今天，来说一个在service中非常高级的知识点，configs.
然后，通过一些示例，来一步一步的演示，如何在service中使用，有什么关键的注意事项。
什么是configs?
configs的准确说法应该是，docker swar service configs.
通过configs这个名字可以看出，一般是存配置数据的。是的，没错，在configs中可以存储非敏感的信息，比如配置文件。
这个配置文件可以是独立于镜像和容器之外的。
也就是说，在容器运行的时候，将配置挂载到容器中。这样，同样的镜像，就可以在不同的环境中运行，仅仅是更新下不同的配置文件就可以了。
同时呢，configs以配置文件挂载容器中，容器不需要以bind挂载的方式，将宿主机中的配置挂载到容器了。
简单来说，configs的好处：
- configs以文件挂载到容器，容器无需bind挂载
- 镜像通用即可，不受环境限制
- configs是独立镜像之外的独立资源对象
注意：docker configs只适用于集群service，不适用于独立的容器。
示例
创建configs
创建配置文件 index.html.tmpl
<html lang="en"> <head><title>Hello Docker</title></head> <body> <p>Hello Docker! You have deployed a HTML page.</p> </body> </html>
创建configs
docker config create homepage index.html.tmpl
查看创建configs
[root@nccztsjb-node-01 ~]# docker config ls ID NAME CREATED UPDATED pj31j03jkm31l6azeen39ibgv homepage 3 seconds ago 3 seconds ago [root@nccztsjb-node-01 ~]#
# 查看详细的config信息 # 发现数据都是加密的
[root@nccztsjb-node-01 ~]# docker config inspect homepage [ { "ID": "pj31j03jkm31l6azeen39ibgv", "Version": { "Index": 3333 }, "CreatedAt": "2022-09-28T02:49:35.559023328Z", "UpdatedAt": "2022-09-28T02:49:35.559023328Z", "Spec": { "Name": "homepage", "Labels": {}, "Data": "PGh0bWwgbGFuZz0iZW4iPgogIDxoZWFkPjx0aXRsZT5IZWxsbyBEb2NrZXI8L3RpdGxlPjwvaGVhZD4KICA8Ym9keT4KICAgIDxwPkhlbGxvIERvY2tlciEgWW91IGhhdmUgZGVwbG95ZWQgYSBIVE1MIHBhZ2UuPC9wPgogIDwvYm9keT4KPC9odG1sPgo=" } } ] [root@nccztsjb-node-01 ~]#
使用config
有了config之后，接下来就是要将这个config挂载到容器的文件系统中
创建service使用这个config,使用--config参数
source : configs的名字
target : 挂载到容器中的位置及名字，注意：名字可以是自定义的
docker service create \ --with-registry-auth \ --name=nginx \ --replicas=4 \ --config source=homepage,target=/usr/share/nginx/html/index.html \ --publish published=8080,target=80 \ 172.20.58.152/middleware/nginx:1.21.4
查看service状态
[root@nccztsjb-node-01 ~]# docker service ps nginx ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS tkntzl1iqppt nginx.1 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-05 Running Running 14 seconds ago t40w6uia7u18 nginx.2 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-04 Running Running 14 seconds ago psk6hhwuktvy nginx.3 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-02 Running Running 14 seconds ago hlvggbg4ym24 nginx.4 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-01 Running Running 14 seconds ago [root@nccztsjb-node-01 ~]#
查看容器中的配置文件
文件以及经挂载到/usr/share/nginx/html/index.html （把镜像中的文件给覆盖掉了）
[root@nccztsjb-node-01 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 48deef4bbd6f 172.20.58.152/middleware/nginx:1.21.4 "/docker-entrypoint.…" About a minute ago Up About a minute 80/tcp nginx.4.hlvggbg4ym241lewhtk8q2h40 [root@nccztsjb-node-01 ~]# docker exec -it 48deef4bbd6f bash root@48deef4bbd6f:/# df -h Filesystem Size Used Avail Use% Mounted on overlay 49G 20G 27G 43% / tmpfs 64M 0 64M 0% /dev tmpfs 7.6G 0 7.6G 0% /sys/fs/cgroup shm 64M 0 64M 0% /dev/shm /dev/vda2 49G 20G 27G 43% /etc/hosts tmpfs 7.6G 4.0K 7.6G 1% /usr/share/nginx/html/index.html tmpfs 7.6G 0 7.6G 0% /proc/acpi tmpfs 7.6G 0 7.6G 0% /proc/scsi tmpfs 7.6G 0 7.6G 0% /sys/firmware root@48deef4bbd6f:/# cat /usr/share/nginx/html/index.html <html lang="en"> <head><title>Hello Docker</title></head> <body> <p>Hello Docker! You have deployed a HTML page.</p> </body> </html> root@48deef4bbd6f:/#
浏览器访问
管理config
删除config
通过下面的命令删除config
[root@nccztsjb-node-01 ~]# docker config rm homepage Error response from daemon: rpc error: code = InvalidArgument desc = config 'homepage' is in use by the following service: nginx [root@nccztsjb-node-01 ~]#
如果这个config正在被service使用是不能进行删除的
将config从service删除后，进行config的删除
[root@nccztsjb-node-01 ~]# docker config rm homepage homepage [root@nccztsjb-node-01 ~]#
将config从service移除
[root@nccztsjb-node-01 ~]# docker service update --config-rm homepage nginx nginx overall progress: 4 out of 4 tasks 1/4: running [==================================================>] 2/4: running [==================================================>] 3/4: running [==================================================>] 4/4: running [==================================================>] verify: Service converged [root@nccztsjb-node-01 ~]# docker service ps nginx ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS 98yv6zykhi0n nginx.1 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-05 Running Running 26 seconds ago tkntzl1iqppt \_ nginx.1 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-05 Shutdown Shutdown 27 seconds ago shk5gyh2fgu0 nginx.2 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-04 Running Running 11 seconds ago t40w6uia7u18 \_ nginx.2 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-04 Shutdown Shutdown 13 seconds ago 5r5uxqzc7zzy nginx.3 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-02 Running Running 16 seconds ago psk6hhwuktvy \_ nginx.3 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-02 Shutdown Shutdown 17 seconds ago ttzbp0q8z9ty nginx.4 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-01 Running Running 21 seconds ago hlvggbg4ym24 \_ nginx.4 172.20.58.152/middleware/nginx:1.21.4 nccztsjb-node-01 Shutdown Shutdown 23 seconds ago [root@nccztsjb-node-01 ~]#
移除就相当于是从新发布了service
现有service中增加config
docker service update --config-add source=homepage,target=/usr/share/nginx/html/index.html nginx
[root@nccztsjb-node-01 ~]# docker service update --config-add source=homepage,target=/usr/share/nginx/html/index.html nginx nginx overall progress: 4 out of 4 tasks 1/4: running [==================================================>] 2/4: running [==================================================>] 3/4: running [==================================================>] 4/4: running [==================================================>] verify: Service converged [root@nccztsjb-node-01 ~]#
多个service共享一个config
再创建一个service用这个config
docker service create \ --with-registry-auth \ --name=nginx-new \ --replicas=4 \ --config source=homepage,target=/usr/share/nginx/html/index.html \ --publish published=8082,target=80 \ 172.20.58.152/middleware/nginx:1.21.4
[root@nccztsjb-node-01 ~]# docker service inspect nginx-new --pretty ID: 7ilcep8nbxuujbfyaft9gbp4e Name: nginx-new Service Mode: Replicated Replicas: 4 Placement: UpdateConfig: Parallelism: 1 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: 172.20.58.152/middleware/nginx:1.21.4@sha256:2f14a471f2c2819a3faf88b72f56a0372ff5af4cb42ec45aab00c03ca5c9989f Init: false Configs: Target: /usr/share/nginx/html/index.html Source: homepage Resources: Endpoint Mode: vip Ports: PublishedPort = 8082 Protocol = tcp TargetPort = 80 PublishMode = ingress [root@nccztsjb-node-01 ~]#
那么，这个service也使用了这个config了。
--config未加target参数默认的挂载位置
如果指定target，默认的位置/config_name
使用模板config
在config中可以使用go 模板，放置一些占位符，然后在创建service，启动容器的时候会自动的获取对应的变量值
使用下面的文件来创建config
<html lang="en"> <head><title>Hello Docker</title></head> <body> <p>Hello {{ env "HELLO" }}! I'm on node {{ env "NODENAME" }}.</p> </body> </html>
其中下面2个，以变量获取的方式，获取对应的值
{{ env "HELLO" }}
{{ env "NODENAME" }}
创建config，使用模板驱动--template-driver golang
docker config create --template-driver golang homepage index.html.tmpl
变量在哪里呢？
创建service的时候，通过--env来设置
--env HELLO="Docker"
--env NODENAME={{.Node.Hostname}}
docker service create \ --with-registry-auth \ --name=nginx \ --replicas=4 \ --env HELLO="Docker" \ --env NODENAME={{.Node.Hostname}} \ --config source=homepage,target=/usr/share/nginx/html/index.html \ --publish published=8080,target=80 \ 172.20.58.152/middleware/nginx:1.21.4
[root@nccztsjb-node-01 ~]# docker service create \ > --with-registry-auth \ > --name=nginx \ > --replicas=4 \ > --env HELLO="Docker" \ > --env NODENAME={{.Node.Hostname}} \ > --config source=homepage,target=/usr/share/nginx/html/index.html \ > --publish published=8080,target=80 \ > 172.20.58.152/middleware/nginx:1.21.4 sywtvyc8ipg6zxxfegzlfmy1i overall progress: 4 out of 4 tasks 1/4: running [==================================================>] 2/4: running [==================================================>] 3/4: running [==================================================>] 4/4: running [==================================================>] verify: Service converged [root@nccztsjb-node-01 ~]#
查看容器中的挂载
文件已经在挂载到容器的时候，将变量给替换了
[root@nccztsjb-node-01 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 1c3358559e56 172.20.58.152/middleware/nginx:1.21.4 "/docker-entrypoint.…" 19 seconds ago Up 18 seconds 80/tcp nginx.3.txrhegcjr0dskys9h19eydgax [root@nccztsjb-node-01 ~]# docker exec -it 1c3358559e56 bash root@1c3358559e56:/# df -h Filesystem Size Used Avail Use% Mounted on overlay 49G 20G 27G 43% / tmpfs 64M 0 64M 0% /dev tmpfs 7.6G 0 7.6G 0% /sys/fs/cgroup shm 64M 0 64M 0% /dev/shm /dev/vda2 49G 20G 27G 43% /etc/hosts tmpfs 7.6G 4.0K 7.6G 1% /usr/share/nginx/html/index.html tmpfs 7.6G 0 7.6G 0% /proc/acpi tmpfs 7.6G 0 7.6G 0% /proc/scsi tmpfs 7.6G 0 7.6G 0% /sys/firmware root@1c3358559e56:/# cat /usr/share/nginx/html/index.html <html lang="en"> <head><title>Hello Docker</title></head> <body> <p>Hello Docker! I'm on node nccztsjb-node-01.</p> </body> </html> root@1c3358559e56:/#
浏览器访问nginx服务
清浏览器缓存之后，再访问
多个实例，是可以通过路由网格，也就是ingress网络，访问到不同的节点上的task的。
注意：是同一个入口！
这样，就实现了将一些信息，动态的加载容器里面！
OK，关于configs就介绍到这里~