in the containers on how they communicate .
you can also create link between them:
docker run --name test -p 8081:8080 --link comm datalogger:latest
I finally worked it out. These are the steps involved for a two-way websocket communication between two Docker containers:
Modify the source code in the containers to use the name of the other container as the destination host address + port number (e.g. comm:port_no inside test, and vice versa).
Expose the same port (8080) in the Dockerfiles of the two containers and build the images. No need to publish them as they are will be visible to other containers on the network.
Create a user-defined bridge network like this:
docker network create my-net
Create my first container and attach it to the network:
docker create --name comm --network my-net comm_module:latest
Create my second container and attach it to the network:
docker create --name test --network my-net datalogger:latest
Start both containers by issuing the docker start command.
And the two-way websocket communication works nicely!
My Solution works fine.
docker network create mynet
docker run -p 443:443 --net=mynet --ip=172.18.0.3 --hostname=frontend.foobar.com foobarfrontend
docker run -p 9999:9999 --net=mynet --ip=172.18.0.2 --hostname=backend.foobar.com foobarbackend
route /P add 172.18.0.0 MASK 255.255.0.0 10.0.75.2
the foobarfrontend calls a wss websocket on foobarbackend on port 9999
PS: i work on docker windows 10 with linuxcontainers
have fun
I'm having a rather awful issue with running a Redis container. For some reason, even though I have attempted to bind the port and what have you, it won't expose the Redis port it claims to expose (6379). Obviously, I've checked this by scanning the open ports on the IP assigned to the Redis container (172.17.0.3) and it returned no open ports whatsoever. How might I resolve this issue?
Docker Redis Page (for reference to where I pulled the image from): https://hub.docker.com/_/redis/
The command variations I have tried:
docker run --name ausbot-ranksync-redis -p 127.0.0.1:6379:6379 -d redis
docker run --name ausbot-ranksync-redis -p 6379:6379 -d redis
docker run --name ausbot-ranksync-redis -d redis
docker run --name ausbot-ranksync-redis --expose=6379 -d redis
https://gyazo.com/991eb379f66eaa434ad44c5d92721b55 (The last container I scan is a MariaDB container)
The command variations I have tried:
docker run --name ausbot-ranksync-redis -p 127.0.0.1:6379:6379 -d redis
docker run --name ausbot-ranksync-redis -p 6379:6379 -d redis
Those two should work and make the port available on your host.
Obviously, I've checked this by scanning the open ports on the IP assigned to the Redis container (172.17.0.3) and it returned no open ports whatsoever. How might I resolve this issue?
You shouldn't be checking the ports directly on the container from outside of docker. If you want to access the container from the host or outside, you publish the port (as done above), and then access the port on the host IP (or 127.0.0.1 on the host in your first example).
For docker networking, you need to run your application listening on all interfaces (not localhost/loopback). The official redis image already does this, and you can verify with:
docker run --rm --net container:ausbot-ranksync-redis nicolaka/netshoot netstat -lnt
or
docker run --rm --net container:ausbot-ranksync-redis nicolaka/netshoot ss -lnt
To access the container from outside of docker, you need to publish the port (docker run -p ... or ports in the docker-compose.yml). Then you connect to the host IP and the published port.
To access the container from inside of docker, you create a shared network, run your containers there, and access using docker's DNS and the container port (publish and expose are not needed for this):
docker network create app
docker run --name ausbot-ranksync-redis --net app -d redis
docker run --name redis-cli --rm --net app redis redis-cli -h ausbot-ranksync-redis ping
I am really confused about this problem. I have two computer in our internal network. Both computers can ping internal servers.
Both computers have same docker version.
I run simple docker container with docker run -it --rm --name cont1 --net=host java:8 command on both computers. Then ssh into containers and try to ping internal server. One of the container can ping an internal server but other one can't reach any internal server.
How it can be possible? Do you have any idea about that?
Thank you
connect container to other systems in the same network is done by port mapping .
for that you need to run docker container with port mapping.
like - docker run -it --rm --name cont1 -p host_ip:host_port:container_port java:8
e.g., docker run -it --rm --name cont1 -p 192.168.134.122:1234:1500 java:8
NOTE : container port given in docker run is exposed in Dockerfile
now for example container ip will be - 172.17.0.2 port given in run is :1500
Now the request send to host_ip(192.168.134.122) and host_port(1234) is redirect to container with ip (172.17.0.2) and port (1500).
See the binding details in iptables -L -n -t nat
Thanks
I have 2 virtual machines (VM1 with IP 192.168.56.101 and VM2 with IP 192.16.56.102 which can ping each other) and these are the steps I'm doing:
- Create consul container on VM1 with 'docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap'
- Create swarm manager on VM1 with 'docker run -d -p 3376:3376 swarm manage -H 0.0.0.0:3376 --advertise 192.168.56.101:3376 consul://192.168.56.101:8500
- Create swarm agents on each VM with 'docker run -d swarm join --advertise <VM-IP>:2376 consul://192.168.56.101:8500
If i run docker -H 0.0.0.0:3376 info I can see both nodes connected to the swarm and they are both healthy. I can also run container and they are scheduled to the nodes. However, If I create a network and assign a few nodes to this network and then SSH into one node and try to ping every other node I can only reach the nodes which are running on the same virtual machine.
Both Virtual Machines have these DOCKER_OPTS:
DOCKER_OPTS = DOCKER_OPTS="--cluster-store=consul://192.168.56.101:8500 --cluster-advertise=<VM-IP>:0 -H tcp://0.0.0.0:2376 -H unix:///var/run/docker.sock"
I don't have a direct quote, but from what I've read on Docker GitHub issue tracker, ICMP packets (ping) are never routed between containers on different nodes.
TCP connection to explicitly opened ports should work. But as of Docker 1.12.1 it is buggy.
Docker 1.12.2 has some bug fixes wrt establishing a connection to containers on other hosts. But ping is not going to work across hosts.
You can only ping containers on the same node because you attach them to a local scope network.
As suggested in the comments, if you want to ping containers across hosts (meaning from a container on VM1 to a container on VM2) using docker swarm (or docker swarm mode) without explicitly opening ports, you need to create an overlay network (or globally scoped network) and assign/start containers on that network.
To create an overlay network:
docker network create -d overlay mynet
Then start the containers using that network:
For Docker Swarm mode:
docker service create --replicas 2 --network mynet --name web nginx
For Docker Swarm (legacy):
docker run -itd --network=mynet busybox
For example, if we create two containers (on legacy Swarm):
docker run -itd --network=mynet --name=test1 busybox
docker run -itd --network=mynet --name=test2 busybox
You should be able to docker attach on test2 to ping test1 and vice-versa.
For more details you can refer to the networking documentation.
Note: If containers still can't ping each other after the creation of an overlay network and attaching containers to it, check the firewall configurations of the VMs and make sure that these ports are open:
data plane / vxlan: UDP 4789
control plane / gossip: TCP/UDP 7946