CentOS 7
Docker 20.10
I want to delete all networks.
docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
As you can see no containers. I was removed it before.
I try this:
docker network ls
NETWORK ID NAME DRIVER SCOPE
1b6758d38df3 bridge bridge local
89dea066d590 host host local
8e235018309e none null local
And this:
docker network rm 1b6758d38df3
Error response from daemon: bridge is a pre-defined network and cannot be removed
P.S the folder /var/lib/docker is empty
Those are the system networks included in every Docker installation, they are not like user-defined networks and cannot be removed.
From the docs for thedocker network prune command:
Note that system networks such as bridge, host, and none will never be pruned
From the Network containers tutorial page:
Every installation of the Docker Engine automatically includes three default networks.
[...]
The network named bridge is a special network. Unless you tell it otherwise, Docker always launches your containers in this network.
This would mean that removing those networks would break some of Docker's networking features.
For what purpose do you want to remove/delete default network provided by Docker... Please share your use case so some one from community can guide you accordingly...
Bridge, Host & None are default & pre defined network... These networks are created during installation of docker....
Bridge - All containers without --network options get created within
bridge network only
To verify this you can run following commands -
docker run -it --rm --name=default-bridge-container1 busybox
As above command does not have --network option then it will be create container default-bridge-container1 under bridge network. To verify this, Run
docker network inspect bridge
Under containers section of inspect command, you will see container name default-bridge-container1 with IP assigned to it from bridge subnet.
Host - this option tells to use underlying host network
None - Container with --network=none means container is running in
isolation & it has no access to inward or outward network.
Related
I have a basic question about Docker that is probably due to lack of knowledge on my part about networking. The Docker container networking documentation states:
By default, when you create a container, it does not publish any of its ports to the outside world. To make a port available to services outside of Docker, or to Docker containers which are not connected to the container’s network, use the --publish or -p flag. This creates a firewall rule which maps a container port to a port on the Docker host.
It sounds like, when you install a container on your computer without mapping any ports from the container to the host machine, the container should not be able to access the internet. However, for example, I install the Ubuntu container with:
docker pull ubuntu
Then I enter the container's command line with:
docker run -ti ubuntu bash
At that point, I can run apt-get update and the container starts pulling information from the internet without mapping any ports (e.g. -p 80:80). How is this possible?
Publishing a port allows machines external to the docker host to access the container, inbound connectivity. By default, containers can access the network with outbound connectivity.
To restrict a container from accessing the network, you can either run the container with no network (note: this still creates a loopback interface, and you can later connect it to another network):
docker run --net none ...
Or you can create a network with the --internal option and run containers on that network:
docker network create --internal internal
docker run --net internal ...
The internal network is created without a gateway interface on the bridge network.
When they talk about publishing ports, they mean inbound ports.
Outbound ports work - depending on your network type - see here for more:
https://docs.docker.com/network/
Can you give me one guide or graph to understand the difference?
The reason why I ask this question is I can't open website with the following method:
docker network create -d bridge mybridge
docker run -d --net mybridge --name db redis
docker run -d --net mybridge -e DB=db -p 8000:5000 --name web chrch/web
But I can open website with the following method:
docker run --rm -d --network host --name my_nginx nginx
I use google cloud platform VM instance and install docker by myself.
According to the docker documentation about bridge networking:
In terms of Docker, a bridge network uses a software bridge which allows containers connected to the same bridge network to communicate, while providing isolation from containers which are not connected to that bridge network.
According to the docker documentation about host networking
If you use the host network driver for a container, that container’s network stack is not isolated from the Docker host. For instance, if you run a container which binds to port 80 and you use host networking, the container’s application will be available on port 80 on the host’s IP address.
If you want to deploy multiple containers connected between them with a private internal network use bridge networking. If you want to deploy a container connected to the same network stack as the host (and access the same networks as the host) use host networking. If you simply want to publish some ports, run the container with the --publish or -p option, such as -p 8080:80.
In your first example I'd expect the application to be reachable on the host's IP address at port 8000 (the remapped port), and in the second port 5000 (there is no remapping option with host networking). If there's some sort of configuration or firewalling issue preventing this from working you should address that, rather than hack around it with --net host.
Bridge networking is Docker's standard networking mode. You should prefer it if at all possible. There are, confusingly, two different modes of it, but the form you show with an explicit docker network create is a best practice and you should use it if at all possible. Host networking completely disables Docker's network isolation. It means containers see and use exactly the same network interfaces the host has available, without an intermediate NAT layer.
With bridge networking, you need the docker run -p option to make specific ports visible outside of Docker. As an operator you can remap ports, bind to specific interfaces on a multi-homed system, or simply decline to make a service visible to other hosts at all. The explicit docker network create form lets containers connect to each other using their docker run --name as host names. If you're running multiple application stacks on the same host, they can be partially isolated from each other by using separate networks. Each container has its own separate network space, and localhost means "this container". This mode is also an easy step to the networking models in multi-host systems like Docker Swarm or Kubernetes.
With host networking, none of the above works at all; you cannot use docker run --net host -p ... and you have no choice about where or how ports are exposed. You can't reach other containers, unless they're configured to publish ports themselves. Since you're using the host's network, localhost means the host's view of itself.
For all that it's frequently recommended in SO answers, --net host is rarely necessary. The two cases I can think of off hand are for a service that needs to interrogate the host's network stack (for instance, a service-discovery system like Consul needs to know every port the host is listening on to advertise that) or for a service that has a large or inconsistent set of ports it uses. If you're using --net host because you've hard-coded localhost in your application, you're better off making that configurable..
Feature
Bridge
Host
Driver
The Bridge network is provided by the Bridge driver
The host network is provided by the host driver.
Default
bridge is the default network and provided by a bridge driver
Host does not default.
Connectivity
The bridge driver provides intercontainer connectivity for all containers running on the same machine.
The host driver instructs Docker not to create any special networking namespace or resources for attached containers.
I'm trying to update the network of a running docker container.
Note: I didn't attach any network while running the container.
[root#stagingrbt ~]# docker network connect host cdf8d6e3013d
Error response from daemon: container sharing network namespace with another container or host cannot be connected to any other network
[root#stagingrbt ~]# docker network connect docker_gwbridge cdf8d6e3013d
error during connect: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.39/networks/docker_gwbridge/connect: EOF
[root#stagingrbt ~]# docker network create -d host my-host-network
Error response from daemon: only one instance of "host" network is allowed
[root#stagingrbt ~]# docker network ls
NETWORK ID NAME DRIVER SCOPE
495080cf93e3 bridge bridge local
cf0408d6f13f docker_gwbridge bridge local
2c5461835eaf host host local
87e9cohcbogh ingress overlay swarm
84dbd78101e3 none null local
774882ac9b09 sudhirnetwork bridge local
When you start a container, such as:
docker run -d --name alpine1 alpine
It is by default connected to the bridge network, check it with:
docker container inspect alpine1
If you try to connect it to host network with:
docker network connect host alpine1
you obtain an error:
Error response from daemon: container cannot be disconnected from host network or connected to host network
you have to delete the container and run it again on the host network:
docker stop alpine1
docker rm alpine1
docker run -d --network host --name alpine1 alpine
This limitation is not present on bridge networks. You can start a container:
docker run -d --name alpine2 alpine
disconnect it from the bridge network and reconnect it to another bridge network.
docker network disconnect bridge alpine2
docker network create --driver bridge alpine-net
docker network connect alpine-net alpine2
Note also that according to the documentation:
The host networking driver only works on Linux hosts, and is not supported on Docker Desktop for Mac, Docker Desktop for Windows, or Docker EE for Windows Server.
If you want to circumvent the command line and change the network of your docker container via portainer, you can do so. I'm not sure exactly which is the best way of doing this, but the steps below worked for me (changing a container that was running on the bridge network by default into the host network):
In the Container list, click on the container name (emby, in my case)
Stop the container
Click on Duplicate/Edit
Scroll down to Advanced container settings and select the Network tab
Change the Network to host (or whatever you want to set it to)
Click on Deploy the container right above.
Confirm that you want to replace the old container (or deploy it under a new name if you want to be on the save side and keep the old one).
Done!
Run or connect a container to a specific network: Note first of all, the network must exist already on the host. Either specify the network at container creation/startup time (docker create or docker run) with the --net option; or attach an existing container by using the docker network connect command. For example:
docker network connect my-network my-container
I am not sure if we can change the container network while running, however, assuming that the new docker network already exists, you can run the following commands to update your container network.
Executed on Version: 20.10.21 Community Edition
# docker stop <container-name>
# docker network disconnect <old-network-id> <container-name>
# docker network connect <new-network-id> <container-name>
# docker start <container-name>
Note: you won't be able to switch to host network from other network
I need to create some docker containers that must be accessed by other computers at the same network.
Problem is that when I create the container, Docker gets IP addresses valid only within the host machine.
I already took a look at Docker documentation (Networking) but nothing has worked.
If I run ifconfig on my machine my IP address is 172.21.46.149. When I go inside the container (Ubuntu) and run ifconfig the IP address is 172.17.0.2. I need Docker to get, for example, 172.21.46.150.
How can I do it?
You have to create a bridge on your host and assign that bridge to the container. This may help you: https://jpetazzo.github.io/2013/10/16/configure-docker-bridge-network/
Multi-host access involves an overlay network with service discovery.
See docker/networking:
An overlay network requires a key-value store. The store maintains information about the network state which includes discovery, networks, endpoints, IP Addresses, and more.
The Docker Engine currently supports Consul, etcd, ZooKeeper (Distributed store), and BoltDB (Local store) key-value store stores.
This example uses Consul.
If if your your nodes (the other computers across the same network) runs their docker daemon with a reference to that key-value store, they will be able to communicate with containers from other nodes.
DOCKER_OPTS="-H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --cluster-store=consul://<NODE-0-PRIVATE-IP>:8500/network --cluster-advertise=eth0:2375"
You just need to create an overlay network:
docker network create -d overlay --subnet=10.10.10.0/24 RED
(it will be available in all computers because of the key-value store)
And run your containers on that network:
docker run -itd --name container1 --net RED busybox
Docker containers can easily be accessed by other network node when a container:port is published through a host:port.
This is done using the -p docker-run option. Here is the sum-up of the man-page ($man docker-run gives more details and example that I won't copy/paste):
-p, --publish=[]
Publish a container's port, or range of ports, to the host.
See the doc online. This question/answer could be interesting to read too.
Basically:
docker run -it --rm -p 8085:8080 my_netcat nc -l -p 8080
Would allow LAN nodes to connect to the docker-host-ip:8085 and discuss with the netcat command.
I wish to make two of my containers available outside of the VM host on their separate, specific IP addresses (192.168.0.222, 192.168.0.227), without port mapping. That means I wish to access any port directly on the containers by using its IP. I already have machines running in the network outside of the VM host in the range 192.168.0.1–192.168.0.221.
Is this now possible with Docker 1.10.0, and if so, how?
I'm on OS X 10.11 with docker version 1.10.0, build 590d5108 and docker-machine version 0.6.0, build e27fb87, using boot2docker/VirtualBox driver.
I have been trying to figure this out for some while, without luck, and I've read the following questions and answers:
How to assign static public IP to docker container
How to expose docker container's ip and port to outside docker host without port mapping?
How can I make other machines on my network access my Docker containers (using port mapping)?
According to Jessie Frazelle, this should now be possible.
See "IPs for all the Things"
This is so cool I can hardly stand it.
In Docker 1.10, the awesome libnetwork team added the ability to specifiy a specific IP for a container. If you want to see the pull request it’s here: docker/docker#19001.
# create a new bridge network with your subnet and gateway for your ip block
$ docker network create --subnet 203.0.113.0/24 --gateway 203.0.113.254 iptastic
# run a nginx container with a specific ip in that block
$ docker run --rm -it --net iptastic --ip 203.0.113.2 nginx
# curl the ip from any other place (assuming this is a public ip block duh)
$ curl 203.0.113.2
# BOOM golden
That does illustrate the new docker run --ip option that you now see in docker network connect.
If specified, the container's IP address(es) is reapplied when a stopped container is restarted. If the IP address is no longer available, the container fails to start.
One way to guarantee that the IP address is available is to specify an --ip-range when creating the network, and choose the static IP address(es) from outside that range. This ensures that the IP address is not given to another container while this container is not on the network.
$ docker network create --subnet 172.20.0.0/16 --ip-range 172.20.240.0/20 multi-host-network
$ docker network connect --ip 172.20.128.2 multi-host-network container2
The "making accessible" part would involve, as usual, port forwarding.