--- layout: "docs" page_title: "Networking - Docker Provider" sidebar_current: "providers-docker-networking" description: |- The Vagrant Docker provider supports using the private network using the `docker network` commands. --- # Networking Vagrant uses the `docker network` command under the hood to create and manage networks for containers. Vagrant will do its best to create and manage networks for any containers configured inside the Vagrantfile. Each docker network is grouped by the subnet used for a requested ip address. For each newly unique network, Vagrant will run the `docker network create` subcommand with the provided options from the network config inside your Vagrantfile. If multiple networks share the same subnet, it will reuse that existing network. Once these networks have been created, Vagrant will attach these networks to the requested containers using the `docker network connect` for each network. Most of the options given to `:private_network` align with the command line flags for the [docker network create](https://docs.docker.com/engine/reference/commandline/network_create/) command. However, if you want the container to have a specific IP instead of using DHCP, you also will have to specify a subnet due to how docker networks behave. It should also be noted that if you want a specific IPv6 address, your `:private_network` option should use `ip6` rather than `ip`. If you just want to use DHCP, you can simply say `type: "dhcp"` insetad. More examples are shared below which demonstrate creating a few common network interfaces. When destroying containers through Vagrant, Vagrant will clean up the network if there are no more containers using the network. ## Docker Network Example The following Vagrantfile will generate these networks for a container: 1. A IPv4 IP address assigned by DHCP 2. A IPv4 IP address 172.20.128.2 on a network with subnet 172.20.0.0/16 3. A IPv6 IP address assigned by DHCP on subnet 2a02:6b8:b010:9020:1::/80 ```ruby Vagrant.configure("2") do |config| config.vm.define "docker" do |docker| docker.vm.network :private_network, type: "dhcp" docker.vm.network :private_network, ip: "172.20.128.2", subnet: "172.20.0.0/16" docker.vm.network :private_network, type: "dhcp", ipv6: "true", subnet: "2a02:6b8:b010:9020:1::/80" docker.vm.provider "docker" do |d| d.build_dir = "docker_build_dir" end end end ``` You can test that your container has the proper configured networks by looking at the result of running `ip addr`, for example: ``` brian@localghost:vagrant-sandbox % docker ps ±[●][master] CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 370f4e5d2217 196a06ef12f5 "tail -f /dev/null" 5 seconds ago Up 3 seconds 80/tcp, 443/tcp vagrant-sandbox_docker-1_1551810440 brian@localghost:vagrant-sandbox % docker exec 370f4e5d2217 ip addr ±[●][master] 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 24: eth0@if25: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:11:00:03 brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 172.17.0.3/16 brd 172.17.255.255 scope global eth0 valid_lft forever preferred_lft forever 27: eth1@if28: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:13:00:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 172.19.0.2/16 brd 172.19.255.255 scope global eth1 valid_lft forever preferred_lft forever 30: eth2@if31: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:14:80:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 172.20.128.2/16 brd 172.20.255.255 scope global eth2 valid_lft forever preferred_lft forever 33: eth3@if34: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:15:00:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 172.21.0.2/16 brd 172.21.255.255 scope global eth3 valid_lft forever preferred_lft forever inet6 2a02:6b8:b010:9020:1::2/80 scope global nodad valid_lft forever preferred_lft forever inet6 fe80::42:acff:fe15:2/64 scope link valid_lft forever preferred_lft forever ``` ## Useful Debugging Tips If you provide Vagrant with a faulty config option when setting up a network, Vagrant will pass that option along to the `docker network` commands it uses. That command line tool should give you some insight if there is something wrong with the option you configured: ```ruby docker.vm.network :private_network, ip: "172.20.128.2", subnet: "172.20.0.0/16", unsupported: "option" ``` ``` A Docker command executed by Vagrant didn't complete successfully! The command run along with the output from the command is shown below. Command: ["docker", "network", "create", "vagrant_network_172.20.0.0/16", "--subnet=172.20.0.0/16", "--unsupported=option", {:notify=>[:stdout, :stderr]}] Stderr: unknown flag: --unsupported See 'docker network create --help'. Stdout: ``` The `docker network` command provides some helpful insights to what might be going on with the networks Vagrant creates. For example, if you want to know what networks you currently have running on your machine, you can run the `docker network ls` command: ``` brian@localghost:vagrant-sandbox % docker network ls ±[●][master] NETWORK ID NAME DRIVER SCOPE a2bfc26bd876 bridge bridge local 2a2845e77550 host host local f36682aeba68 none null local 00d4986c7dc2 vagrant_network bridge local d02420ff4c39 vagrant_network_2a02:6b8:b010:9020:1::/80 bridge local 799ae9dbaf98 vagrant_network_172.20.0.0/16 bridge local ``` You can also inspect any network for more information: ``` brian@localghost:vagrant-sandbox % docker network inspect vagrant_network ±[●][master] [ { "Name": "vagrant_network", "Id": "00d4986c7dc2ed7bf1961989ae1cfe98504c711f9de2f547e5dfffe2bb819fc2", "Created": "2019-03-05T10:27:21.558824922-08:00", "Scope": "local", "Driver": "bridge", "EnableIPv6": false, "IPAM": { "Driver": "default", "Options": {}, "Config": [ { "Subnet": "172.19.0.0/16", "Gateway": "172.19.0.1" } ] }, "Internal": false, "Attachable": false, "Ingress": false, "ConfigFrom": { "Network": "" }, "ConfigOnly": false, "Containers": { "370f4e5d2217e698b16376583fbf051dd34018e5fd18958b604017def92fea63": { "Name": "vagrant-sandbox_docker-1_1551810440", "EndpointID": "166b7ca8960a9f20a150bb75a68d07e27e674781ed9f916e9aa58c8bc2539a61", "MacAddress": "02:42:ac:13:00:02", "IPv4Address": "172.19.0.2/16", "IPv6Address": "" } }, "Options": {}, "Labels": {} } ] ``` ## Caveats For now, Vagrant only looks at the subnet when figuring out if it should create a new network for a guest container. If you bring up a container with a network, and then change or add some new options (but leave the subnet the same), it will not apply those changes or create a new network. Because the `--link` flag for the `docker network connect` command is considered legacy, Vagrant does not support that option when creating containers and connecting networks. ## More Information For more information on how docker manages its networks, please refer to their documentation: - https://docs.docker.com/network/ - https://docs.docker.com/engine/reference/commandline/network/