How to find docker storage device and its size (device mapper storage driver) How to add new host entry in /etc/hosts when a docker container is run; How to install Docker on Mac “while” Loop Examples in Shell Scripts; How to Configure Btrfs as the Storage Engine in Docker; How to Use user-defined Functions in awk. This article discusses four ways to make a Docker container appear on a local network. Apr 01, 2020 sudo docker exec -d leaf12 ip netns exec swnet sysctl net.ipv6.conf.swport5.disableipv6=1 sudo docker exec -d leaf12 ip netns exec swnet ip link set swport5 up sudo docker exec -d leaf12 ip link set dev swport6 netns swnet. Docker-machine ls If my memory serves right and toolbox works the same in Mac and Windows works, the ip address should be 192.168.99.100.

Update (2018-03-22) Since I wrote this document back in 2014,Docker has developed the macvlan networkdriver. That gives you asupported mechanism for direct connectivity to a local layer 2network. I’ve written an article about working with the macvlandriver.

This article discusses four ways to make a Docker container appear ona local network. These are not suggested as practical solutions, butare meant to illustrate some of the underlying network technologyavailable in Linux.

Docker 会尝试寻找没有被主机使用的 ip 段，尽管它适用于大多数情况下，但是它不是万能的，有时候我们还是需要对ip进一步规划。 Docker允许你管理docker0桥接或者通过-b选项自定义桥接网卡，需要安装bridge-utils软件包。 基本步骤如下： 1、确保docker的进程是停止的。. In the previous blog post, we deep-dived into Service Discovery aspects of Docker. A service is now a first class citizen in Docker 1.12.0 which allows replication, update of images and dynamic load-balancing. With Docker 1.12, services can be exposed on ports on all Swarm nodes and load balanced internally by Docker using either a virtual IP(VIP) based or DNS round.

If you were actually going to use one of these solutions as anythingother than a technology demonstration, you might look to the pipework script, which can automate many of these configurations.

Goals and Assumptions

In the following examples, we have a host with address 10.12.0.76 onthe 10.12.0.0/21 network. We are creating a Docker container that wewant to expose as 10.12.0.117.

I am running Fedora 20 with Docker 1.1.2. This means, in particular,that my utils-linux package is recent enough to include thensenter command. If you don’t have that handy, there is aconvenient Docker recipe to build it for you at jpetazzo/nsenteron GitHub.

A little help along the way

In this article we will often refer to the PID of a docker container.In order to make this convenient, drop the following into a scriptcalled docker-pid, place it somewhere on your PATH, and make itexecutable:

This allows us to conveniently get the PID of a docker container byname or ID:

In a script called docker-ip, place the following:

And now we can get the ip address of a container like this:

Using NAT

This uses the standard Docker network model combined with NAT rules onyour host to redirect inbound traffic to/outbound traffic from theappropriate IP address.

Assign our target address to your host interface:

Start your docker container, using the -p option to bind exposedports to an ip address and port on the host:

With this command, Docker will set up the standard network model:

• It will create a veth interface pair.
• Connect one end to the docker0 bridge.
• Place the other inside the container namespace as eth0.
• Assign an ip address from the network used by the docker0 bridge.

Because we added -p 10.12.0.117:80:80 to our command line, Dockerwill also create the following rule in the nat table DOCKERchain (which is run from the PREROUTING chain):

This matches traffic TO our target address (-d 10.12.0.117/32) notoriginating on the docker0 bridge (! -i docker0) destined fortcp port 80 (-p tcp -m tcp --dport 80). Matching traffic hasit’s destination set to the address of our docker container (-j DNAT --to-destination 172.17.0.4:80).

From a host elsewhere on the network, we can now access the web serverat our selected ip address:

If our container were to initiate a network connection with anothersystem, that connection would appear to originate with ip address ofour host. We can fix that my adding a SNAT rule to thePOSTROUTING chain to modify the source address:

Note here the use of -I POSTROUTING, which places the rule at thetop of the POSTROUTING chain. This is necessary because, bydefault, Docker has already added the following rule to the top of thePOSTROUTING chain:

Because this MASQUERADE rule matches traffic from any container, weneed to place our rule earlier in the POSTROUTING chain for it tohave any affect.

With these rules in place, traffic to 10.12.0.117 (port 80) isdirected to our web container, and traffic originating in the webcontainer will appear to come from 10.12.0.117.

With Linux Bridge devices

The previous example was relatively easy to configure, but has a fewshortcomings. If you need to configure an interface using DHCP, or ifyou have an application that needs to be on the same layer 2 broadcastdomain as other devices on your network, NAT rules aren’t going towork out.

This solution uses a Linux bridge device, created using brctl, toconnect your containers directly to a physical network.

Start by creating a new bridge device. In this example, we’ll createone called br-em1:

We’re going to add em1 to this bridge, and move the ip address fromem1 onto the bridge.

WARNING: This is not something you should do remotely, especiallyfor the first time, and making this persistent varies fromdistribution to distribution, so this will not be a persistentconfiguration.

Look at the configuration of interface em1 and note the existing ipaddress:

Look at your current routes and note the default route:

Now, add this device to your bridge:

Configure the bridge with the address that used to belong toem1:

And move the default route to the bridge:

If you were doing this remotely; you would do this all in one linelike this:

At this point, verify that you still have network connectivity:

Start up the web container:

This will give us the normal eth0 interface inside the container,but we’re going to ignore that and add a new one.

Create a veth interface pair:

Add the web-ext link to the br-eth0 bridge:

And add the web-int interface to the namespace of the container:

Next, we’ll use the nsenter command (part of the util-linux package) to run some commands inside the web container. Start by bringing up the link inside the container:

Assign our target ip address to the interface:

And set a new default route inside the container:

Again, we can verify from another host that the web server isavailable at 10.12.0.117:

Note that in this example we have assigned a static ip address, but wecould just have easily acquired an address using DHCP. After running:

We can run:

With Open vSwitch Bridge devices

This process is largely the same as in the previous example, but weuse Open vSwitch instead of the legacy Linux bridge devices.These instructions assume that you have already installed and startedOpen vSwitch on your system.

Create an OVS bridge using the ovs-vsctl command:

And add your external interface:

And then proceed as in the previous set of instructions.

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The equivalent all-in-one command is:

Once that completes, your openvswitch configuration should look likethis:

To add the web-ext interface to the bridge, run:

Instead of:

WARNING: The Open vSwitch configuration persists between reboots.This means that when your system comes back up, em1 will still be amember of br-em, which will probably result in no networkconnectivity for your host.

Before rebooting your system, make sure to ovs-vsctl del-port br-em1 em1.

With macvlan devices

This process is similar to the previous two, but instead of using abridge device we will create a macvlan, which is a virtual networkinterface associated with a physical interface. Unlike the previoustwo solutions, this does not require any interruption to your primarynetwork interface.

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Start by creating a docker container as in the previous examples:

Create a macvlan interface associated with your physical interface:

This creates a new macvlan interface named em1p0 (but you canname it anything you want) associated with interface em1. We aresetting it up in bridge mode, which permits all macvlan interfacesto communicate with eachother.

Add this interface to the container’s network namespace:

Bring up the link:

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And configure the ip address and routing:

And demonstrate that from another host the web server is availableat 10.12.0.117:

But note that if you were to try the same thing on the host, you wouldget:

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The host is unable to communicate with macvlan devices via theprimary interface. You can create anothermacvlan interface onthe host, give it an address on the appropriate network, and then setup routes to your containers via that interface: