--- 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, Vagrant will reuse that existing network for multiple containers. Once these networks have been created, Vagrant will attach these networks to the requested containers using the `docker network connect` for each network. Vagrant names the networks inside docker as `vagrant_network` or `vagrant_network_` where `` is the subnet for the network if defined by the user. An example of these networks is shown later in this page. If no subnet is requested for the network, Vagrant will connect the `vagrant_network` to the container. When destroying containers through Vagrant, Vagrant will clean up the network if there are no more containers using the network. ## Docker Network Options Most of the options work similar to other Vagrant providers. Defining either an ip or using `type: 'dhcp'` will give you a network on your container. ```ruby docker.vm.network :private_network, type: "dhcp" docker.vm.network :private_network, ip: "172.20.128.2" ``` If you want to set something specific with a new network you can use scoped options which align with the command line flags for the [docker network create](https://docs.docker.com/engine/reference/commandline/network_create/) command. If there are any specific options you want to enable from the `docker network create` command, you can specify them like this: ```ruby docker.vm.network :private_network, type: "dhcp", docker_network__internal: true ``` This will enable the `internal` option for the network when created with `docker network create`. Where `option` corresponds to the given flag that will be provided to the `docker network create` command. Similarly, if there is a value you wish to enable when connecting a container to a given network, you can use the following value in your network config: ```ruby docker_connect__option: "value" ``` When the docker provider creates a new network a netmask is required. If the netmask is not provided, Vagrant will default to a `/24` for IPv4 and `/64` for IPv6. To provide a different mask, set it using the `netmask` option: ```ruby docker.vm.network :private_network, ip: "172.20.128.2", netmask: 16 ``` For networks which set the type to "dhcp", it is also possible to specify a specific subnet for the network connection. This allows containers to connect to networks other than the default `vagrant_network` network. The docker provider supports specifying the desired subnet in two ways. The first is by using the `ip` and `netmask` options: ```ruby docker.vm.network :private_network, type: "dhcp", ip: "172.20.128.0", netmask: 24 ``` The second is by using the `subnet` option: ```ruby docker.vm.network :private_network, type: "dhcp", subnet: "172.20.128.0/24" ``` ### Public Networks The Vagrant docker provider also supports defining public networks. The easiest way to define a public network is by setting the `type` option to "dhcp": ```ruby docker.vm.network :public_network, type: "dhcp" ``` A bridge interface is required when setting up a public network. When no bridge device name is provided, Vagrant will prompt for the appropriate device to use. This can also be set using the `bridge` option: ```ruby docker.vm.network :public_network, type: "dhcp", bridge: "eth0" ``` The `bridge` option also supports a list of interfaces which can be used for setting up the network. Vagrant will inspect the defined interfaces and use the first active interface when setting up the network: ```ruby docker.vm.network :public_network, type: "dhcp", bridge: ["eth0", "wlan0"] ``` The available IP range for the bridge interface must be known when setting up the docker network. Even though a DHCP service may be available on the public network, docker will manage IP addresses provided to containers. This means that the subnet provided when defining the available IP range for the network should not be included within the subnet managed by the DHCP service. Vagrant will prompt for the available IP range information, however, it can also be provided in the Vagrantfile using the `docker_network__ip_range` option: ```ruby docker.vm.network :public_network, type: "dhcp", bridge: "eth0", docker_network__ip_range: "192.168.1.252/30" ``` Finally, the gateway for the interface is required during setup. The docker provider will default the gateway address to the first address available for the subnet of the bridge device. Vagrant will prompt for confirmation to use the default address. The address can also be manually set in the Vagrantfile using the `docker_network__gateway` option: ```ruby docker.vm.network :public_network, type: "dhcp", bridge: "eth0", docker_network__gateway: "192.168.1.2" ``` More examples are shared below which demonstrate creating a few common network interfaces. ## 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_network__internal: true docker.vm.network :private_network, ip: "172.20.128.2", netmask: "16" docker.vm.network :private_network, type: "dhcp", 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 ``` You can also connect your containers to a docker network that was created outside of Vagrant: ``` $ docker network create my-custom-network --subnet=172.20.0.0/16 ``` ```ruby Vagrant.configure("2") do |config| config.vm.define "docker" do |docker| docker.vm.network :private_network, type: "dhcp" name: "my-custom-network" docker.vm.provider "docker" do |d| d.build_dir = "docker_build_dir" end end end ``` Vagrant will not delete or modify these outside networks when deleting the container, however. ## Useful Debugging Tips 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/