Docker Swarm で sticky session の LBを立てる
検証のため sticky sessionのLBが欲しかったのです。
nginx とか Apache でLB作ってもいいんですが、コンパイルが必要だったりモジュール入れたりめんどくさそう・・・
いろいろ調べてたら なんか Docker Swarm で traefik を使えばできそうだったのでやってみました。
環境
OS version
$ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=18.04 DISTRIB_CODENAME=bionic DISTRIB_DESCRIPTION="Ubuntu 18.04.1 LTS"
docker version
# docker version Client: Version: 18.09.0 API version: 1.39 Go version: go1.10.4 Git commit: 4d60db4 Built: Wed Nov 7 00:49:01 2018 OS/Arch: linux/amd64 Experimental: false Server: Docker Engine - Community Engine: Version: 18.09.0 API version: 1.39 (minimum version 1.12) Go version: go1.10.4 Git commit: 4d60db4 Built: Wed Nov 7 00:16:44 2018 OS/Arch: linux/amd64 Experimental: false
手順
swarm mode
swame mode にします。
# docker swarm init Swarm initialized: current node (y66s0tr38tdfobqklee89d5i7) is now a manager. # docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION y66s0tr38tdfobqklee89d5i7 * **** Ready Active Leader 18.09.0
docker compose ファイルを作成します
version: "3"
services:
whoami:
image: tutum/hello-world
networks:
- net
ports:
- "80"
deploy:
restart_policy:
condition: any
mode: replicated
replicas: 5
update_config:
delay: 2s
labels:
- "traefik.docker.network=test_net"
- "traefik.port=80"
- "traefik.frontend.rule=PathPrefix:/hello;"
- "traefik.backend.loadbalancer.sticky=true"
loadbalancer:
image: traefik
command: --docker \
--docker.swarmmode \
--docker.watch \
--web \
--loglevel=DEBUG
ports:
- 80:80
- 9090:8080
volumes:
- /var/run/docker.sock:/var/run/docker.sock
deploy:
restart_policy:
condition: any
mode: replicated
replicas: 1
update_config:
delay: 2s
placement:
constraints: [node.role == manager]
networks:
- net
networks:
net:
docker stack deploy
docker swarm に 先程作ったcomposeファイルを使用してコンテナのデプロイを行います
# docker stack deploy -c docker-compose.swarm.yml test Creating network test_net Creating service test_whoami Creating service test_loadbalancer # docker stack ls NAME SERVICES ORCHESTRATOR test 2 Swarm # docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 93f4aedc3e2c traefik:latest "/traefik --docker '…" 23 seconds ago Up 9 seconds 80/tcp test_loadbalancer.1.g29b0pvnvna3dznnx2itt7gbr fa9b6f64e7d3 tutum/hello-world:latest "/bin/sh -c 'php-fpm…" 29 seconds ago Up 6 seconds 80/tcp test_whoami.4.qn4wph6t3vqtjq5o7uc2r12zs b25c164b5658 tutum/hello-world:latest "/bin/sh -c 'php-fpm…" 29 seconds ago Up 9 seconds 80/tcp test_whoami.1.lbh83j9ruenjv8vsrzj0mk17g 93842a9fffd5 tutum/hello-world:latest "/bin/sh -c 'php-fpm…" 29 seconds ago Up 9 seconds 80/tcp test_whoami.5.aezv9xt4fda4y72tb5a3v72d7 74b06ecaa0b9 tutum/hello-world:latest "/bin/sh -c 'php-fpm…" 29 seconds ago Up 10 seconds 80/tcp test_whoami.3.50uxml9u0xco2ulqjj3ujtbsg 10cb355434a8 tutum/hello-world:latest "/bin/sh -c 'php-fpm…" 29 seconds ago Up 11 seconds 80/tcp test_whoami.2.dxik1yuou7pf3y6zkmptbcgkq
起動確認
http://127.0.0.1:9090 にアクセスしてみます
こんな感じに コンテナが5個見えれば無事起動できてます
sticky session の確認
# curl -vs -c cookie.txt -b cookie.txt http://127.0.0.1/hello -o /dev/null
* Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to 127.0.0.1 (127.0.0.1) port 80 (#0)
> GET /hello HTTP/1.1
> Host: 127.0.0.1
> User-Agent: curl/7.58.0
> Accept: */*
> Cookie: _TRAEFIK_BACKEND=http://10.0.0.6:80
>
< HTTP/1.1 200 OK
< Content-Type: text/html; charset=UTF-8
< Date: Tue, 08 Jan 2019 13:34:56 GMT
< Server: nginx/1.8.0
< X-Powered-By: PHP/5.6.14
< Content-Length: 478
<
{ [478 bytes data]
* Connection #0 to host 127.0.0.1 left intact
何回試しても Cookie: _TRAEFIK_BACKEND のIPが同じになります
また cookie.txt を一回消すと変わることが確認できます
止め方
# docker stack rm test Removing service test_loadbalancer Removing service test_whoami Removing network test_net
資料
以下の資料を参考にしてます
moremagic
2019-01-08