I got confused between these two ip addresses :
$ docker-machine ls
NAME ACTIVE URL STATE URL SWARM DOCKER ERRORS
default * virtualbox Running tcp://192.168.99.100:2376 v1.10.3
and:
$ docker inspect aa769fbe3a3a | grep IPAddress | cut -d '"' -f 4
172.17.0.2
I looked in the docker doc, but can't find an answer.
Can someone explain to me what the ip 192.168.99.100 is used for ?
And what the other ip 172.17.0.2 used for ?
The first one is the IP of the Linux host which runs the docker daemon
The second one is the IP of the container aa769fbe3a3a using the bridge network eth0 to docker0.
Se for instance "Docker Networking" :
Also "Concerning Containers' Connections: on Docker Networking":
When the Docker service dæmon starts, it configures a virtual bridge, docker0, on the host system (Figure below).
Docker picks a subnet not in use on the host and assigns a free IP address to the bridge. The first try is 172.17.42.1/16, but that could be different if there are conflicts.
This virtual bridge handles all host-containers communications.
When Docker starts a container, by default, it creates a virtual interface on the host with a unique name, such as veth220960a, and an address within the same subnet.
This new interface will be connected to the eth0 interface on the container itself.
In order to allow connections, iptables rules are added, using a DOCKER-named chain. Network address translation (NAT) is used to forward traffic to external hosts, and the host machine must be set up to forward IP packets.
Related
I have multiple private ipv4 addresses on my machine (each one bound to a separate public IP address)
10.0.0.4
10.0.0.5
10.0.0.6
10.0.0.7
10.0.0.8
When I run my application which uses each IP address to perform some requests everything works fine and as expected. However, when I try to run it in docker my application claims that it failed to bind to the IP address. I believe this is because docker networking is isolated.
I'm wondering how I can "expose" these ipv4 addresses to my service via a docker-compose.yml file.
You're right that Docker's network isolation is involved: your application will see a single unpredictable IP address, and Docker provides a NAT layer that translates the host's network addresses to this.
The most common way to set this up is to set your application to bind to 0.0.0.0, "all interfaces". The Compose ports: setting takes an optional IP address part, which also defaults to 0.0.0.0. You can have multiple ports: targeting the same container port, so long as the host IP and port pairs don't conflict with other bound ports or non-Docker services.
As a hypothetical example:
version: '3.8'
services:
app:
image: registry.example.com/app
environment:
# Tell the application to listen on all interfaces, port 8080
BIND_ADDR: '0.0.0.0:8080'
ports:
# As the default HTTP service on the first IP address
- '10.0.0.4:80:8080'
# On its own port on the last IP address
- '10.0.0.8:8080:8080'
# And not on any of the other IP addresses at all
An alternative is to disable Docker's networking stack with network_mode: host. In this mode your application will see all of the host interfaces directly, and if it has specific logic to selectively bind to them, that will work just as if the program wasn't running in a container. However, this also disables all other Docker networking functionality: you cannot hide or remap ports, and you cannot communicate with other containers by hostname, only via their published ports. I'd generally discourage host networking, but it might be a reasonable approach to this particular scenario.
You can configure your docker container to use multiple IP addresses, at least in two ways:
Add additional IP addresses inside the container manually:
container # ip address add 172.17.1.4/32 dev eth0
container # ip address add 172.17.1.5/32 dev eth0
...
Note: These addresses probably need to belong to the container's subnet, not sure. docker network inspect bridge prints the default bridge network's subnet, 172.17.0.0/16 for me.
(source: Multiple ip on same interface in Docker container)
or
Create multiple bridge networks, each with a different subnet (IP range), then attach your container to these multiple networks.
For details, see
https://docs.docker.com/engine/reference/commandline/network_create/#specify-advanced-options
https://docs.docker.com/network/network-tutorial-standalone/#use-user-defined-bridge-networks
Then you can configure your docker host to route (packets from) these different container IP addresses via your different host IP addresses:
host # iptables -t nat -I POSTROUTING -p all -s 172.17.1.4/32 -j SNAT --to-source 10.0.0.4
host # iptables -t nat -I POSTROUTING -p all -s 172.17.1.5/32 -j SNAT --to-source 10.0.0.5
...
(source: https://serverfault.com/a/686107)
The end result is, traffic outgoing from your container via the different container IPs is routed via the different host IPs. You can confirm this eg. with:
container # curl -v --interface 172.17.1.4 <some destination that will show which host IP is used>
Regarding docker compose, I don't know enough about it to answer that part of your question.
I am currently trying to set a ip to container which can accessed by any other machine within the network. The network in which my docker-host machine is 9.158.143.0/24 with a gateway 9.158.143.254.
Tried setting the ip(any free) within the subnet 9.158.143.0/24 with network type as bridge.It did not work(not even able to ping the container within docker host machine).
Then created a user defined network with subnet 9.10.10.0/24 and network driver as bridge. the container created is pingable but only within docker host machine.
Is there any way that this container be accessible from all the machine within the network(not just docker host machine).
PS: i do not want to expose the port.(Is changing routes helpful ..i know very little networking)
I aso tried userdefined network with macvlan driver. in this case i am able to ping container from other machines but not from docker host machine where container is present
To do this, you need to:
1- dedicate a new address for this container, on your local network;
2- configure this address as a secondary address on your docker engine host;
3- enable routing between local interfaces on your docker engine host;
4- use iptables to redirect the connections to this new address to your container.
Here is an example:
We suppose:
your container instance is named myinstance
your LAN network interface is named eth0
you have chosen the available network address 192.168.1.178 on your LAN
So, you need to do the following:
start your container (in this example, we start a web server):
docker run --rm -t -i --name=mycontainer httpd:2.2-alpine
enable local IP routing:
sysctl -w net.ipv4.ip_forward=1
add a secondary address for your container:
ip addr add 192.168.1.178/24 dev eth0
redirect connections for this address to your container:
First, find your container local address:
% docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' mycontainer
172.17.0.2
Now, use this local address with iptables:
iptables -t nat -A PREROUTING -i eth0 -d 192.168.1.178/32 -j DNAT --to 172.17.0.2
Finally, you can check it works by accessing http://192.168.1.178/ from any other host on your LAN.
I have two containers say container1 and container2 running in same machine. I know i can communicate between both the container using link alias option. I have a scenario where i want to communicate between 2 containers using the IP address of the host machine. I have a property file in container1 where i need to provide the ip address of the container2 (Here i have to provide the ip address and not hostname of container). Everytime when i restart the container, the container ip gets changed. so is there any way to map the ip address of the host machine to link between container ?
Please check this doc which describes how to create docker network and assign IP address and range to docker container. In case of lack of time use commands below:
docker network create --subnet=192.168.0.0/16 docnet0
docker run --net docnet0 --ip 192.168.0.10 -it "your_docker_image" bash
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.
I have just started to have some experimentation with docker.
On my Windows host I have a virtual machine which holds a docker container. I want to have a communication between host and container or may be other VMs and this container.
Host ip is 192.168.2.10 with subnet mask 255.255.255.0
VM ip is 192.168.254.130 with subnet mask 255.255.255.0
Container gets an ip 172.17.0.13
I have seen few blogs talking about bridging but I am still not sure about it and how to do that. I am not very much into networking stuff.
A little guidance will help.
Thanks
EDIT:
I followed this bridge-building but could not understand what ip range to give to bridge, so, I gave 192.168.254.1/24. The command ip addr show bridge0 shows state UNKNOWN.
The normal way to do this is just to publish a port on the container and use the IP of the VM e.g:
docker run -d -p 80:80 nginx
Then visit the IP of the VM in a browser running on your host and you should get the webpage.
I'll assume you are using Docker on Windows with Linux host running on Virtualbox. Note that by default docker-machine creates a NAT adapter (with a port forward) and a host-only adapter, sometimes it is tricky to get different machines to talk to the correct ip.
As answered by Adrian you typically "publish" ports by port forwarding, but if your container has to communicate via many ports and you are only running one such container / host it could be easier to start the container via docker run --net host ..., this way host's ethernet adapters are directly visible within the container (as I discovered here).