Ceci est une ancienne révision du document !
Table des matières
Version : 2023.01
Last update : 2023/12/17 11:17
DOF606 - Overlay Network Management with Docker in Swarm Mode
Contents
- DOF606 - Overlay Network Management with Docker in Swarm mode
- Contents
- The Docker Network Model
- LAB #1 - Overlay Network Management
- 1.1 - Creating a network overlay
- 1.2 - Creating a Service
- 1.3 - Moving the Service to another Overlay Network
- 1.4 - DNS container discovery
- 1.5 - Creating a Custom Overlay Network
- LAB #2 - Microservices Architecture Management
- 2.1 - Implementing Docker Swarm with overlay networks
The Docker Network Model
The Docker network model is libnetwork, which implements the Container Network Model (CNM). There are three components in this model:
- Sandbox,
- contains the container's network configuration, i.e. interface management, routing table and DNS,
- Endpoint,
- connects a sandbox to a network,
- Network,
- a group of endpoints which communicate directly.
LAB #1 - Network overlay management
In addition to the bridge, host and none networks, Docker offers two other types of network, namely overlay and macvlan. This module is about overlay. For more information about the macvlan type, see the Docker documentation site ici.
As the name suggests, an overlay network is a network that sits on top of the host network. When an overlay network is created, by default it is only available to swarm services. However, it is possible to connect autonomous containers to the overlay network if the –attachable option is specified when the network is created. This type of use of the overlay network is not recommended by Docker, which says that support for this feature may be withdrawn.
Traffic linked to the management of swarm services is encrypted by default using the AES algorithm in GCM mode. In order to encrypt application-related data traffic, it is possible to use the –opt encrypted option when creating the overlay network. In this case, Docker creates IPSEC tunnels between each node using the same algorithm as the swarm services traffic. There is therefore a performance degradation to be assessed before going into production. In both cases the keys are changed every 12 hours (see https://www.vaultproject.io/docs/internals/rotation.html)
CAUTION: Encryption of application-related data is not compatible with Windows™. When connecting the Windows™ node to an encrypted overlay network, no errors will be reported. However the node will be unable to communicate.
Start by re-creating a swarm using the manager, worker1 and worker2 virtual machines:
root@debian11:~# ssh -l trainee 10.0.3.62
The authenticity of host '10.0.3.62 (10.0.3.62)' can't be established.
ECDSA key fingerprint is SHA256:sEfHBv9azmK60cjqF/aJgUc9jg56slNaZQdAUcvBOvE.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.0.3.62' (ECDSA) to the list of known hosts.
trainee@10.0.3.62's password: trainee
Linux manager.i2tch.loc 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Sun Jul 17 08:27:29 2022 from 10.0.3.1
trainee@manager:~$ su -
Mot de passe : fenestros
root@manager:~#
root@manager:~# docker swarm leave
Node left the swarm.
root@manager:~# docker swarm init --advertise-addr 10.0.3.62
Swarm initialized: current node (tpn1zsk20sfsfafmk2cvefqjc) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-23d7n1fkkk9rvlhty106q9390bfpf9daljjguq3s807le6c5qs-e0s1yqsajvmi7s8t9l9mw48ao 10.0.3.62:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
Connect to worker1 :
root@manager:~# ssh -l trainee 10.0.3.63 The authenticity of host '10.0.3.63 (10.0.3.63)' can't be established. ECDSA key fingerprint is SHA256:sEfHBv9azmK60cjqF/aJgUc9jg56slNaZQdAUcvBOvE. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '10.0.3.63' (ECDSA) to the list of known hosts. trainee@10.0.3.63's password: trainee Linux worker1.i2tch.loc 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Sun Mar 21 16:34:26 2021 from 10.0.3.11 trainee@worker1:~$ su - Mot de passe : fenestros root@worker1:~# root@worker1:~# docker swarm leave Node left the swarm. root@worker1:~# docker swarm join --token SWMTKN-1-23d7n1fkkk9rvlhty106q9390bfpf9daljjguq3s807le6c5qs-e0s1yqsajvmi7s8t9l9mw48ao 10.0.3.62:2377 This node joined a swarm as a worker. root@worker1:~# exit déconnexion trainee@worker1:~$ exit déconnexion Connection to 10.0.3.63 closed. root@manager:~#
Connect to worker2 :
root@manager:~# ssh -l trainee 10.0.3.64 The authenticity of host '10.0.3.64 (10.0.3.64)' can't be established. ECDSA key fingerprint is SHA256:sEfHBv9azmK60cjqF/aJgUc9jg56slNaZQdAUcvBOvE. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '10.0.3.64' (ECDSA) to the list of known hosts. trainee@10.0.3.64's password: trainee Linux worker2.i2tch.loc 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Sun Mar 21 16:18:25 2021 from 10.0.3.11 trainee@worker2:~$ su - Mot de passe : fenestros root@worker2:~# root@worker2:~# docker swarm leave Node left the swarm. root@worker2:~# docker swarm join --token SWMTKN-1-23d7n1fkkk9rvlhty106q9390bfpf9daljjguq3s807le6c5qs-e0s1yqsajvmi7s8t9l9mw48ao 10.0.3.62:2377 This node joined a swarm as a worker. root@worker2:~# exit déconnexion trainee@worker2:~$ exit déconnexion Connection to 10.0.3.64 closed. root@manager:~#
Check the state of the swarm:
root@manager:~# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION b85hxlixbr1mh1txd1hrfe4us * manager.i2tch.loc Ready Active Leader 19.03.4 4sui75vvdhmet4qvt0zbvzlzl worker1.i2tch.loc Ready Active 19.03.4 lbjtg5o9kw3x6xg7frm07jfuw worker2.i2tch.loc Ready Active 19.03.4 root@manager:~# docker node ls --filter role=manager ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION b85hxlixbr1mh1txd1hrfe4us * manager.i2tch.loc Ready Active Leader 19.03.4 root@manager:~# docker node ls --filter role=worker ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION 4sui75vvdhmet4qvt0zbvzlzl worker1.i2tch.loc Ready Active 19.03.4 lbjtg5o9kw3x6xg7frm07jfuw worker2.i2tch.loc Ready Active 19.03.4
Check the presence of the overlay network ingress as well as the bridged network docker_gwbridge :
root@manager:~# docker network ls NETWORK ID NAME DRIVER SCOPE 4edb7186dcc9 bridge bridge local d4c9b0c9437a docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm de563e30d473 none null local
Info: The docker_gwbridge network connects the ingress network to the host's network adapter and therefore connects the Docker daemon to the other Docker daemons participating in swarm.
Best Practice : Docker recommends using different overlay networks for each application or group of applications.
.1 - Creating an Overlay Network
From the Manager, create an overlay type network called nginx-net :
root@manager:~# docker network create -d overlay nginx-net j57jhtug4kjxp22ai1y664lqr root@manager:~# docker network ls NETWORK ID NAME DRIVER SCOPE dde514eea83f bridge bridge local d4c9b0c9437a docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm j57jhtug4kjx nginx-net overlay swarm de563e30d473 none null local
.2 - Creating a Service
Create a nginx service that uses the nginx-net network:
root@manager:~# docker service create --name my-nginx --publish target=80,published=80 --replicas=5 --network nginx-net nginx fpydgix3e1rc1qum72gvwcb7f overall progress: 5 out of 5 tasks 1/5: running [==================================================>] 2/5: running [==================================================>] 3/5: running [==================================================>] 4/5: running [==================================================>] 5/5: running [==================================================>] verify: Service converged
Info : The service publishes port 80, which is visible from the outside. Containers communicate with each other without opening additional ports.
Check that the service is working before continuing:
root@manager:~# docker service ls ID NAME MODE REPLICAS IMAGE PORTS fpydgix3e1rc my-nginx replicated 5/5 nginx:latest *:80->80/tcp
Now take a look at the service details:
root@manager:~# docker service inspect my-nginx
[
{
"ID": "fpydgix3e1rc1qum72gvwcb7f",
"Version": {
"Index": 40
},
"CreatedAt": "2019-10-28T06:23:29.17883246Z",
"UpdatedAt": "2019-10-28T06:23:29.183438696Z",
"Spec": {
"Name": "my-nginx",
"Labels": {},
"TaskTemplate": {
"ContainerSpec": {
"Image": "nginx:latest@sha256:922c815aa4df050d4df476e92daed4231f466acc8ee90e0e774951b0fd7195a4",
"Init": false,
"StopGracePeriod": 10000000000,
"DNSConfig": {},
"Isolation": "default"
},
"Resources": {
"Limits": {},
"Reservations": {}
},
"RestartPolicy": {
"Condition": "any",
"Delay": 5000000000,
"MaxAttempts": 0
},
"Placement": {
"Platforms": [
{
"Architecture": "amd64",
"OS": "linux"
},
{
"OS": "linux"
},
{
"Architecture": "arm64",
"OS": "linux"
},
{
"Architecture": "386",
"OS": "linux"
},
{
"Architecture": "ppc64le",
"OS": "linux"
},
{
"Architecture": "s390x",
"OS": "linux"
}
]
},
"Networks": [
{
"Target": "j57jhtug4kjxp22ai1y664lqr"
}
],
"ForceUpdate": 0,
"Runtime": "container"
},
"Mode": {
"Replicated": {
"Replicas": 5
}
},
"UpdateConfig": {
"Parallelism": 1,
"FailureAction": "pause",
"Monitor": 5000000000,
"MaxFailureRatio": 0,
"Order": "stop-first"
},
"RollbackConfig": {
"Parallelism": 1,
"FailureAction": "pause",
"Monitor": 5000000000,
"MaxFailureRatio": 0,
"Order": "stop-first"
},
"EndpointSpec": {
"Mode": "vip",
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
]
}
},
"Endpoint": {
"Spec": {
"Mode": "vip",
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
]
},
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
],
"VirtualIPs": [
{
"NetworkID": "r8htcvc8oxmzy896xvwvv87k5",
"Addr": "10.255.0.5/16"
},
{
"NetworkID": "j57jhtug4kjxp22ai1y664lqr",
"Addr": "10.0.0.2/24"
}
]
}
}
]
Important: Note here information about the ports and Endpoints used by the service.
.3 - Move the Service to another Network overlay
Check the overlay network nginx-net on the three nodes:
root@manager:~# docker inspect nginx-net
[
{
"Name": "nginx-net",
"Id": "j57jhtug4kjxp22ai1y664lqr",
"Created": "2019-10-28T07:23:29.492986337+01:00",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.0.0.0/24",
"Gateway": "10.0.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"b2e882e530b10f8fd0b2481f851007f864ce1495bc9fdedcf51a475c0fc03aeb": {
"Name": "my-nginx.2.bo4q3us1f6m0uwxhqgtau1yg5",
"EndpointID": "f6f82bcb81ba82191f3988702b0e91f7f5f139c5c88899ad7c95e12ab189e055",
"MacAddress": "02:42:0a:00:00:04",
"IPv4Address": "10.0.0.4/24",
"IPv6Address": ""
},
"c0a76b54dad58b0faf80d2f915a10072aa7d726c46036caa3157d22c30dba843": {
"Name": "my-nginx.4.aqj5vafpqtkc8f4rn4v04x4kn",
"EndpointID": "813bef65edc4de42d5ec4357013f5b711cd21ce7d1a1c8361c1d989d0d709071",
"MacAddress": "02:42:0a:00:00:06",
"IPv4Address": "10.0.0.6/24",
"IPv6Address": ""
},
"lb-nginx-net": {
"Name": "nginx-net-endpoint",
"EndpointID": "d087f5fe91481b12ca0b966d01584d143b25c746952bb517441cfad6beba90de",
"MacAddress": "02:42:0a:00:00:08",
"IPv4Address": "10.0.0.8/24",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.driver.overlay.vxlanid_list": "4097"
},
"Labels": {},
"Peers": [
{
"Name": "1199cab4a6dd",
"IP": "10.0.3.62"
},
{
"Name": "69676ae46ab9",
"IP": "10.0.3.63"
},
{
"Name": "d058d363197d",
"IP": "10.0.3.64"
}
]
}
]
root@worker1:~# docker inspect nginx-net
[
{
"Name": "nginx-net",
"Id": "j57jhtug4kjxp22ai1y664lqr",
"Created": "2019-10-28T07:23:29.561068917+01:00",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.0.0.0/24",
"Gateway": "10.0.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"50b205e2ed4ccaaad5adc06c508af235557c89c116c819e367a1d925e9c2b564": {
"Name": "my-nginx.1.gcz867ezj0y46tsdgoz8j3jz2",
"EndpointID": "a48a43da98acef2748f42ffa992ba302863ed3c417fa3289cbd3aed0e33e97fa",
"MacAddress": "02:42:0a:00:00:03",
"IPv4Address": "10.0.0.3/24",
"IPv6Address": ""
},
"lb-nginx-net": {
"Name": "nginx-net-endpoint",
"EndpointID": "54ed15511cdd574cb60d37d39257cbf7b30331b24bb069aadb33b457b2864789",
"MacAddress": "02:42:0a:00:00:0a",
"IPv4Address": "10.0.0.10/24",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.driver.overlay.vxlanid_list": "4097"
},
"Labels": {},
"Peers": [
{
"Name": "69676ae46ab9",
"IP": "10.0.3.63"
},
{
"Name": "d058d363197d",
"IP": "10.0.3.64"
},
{
"Name": "1199cab4a6dd",
"IP": "10.0.3.62"
}
]
}
]
root@worker2:~# docker inspect nginx-net
[
{
"Name": "nginx-net",
"Id": "j57jhtug4kjxp22ai1y664lqr",
"Created": "2019-10-28T07:23:29.562818383+01:00",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.0.0.0/24",
"Gateway": "10.0.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"31bcb5e553886cd9b3a6b8e70fe0c2bed92fe081bd0def0c94864631a940cbd6": {
"Name": "my-nginx.5.t3be85jtp2qlhpmvsl4866s5m",
"EndpointID": "ffa92f5f3bb7fd2665a8be336ef1e4e2d786790852eb152dac1a2c45f18518ba",
"MacAddress": "02:42:0a:00:00:07",
"IPv4Address": "10.0.0.7/24",
"IPv6Address": ""
},
"8e2ce40a6e0d9fb2bc64c264b92164b6ea241a2369d8e6844d00b8952f5729a7": {
"Name": "my-nginx.3.dma616z2rkbted13zd824fyo2",
"EndpointID": "99cfb31ce34ccd9b6b15f71c87eddb5f39a84512ec76d215d54bdaaf851d5129",
"MacAddress": "02:42:0a:00:00:05",
"IPv4Address": "10.0.0.5/24",
"IPv6Address": ""
},
"lb-nginx-net": {
"Name": "nginx-net-endpoint",
"EndpointID": "c0816f6f1e5c046ac1deb8163c5a8cf40765a126bf76b6f10bf1bb708a51dfa1",
"MacAddress": "02:42:0a:00:00:09",
"IPv4Address": "10.0.0.9/24",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.driver.overlay.vxlanid_list": "4097"
},
"Labels": {},
"Peers": [
{
"Name": "d058d363197d",
"IP": "10.0.3.64"
},
{
"Name": "69676ae46ab9",
"IP": "10.0.3.63"
},
{
"Name": "1199cab4a6dd",
"IP": "10.0.3.62"
}
]
}
]
Important: Note that the nginx-net network has been created automatically on both Workers. Also note the contents of the Peers section, which lists the nodes, as well as the Containers section, which lists the containers on each node that are connected to the overlay network.
Now create a second overlay network, called nginx-net-2 :
root@manager:~# docker network create -d overlay nginx-net-2 aez5huut9hd472qmldzf2tsud
Move the my-nginx service to the nginx-net-2 network:
root@manager:~# docker service update --network-add nginx-net-2 --network-rm nginx-net my-nginx my-nginx overall progress: 5 out of 5 tasks 1/5: running [==================================================>] 2/5: running [==================================================>] 3/5: running [==================================================>] 4/5: running [==================================================>] 5/5: running [==================================================>] verify: Service converged
Check that the service is running before continuing:
root@manager:~# docker service ls ID NAME MODE REPLICAS IMAGE PORTS fpydgix3e1rc my-nginx replicated 5/5 nginx:latest *:80->80/tcp
Check that there are no containers in the nginx-net network:
root@manager:~# docker network inspect nginx-net
[
{
"Name": "nginx-net",
"Id": "j57jhtug4kjxp22ai1y664lqr",
"Created": "2019-10-28T06:21:18.337578134Z",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.0.0.0/24",
"Gateway": "10.0.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": null,
"Options": {
"com.docker.network.driver.overlay.vxlanid_list": "4097"
},
"Labels": null
}
]
Now check that the containers are in the nginx-net-2 network :
root@manager:~# docker network inspect nginx-net-2
[
{
"Name": "nginx-net-2",
"Id": "aez5huut9hd472qmldzf2tsud",
"Created": "2019-10-28T10:09:54.465105557+01:00",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.0.1.0/24",
"Gateway": "10.0.1.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"0bf159064e30d5e788a12baca53ee8e9504a2d7300017fb268cb9e90caaea27a": {
"Name": "my-nginx.2.81pveqac42zesvuulpbiho7k6",
"EndpointID": "25c9587e76cfca10d17b10fa967186bc73ca6b444cc2689e43a7243f5d1795b2",
"MacAddress": "02:42:0a:00:01:05",
"IPv4Address": "10.0.1.5/24",
"IPv6Address": ""
},
"74e656da8c670fca23270078565af164c4d42415f012ff51ccb02395c6d121e9": {
"Name": "my-nginx.3.mjj1bsguaaewk61dw7yxxjdlu",
"EndpointID": "2be3c3e0286d3afb5ba47bbd903151a4d337a45743cb30c46595160223e02fba",
"MacAddress": "02:42:0a:00:01:07",
"IPv4Address": "10.0.1.7/24",
"IPv6Address": ""
},
"lb-nginx-net-2": {
"Name": "nginx-net-2-endpoint",
"EndpointID": "768a4cc926b5c94a20904e5db500dc62b40a063077a49769ccccc007a6cb61ac",
"MacAddress": "02:42:0a:00:01:06",
"IPv4Address": "10.0.1.6/24",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.driver.overlay.vxlanid_list": "4098"
},
"Labels": {},
"Peers": [
{
"Name": "69676ae46ab9",
"IP": "10.0.3.63"
},
{
"Name": "1199cab4a6dd",
"IP": "10.0.3.62"
},
{
"Name": "d058d363197d",
"IP": "10.0.3.64"
}
]
}
]
Now remove the my-nginx service as well as the two overlay networks nginx-net and nginx-net-2 :
root@manager:~# docker service rm my-nginx my-nginx root@manager:~# docker network rm nginx-net nginx-net-2 nginx-net nginx-net-2
.4 - DNS container discovery
The Docker daemon runs an embedded DNS server at address 127.0.0.11 that enables name resolution in a custom network. If this server is unable to perform the resolution, it transfers the request to any external server defined in the container.
For DNS container discovery to work, the following ports must be open on the nodes:
- 2377/tcp
- 7946/tcp
- 7946/udp
- 4789/udp
Now create the overlay network test-net :
root@manager:~# docker network create --driver=overlay --attachable test-net hrs25w4l951kkickhj6262mjg
Important: Note that the NETWORK-ID here is hrs25w4l951kkickhj6262mjg.
On the Manager, start an interactive container called alpine1 that connects to the test-net network:
root@manager:~# docker run -it --name alpine1 --network test-net alpine Unable to find image 'alpine:latest' locally latest: Pulling from library/alpine 89d9c30c1d48: Pull complete Digest: sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a Status: Downloaded newer image for alpine:latest / #
List the networks available on Worker1 :
root@worker1:~# docker network ls NETWORK ID NAME DRIVER SCOPE 3fe43b514f9d bridge bridge local ee22b3e623ca docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm de563e30d473 none null local
Important: Note that the test-net network has not been created.
Now start a alpine2 container on Worker1 :
root@worker1:~# docker run -dit --name alpine2 --network test-net alpine Unable to find image 'alpine:latest' locally latest: Pulling from library/alpine 89d9c30c1d48: Pull complete Digest: sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a Status: Downloaded newer image for alpine:latest 5734e84cd460cdd33ce90970d98a96837a0305832a86fc4d86be38aecf51b23b
Enter the docker network ls command on Worker1 :
root@worker1:~# docker network ls NETWORK ID NAME DRIVER SCOPE 3fe43b514f9d bridge bridge local ee22b3e623ca docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm de563e30d473 none null local hrs25w4l951k test-net overlay swarm
Important: Note that the test-net network, having the same NETWORK ID, was automatically created when the alpine2 container was created.
List the networks available on Worker2:
root@worker2:~# docker network ls NETWORK ID NAME DRIVER SCOPE ff7308310f60 bridge bridge local 0ce1d8369c29 docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm de563e30d473 none null local
Important: Note that the test-net network has not been created.
Attach to the alpine2 container on Worker1 and try to contact the alpine1 container :
root@worker1:~# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES ce9097b864dc alpine "/bin/sh" 23 minutes ago Up 23 minutes alpine2 root@worker1:~# docker attach alpine2 / # / # ping -c 2 alpine1 PING alpine1 (10.0.3.2): 56 data bytes 64 bytes from 10.0.3.2: seq=0 ttl=64 time=1.874 ms 64 bytes from 10.0.3.2: seq=1 ttl=64 time=1.669 ms --- alpine1 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max = 1.669/1.771/1.874 ms / #
Return to the Manager VM and try to contact the alpine2 container from the alpine1 container:
root@manager:~# docker attach alpine1 / # / # ping -c 2 alpine2 PING alpine2 (10.0.0.4): 56 data bytes 64 bytes from 10.0.0.4: seq=0 ttl=64 time=0.666 ms 64 bytes from 10.0.0.4: seq=1 ttl=64 time=1.239 ms --- alpine2 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max = 0.666/0.952/1.239 ms / #
Then create the alpine3 container on the Worker2 try to contact the alpine1 container :
root@worker2:~# docker run -it --rm --name alpine3 --network test-net alpine Unable to find image 'alpine:latest' locally latest: Pulling from library/alpine c9b1b535fdd9: Pull complete Digest: sha256:ab00606a42621fb68f2ed6ad3c88be54397f981a7b70a79db3d1172b11c4367d Status: Downloaded newer image for alpine:latest / # / # ping -c 2 alpine1 PING alpine1 (10.0.3.2): 56 data bytes 64 bytes from 10.0.3.2: seq=0 ttl=64 time=0.642 ms 64 bytes from 10.0.3.2: seq=1 ttl=64 time=1.684 ms --- alpine1 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max = 0.642/1.163/1.684 ms / # exit
Now stop the alpine2 container on Worker1 :
root@worker1:~# docker container stop alpine2 alpine2
Enter the docker network ls command:
root@worker1:~# docker network ls NETWORK ID NAME DRIVER SCOPE 3bb80f391804 bridge bridge local ee22b3e623ca docker_gwbridge bridge local f3cb3bc3c581 host host local r8htcvc8oxmz ingress overlay swarm de563e30d473 none null local
Important: Note that the test-net network has been removed.
Delete the alpine2 container:
root@worker1:~# docker container rm alpine2 alpine2
Stop the alpine1 container and delete the test-net network on Manager:
/ # exit root@manager:~# docker container stop alpine1 alpine1 root@manager:~# docker network ls NETWORK ID NAME DRIVER SCOPE a604e7db6f95 bridge bridge local d4c9b0c9437a docker_gwbridge bridge local f3cb3bc3c581 host host local jxu667wzmj2u ingress overlay swarm de563e30d473 none null local 518l09lcjhsp test-net overlay swarm root@manager:~# docker network rm test-net test-net
2.5 - Creating a Custom Network overlay
It is possible to create a custom overlay network. In this case, the existing ingress network must be deleted:
root@manager:~# docker network rm ingress WARNING! Before removing the routing-mesh network, make sure all the nodes in your swarm run the same docker engine version. Otherwise, removal may not be effective and functionality of newly create ingress networks will be impaired. Are you sure you want to continue? [y/N] y ingress
Next, create your custom network:
root@manager:~# docker network create --driver overlay --ingress --subnet=10.11.0.0/16 --gateway=10.11.0.2 --opt com.docker.network.driver.mtu=1200 my-ingress 44ozn3vtg23zkksrvloxuulcl root@manager:~# docker network ls NETWORK ID NAME DRIVER SCOPE 24be8a0f0ef5 bridge bridge local d4c9b0c9437a docker_gwbridge bridge local f3cb3bc3c581 host host local 44ozn3vtg23z my-ingress overlay swarm de563e30d473 none null local
Create the my-nginx service again:
root@manager:~# docker service create --name my-nginx --publish target=80,published=80 --replicas=5 nginx gp1iozmbi25dx3skn00m6suoz overall progress: 5 out of 5 tasks 1/5: running [==================================================>] 2/5: running [==================================================>] 3/5: running [==================================================>] 4/5: running [==================================================>] 5/5: running [==================================================>] verify: Service converged root@manager:~# docker service ls ID NAME MODE REPLICAS IMAGE PORTS gp1iozmbi25d my-nginx replicated 5/5 nginx:latest *:80->80/tcp root@manager:~# docker service ps my-nginx ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS upmbwmtr76cm my-nginx.1 nginx:latest worker1.i2tch.loc Running Running about a minute ago qz6p1li7zmef my-nginx.2 nginx:latest worker2.i2tch.loc Running Running about a minute ago me50mkhd11yk my-nginx.3 nginx:latest manager.i2tch.loc Running Running about a minute ago sctjud70ihkl my-nginx.4 nginx:latest worker1.i2tch.loc Running Running about a minute ago kql9qx3phb73 my-nginx.5 nginx:latest worker2.i2tch.loc Running Running about a minute ago
View information about the my-nginx service:
root@manager:~# docker service inspect my-nginx
[
{
"ID": "gp1iozmbi25dx3skn00m6suoz",
"Version": {
"Index": 230
},
"CreatedAt": "2019-10-28T14:49:33.6719228Z",
"UpdatedAt": "2019-10-28T14:49:33.679624758Z",
"Spec": {
"Name": "my-nginx",
"Labels": {},
"TaskTemplate": {
"ContainerSpec": {
"Image": "nginx:latest@sha256:922c815aa4df050d4df476e92daed4231f466acc8ee90e0e774951b0fd7195a4",
"Init": false,
"StopGracePeriod": 10000000000,
"DNSConfig": {},
"Isolation": "default"
},
"Resources": {
"Limits": {},
"Reservations": {}
},
"RestartPolicy": {
"Condition": "any",
"Delay": 5000000000,
"MaxAttempts": 0
},
"Placement": {
"Platforms": [
{
"Architecture": "amd64",
"OS": "linux"
},
{
"OS": "linux"
},
{
"Architecture": "arm64",
"OS": "linux"
},
{
"Architecture": "386",
"OS": "linux"
},
{
"Architecture": "ppc64le",
"OS": "linux"
},
{
"Architecture": "s390x",
"OS": "linux"
}
]
},
"ForceUpdate": 0,
"Runtime": "container"
},
"Mode": {
"Replicated": {
"Replicas": 5
}
},
"UpdateConfig": {
"Parallelism": 1,
"FailureAction": "pause",
"Monitor": 5000000000,
"MaxFailureRatio": 0,
"Order": "stop-first"
},
"RollbackConfig": {
"Parallelism": 1,
"FailureAction": "pause",
"Monitor": 5000000000,
"MaxFailureRatio": 0,
"Order": "stop-first"
},
"EndpointSpec": {
"Mode": "vip",
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
]
}
},
"endpoint": {
"Spec": {
"Mode": "vip",
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
]
},
"Ports": [
{
"Protocol": "tcp",
"TargetPort": 80,
"PublishedPort": 80,
"PublishMode": "ingress"
}
],
"VirtualIPs": [
{
"NetworkID": "44ozn3vtg23zkksrvloxuulcl",
"Addr": "10.11.0.1/16"
}
]
}
}
]
Now check that the containers are in the my-ingress network:
root@manager:~# docker inspect my-ingress
[
{
"Name": "my-ingress",
"Id": "l11ucu5ufjfwwz6e0umtygdqy",
"Created": "2020-03-10T11:02:38.278429829+01:00",
"Scope": "swarm",
"Driver": "overlay",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "10.11.0.0/16",
"Gateway": "10.11.0.2"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": true,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"6f0168ff5153b899af31098740de34997b12417ef7c0f3824938edf79b2bca7f": {
"Name": "my-nginx.3.me50mkhd11ykwz7aj07znloh1",
"EndpointID": "41531d43496f4723cb62cad1d57c5a088faebe79c430d04a1765022e31d8ae17",
"MacAddress": "02:42:0a:0b:00:05",
"IPv4Address": "10.11.0.5/16",
"IPv6Address": ""
},
"my-ingress-sbox": {
"Name": "my-ingress-endpoint",
"EndpointID": "0205796eeb005ef77b3ea382fd1e72c312a58fd717b5a79ca6cacc7e090068e6",
"MacAddress": "02:42:0a:0b:00:0a",
"IPv4Address": "10.11.0.10/16",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.driver.mtu": "1200",
"com.docker.network.driver.overlay.vxlanid_list": "4100"
},
"Labels": {},
"Peers": [
{
"Name": "9a00e8bc72fe",
"IP": "10.0.3.62"
},
{
"Name": "3ea669d48ca2",
"IP": "10.0.3.64"
},
{
"Name": "f30e39df1704",
"IP": "10.0.3.63"
}
]
}
]
Now remove the my-nginx service:
root@manager:~# docker service rm my-nginx my-nginx
LAB #2 - Managing a Microservices Architecture
You are going to set up a simple application, called demo-voting-app and developed by Docker, in the form of microservices:
In this application, the voting-app container allows you to vote for cats or dogs. This application runs under Python and provides an HTML interface:
During the vote, the result of the vote is stored in Redis in an in-memory database. The result is then passed to the Worker container, which runs under .NET and updates the persistent database in the db container, which runs under PostgreSQL.
The result-app application running in NodeJS then reads the table from the PostgreSQL database and displays the result in HTML form:
}
2.1 - Setting up with Docker Swarm using Overlay networks
This application can be set up using docker swarm with the docker stack command. A stack is a group of services. First, check the state of the Swarm:
root@manager:~# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION b85hxlixbr1mh1txd1hrfe4us * manager.i2tch.loc Ready Active Leader 19.03.4 4sui75vvdhmet4qvt0zbvzlzl worker1.i2tch.loc Ready Active 19.03.4 lbjtg5o9kw3x6xg7frm07jfuw worker2.i2tch.loc Ready Active 19.03.4
Now create the docker-stack.yml file:
root@manager:~# vi docker-stack.yml
root@manager:~# cat docker-stack.yml
version: "3"
services:
redis:
image: redis:alpine
networks:
- frontend
deploy:
replicas: 1
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure
db:
image: postgres:9.4
environment:
POSTGRES_USER: "postgres"
POSTGRES_PASSWORD: "postgres"
volumes:
- db-data:/var/lib/postgresql/data
networks:
- backend
deploy:
placement:
constraints: [node.role == manager]
vote:
image: dockersamples/examplevotingapp_vote:before
ports:
- 5000:80
networks:
- frontend
depends_on:
- redis
deploy:
replicas: 2
update_config:
parallelism: 2
restart_policy:
condition: on-failure
result:
image: dockersamples/examplevotingapp_result:before
ports:
- 5001:80
networks:
- backend
depends_on:
- db
deploy:
replicas: 1
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure
worker:
image: dockersamples/examplevotingapp_worker
networks:
- frontend
- backend
depends_on:
- db
- redis
deploy:
mode: replicated
replicas: 1
labels: [APP=VOTING]
restart_policy:
condition: on-failure
delay: 10s
max_attempts: 3
window: 120s
placement:
constraints: [node.role == manager]
visualizer:
image: dockersamples/visualizer:stable
ports:
- "8080:8080"
stop_grace_period: 1m30s
volumes:
- "/var/run/docker.sock:/var/run/docker.sock"
deploy:
placement:
constraints: [node.role == manager]
networks:
frontend:
backend:
volumes:
db-data:
In this file we can see 6 services, redis, db, vote, result, worker and visualizer. The first 5 services together form the application, while the visualizer service will allow us to see how the application has been set up.
First, look at the deploy key for the worker service:
...
deploy:
mode: replicated
replicas: 1
labels: [APP=VOTING]
restart_policy:
condition: on-failure
delay: 10s
max_attempts: 3
window: 120s
placement:
constraints: [node.role == manager]
...
The deploy key is used to specify options when deploying the service :
- mode - There are two types of service. Replicated where we specify the number of instances that Docker should set up on available hosts depending on the value of replicas and Global which implies that Docker will start an instance of the service on each host each time a host becomes available.
- *replicas - specifies the number of replicas restart_policy specifies what happens if the service is stopped. In the case above, docker will try to restart the service 3 times (max_attempts) at 10 second intervals (delay), waiting 120 seconds (window) each time to see if the service has actually restarted, placement - specifies where the service should be started. Now deploy the stack: <code> root@manager:~# docker stack deploy -c docker-stack.yml app Creating network app_backend Creating network app_default Creating network app_frontend Creating service app_worker Creating service app_visualizer Creating service app_redis Creating service app_db Creating service app_vote Creating service app_result </code>
Important - Note that each network and service has the application name app as its prefix.
Now check the status of the stack: <code> root@manager:~# docker stack ls NAME SERVICES ORCHESTRATOR app 6 Swarm </code> Then check the status of the services: <code> root@manager:~# docker service ls ID NAME MODE REPLICAS IMAGE PORTS d0i4ac4fshw0 app_db replicated 1/1 postgres:9.4 funp5kboyip1 app_redis replicated 1/1 redis:alpine dpdkc49oj671 app_result replicated 1/1 dockersamples/examplevotingapp_result:before *:5001→80/tcp vrkahv38v5mn app_visualizer replicated 1/1 dockersamples/visualizer:stable *:8080→8080/tcp t4u16cpdrx21 app_vote replicated 2/2 dockersamples/examplevotingapp_vote:before *:5000→80/tcp so40eljbcviy app_worker replicated 1/1 dockersamples/examplevotingapp_worker:latest </code>
Important: Note that the visualizer service configuration has exposed port 8080. This way, this service is available on port 8080 of every node in the swarm.
Return to the Apache Guacamole window in
your computer's browser. Click on the Debian11_10.0.3.46_VNC connection. Then launch an Internet browser. Go to the URL http://10.0.3.62:8080 and consult the visualizer service:
As you can see, according to the docker-stack.yml file, the three containers db, worker and visualizer have been started on the manager node.
Go back to your SSH connection and check the status of the networks in the three nodes:
<code>
root@manager:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
sw489bb290zb app_backend overlay swarm
smuxoglyudpo app_default overlay swarm
lfizui95od90 app_frontend overlay swarm
24be8a0f0ef5 bridge bridge local
d4c9b0c9437a docker_gwbridge bridge local
f3cb3bc3c581 host host local
x7l4mk4ldb75 my-ingress overlay swarm
de563e30d473 none null local
</code>
Important: Note that the three networks created are of type overlay.
<code> root@worker1:~# docker network ls NETWORK ID NAME DRIVER SCOPE qhysvpoolsw0 app_frontend overlay swarm f9a69d02de3b bridge bridge local ee22b3e623ca docker_gwbridge bridge local f3cb3bc3c581 host host local x7l4mk4ldb75 my-ingress overlay swarm de563e30d473 none null local </code>
Important: Note that only the app_frontend network has been created in worker1.
<code> root@worker2:~# docker network ls NETWORK ID NAME DRIVER SCOPE s4gbgi4isp1i app_backend overlay swarm qhysvpoolsw0 app_frontend overlay swarm 0e6c118bf3fd bridge bridge local 0ce1d8369c29 docker_gwbridge bridge local f3cb3bc3c581 host host local x7l4mk4ldb75 my-ingress overlay swarm de563e30d473 none null local </code>
Important: Note that the two networks app_frontend and app_backend were created in worker2.
View information about the
app_backend network: <code> root@manager:~# docker inspect app_backend [ { “Name”: “app_backend”, “Id”: “s4gbgi4isp1i5wjpgnf4uci2a”, “Created”: “2019-11-03T17:30:56.822222239+01:00”, “Scope”: “swarm”, “Driver”: “overlay”, “EnableIPv6”: false, “IPAM”: { “Driver”: “default”, “Options”: null, “Config”: [ { “Subnet”: “10.0.3.0/24”, “Gateway”: “10.0.3.1” } ] }, “Internal”: false, “Attachable”: false, “Ingress”: false, “ConfigFrom”: { “Network”: “” }, “ConfigOnly”: false, “Containers”: { “7d0b28e4e1828b437af1a41f322acb5cf19afc25c42303986dd2c7b4d5aea568”: { “Name”: “app_db.1.s6g6w47k532rvaeoyske8as9i”, “EndpointID”: “c26795c837f6dc736a3f9be34525ae505e9db6381a2144bb62087b3ee6c7ff25”, “MacAddress”: “02:42:0a:00:03:03”, “IPv4Address”: “10.0.3.3/24”, “IPv6Address”: “” }, “ef7227281d297b001bb0f60ac81a0c9926e8fb663a7f43eb201cced632dc5564”: { “Name”: “app_worker.1.38kniuqoe1vfyonwdcytlhpqo”, “EndpointID”: “990065eec5062ff159e82bc1e4666fd098d5597439221995af4f01040ab24599”, “MacAddress”: “02:42:0a:00:03:09”, “IPv4Address”: “10.0.3.9/24”, “IPv6Address”: “” }, “lb-app_backend”: { “Name”: “app_backend-endpoint”, “EndpointID”: “913845cbab9a6c3011eaaa87fcc66f10268b5e11554be9f1a20b1078f7b9b8a4”, “MacAddress”: “02:42:0a:00:03:04”, “IPv4Address”: “10.0.3.4/24”, “IPv6Address”: “” } }, “Options”: { “com.docker.network.driver.overlay.vxlanid_list”: “4101” }, “Labels”: { “com.docker.stack.namespace”: “app” }, “Peers”: [ { “Name”: “377986fb7d5a”, “IP”: “10.0.3.62” }, { “Name”: “5cc4b863da9f”, “IP”: “10.0.3.64” } ] } ] </code>Important: Note that the network is 10.0.3.0/24 and the gateway 10.0.3.1.
View information about the
app_frontend network: <code> root@manager:~# docker inspect app_frontend [ { “Name”: “app_frontend”, “Id”: “qhysvpoolsw0318gsubbvd3rx”, “Created”: “2019-11-03T17:31:27.354293132+01:00”, “Scope”: “swarm”, “Driver”: “overlay”, “EnableIPv6”: false, “IPAM”: { “Driver”: “default”, “Options”: null, “Config”: [ { “Subnet”: “10.0.2.0/24”, “Gateway”: “10.0.2.1” } ] }, “Internal”: false, “Attachable”: false, “Ingress”: false, “ConfigFrom”: { “Network”: “” }, “ConfigOnly”: false, “Containers”: { “ef7227281d297b001bb0f60ac81a0c9926e8fb663a7f43eb201cced632dc5564”: { “Name”: “app_worker.1.38kniuqoe1vfyonwdcytlhpqo”, “EndpointID”: “3fad9773920412464b6aeee59f8d9ffc5aac2e937b88dc384268591cf7d21fb9”, “MacAddress”: “02:42:0a:00:02:0a”, “IPv4Address”: “10.0.2.10/24”, “IPv6Address”: “” }, “lb-app_frontend”: { “Name”: “app_frontend-endpoint”, “EndpointID”: “343887373c1f92ac08b271ee52dd160089eeed7cad13b7924e438919254b6442”, “MacAddress”: “02:42:0a:00:02:0b”, “IPv4Address”: “10.0.2.11/24”, “IPv6Address”: “” } }, “Options”: { “com.docker.network.driver.overlay.vxlanid_list”: “4100” }, “Labels”: { “com.docker.stack.namespace”: “app” }, “Peers”: [ { “Name”: “0e21ba1bbfab”, “IP”: “10.0.3.63” }, { “Name”: “5cc4b863da9f”, “IP”: “10.0.3.64” }, { “Name”: “377986fb7d5a”, “IP”: “10.0.3.62” } ] } ] </code>Important: Note that the network is 10.0.2.0/24 and the gateway 10.0.2.1.
Check the network information
app_default : <code> root@manager:~# docker inspect app_default [ { “Name”: “app_default”, “Id”: “z62t49w18wl2mrboa92tunrhq”, “Created”: “2019-10-28T17:22:44.724040846+01:00”, “Scope”: “swarm”, “Driver”: “overlay”, “EnableIPv6”: false, “IPAM”: { “Driver”: “default”, “Options”: null, “Config”: [ { “Subnet”: “10.0.1.0/24”, “Gateway”: “10.0.1.1” } ] }, “Internal”: false, “Attachable”: false, “Ingress”: false, “ConfigFrom”: { “Network”: “” }, “ConfigOnly”: false, “Containers”: { “2032d9eae353130e283a91bc09b65b4a84b7e8f5602a466f4ea1bd9c64e964dc”: { “Name”: “app_visualizer.1.nbf78cn5g37dmu0fwrxt7kbrg”, “EndpointID”: “d5274ff057c9d9af0288efb7f9bfed3a5ca1b3e656e265ad343f52c0b1c161f5”, “MacAddress”: “02:42:0a:00:01:03”, “IPv4Address”: “10.0.1.3/24”, “IPv6Address”: “” }, “lb-app_default”: { “Name”: “app_default-endpoint”, “EndpointID”: “6afb8909d94528633e4150054311f645790280b1ab1c686c43e865ba97ec3df9”, “MacAddress”: “02:42:0a:00:01:04”, “IPv4Address”: “10.0.1.4/24”, “IPv6Address”: “” } }, “Options”: { “com.docker.network.driver.overlay.vxlanid_list”: “4099” }, “Labels”: { “com.docker.stack.namespace”: “app” }, “Peers”: [ { “Name”: “377986fb7d5a”, “IP”: “10.0.3.62” } ] } ] </code>Important: Note that the network is 10.0.1.0/24 and the gateway 10.0.1.1.
Schematically, the implementation of the application in the Swarm is as follows:
Lastly, delete the stack:
<code>
root@manager:~# docker stack ls
NAME SERVICES ORCHESTRATOR
app 6 Swarm
root@manager:~# docker stack rm app
Removing service app_db
Removing service app_redis
Removing service app_result
Removing service app_visualizer
Removing service app_vote
Removing service app_worker
Removing network app_frontend
Removing network app_backend
Removing network app_default
root@manager:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d02c6115724c alpine “/bin/sh” 6 days ago Exited (0) 6 days ago alpine1
</code>
—–
Copyright © 2023 Hugh Norris.
