docker swam集群如何实现负载均衡

$ docker swarm init
Swarm initialized: current node (9qksq9kb8tt9i5un3y2eqbhlj) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-5b3w5w10px9ok0t39zs1nujng8x37rcapfkg885hmrokb5wvqi-9v45djurbjeajp3ln80zqcevu 172.17.0.6:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

$ docker swarm join 172.17.0.6:2377 --token $(ssh -o StrictHostKeyChecking=no 172.17.0.6 "docker swarm join-token -q worker")
Warning: Permanently added '172.17.0.6' (ECDSA) to the list of known hosts.
This node joined a swarm as a worker.

$ docker service create --name lbapp1 --replicas 2 -p 81:80 katacoda/docker-http-server
7w8k1esxuyx1gs17hwa4svop5

$ curl host01:81
<h1>This request was processed by host: cbc4fa365043</h1>
$ curl host01:81
<h1>This request was processed by host: faecced3dc9f</h1>

$ docker network create --attachable -d overlay eg1
cf4fx7p2a75irup0pjafylpd4

$ docker service create --name http --network eg1 --replicas 2 katacoda/docker-http-server

$ docker run --name=dig --network eg1 benhall/dig dig http
Unable to find image 'benhall/dig:latest' locally
latest: Pulling from benhall/dig
12b41071e6ce: Pull complete d23aaa6caac4: Pull complete a3ed95caeb02: Pull complete Digest: sha256:ed7d241f0faea3a015d13117824c04a433a79032619862e4e3741a31eb9e4272
Status: Downloaded newer image for benhall/dig:latest

; <<>> DiG 9.10.2 <<>> http
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59560
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;http.                          IN      A

;; ANSWER SECTION:
http.                   600     IN      A       10.0.1.2

;; Query time: 1 msec
;; SERVER: 127.0.0.11#53(127.0.0.11)
;; WHEN: Thu Sep 30 07:59:23 UTC 2021
;; MSG SIZE  rcvd: 42

$ docker run --name=ping --network eg1 alpine ping -c5 http
PING http (10.0.1.2): 56 data bytes
64 bytes from 10.0.1.2: seq=0 ttl=64 time=0.287 ms
64 bytes from 10.0.1.2: seq=1 ttl=64 time=0.108 ms
64 bytes from 10.0.1.2: seq=2 ttl=64 time=0.160 ms
64 bytes from 10.0.1.2: seq=3 ttl=64 time=0.157 ms
64 bytes from 10.0.1.2: seq=4 ttl=64 time=0.131 ms

--- http ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 0.108/0.168/0.287 ms

$ docker service inspect http --format="{{.Endpoint.VirtualIPs}}"
[{cf4fx7p2a75irup0pjafylpd4 10.0.1.2/24}]

$ docker inspect --format="{{.NetworkSettings.Networks.eg1.IPAddress}}" $(docker'{print $1}')cker-http-server | head -n1 | awk  
10.0.1.4

$ docker network create -d overlay app1-network

$ docker service create --name redis --network app1-network redis:alpine

$ docker ps
CONTAINER ID        IMAGE                                COMMAND                  CREATED             STATUS              PORTS               NAMES
06f131fda216        redis:alpine                         "docker-entrypoint.s…"   27 seconds ago      Up 25 seconds       6379/tcp            redis.1.mq95cigfa7etgefqs1pye9crv
1890d08df8cc        katacoda/docker-http-server:latest   "/app"                   7 minutes ago       Up 7 minutes        80/tcp              http.2.j5c4ari06egpy3zqw6b0n3iyl