# Network Management > New as of 0.11.0, Enhanced in 0.20.0 ``` network:create # Creates an attachable docker network network:destroy # Destroys a docker network network:exists # Checks if a docker network exists network:info # Outputs information about a docker network network:list # Lists all docker networks network:report [] [] # Displays a network report for one or more apps network:rebuild # Rebuilds network settings for an app network:rebuildall # Rebuild network settings for all apps network:set () # Set or clear a network property for an app ``` The Network plugin allows developers to abstract the concept of container network management, allowing developers to both change what networks a given container is attached to as well as rebuild the configuration on the fly. ## Usage ### Listing networks > New as of 0.20.0, Requires Docker 1.21+ You can easily list all available networks using the `network:list` command: ```shell dokku network:list ``` ``` =====> Networks bridge host none test-network ``` Note that you can easily hide extra output from Dokku commands by using the `--quiet` flag, which makes it easier to parse on the command line. ```shell dokku --quiet network:list ``` ``` bridge host none test-network ``` ### Creating a network > New as of 0.20.0, Requires Docker 1.21+ Docker networks can be created via the `network:create` command. Executing this command will create an attachable `bridge` network. This can be used to route requests between containers without going through any public network. ```shell dokku network:create test-network ``` ``` -----> Creating network test-network ``` Specifying other additional flags or other types of networks can be created directly via the `docker` command. ### Destroying a network > New as of 0.20.0, Requires Docker 1.21+ A Docker network without any associated containers may be destroyed via the `network:destroy` command. Docker will refuse to destroy networks that have containers attached. ```shell dokku network:destroy test-network ``` ```shell ! WARNING: Potentially Destructive Action ! This command will destroy network test. ! To proceed, type "test" > test -----> Destroying network test ``` As the command is destructive, it will default to asking for confirmation before executing the removal of the network. This may be avoided by providing the `--force` flag: ```shell dokku --force network:destroy test-network ``` ```shell -----> Destroying network test ``` ### Checking if a network exists > New as of 0.20.0, Requires Docker 1.21+ For CI/CD pipelines, it may be useful to see if an network exists before creating a new network. You can do so via the `network:exists` command: ```shell dokku network:exists nonexistent-network ``` ``` Network does not exist ``` The `network:exists` command will return non-zero if the network does not exist, and zero if it does. ### Checking network info > New as of 0.20.0, Requires Docker 1.21+ Network information can be retrieved via the `network:info` command. This is a slightly different version of the `docker network` command. ```shell dokku network:info test-network ``` ``` // TODO ``` ### Attaching an app to a network > New as of 0.20.0, Requires Docker 1.21+ Apps will default to being associated with the `bridge` network, but can be attached to `attachable` networks by changing the `attach-post-create` or `attach-post-deploy` network properties when using the [docker-local scheduler](/docs/advanced-usage/schedulers/docker-local.md). A change in these values will require an app deploy or rebuild. ```shell # associates the network after a container is created but before it is started dokku network:set node-js-app attach-post-create test-network # associates the network after the deploy is successful but before the proxy is updated dokku network:set node-js-app attach-post-deploy other-test-network ``` Setting the `attach` network property to an empty value will de-associate the container with the network. ```shell dokku network:set node-js-app attach-post-create dokku network:set node-js-app attach-post-deploy ``` When a container created for a deployment is being attached to a network - regardless of which `attach` property was used - a network alias of the pattern `APP.PROC_TYPE` will be added to all containers. This can be used to load-balance requests between containers. #### When to attach containers to a network Containers can be attached to a network for a variety of reasons: - A background process in one app needs to communicate to a webservice in another app - An app needs to talk to a container not managed by Dokku in a secure manner - A custom network that allows transparent access to another host exists and is necessary for an app to run Whatever the reason, the semantics of the two network hooks are important and are outlined before. - `attach-post-create`: - Phase it applies to: - `build`: Intermediate containers created during the build process. - `deploy`: Deployed app containers. - `run`: Containers created by the `run` command. - Container state on attach: `created` but not `running` - Use case: When the container needs to access a resource on the network. - Example: The app needs to talk to a database on the same network when it first boots. - `attach-post-deploy` - Phase it applies to: - `deploy`: Deployed app containers. - Container state on attach: `running` - Use case: When another container on the network needs to access _this_ container. - Example: A background process needs to communicate with the web process exposed by this container. > Warning: If the attachment fails at this stage, this may result in your application failing to respond to proxied requests once older containers are removed. ### Rebuilding network settings There are cases where you may need to rebuild the network configuration for an app, such as on app boot or container restart. In these cases, you can use the `network:rebuild` command: ```shell dokku network:rebuild node-js-app ``` > This command will exit a non-zero number that depends on the number of containers for which configuration could not be built ### Rebuilding all network settings In some cases, a docker upgrade may reset container IPs or Ports. In both cases, you can quickly rewrite those files by using the `network:rebuildall` command: ```shell dokku network:rebuildall ``` > This command will exit a non-zero number that depends on the number of containers for which configuration could not be built ### Container network interface binding > This functionality does not control the `--network` docker flag. Please use the [docker-options plugin](docs/advanced-usage/docker-options.md) to manage this flag. By default, an app will only bind to the internal interface. This behavior can be modified per app by changing the `bind-all-interfaces` network property. ```shell # bind to the default docker interface (`docker0`) with a random internal ip # this is the default behavior dokku network:set node-js-app bind-all-interfaces false # bind to all interfaces (`0.0.0.0`) on a random port for each upstream port # this will make the app container directly accessible by other hosts on your network # ports are randomized for every deploy, e.g. `0.0.0.0:32771->5000/tcp`. dokku network:set node-js-app bind-all-interfaces true ``` By way of example, in the default case, each container is bound to the docker interface: ```shell docker ps ``` ``` CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 1b88d8aec3d1 dokku/node-js-app:latest "/bin/bash -c '/star About a minute ago Up About a minute node-js-app.web.1 ``` As such, the container's IP address will be an internal IP, and thus it is only accessible on the host itself: ``` docker inspect --format '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' node-js-app.web.1 ``` ``` 172.17.0.6 ``` However, you can disable the internal proxying via the `network:set` command so that it will listen on the host's IP address: ```shell dokku network:set node-js-app bind-all-interfaces true # container bound to all interfaces docker ps ``` ``` CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES d6499edb0edb dokku/node-js-app:latest "/bin/bash -c '/star About a minute ago Up About a minute 0.0.0.0:49153->5000/tcp node-js-app.web.1 ``` ### Displaying network reports for an app You can get a report about the app's network status using the `network:report` command: ```shell dokku network:report ``` ``` =====> node-js-app network information Network bind all interfaces: false Network listeners: 172.17.0.1:5000 =====> python-sample network information Network bind all interfaces: false Network listeners: 172.17.0.2:5000 =====> ruby-sample network information Network bind all interfaces: true Network listeners: ``` You can run the command for a specific app also. ```shell dokku network:report node-js-app ``` ``` =====> node-js-app network information Network bind all interfaces: false Network listeners: 172.17.0.1:5000 ``` You can pass flags which will output only the value of the specific information you want. For example: ```shell dokku network:report node-js-app --network-bind-all-interfaces ```