diff --git a/docs/swarm/images/service-vip.png b/docs/swarm/images/service-vip.png new file mode 100644 index 0000000000000..63e4739730de0 Binary files /dev/null and b/docs/swarm/images/service-vip.png differ diff --git a/docs/swarm/images/src/service-vip.svg b/docs/swarm/images/src/service-vip.svg new file mode 100644 index 0000000000000..57776649facc8 --- /dev/null +++ b/docs/swarm/images/src/service-vip.svg @@ -0,0 +1 @@ +node1node3node2my-web.210.0.9.4my-web.110.0.9.3my-web.310.0.9.5my-web3replicanginxservicemy-webVIP:10.0.9.2my-networkmy-network \ No newline at end of file diff --git a/docs/swarm/networking.md b/docs/swarm/networking.md new file mode 100644 index 0000000000000..ae90dc313eb6c --- /dev/null +++ b/docs/swarm/networking.md @@ -0,0 +1,308 @@ + + +# Attach services to an overlay network + +Docker Engine swarm mode natively supports **overlay networks**, so you can +enable container-to-container networks. When you use swarm mode, you don't need +an external key-value store. Features of swarm mode overlay networks include the +following: + +* You can attach multiple services to the same network. +* By default, **service discovery** assigns a virtual IP address (VIP) and DNS +entry to each service in the swarm, making it available by its service name to +containers on the same network. +* You can configure the service to use DNS round-robin instead of a VIP. + +In order to use overlay networks in the swarm, you need to have the following +ports open between the swarm nodes before you enable swarm mode: + +* Port `7946` TCP/UDP for container network discovery. +* Port `4789` UDP for the container overlay network. + +## Create an overlay network in a swarm + +When you run Docker Engine in swarm mode, you can run `docker network create` +from a manager node to create an overlay network. For instance, to create a +network named `my-network`: + +``` +$ docker network create \ + --driver overlay \ + --subnet 10.0.9.0/24 \ + --opt encrypted \ + my-network + +273d53261bcdfda5f198587974dae3827e947ccd7e74a41bf1f482ad17fa0d33 +``` + +By default nodes in the swarm encrypt traffic between themselves and other +nodes. The optional `--opt encrypted` flag enables an additional layer of +encryption in the overlay driver for vxlan traffic between containers on +different nodes. For more information, refer to [Docker swarm mode overlay network security model](../userguide/networking/overlay-security-model.md). + +The `--subnet` flag specifies the subnet for use with the overlay network. When +you don't specify a subnet, the swarm manager automatically chooses a subnet and +assigns it to the network. On some older kernels, including kernel 3.10, +automatically assigned adresses may overlap with another subnet in your +infrastructure. Such overlaps can cause connectivity issues or failures with containers connected to the network. + +Before you attach a service to the network, the network only extends to manager +nodes. You can run `docker network ls` to view the network: + +```bash +$ docker network ls + +NETWORK ID NAME DRIVER SCOPE +f9145f09b38b bridge bridge local +..snip.. +bd0befxwiva4 my-network overlay swarm +``` + +The `swarm` scope indicates that the network is available for use with services +deployed to the swarm. After you create a service attached to the network, the +swarm only extends the network to worker nodes where the scheduler places tasks +for the service. On workers without tasks running for a service attached to the +network, `network ls` does not display the network. + +## Attach a service to an overlay network + +To attach a service to an overlay network, pass the `--network` flag when you +create a service. For example to create an nginx service attached to a +network called `my-network`: + +```bash +$ docker service create \ + --replicas 3 \ + --name my-web \ + --network my-network \ + nginx +``` + +>**Note:** You have to create the network before you can attach a service to it. + +The containers for the tasks in the service can connect to one another on the +overlay network. The swarm extends the network to all the nodes with `Running` +tasks for the service. + +From a manager node, run `docker service ps ` to view the nodes where +tasks are running for the service: + +```bash +$ docker service ps my-web + +ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR +63s86gf6a0ms34mvboniev7bs my-web.1 nginx node1 Running Running 58 seconds ago +6b3q2qbjveo4zauc6xig7au10 my-web.2 nginx node2 Running Running 58 seconds ago +66u2hcrz0miqpc8h0y0f3v7aw my-web.3 nginx node3 Running Running about a minute ago +``` + +![service vip image](images/service-vip.png) + +You can inspect the network from any node with a `Running` task for a service +attached to the network: + +```bash +$ docker network inspect +``` + +The network information includes a list of the containers on the node that are +attached to the network. For instance: + +```bash +$ docker network inspect my-network +[ + { + "Name": "my-network", + "Id": "7m2rjx0a97n88wzr4nu8772r3", + "Scope": "swarm", + "Driver": "overlay", + "EnableIPv6": false, + "IPAM": { + "Driver": "default", + "Options": null, + "Config": [ + { + "Subnet": "10.0.9.0/24", + "Gateway": "10.0.9.1" + } + ] + }, + "Internal": false, + "Containers": { + "404d1dec939a021678132a35259c3604b9657649437e59060621a17edae7a819": { + "Name": "my-web.1.63s86gf6a0ms34mvboniev7bs", + "EndpointID": "3c9588d04db9bc2bf8749cb079689a3072c44c68e544944cbea8e4bc20eb7de7", + "MacAddress": "02:42:0a:00:09:03", + "IPv4Address": "10.0.9.3/24", + "IPv6Address": "" + } + }, + "Options": { + "com.docker.network.driver.overlay.vxlanid_list": "257" + }, + "Labels": {} + } +] +``` + +In the example above, the container `my-web.1.63s86gf6a0ms34mvboniev7bs` for the +`my-web` service is attached to the `my-network` network on node2. + +## Use swarm mode service discovery + +By default, when you create a service attached to a network, the swarm assigns +the service a VIP. The VIP maps to a DNS alias based upon the service name. +Containers on the network share DNS mappings for the service via gossip so any container on the network can access the service via its service +name. + +You don't need to expose service-specific ports to make the service +available to other services on the same overlay network. The swarm's internal +load balancer automatically distributes requests to the service VIP among the +active tasks. + +You can inspect the service to view the virtual IP. For example: + +```bash +$ docker service inspect \ + --format='{{json .Endpoint.VirtualIPs}}' \ + my-web + +[{"NetworkID":"7m2rjx0a97n88wzr4nu8772r3" "Addr":"10.0.0.2/24"}] +``` + +The following example shows how you can add a `busybox` service on the same +network as the `nginx` service and the busybox service is able to access `nginx` +using the DNS name `my-web`: + +1. From a manager node, deploy a busybox service to the same network as +`my-web`: + + ```bash + $ docker service create \ + --name my-busybox \ + --network my-network \ + busybox \ + sleep 3000 + ``` + +2. Lookup the node where `my-busybox` is running: + + ```bash + $ docker service ps my-busybox + + ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR + 1dok2cmx2mln5hbqve8ilnair my-busybox.1 busybox node1 Running Running 5 seconds ago + ``` + +3. From the node where the busybox task is running, open an interactive shell to +the busybox container: + + ```bash + $ docker exec -it my-busybox.1.1dok2cmx2mln5hbqve8ilnair /bin/sh + ``` + + You can deduce the container name as ``+``. Alternatively, + you can run `docker ps` on the node where the task is running. + +4. From inside the busybox container, query the DNS to view the VIP for the +`my-web` service: + + ```bash + $ nslookup my-web + + Server: 127.0.0.11 + Address 1: 127.0.0.11 + + Name: my-web + Address 1: 10.0.9.2 ip-10-0-9-2.us-west-2.compute.internal + ``` + + >**Note:** the examples here use `nslookup`, but you can use `dig` or any + available DNS query tool. + +5. From inside the busybox container, query the DNS using a special query + to find the IP addresses of all the containers for the +`my-web` service: + + ```bash + $ nslookup tasks.my-web + + Server: 127.0.0.11 + Address 1: 127.0.0.11 + + Name: tasks.my-web + Address 1: 10.0.9.4 my-web.2.6b3q2qbjveo4zauc6xig7au10.my-network + Address 2: 10.0.9.3 my-web.1.63s86gf6a0ms34mvboniev7bs.my-network + Address 3: 10.0.9.5 my-web.3.66u2hcrz0miqpc8h0y0f3v7aw.my-network + ``` + +6. From inside the busybox container, run `wget` to access the nginx web server +running in the `my-web` service: + + ```bash + $ wget -O- my-web + + Connecting to my-web (10.0.9.2:80) + + + + Welcome to nginx! + ...snip... + ``` + + The swarm load balancer automatically routes the HTTP request to the + service's VIP to an active task. It distributes subsequent requests to + other tasks using round-robin selection. + +## Use DNS round-robin for a service + +You can configure the service to use DNS round-robin directly without using a +VIP, by setting the `--endpoint-mode dnsrr` when you create the service. DNS round-robin is useful in cases where you want to use your own load balancer. + +The following example shows a service with `dnsrr` endpoint mode: + +```bash +$ docker service create \ + --replicas 3 \ + --name my-dnsrr-service \ + --network my-network \ + --endpoint-mode dnsrr \ + nginx +``` + +When you query the DNS for the service name, the DNS service returns the IP +addresses for all the task containers: + +```bash +$ nslookup my-dnsrr-service +Server: 127.0.0.11 +Address 1: 127.0.0.11 + +Name: my-dnsrr +Address 1: 10.0.9.8 my-dnsrr-service.1.bd3a67p61by5dfdkyk7kog7pr.my-network +Address 2: 10.0.9.10 my-dnsrr-service.3.0sb1jxr99bywbvzac8xyw73b1.my-network +Address 3: 10.0.9.9 my-dnsrr-service.2.am6fx47p3bropyy2dy4f8hofb.my-network +``` + +## Confirm VIP connectivity + +In genaral we recommend you use `dig`, `nslookup`, or another DNS query tool to +test access to the service name via DNS. Because a VIP is a logical IP, `ping` +is not the right tool to confirm VIP connectivity. + +## Learn More + +* [Deploy services to a swarm](services.md) +* [Swarm administration guide](admin_guide.md) +* [Docker Engine command line reference](../reference/commandline/index.md) +* [Swarm mode tutorial](swarm-tutorial/index.md) diff --git a/docs/swarm/services.md b/docs/swarm/services.md index 21b85072d75b9..d5494b6fe3d71 100644 --- a/docs/swarm/services.md +++ b/docs/swarm/services.md @@ -213,8 +213,9 @@ $ docker service create \ The swarm extends `my-network` to each node running the service. - +For more information on overlay networking and service discovery, refer to +[Attach services to an overlay network](networking.md). See also +[Docker swarm mode overlay network security model](../userguide/networking/overlay-security-model.md). ## Configure update behavior diff --git a/docs/userguide/networking/dockernetworks.md b/docs/userguide/networking/dockernetworks.md deleted file mode 100644 index 511680a19a653..0000000000000 --- a/docs/userguide/networking/dockernetworks.md +++ /dev/null @@ -1,538 +0,0 @@ - - -# Understand Docker container networks - -To build web applications that act in concert but do so securely, use the Docker -networks feature. Networks, by definition, provide complete isolation for -containers. So, it is important to have control over the networks your -applications run on. Docker container networks give you that control. - -This section provides an overview of the default networking behavior that Docker -Engine delivers natively. It describes the type of networks created by default -and how to create your own, user-defined networks. It also describes the -resources required to create networks on a single host or across a cluster of -hosts. - -## Default Networks - -When you install Docker, it creates three networks automatically. You can list -these networks using the `docker network ls` command: - -``` -$ docker network ls - -NETWORK ID NAME DRIVER -7fca4eb8c647 bridge bridge -9f904ee27bf5 none null -cf03ee007fb4 host host -``` - -Historically, these three networks are part of Docker's implementation. When -you run a container you can use the `--network` flag to specify which network you -want to run a container on. These three networks are still available to you. - -The `bridge` network represents the `docker0` network present in all Docker -installations. Unless you specify otherwise with the `docker run ---network=` option, the Docker daemon connects containers to this network -by default. You can see this bridge as part of a host's network stack by using -the `ifconfig` command on the host. - -``` -$ ifconfig - -docker0 Link encap:Ethernet HWaddr 02:42:47:bc:3a:eb - inet addr:172.17.0.1 Bcast:0.0.0.0 Mask:255.255.0.0 - inet6 addr: fe80::42:47ff:febc:3aeb/64 Scope:Link - UP BROADCAST RUNNING MULTICAST MTU:9001 Metric:1 - RX packets:17 errors:0 dropped:0 overruns:0 frame:0 - TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:1100 (1.1 KB) TX bytes:648 (648.0 B) -``` - -The `none` network adds a container to a container-specific network stack. That container lacks a network interface. Attaching to such a container and looking at its stack you see this: - -``` -$ docker attach nonenetcontainer - -root@0cb243cd1293:/# cat /etc/hosts -127.0.0.1 localhost -::1 localhost ip6-localhost ip6-loopback -fe00::0 ip6-localnet -ff00::0 ip6-mcastprefix -ff02::1 ip6-allnodes -ff02::2 ip6-allrouters -root@0cb243cd1293:/# ifconfig -lo Link encap:Local Loopback - inet addr:127.0.0.1 Mask:255.0.0.0 - inet6 addr: ::1/128 Scope:Host - UP LOOPBACK RUNNING MTU:65536 Metric:1 - RX packets:0 errors:0 dropped:0 overruns:0 frame:0 - TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) - -root@0cb243cd1293:/# -``` ->**Note**: You can detach from the container and leave it running with `CTRL-p CTRL-q`. - -The `host` network adds a container on the hosts network stack. You'll find the -network configuration inside the container is identical to the host. - -With the exception of the `bridge` network, you really don't need to -interact with these default networks. While you can list and inspect them, you -cannot remove them. They are required by your Docker installation. However, you -can add your own user-defined networks and these you can remove when you no -longer need them. Before you learn more about creating your own networks, it is -worth looking at the default `bridge` network a bit. - - -### The default bridge network in detail -The default `bridge` network is present on all Docker hosts. The `docker network inspect` -command returns information about a network: - -``` -$ docker network inspect bridge - -[ - { - "Name": "bridge", - "Id": "f7ab26d71dbd6f557852c7156ae0574bbf62c42f539b50c8ebde0f728a253b6f", - "Scope": "local", - "Driver": "bridge", - "IPAM": { - "Driver": "default", - "Config": [ - { - "Subnet": "172.17.0.1/16", - "Gateway": "172.17.0.1" - } - ] - }, - "Containers": {}, - "Options": { - "com.docker.network.bridge.default_bridge": "true", - "com.docker.network.bridge.enable_icc": "true", - "com.docker.network.bridge.enable_ip_masquerade": "true", - "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0", - "com.docker.network.bridge.name": "docker0", - "com.docker.network.driver.mtu": "9001" - } - } -] -``` -The Engine automatically creates a `Subnet` and `Gateway` to the network. -The `docker run` command automatically adds new containers to this network. - -``` -$ docker run -itd --name=container1 busybox - -3386a527aa08b37ea9232cbcace2d2458d49f44bb05a6b775fba7ddd40d8f92c - -$ docker run -itd --name=container2 busybox - -94447ca479852d29aeddca75c28f7104df3c3196d7b6d83061879e339946805c -``` - -Inspecting the `bridge` network again after starting two containers shows both newly launched containers in the network. Their ids show up in the "Containers" section of `docker network inspect`: - -``` -$ docker network inspect bridge - -{[ - { - "Name": "bridge", - "Id": "f7ab26d71dbd6f557852c7156ae0574bbf62c42f539b50c8ebde0f728a253b6f", - "Scope": "local", - "Driver": "bridge", - "IPAM": { - "Driver": "default", - "Config": [ - { - "Subnet": "172.17.0.1/16", - "Gateway": "172.17.0.1" - } - ] - }, - "Containers": { - "3386a527aa08b37ea9232cbcace2d2458d49f44bb05a6b775fba7ddd40d8f92c": { - "EndpointID": "647c12443e91faf0fd508b6edfe59c30b642abb60dfab890b4bdccee38750bc1", - "MacAddress": "02:42:ac:11:00:02", - "IPv4Address": "172.17.0.2/16", - "IPv6Address": "" - }, - "94447ca479852d29aeddca75c28f7104df3c3196d7b6d83061879e339946805c": { - "EndpointID": "b047d090f446ac49747d3c37d63e4307be745876db7f0ceef7b311cbba615f48", - "MacAddress": "02:42:ac:11:00:03", - "IPv4Address": "172.17.0.3/16", - "IPv6Address": "" - } - }, - "Options": { - "com.docker.network.bridge.default_bridge": "true", - "com.docker.network.bridge.enable_icc": "true", - "com.docker.network.bridge.enable_ip_masquerade": "true", - "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0", - "com.docker.network.bridge.name": "docker0", - "com.docker.network.driver.mtu": "9001" - } - } -] -``` - -The `docker network inspect` command above shows all the connected containers and their network resources on a given network. Containers in this default network are able to communicate with each other using IP addresses. Docker does not support automatic service discovery on the default bridge network. If you want to communicate with container names in this default bridge network, you must connect the containers via the legacy `docker run --link` option. - -You can `attach` to a running `container` and investigate its configuration: - -``` -$ docker attach container1 - -root@0cb243cd1293:/# ifconfig -ifconfig -eth0 Link encap:Ethernet HWaddr 02:42:AC:11:00:02 - inet addr:172.17.0.2 Bcast:0.0.0.0 Mask:255.255.0.0 - inet6 addr: fe80::42:acff:fe11:2/64 Scope:Link - UP BROADCAST RUNNING MULTICAST MTU:9001 Metric:1 - RX packets:16 errors:0 dropped:0 overruns:0 frame:0 - TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:1296 (1.2 KiB) TX bytes:648 (648.0 B) - -lo Link encap:Local Loopback - inet addr:127.0.0.1 Mask:255.0.0.0 - inet6 addr: ::1/128 Scope:Host - UP LOOPBACK RUNNING MTU:65536 Metric:1 - RX packets:0 errors:0 dropped:0 overruns:0 frame:0 - TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) -``` - -Then use `ping` for about 3 seconds to test the connectivity of the containers on this `bridge` network. - -``` -root@0cb243cd1293:/# ping -w3 172.17.0.3 - -PING 172.17.0.3 (172.17.0.3): 56 data bytes -64 bytes from 172.17.0.3: seq=0 ttl=64 time=0.096 ms -64 bytes from 172.17.0.3: seq=1 ttl=64 time=0.080 ms -64 bytes from 172.17.0.3: seq=2 ttl=64 time=0.074 ms - ---- 172.17.0.3 ping statistics --- -3 packets transmitted, 3 packets received, 0% packet loss -round-trip min/avg/max = 0.074/0.083/0.096 ms -``` - -Finally, use the `cat` command to check the `container1` network configuration: - -``` -root@0cb243cd1293:/# cat /etc/hosts - -172.17.0.2 3386a527aa08 -127.0.0.1 localhost -::1 localhost ip6-localhost ip6-loopback -fe00::0 ip6-localnet -ff00::0 ip6-mcastprefix -ff02::1 ip6-allnodes -ff02::2 ip6-allrouters -``` -To detach from a `container1` and leave it running use `CTRL-p CTRL-q`.Then, attach to `container2` and repeat these three commands. - -``` -$ docker attach container2 - -root@0cb243cd1293:/# ifconfig - -eth0 Link encap:Ethernet HWaddr 02:42:AC:11:00:03 - inet addr:172.17.0.3 Bcast:0.0.0.0 Mask:255.255.0.0 - inet6 addr: fe80::42:acff:fe11:3/64 Scope:Link - UP BROADCAST RUNNING MULTICAST MTU:9001 Metric:1 - RX packets:15 errors:0 dropped:0 overruns:0 frame:0 - TX packets:13 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:1166 (1.1 KiB) TX bytes:1026 (1.0 KiB) - -lo Link encap:Local Loopback - inet addr:127.0.0.1 Mask:255.0.0.0 - inet6 addr: ::1/128 Scope:Host - UP LOOPBACK RUNNING MTU:65536 Metric:1 - RX packets:0 errors:0 dropped:0 overruns:0 frame:0 - TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 - collisions:0 txqueuelen:0 - RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) - -root@0cb243cd1293:/# ping -w3 172.17.0.2 - -PING 172.17.0.2 (172.17.0.2): 56 data bytes -64 bytes from 172.17.0.2: seq=0 ttl=64 time=0.067 ms -64 bytes from 172.17.0.2: seq=1 ttl=64 time=0.075 ms -64 bytes from 172.17.0.2: seq=2 ttl=64 time=0.072 ms - ---- 172.17.0.2 ping statistics --- -3 packets transmitted, 3 packets received, 0% packet loss -round-trip min/avg/max = 0.067/0.071/0.075 ms -/ # cat /etc/hosts -172.17.0.3 94447ca47985 -127.0.0.1 localhost -::1 localhost ip6-localhost ip6-loopback -fe00::0 ip6-localnet -ff00::0 ip6-mcastprefix -ff02::1 ip6-allnodes -ff02::2 ip6-allrouters -``` - -The default `docker0` bridge network supports the use of port mapping and `docker run --link` to allow communications between containers in the `docker0` network. These techniques are cumbersome to set up and prone to error. While they are still available to you as techniques, it is better to avoid them and define your own bridge networks instead. - -## User-defined networks - -You can create your own user-defined networks that better isolate containers. -Docker provides some default **network drivers** for creating these -networks. You can create a new **bridge network** or **overlay network**. You -can also create a **network plugin** or **remote network** written to your own -specifications. - -You can create multiple networks. You can add containers to more than one -network. Containers can only communicate within networks but not across -networks. A container attached to two networks can communicate with member -containers in either network. When a container is connected to multiple -networks, its external connectivity is provided via the first non-internal -network, in lexical order. - -The next few sections describe each of Docker's built-in network drivers in -greater detail. - -### A bridge network - -The easiest user-defined network to create is a `bridge` network. This network -is similar to the historical, default `docker0` network. There are some added -features and some old features that aren't available. - -``` -$ docker network create --driver bridge isolated_nw -1196a4c5af43a21ae38ef34515b6af19236a3fc48122cf585e3f3054d509679b - -$ docker network inspect isolated_nw - -[ - { - "Name": "isolated_nw", - "Id": "1196a4c5af43a21ae38ef34515b6af19236a3fc48122cf585e3f3054d509679b", - "Scope": "local", - "Driver": "bridge", - "IPAM": { - "Driver": "default", - "Config": [ - { - "Subnet": "172.21.0.0/16", - "Gateway": "172.21.0.1" - } - ] - }, - "Containers": {}, - "Options": {} - } -] - -$ docker network ls - -NETWORK ID NAME DRIVER -9f904ee27bf5 none null -cf03ee007fb4 host host -7fca4eb8c647 bridge bridge -c5ee82f76de3 isolated_nw bridge - -``` - -After you create the network, you can launch containers on it using the `docker run --network=` option. - -``` -$ docker run --network=isolated_nw -itd --name=container3 busybox - -8c1a0a5be480921d669a073393ade66a3fc49933f08bcc5515b37b8144f6d47c - -$ docker network inspect isolated_nw -[ - { - "Name": "isolated_nw", - "Id": "1196a4c5af43a21ae38ef34515b6af19236a3fc48122cf585e3f3054d509679b", - "Scope": "local", - "Driver": "bridge", - "IPAM": { - "Driver": "default", - "Config": [ - {} - ] - }, - "Containers": { - "8c1a0a5be480921d669a073393ade66a3fc49933f08bcc5515b37b8144f6d47c": { - "EndpointID": "93b2db4a9b9a997beb912d28bcfc117f7b0eb924ff91d48cfa251d473e6a9b08", - "MacAddress": "02:42:ac:15:00:02", - "IPv4Address": "172.21.0.2/16", - "IPv6Address": "" - } - }, - "Options": {} - } -] -``` - -The containers you launch into this network must reside on the same Docker host. -Each container in the network can immediately communicate with other containers -in the network. Though, the network itself isolates the containers from external -networks. - -![An isolated network](images/bridge_network.png) - -Within a user-defined bridge network, linking is not supported. You can -expose and publish container ports on containers in this network. This is useful -if you want to make a portion of the `bridge` network available to an outside -network. - -![Bridge network](images/network_access.png) - -A bridge network is useful in cases where you want to run a relatively small -network on a single host. You can, however, create significantly larger networks -by creating an `overlay` network. - - -### An overlay network - -Docker's `overlay` network driver supports multi-host networking natively -out-of-the-box. This support is accomplished with the help of `libnetwork`, a -built-in VXLAN-based overlay network driver, and Docker's `libkv` library. - -The `overlay` network requires a valid key-value store service. Currently, -Docker's `libkv` supports Consul, Etcd, and ZooKeeper (Distributed store). Before -creating a network you must install and configure your chosen key-value store -service. The Docker hosts that you intend to network and the service must be -able to communicate. - -![Key-value store](images/key_value.png) - -Each host in the network must run a Docker Engine instance. The easiest way to -provision the hosts are with Docker Machine. - -![Engine on each host](images/engine_on_net.png) - -You should open the following ports between each of your hosts. - -| Protocol | Port | Description | -|----------|------|-----------------------| -| udp | 4789 | Data plane (VXLAN) | -| tcp/udp | 7946 | Control plane | - -Your key-value store service may require additional ports. -Check your vendor's documentation and open any required ports. - -Once you have several machines provisioned, you can use Docker Swarm to quickly -form them into a swarm which includes a discovery service as well. - -To create an overlay network, you configure options on the `daemon` on each -Docker Engine for use with `overlay` network. There are three options to set: - - - - - - - - - - - - - - - - - - - - - - -
OptionDescription
--cluster-store=PROVIDER://URL
Describes the location of the KV service.
--cluster-advertise=HOST_IP|HOST_IFACE:PORT
The IP address or interface of the HOST used for clustering.
--cluster-store-opt=KEY-VALUE OPTIONS
Options such as TLS certificate or tuning discovery Timers
- -Create an `overlay` network on one of the machines in the swarm. - - $ docker network create --driver overlay my-multi-host-network - -This results in a single network spanning multiple hosts. An `overlay` network -provides complete isolation for the containers. - -![An overlay network](images/overlay_network.png) - -Then, on each host, launch containers making sure to specify the network name. - - $ docker run -itd --network=my-multi-host-network busybox - -Once connected, each container has access to all the containers in the network -regardless of which Docker host the container was launched on. - -![Published port](images/overlay-network-final.png) - -If you would like to try this for yourself, see the [Getting started for -overlay](get-started-overlay.md). - -### Custom network plugin - -If you like, you can write your own network driver plugin. A network -driver plugin makes use of Docker's plugin infrastructure. In this -infrastructure, a plugin is a process running on the same Docker host as the -Docker `daemon`. - -Network plugins follow the same restrictions and installation rules as other -plugins. All plugins make use of the plugin API. They have a lifecycle that -encompasses installation, starting, stopping and activation. - -Once you have created and installed a custom network driver, you use it like the -built-in network drivers. For example: - - $ docker network create --driver weave mynet - -You can inspect it, add containers to and from it, and so forth. Of course, -different plugins may make use of different technologies or frameworks. Custom -networks can include features not present in Docker's default networks. For more -information on writing plugins, see [Extending Docker](../../extend/index.md) and -[Writing a network driver plugin](../../extend/plugins_network.md). - -### Docker embedded DNS server - -Docker daemon runs an embedded DNS server to provide automatic service discovery -for containers connected to user defined networks. Name resolution requests from -the containers are handled first by the embedded DNS server. If the embedded DNS -server is unable to resolve the request it will be forwarded to any external DNS -servers configured for the container. To facilitate this when the container is -created, only the embedded DNS server reachable at `127.0.0.11` will be listed -in the container's `resolv.conf` file. More information on embedded DNS server on -user-defined networks can be found in the [embedded DNS server in user-defined networks] -(configure-dns.md) - -## Links - -Before the Docker network feature, you could use the Docker link feature to -allow containers to discover each other. With the introduction of Docker networks, -containers can be discovered by its name automatically. But you can still create -links but they behave differently when used in the default `docker0` bridge network -compared to user-defined networks. For more information, please refer to -[Legacy Links](default_network/dockerlinks.md) for link feature in default `bridge` network -and the [linking containers in user-defined networks](work-with-networks.md#linking-containers-in-user-defined-networks) for links -functionality in user-defined networks. - -## Related information - -- [Work with network commands](work-with-networks.md) -- [Get started with multi-host networking](get-started-overlay.md) -- [Managing Data in Containers](../../tutorials/dockervolumes.md) -- [Docker Machine overview](https://docs.docker.com/machine) -- [Docker Swarm overview](https://docs.docker.com/swarm) -- [Investigate the LibNetwork project](https://github.com/docker/libnetwork) diff --git a/docs/userguide/networking/get-started-overlay.md b/docs/userguide/networking/get-started-overlay.md index 73b2d441816e5..f7b22b614faa5 100644 --- a/docs/userguide/networking/get-started-overlay.md +++ b/docs/userguide/networking/get-started-overlay.md @@ -54,6 +54,7 @@ $ $ docker service create --replicas 2 --network my-multi-host-network --name my Overlay networks for a swarm are not available to unmanaged containers. For more information refer to [Docker swarm mode overlay network security model](overlay-security-model.md). +See also [Attach services to an overlay network](../../swarm/networking.md). ## Overlay networking with an external key-value store diff --git a/docs/userguide/networking/index.md b/docs/userguide/networking/index.md index 8731dcbe45060..c7491312df6fc 100644 --- a/docs/userguide/networking/index.md +++ b/docs/userguide/networking/index.md @@ -437,6 +437,8 @@ Overlay networks for a swarm are not available to containers started with `docker run` that don't run as part of a swarm mode service. For more information refer to [Docker swarm mode overlay network security model](overlay-security-model.md). +See also [Attach services to an overlay network](../../swarm/networking.md). + ### An overlay network with an external key-value store If you are not using Docker Engine in swarm mode, the `overlay` network requires