Add Swarm section to the Docker Provider Documentation
This commit is contained in:
Damien Duportal
Traefiker Bot
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2 changed files with 136 additions and 52 deletions
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@ -7,6 +7,9 @@ A Story of Labels & Containers
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Attach labels to your containers and let Traefik do the rest!
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Traefik works with both [Docker (standalone) Engine](https://docs.docker.com/engine/)
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and [Docker Swarm Mode](https://docs.docker.com/engine/swarm/).
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!!! tip "The Quick Start Uses Docker"
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If you haven't already, maybe you'd like to go through the [quick start](../getting-started/quick-start.md) that uses the docker provider!
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@ -80,15 +83,136 @@ Attach labels to your containers and let Traefik do the rest!
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- traefik.http.services.my-container-service.loadbalancer.server.port=8080
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```
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!!! important "Labels in Docker Swarm Mode"
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While in Swarm Mode, Traefik uses labels found on services, not on individual containers.
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Therefore, if you use a compose file with Swarm Mode, labels should be defined in the `deploy` part of your service.
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This behavior is only enabled for docker-compose version 3+ ([Compose file reference](https://docs.docker.com/compose/compose-file/#labels-1)).
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## Routing Configuration
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See the dedicated section in [routing](../routing/providers/docker.md).
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When using Docker as a [provider](https://docs.traefik.io/providers/overview/),
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Trafik uses [container labels](https://docs.docker.com/engine/reference/commandline/run/#set-metadata-on-container--l---label---label-file) to retrieve its routing configuration.
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See the list of labels in the dedicated [routing](../routing/providers/docker.md) section.
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### Routing Configuration with Labels
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By default, Traefik watches for [container level labels](https://docs.docker.com/config/labels-custom-metadata/) on a standalone Docker Engine.
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When using Docker Compose, labels are specified by the directive
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[`labels`](https://docs.docker.com/compose/compose-file/#labels) from the
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["services" objects](https://docs.docker.com/compose/compose-file/#service-configuration-reference).
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!!! tip "Not Only Docker"
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Please note that any tool like Nomad, Terraform, Ansible, etc.
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that is able to define a Docker container with labels can work
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with Traefik & the Docker provider.
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### Port Detection
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Traefik retrieves the private IP and port of containers from the Docker API.
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Ports detection works as follows:
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- If a container [exposes](https://docs.docker.com/engine/reference/builder/#expose) only one port,
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then Traefik uses this port for private communication.
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- If a container [exposes](https://docs.docker.com/engine/reference/builder/#expose) multiple ports,
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or does not expose any port, then you must manually specify which port Traefik should use for communication
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by using the label `traefik.http.services.<service_name>.loadbalancer.server.port`
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(Read more on this label in the dedicated section in [routing](../routing/providers/docker.md#port)).
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### Docker API Access
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Traefik requires access to the docker socket to get its dynamic configuration.
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You can specify which Docker API Endpoint to use with the directive [`endpoint`](#endpoint).
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!!! warning "Security Note"
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Accessing the Docker API without any restriction is a security concern:
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If Traefik is attacked, then the attacker might get access to the underlying host.
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{: #security-note }
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As explained in the Docker documentation: ([Docker Daemon Attack Surface page](https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface)):
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!!! quote
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[...] only **trusted** users should be allowed to control your Docker daemon [...]
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??? success "Solutions"
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Expose the Docker socket over TCP, instead of the default Unix socket file.
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It allows different implementation levels of the [AAA (Authentication, Authorization, Accounting) concepts](https://en.wikipedia.org/wiki/AAA_(computer_security)), depending on your security assessment:
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- Authentication with Client Certificates as described in ["Protect the Docker daemon socket."](https://docs.docker.com/engine/security/https/)
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- Authorize and filter requests to restrict possible actions with [the TecnativaDocker Socket Proxy](https://github.com/Tecnativa/docker-socket-proxy).
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- Authorization with the [Docker Authorization Plugin Mechanism](https://docs.docker.com/engine/extend/plugins_authorization/)
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- Accounting at networking level, by exposing the socket only inside a Docker private network, only available for Traefik.
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- Accounting at container level, by exposing the socket on a another container than Traefik's.
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With Swarm mode, it allows scheduling of Traefik on worker nodes, with only the "socket exposer" container on the manager nodes.
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- Accounting at kernel level, by enforcing kernel calls with mechanisms like [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux), to only allows an identified set of actions for Traefik's process (or the "socket exposer" process).
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??? info "More Resources and Examples"
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- ["Paranoid about mounting /var/run/docker.sock?"](https://medium.com/@containeroo/traefik-2-0-paranoid-about-mounting-var-run-docker-sock-22da9cb3e78c)
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- [Traefik and Docker: A Discussion with Docker Captain, Bret Fisher](https://blog.containo.us/traefik-and-docker-a-discussion-with-docker-captain-bret-fisher-7f0b9a54ff88)
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- [KubeCon EU 2018 Keynote, Running with Scissors, from Liz Rice](https://www.youtube.com/watch?v=ltrV-Qmh3oY)
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- [Don't expose the Docker socket (not even to a container)](https://www.lvh.io/posts/dont-expose-the-docker-socket-not-even-to-a-container/)
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- [A thread on Stack Overflow about sharing the `/var/run/docker.sock` file](https://news.ycombinator.com/item?id=17983623)
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- [To DinD or not to DinD](https://blog.loof.fr/2018/01/to-dind-or-not-do-dind.html)
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- [Traefik issue GH-4174 about security with Docker socket](https://github.com/containous/traefik/issues/4174)
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- [Inspecting Docker Activity with Socat](https://developers.redhat.com/blog/2015/02/25/inspecting-docker-activity-with-socat/)
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- [Letting Traefik run on Worker Nodes](https://blog.mikesir87.io/2018/07/letting-traefik-run-on-worker-nodes/)
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- [Docker Socket Proxy from Tecnativa](https://github.com/Tecnativa/docker-socket-proxy)
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## Docker Swarm Mode
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To enable Docker Swarm (instead of standalone Docker) as a configuration provider,
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set the [`swarmMode`](#swarmmode) directive to `true`.
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### Routing Configuration with Labels
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While in Swarm Mode, Traefik uses labels found on services, not on individual containers.
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Therefore, if you use a compose file with Swarm Mode, labels should be defined in the
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[`deploy`](https://docs.docker.com/compose/compose-file/#labels-1) part of your service.
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This behavior is only enabled for docker-compose version 3+ ([Compose file reference](https://docs.docker.com/compose/compose-file)).
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### Port Detection
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Docker Swarm does not provide any [port detection](#port-detection) information to Traefik.
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Therefore you **must** specify the port to use for communication by using the label `traefik.http.services.<service_name>.loadbalancer.server.port`
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(Check the reference for this label in the [routing section for Docker](../routing/providers/docker.md#port)).
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### Docker API Access
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Docker Swarm Mode follows the same rules as Docker [API Access](#docker-api-access).
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As the Swarm API is only exposed on the [manager nodes](https://docs.docker.com/engine/swarm/how-swarm-mode-works/nodes/#manager-nodes), you should schedule Traefik on the Swarm manager nodes by default,
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by deploying Traefik with a [constraint](https://success.docker.com/article/using-contraints-and-labels-to-control-the-placement-of-containers) on the node's "role":
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```shell tab="With Docker CLI"
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docker service create \
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--constraint=node.role==manager \
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#... \
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```
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```yml tab="With Docker Compose"
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version: '3'
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services:
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traefik:
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# ...
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deploy:
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placement:
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constraints:
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- node.role == manager
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```
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!!! tip "Scheduling Traefik on Worker Nodes"
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Following the guidelines given in the previous section ["Docker API Access"](#docker-api-access),
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if you expose the Docker API through TCP, then Traefik can be scheduled on any node if the TCP
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socket is reachable.
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Please consider the security implications by reading the [Security Note](#security-note).
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A good example can be found on [Bret Fisher's repository](https://github.com/BretFisher/dogvscat/blob/master/stack-proxy-global.yml#L124).
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## Provider Configuration
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@ -111,48 +235,7 @@ providers:
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--providers.docker.endpoint=unix:///var/run/docker.sock
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```
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Traefik requires access to the docker socket to get its dynamic configuration.
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??? warning "Security Notes"
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Depending on your context, accessing the Docker API without any restriction can be a security concern: If Traefik is attacked, then the attacker might get access to the Docker (or Swarm Mode) backend.
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As explained in the Docker documentation: ([Docker Daemon Attack Surface page](https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface)):
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`[...] only **trusted** users should be allowed to control your Docker daemon [...]`
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!!! tip "Improved Security"
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[TraefikEE](https://containo.us/traefikee) solves this problem by separating the control plane (connected to Docker) and the data plane (handling the requests).
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??? info "Resources about Docker's Security"
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- [KubeCon EU 2018 Keynote, Running with Scissors, from Liz Rice](https://www.youtube.com/watch?v=ltrV-Qmh3oY)
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- [Don't expose the Docker socket (not even to a container)](https://www.lvh.io/posts/dont-expose-the-docker-socket-not-even-to-a-container/)
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- [A thread on Stack Overflow about sharing the `/var/run/docker.sock` file](https://news.ycombinator.com/item?id=17983623)
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- [To DinD or not to DinD](https://blog.loof.fr/2018/01/to-dind-or-not-do-dind.html)
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??? tip "Security Compensation"
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Expose the Docker socket over TCP, instead of the default Unix socket file.
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It allows different implementation levels of the [AAA (Authentication, Authorization, Accounting) concepts](https://en.wikipedia.org/wiki/AAA_(computer_security)), depending on your security assessment:
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- Authentication with Client Certificates as described in ["Protect the Docker daemon socket."](https://docs.docker.com/engine/security/https/)
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- Authorization with the [Docker Authorization Plugin Mechanism](https://docs.docker.com/engine/extend/plugins_authorization/)
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- Accounting at networking level, by exposing the socket only inside a Docker private network, only available for Traefik.
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- Accounting at container level, by exposing the socket on a another container than Traefik's.
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With Swarm mode, it allows scheduling of Traefik on worker nodes, with only the "socket exposer" container on the manager nodes.
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- Accounting at kernel level, by enforcing kernel calls with mechanisms like [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux), to only allows an identified set of actions for Traefik's process (or the "socket exposer" process).
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??? info "Additional Resources"
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- [Traefik issue GH-4174 about security with Docker socket](https://github.com/containous/traefik/issues/4174)
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- [Inspecting Docker Activity with Socat](https://developers.redhat.com/blog/2015/02/25/inspecting-docker-activity-with-socat/)
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- [Letting Traefik run on Worker Nodes](https://blog.mikesir87.io/2018/07/letting-traefik-run-on-worker-nodes/)
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- [Docker Socket Proxy from Tecnativa](https://github.com/Tecnativa/docker-socket-proxy)
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!!! info "Traefik & Swarm Mode"
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To let Traefik access the Docker Socket of the Swarm manager, it is mandatory to schedule Traefik on the Swarm manager nodes.
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See the sections [Docker API Access](#docker-api-access) and [Docker Swarm API Access](#docker-api-access_1) for more information.
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??? example "Using the docker.sock"
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@ -343,7 +426,7 @@ providers:
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# ...
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```
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Activates the Swarm Mode.
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Activates the Swarm Mode (instead of standalone Docker).
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### `swarmModeRefreshSeconds`
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@ -247,7 +247,8 @@ you'd add the label `traefik.http.services.<name-of-your-choice>.loadbalancer.pa
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Registers a port.
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Useful when the container exposes multiples ports.
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Mandatory for Docker Swarm.
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Mandatory for Docker Swarm (see the section ["Port Detection with Docker Swarm"](../../providers/docker.md#port-detection_1)).
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{: #port }
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```yaml
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- "traefik.http.services.myservice.loadbalancer.server.port=8080"
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