Docker Swarm 集群
概括来说，Swarm 有两个核心组件：
- 企业级的 Docker 安全集群
- 微服务应用编排引擎
1 环境
Swarm 对主机（节点）的要求并不高，我在4台 f1-micro（1 个 vCPU，0.6 GB 内存）+ 10G磁盘上操作，开启三个小型的服务共40个副本（采取逐步调整 scale，每个副本 13M 左右，平均一个节点10个副本），副本太多容易导致 Leader 节点编排的时候 Docker 服务宕掉，所以 Leader 性能要好一点。总之对学习来说并不存在环境障碍。
- 用四台机器进行部署：
姓名 地区 内部 IP
binke01 asia-northeast1-a 10.146.0.2 (nic0)
binke01-1 asia-northeast1-a 10.146.0.3 (nic0)
binke01-2 asia-northeast1-a 10.146.0.4 (nic0)
binke01-3 asia-northeast1-a 10.146.0.5 (nic0)
- 开放端口，一般云服务器内网不需要此操作
firewall-cmd --permanent --add-port=2377/tcp
firewall-cmd --permanent --add-port=7946/tcp
firewall-cmd --permanent --add-port=7946/udp
firewall-cmd --permanent --add-port=4789/tcp
firewall-cmd --reload
- 准备应用代码，我是用 Go 写的一个小应用，一共两个版本，只是把“this is version 1”中的改为2即可，build 完后必须推到 hub 库，创建服务的时候节点在本地查找镜像，没找到会去拉取；代码读取容器的 HOSTNAME（容器的 HOSTNAME 其实就是容器的 ID），可以检验基于 Ingress 的容器负载均衡：
cat <<EOF >main.go
package main
import (
"fmt"
"net/http"
"os"
)
func IndexHandler(w http.ResponseWriter, r *http.Request) {
host := os.Getenv("HOSTNAME")
fmt.Fprintln(w, "hello world "+ host +", this is version 1." )
}
func main() {
http.Handle("/pattern", http.HandlerFunc(IndexHandler))
http.ListenAndServe(":80", nil)
}
EOF
- 编写 Dockerfile，采用多阶段构建方式，使得镜像只有 12.9MB
cat <<EOF >Dockerfile
FROM golang:1.12.4-alpine3.9 AS front
COPY main.go /go/src/github.com/wpxun/onlygo/
RUN set -xe && go install github.com/wpxun/onlygo
FROM alpine:3.9
ENV GOM_VERSION 1904.1
COPY --from=front /go/bin /go/bin/
EXPOSE 80
CMD ["/go/bin/onlygo"]
EOF
2 集群初始化
只能在管理节点上初始化 Swarm 集群。我把 binke01-1 节点初始化：
> docker swarm init
Swarm initialized: current node (qr7i763tagufpcyn4qf37b5fs) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-33x2n6mrudf0x4s4j3zque3lec9c2dq5jeiaj17b7yujuaklns-ayc7mxqui49frdgb8hadcmmyf 10.146.0.3:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
按上面的提示把其它节点 join 进来，查看节点列表：
> docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
0kjqucshibpm35zhq7kizldp0 binke01 Ready Active 18.09.3
qr7i763tagufpcyn4qf37b5fs * binke01-1 Ready Active Leader 18.09.5
186b6a4dpvy8alzdfuf3jtrv4 binke01-2 Ready Active 18.09.5
ogvwkwq0zxw3s05shey2ruzqa binke01-3 Ready Active Reachable 18.09.5
其中 * 表示当前命令所在的节点，工作节点不能查看或者管理集群状态（node、service 等子命令不能用）。 Docker Swarm 推荐奇数个管理节点（1，3，5，不要大于7个）。
创建一个覆盖网络（即驱动类型：overlay） bridge 是 single-host network，其 SCOPE 只能是 local；而 overlay 是 multi-host network，其 SCOPE 则是 swarm。且只能在 manager node 创建，此时只有当前的 Swarm 管理节点可见，其它节点如果有容器接入该网络后也是可见的。 如果是 docker-compose 创建的，其名称是“目录名_网络名”。
>docker network create -d overlay onlygo-net
fe1wzq8dljvcqzd8o5vhw7bma
> docker network ls
NETWORK ID NAME DRIVER SCOPE
079de4d69078 bridge bridge local
41c3503514c2 docker_gwbridge bridge local
e6f7a28b3b05 host host local
njzh016c5qrl ingress overlay swarm
cf1660673a83 none null local
fe1wzq8dljvc onlygo-net overlay swarm
3 创建服务
无论哪种模式，即使主节点（Leader）挂掉，其它没挂掉的节点还是可以访问。而挂掉的节点其 IP 一定不能访问。
- 入站模式（Ingress Mode），也是默认的模式，是在 Swarm 中的所有节点开放端口：
- 即使节点上没有服务的副本，通过 IP 也可以访问，所有的节点都配置有映射，因此会将请求转发给运行有服务副本的节点，相当有了负载的能力，即基于 Ingress 的容器负载均衡；当然如果某个节点 Down 掉，则不可能再访问那个节点的 IP。
- 一个节点可以有多个副本，如下的 binke01-2 节点有两个副本
- 通过端口显示（为空或 80/tcp）就可以看出是服务提供统一端口，单引擎和 Swarm 端口冲突时不管谁先启动，以 Swarm 优先，即如果宿主机端口已经占用，docker 会把它分配回给 Swarm，从这一点看如果已经是 Swarm 就不建议同时作为单引擎使用了，当然如果端口不冲突那是可以共用的。
> docker service create --name onlygo-svc -p 80:80 --replicas 5 --network onlygo-net wpxun/onlygo:v1
# PORTS 看出服务提供端口
> docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
zai8apyhcv0c onlygo-svc replicated 5/5 wpxun/onlygo:v1 *:80->80/tcp
# PORTS 看出节点并没有提供端口
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
asda8ds4ae70 onlygo-svc.1 wpxun/onlygo:v1 binke01-2 Running Running 31 seconds ago
0dpg2041gjhv onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Running Running 31 seconds ago
h0a302tciz4d onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Running Running 32 seconds ago
c4zs50l7ji3m onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 35 seconds ago
lm5rvn4oc2h6 onlygo-svc.5 wpxun/onlygo:v1 binke01 Running Running 32 seconds ago
> docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
6389302152c1 wpxun/onlygo:v1 "/go/bin/onlygo" About a minute ago Up About a minute 80/tcp onlygo-svc.4.c4zs50l7ji3mw4ate9iz7m6bv
- 主机模式（Host Mode），即仅在运行有容器副本的节点上开放端口：
- 节点上如果没有服务的副本，就不能通过 IP 访问，节点不配置映射，相当于没有负载
- 一个节点最多只能有一个副本，如果副本多于节点，会提示 no suitable node (host-mode port already in use on 4 nodes)
- 通过端口显示（*:80->80/tcp 和 0.0.0.0:80->80/tcp）就可以看出是各节点各自提供端口；另外还要防止端口冲突：Bind for 0.0.0.0:80 failed: port is already allocated
> docker service create --name onlygo-svc --publish published=80,target=80,mode=host --replicas 5 --network onlygo-net wpxun/onlygo:v1
# PORTS 看出节点提供端口
> docker service ps --no-trunc onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
u7a6xsh8si0uz9917j3i3gp3d onlygo-svc.1 wpxun/onlygo:v1@sha256:b98f1f36fe80f113f4e23932fc5a0314ced0ef87f5e1b33d0528a05acbd2c2f5 binke01-2 Running Running 8 minutes ago *:80->80/tcp
f51qf2f3cl5pt2jjda1323pux onlygo-svc.2 wpxun/onlygo:v1@sha256:b98f1f36fe80f113f4e23932fc5a0314ced0ef87f5e1b33d0528a05acbd2c2f5 binke01-3 Running Running 8 minutes ago *:80->80/tcp
n9rgob84kpa4d2b7fgswnt1ib onlygo-svc.3 wpxun/onlygo:v1@sha256:b98f1f36fe80f113f4e23932fc5a0314ced0ef87f5e1b33d0528a05acbd2c2f5 binke01-1 Running Running 8 minutes ago *:80->80/tcp
n3wjdse90bjp47cauozew8rny onlygo-svc.4 wpxun/onlygo:v1@sha256:b98f1f36fe80f113f4e23932fc5a0314ced0ef87f5e1b33d0528a05acbd2c2f5 binke01 Running Running 53 seconds ago *:80->80/tcp
m3k4wlocswfila6evuvrocydv onlygo-svc.5 wpxun/onlygo:v1@sha256:b98f1f36fe80f113f4e23932fc5a0314ced0ef87f5e1b33d0528a05acbd2c2f5 Running Pending 55 seconds ago "no suitable node (host-mode port already in use on 4 nodes)"
[feixin10@binke01-3 ~]$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
51b3c95d4772 wpxun/onlygo:v1 "/go/bin/onlygo" 30 minutes ago Up 30 minutes 0.0.0.0:80->80/tcp onlygo-svc.2.f51qf2f3cl5pt2jjda1323pux
另外要注意几点：
（1）通过 docker service ls 列表的 PORTS 表示服务的端口，而通过 docker service ps onlygo-svc 列表的 PORTS 表示节点的端口。
（2）拉取的镜像 tag 为 none(如下图正常 create 时 tag 为 v1 和 v2)，不要进行修改，否则运行的容器会退出。当然可以退出副本看管理节点自动控制能力，docker service ps 列表的 ERROR 行也可以看出哪些副本状态异常。
> docker images -a
REPOSITORY TAG IMAGE ID CREATED SIZE
wpxun/onlygo <none> c36b4eaf86ea 6 hours ago 12.9MB
wpxun/onlygo <none> bb89b247fa08 6 hours ago 12.9MB
4 Scale 规模
缩放 scale 和 create 是很像的，如果有副本异常会持续编排，可能通过 ctrl+c 中断（不会影响正常运行的副本）。
> docker service scale onlygo-svc=3
onlygo-svc scaled to 3
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
5 滚动升级
docker service update --image wpxun/onlygo:v2 --update-parallelism 2 --update-delay 80s onlygo-svc
- image 要升级为的镜像
- update-parallelism 每次使用新镜像更新的副本数
- update-delay 每次更新的延迟时间
下面是运行结果，初始是 5 个副本，每次更新 2 个副本，经过三轮更新，每轮 80s 延迟。
# 初始 5 个副本
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
vrenb115qwe9 onlygo-svc.1 wpxun/onlygo:v1 binke01 Running Running 9 minutes ago
w4sz99i5xfgm onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Running Running 9 minutes ago
fe5bh6j2o6jq onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Running Running 9 minutes ago
vyv2hj1q8tdn onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 9 minutes ago
usrztf48878j onlygo-svc.5 wpxun/onlygo:v1 binke01 Running Running 9 minutes ago
# 第一轮更新
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
vrenb115qwe9 onlygo-svc.1 wpxun/onlygo:v1 binke01 Running Running 10 minutes ago
obtas0qo4lq6 onlygo-svc.2 wpxun/onlygo:v2 binke01-3 Running Running less than a second ago
w4sz99i5xfgm \_ onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Shutdown Shutdown 5 seconds ago
xl3fldhit8s4 onlygo-svc.3 wpxun/onlygo:v2 binke01-2 Running Running 4 seconds ago
fe5bh6j2o6jq \_ onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Shutdown Shutdown 6 seconds ago
vyv2hj1q8tdn onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 10 minutes ago
usrztf48878j onlygo-svc.5 wpxun/onlygo:v1 binke01 Running Running 10 minutes ago
# 等待 80s
# 第二轮更新
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
4hrqsqc59stn onlygo-svc.1 wpxun/onlygo:v2 binke01 Running Running 28 seconds ago
vrenb115qwe9 \_ onlygo-svc.1 wpxun/onlygo:v1 binke01 Shutdown Shutdown 29 seconds ago
obtas0qo4lq6 onlygo-svc.2 wpxun/onlygo:v2 binke01-3 Running Running about a minute ago
w4sz99i5xfgm \_ onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Shutdown Shutdown about a minute ago
xl3fldhit8s4 onlygo-svc.3 wpxun/onlygo:v2 binke01-2 Running Running about a minute ago
fe5bh6j2o6jq \_ onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Shutdown Shutdown about a minute ago
vyv2hj1q8tdn onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 12 minutes ago
7jcq34xnxhpw onlygo-svc.5 wpxun/onlygo:v2 binke01-3 Running Running 32 seconds ago
usrztf48878j \_ onlygo-svc.5 wpxun/onlygo:v1 binke01 Shutdown Shutdown 33 seconds ago
# 等待 80s
# 第三轮更新
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
4hrqsqc59stn onlygo-svc.1 wpxun/onlygo:v2 binke01 Running Running about a minute ago
vrenb115qwe9 \_ onlygo-svc.1 wpxun/onlygo:v1 binke01 Shutdown Shutdown about a minute ago
obtas0qo4lq6 onlygo-svc.2 wpxun/onlygo:v2 binke01-3 Running Running 2 minutes ago
w4sz99i5xfgm \_ onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Shutdown Shutdown 3 minutes ago
xl3fldhit8s4 onlygo-svc.3 wpxun/onlygo:v2 binke01-2 Running Running 3 minutes ago
fe5bh6j2o6jq \_ onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Shutdown Shutdown 3 minutes ago
tmnwlqvydpgn onlygo-svc.4 wpxun/onlygo:v2 binke01-1 Running Running 11 seconds ago
vyv2hj1q8tdn \_ onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Shutdown Shutdown 12 seconds ago
7jcq34xnxhpw onlygo-svc.5 wpxun/onlygo:v2 binke01-3 Running Running about a minute ago
usrztf48878j \_ onlygo-svc.5 wpxun/onlygo:v1 binke01 Shutdown Shutdown about a minute ago
# 查看每个节点运行的容器，比如在 binke01-1 上查看
> docker container ls -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
107b41631240 wpxun/onlygo:v2 "/go/bin/onlygo" 8 minutes ago Up 8 minutes 80/tcp onlygo-svc.4.tmnwlqvydpgng67an6hliqibx
a5faabc04466 wpxun/onlygo:v1 "/go/bin/onlygo" 22 minutes ago Exited (2) 8 minutes ago onlygo-svc.4.vyv2hj1q8tdnedue98c2725z3
可以注意到，Swarm 在升级中会均衡的将副本分配给 Swarm 中的所有节点。
查看 inspect 可以看到，更新的配置已经成为服务定义的一部分，之后的更新将会自动使用这些设置，直到使用参数覆盖它们。
> docker service inspect --pretty onlygo-svc
ID: p9p5hfije6krnjtrusz3ut1st
Name: onlygo-svc
Service Mode: Replicated
Replicas: 5
UpdateStatus:
State: completed
Started: 19 minutes ago
Completed: 14 minutes ago
Message: update completed
Placement:
UpdateConfig:
Parallelism: 2
Delay: 1m20s
On failure: pause
Monitoring Period: 5s
Max failure ratio: 0
Update order: stop-first
RollbackConfig:
Parallelism: 1
On failure: pause
Monitoring Period: 5s
Max failure ratio: 0
Rollback order: stop-first
ContainerSpec:
Image: wpxun/onlygo:v2@sha256:5a4e11c60f0ff8956b7ae972e0588753c27fc0376025e1fc02582af21d84dab7
Init: false
Resources:
Endpoint Mode: vip
Ports:
PublishedPort = 80
Protocol = tcp
TargetPort = 80
PublishMode = ingress
再次“升级”回 v1 版本 docker service update --image wpxun/onlygo:v1 onlygo-svc：
# 第三轮升级等待中
> docker service update --image wpxun/onlygo:v1 onlygo-svc
onlygo-svc
overall progress: 4 out of 5 tasks
1/5: running [==================================================>]
2/5: running [==================================================>]
3/5:
4/5: running [==================================================>]
5/5: running [==================================================>]
# 升级完成查看副本列表
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
xsry6d3b57qy onlygo-svc.1 wpxun/onlygo:v1 binke01 Running Running 2 minutes ago
4hrqsqc59stn \_ onlygo-svc.1 wpxun/onlygo:v2 binke01 Shutdown Shutdown 3 minutes ago
vrenb115qwe9 \_ onlygo-svc.1 wpxun/onlygo:v1 binke01 Shutdown Shutdown 24 minutes ago
39g1ghfjc2up onlygo-svc.2 wpxun/onlygo:v1 binke01-3 Running Running about a minute ago
obtas0qo4lq6 \_ onlygo-svc.2 wpxun/onlygo:v2 binke01-3 Shutdown Shutdown about a minute ago
w4sz99i5xfgm \_ onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Shutdown Shutdown 26 minutes ago
jsbd3x38qouo onlygo-svc.3 wpxun/onlygo:v1 binke01-2 Running Running about a minute ago
xl3fldhit8s4 \_ onlygo-svc.3 wpxun/onlygo:v2 binke01-2 Shutdown Shutdown about a minute ago
fe5bh6j2o6jq \_ onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Shutdown Shutdown 26 minutes ago
ig89pa0ylmrf onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 7 seconds ago
tmnwlqvydpgn \_ onlygo-svc.4 wpxun/onlygo:v2 binke01-1 Shutdown Shutdown 9 seconds ago
vyv2hj1q8tdn \_ onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Shutdown Shutdown 23 minutes ago
ud4kn771erry onlygo-svc.5 wpxun/onlygo:v1 binke01 Running Running 2 minutes ago
7jcq34xnxhpw \_ onlygo-svc.5 wpxun/onlygo:v2 binke01-3 Shutdown Shutdown 3 minutes ago
usrztf48878j \_ onlygo-svc.5 wpxun/onlygo:v1 binke01 Shutdown Shutdown 24 minutes ago
# 在某个节点上查看运行的容器，对应上面该节点上的副本的状态
[feixin10@binke01 ~]$ docker container ls -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
619e375ca3f9 wpxun/onlygo:v1 "/go/bin/onlygo" 5 minutes ago Up 5 minutes 80/tcp onlygo-svc.5.ud4kn771erryzg2d0cansm3md
26ac4c19a78f wpxun/onlygo:v1 "/go/bin/onlygo" 5 minutes ago Up 5 minutes 80/tcp onlygo-svc.1.xsry6d3b57qy1bpc2x8ptbxyd
0f54cadb8f00 wpxun/onlygo:v2 "/go/bin/onlygo" 26 minutes ago Exited (2) 5 minutes ago onlygo-svc.1.4hrqsqc59stnioxgmo94h6gsa
75b3967ee0c9 wpxun/onlygo:v1 "/go/bin/onlygo" 38 minutes ago Exited (2) 26 minutes ago onlygo-svc.5.usrztf48878jn3490qeujwjc6
13ccf9d7fbaa wpxun/onlygo:v1 "/go/bin/onlygo" 38 minutes ago Exited (2) 26 minutes ago onlygo-svc.1.vrenb115qwe9qg488megfnq1j
6 节点管理
节点的选择可以用 ID 或 HOSTNAME。
6.1 新增节点
docker swarm join --token
下面新增节点 binke01-4，ip:10.146.0.6，然后修改 scale = 9，然后查看编排结果：
> docker swarm join --token SWMTKN-1-33x2n6mrudf0x4s4j3zque3lec9c2dq5jeiaj17b7yujuaklns-ayc7mxqui49frdgb8hadcmmyf 10.146.0.3:2377
> docker service scale onlygo-svc=9
> docker service ps onlygo-svc
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
xsry6d3b57qy onlygo-svc.1 wpxun/onlygo:v1 binke01 Running Running 18 minutes ago
4hrqsqc59stn \_ onlygo-svc.1 wpxun/onlygo:v2 binke01 Shutdown Shutdown 18 minutes ago
vrenb115qwe9 \_ onlygo-svc.1 wpxun/onlygo:v1 binke01 Shutdown Shutdown 40 minutes ago
39g1ghfjc2up onlygo-svc.2 wpxun/onlygo:v1 binke01-3 Running Running 17 minutes ago
obtas0qo4lq6 \_ onlygo-svc.2 wpxun/onlygo:v2 binke01-3 Shutdown Shutdown 17 minutes ago
w4sz99i5xfgm \_ onlygo-svc.2 wpxun/onlygo:v1 binke01-2 Shutdown Shutdown 41 minutes ago
jsbd3x38qouo onlygo-svc.3 wpxun/onlygo:v1 binke01-2 Running Running 17 minutes ago
xl3fldhit8s4 \_ onlygo-svc.3 wpxun/onlygo:v2 binke01-2 Shutdown Shutdown 17 minutes ago
fe5bh6j2o6jq \_ onlygo-svc.3 wpxun/onlygo:v1 binke01-3 Shutdown Shutdown 41 minutes ago
ig89pa0ylmrf onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Running Running 15 minutes ago
tmnwlqvydpgn \_ onlygo-svc.4 wpxun/onlygo:v2 binke01-1 Shutdown Shutdown 15 minutes ago
vyv2hj1q8tdn \_ onlygo-svc.4 wpxun/onlygo:v1 binke01-1 Shutdown Shutdown 38 minutes ago
ud4kn771erry onlygo-svc.5 wpxun/onlygo:v1 binke01 Running Running 18 minutes ago
7jcq34xnxhpw \_ onlygo-svc.5 wpxun/onlygo:v2 binke01-3 Shutdown Shutdown 18 minutes ago
usrztf48878j \_ onlygo-svc.5 wpxun/onlygo:v1 binke01 Shutdown Shutdown 40 minutes ago
lxjhy78nsn45 onlygo-svc.6 wpxun/onlygo:v1 binke01-4 Running Running 10 seconds ago
nzc6wenlsl8o onlygo-svc.7 wpxun/onlygo:v1 binke01-4 Running Running 10 seconds ago
fz51eign4ms1 onlygo-svc.8 wpxun/onlygo:v1 binke01-3 Running Running 15 seconds ago
ma78euhri5p6 onlygo-svc.9 wpxun/onlygo:v1 binke01-1 Running Running 15 seconds ago
6.2 更新节点
-
docker node update --role worker binke01-3把节点转成工作节点，转换后至少还存在一个管理节点就可以，比如有两个管理节点，把 leader 转成工作节点，则另一个管理节点会转成 leader；–role 有两个选项 worker|manager -
docker node update --availability drain binke01-4
- availability string(“active”|“pause”|“drain”) 其中 drain 即是排空节点，把节点上的副本移到其它节点，同时阻止在该节点上分配新的副本；
6.3 删除节点
- 离开 Swarm 群，可以在任意节点上操作，使其连通状态为 Down；
[feixin10@binke01-4 ~]$ docker swarm leave
Node left the swarm.
查看节点列表，status 表示节点连通状态有 Ready|Down；availability 表示可编排状态，有 active|pause|drain 三种状态。
> docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
0kjqucshibpm35zhq7kizldp0 binke01 Ready Active 18.09.3
qr7i763tagufpcyn4qf37b5fs * binke01-1 Ready Active Reachable 18.09.5
186b6a4dpvy8alzdfuf3jtrv4 binke01-2 Ready Active 18.09.5
ogvwkwq0zxw3s05shey2ruzqa binke01-3 Ready Active Leader 18.09.5
zadyw6n9o8h14x0flsjmrkoyl binke01-4 Down Drain 18.09.5
除此之外，节点的 Docker 服务未开启时也是 Down 状态。
- 删除节点，只有 Down 状态下才可能删除(不在乎 availability 的状态)，另外还有强制删除但不建议使用；
docker node rm binke01-4
7 删除服务
docker service rm onlygo-svc，没有任何警告，直接删除服务和所有的副本，但不会删除拉取过的镜像。
参考文献 [1] Nigel Poulton. 深入浅出 Dokcer. 版次：2019年4月第1版 [2] Getting started with swarm mode. https://docs.docker.com/engine/swarm/swarm-tutorial/