用Docker弹性部署自己的服务

很久不看docker的东西了,之前了解的一些基本命令都忘得差不多了,适逢工作需要,再来复习巩固下。今天想完成的是:借助docker不部署下自己的服务。

环境准备

都说"巧妇难为无米之炊",所以还是需要先准备下的。

OS:Ubuntu 16.04, 2G内存
docker:1.13.2
coding language: golang (gin web framework)

编码

将服务跑起来,是我们要完成的第一个步骤,而且是最重要的一个步骤。所以这一步需要仔细调试,为了方便,我就写的简单点。

1. app.go

package main
import (
 "os"
 "log"
 "github.com/gin-gonic/gin"
 "net/http"
 "time"
)
func GetHostName() string {
 hostname, err := os.Hostname()
 if err != nil {
 log.Fatal(err)
 }
 return hostname
}
func GetCurrentTime() string {
 timer := time.Now()
 return timer.String()
}
func startGinApp() {
 app := gin.Default()
 app.GET("/ping", func(context *gin.Context) {
 context.JSON(http.StatusOK, gin.H{
 "message": "当前为您服务的主机为:" + GetHostName(),
 })
 })
 app.GET("/", func(context *gin.Context) {
 context.JSON(http.StatusOK, gin.H{
 "message": "当前时间为:" + GetCurrentTime(),
 })
 })
 app.Run(":8080")
}
func main() {
 startGinApp()
}

2. 把服务跑起来

go run app.go

3. curl一下看看服务是否正确跑起来了

➜ gin curl http://localhost:8080
{"message":"当前时间为:2018年10月14日 11:31:23.016121853 +0800 CST m=+0.254631109"}% 
➜ gin curl http://localhost:8080/ping
{"message":"当前为您服务的主机为:BiaodeMacBook-Pro.local"}% 
➜ gin

制作Makefile

经过刚才的测试,代码可以正确跑起来了。但是要做到"一次编码,到处运行",还是需要在构建阶段下点心思的,为了更好的维护,借助Makefile来规范构建过程,是比较合适的方法。

1. Makefile

# 这个是注释
# 开头可以声明一大堆变量名
BUILD_NAME ?= httpserver
COMPILER ?= go
BUILD ?= build
# 上方留一个空格,区分变量区和构建区
all: build test deploy clean
build:
 CGO_ENABLED=0 GOOS=linux GOARCH=amd64 $(COMPILER) $(BUILD) -o $(BUILD_NAME)
test:
 echo "test over."
deploy:
 echo "deploy over."
clean:
 echo "clean over."
.PHONY: build test deploy clean

2. 构建服务

➜ gin ls
Makefile app.go
➜ gin make all
go build -o httpserver
echo "test over."
test over.
echo "deploy over."
deploy over.
echo "clean over."
clean over.
➜ gin ls
Makefile app.go httpserver
➜ gin ./httpserver &
[1] 6450
➜ gin [GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.
[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env: export GIN_MODE=release
 - using code: gin.SetMode(gin.ReleaseMode)
[GIN-debug] GET /ping --> main.startGinApp.func1 (3 handlers)
[GIN-debug] GET / --> main.startGinApp.func2 (3 handlers)
[GIN-debug] Listening and serving HTTP on :8080
➜ gin curl http://localhost:8080/ping
[GIN] 2018年10月14日 - 11:50:23 | 200 | 214.161μs | ::1 | GET /ping
{"message":"当前为您服务的主机为:BiaodeMacBook-Pro.local"}% 
➜ gin

好了基本没什么问题,然后就可以通过scp命令将文件拷贝到linux服务器上了。

制作Dockerfile

由于golang构建出来的是二进制可执行程序,所以制作Dockerfile很简单。

1. Dockerfile

FROM ubuntu:latest
MAINTAINER guopu marksinoberg@gmail.com
WORKDIR /app
EXPOSE 8080
ADD . /app
CMD ["./httpserver"]

2. 构建自己的镜像

root@Server218 /h/d/g/d/httpserver# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ginserver latest 6277a0180f4f 19 hours ago 101 MB
flaskindocker latest 170c6c0a41db 22 hours ago 131 MB
python 2.7-slim 14dad3ead5f4 4 days ago 120 MB
docker/compose 1.23.0-rc2 dc59a0b5e981 5 days ago 45.6 MB
ubuntu latest cd6d8154f1e1 5 weeks ago 84.1 MB
root@Server218 /h/d/g/d/httpserver# docker build -t httpserver .
Sending build context to Docker daemon 17.07 MB
Step 1/6 : FROM ubuntu:latest
 ---> cd6d8154f1e1
Step 2/6 : MAINTAINER guopu marksinoberg@gmail.com
 ---> Running in 7106748df3ad
 ---> 0ae808029537
Removing intermediate container 7106748df3ad
Step 3/6 : WORKDIR /app
 ---> 7278bf9659e7
Removing intermediate container f7fdc76b19a8
Step 4/6 : EXPOSE 8080
 ---> Running in bedfabcb4b16
 ---> edf4c123f72f
Removing intermediate container bedfabcb4b16
Step 5/6 : ADD . /app
 ---> 36390e554a2f
Removing intermediate container b14cce9da53e
Step 6/6 : CMD ./httpserver
 ---> Running in 6682c8364717
 ---> b490fef8a9ca
Removing intermediate container 6682c8364717
Successfully built b490fef8a9ca
root@Server218 /h/d/g/d/httpserver# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
httpserver latest b490fef8a9ca 4 seconds ago 101 MB
ginserver latest 6277a0180f4f 19 hours ago 101 MB
flaskindocker latest 170c6c0a41db 22 hours ago 131 MB
python 2.7-slim 14dad3ead5f4 4 days ago 120 MB
docker/compose 1.23.0-rc2 dc59a0b5e981 5 days ago 45.6 MB
ubuntu latest cd6d8154f1e1 5 weeks ago 84.1 MB
root@Server218 /h/d/g/d/httpserver#

3. 让服务在docker中跑起来

root@Server218 /h/d/g/d/httpserver# docker run -d -p 8000:8080 httpserver
ebb1926206cdaf16eae9f4e13d5a7e70dd695da91463b438f77e45c6f65d3323
root@Server218 /h/d/g/d/httpserver# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ebb1926206cd httpserver "./httpserver" 4 seconds ago Up 3 seconds 0.0.0.0:8000->8080/tcp nostalgic_wright
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:ebb1926206cd"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/
{"message":"当前时间为:2018年10月14日 04:14:29.116207751 +0000 UTC"}~ root@Server218 /h/d/g/d/httpserver#

至此,看起来服务已经成功在服务器环境下的docker中运行了。

弹性服务

一个容器跑一个服务,有些服务访问峰差很大的场景,就需要做下弹性适配,于是需要用一下docker swarm服务。这个在linux环境下需要进行安装。具体可以参考官网链接: https://github.com/docker/compose/releases
其运行以来一个YAML配置文件,具体细节不多说,上手吧。

1. docker-compose.yml

version: "3"
services:
 web:
 image: httpserver:latest
 deploy:
 replicas: 5
 resources:
 limits:
 cpus: "0.1"
 memory: 50M
 restart_policy:
 condition: on-faliure
 ports:
 - "8000:8080"
 networks:
 - webnet
networks:
 webnet:

2. 初始化swarm

root@Server218 /h/d/g/d/httpserver# docker swarm init
Swarm initialized: current node (atiuy6c8k1qcig5w3br1bwf0n) is now a manager.
To add a worker to this swarm, run the following command:
 docker swarm join \
 --token SWMTKN-1-5e0sj0glbwl5w5rqytyqokeg91n7piwdyw9ik598x0poiz5s20-do445zhrdr5io93lplov42c2y \
 172.31.237.68:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
root@Server218 /h/d/g/d/httpserver#

3. 发布服务到swarm中

root@Server218 /h/d/g/d/httpserver# docker stack deploy -c docker-compose.yml httpserver
Creating service httpserver_web
root@Server218 /h/d/g/d/httpserver#
root@Server218 /h/d/g/d/httpserver#
root@Server218 /h/d/g/d/httpserver#
root@Server218 /h/d/g/d/httpserver# docker stack ps httpserver
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
kvpvwptlj44c httpserver_web.1 httpserver:latest Server218 Running Running 14 seconds ago
6549g79dz5iz httpserver_web.2 httpserver:latest Server218 Running Running 14 seconds ago
xkz42mnetmws httpserver_web.3 httpserver:latest Server218 Running Running 14 seconds ago
rpziwzmpogn2 httpserver_web.4 httpserver:latest Server218 Running Running 14 seconds ago
y2kfe8bp09ld httpserver_web.5 httpserver:latest Server218 Running Running 6 seconds ago
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:a5419e3d3f9c"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:f636819bd9c4"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:97a6e3c9a064"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:7f1b28e14970"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:0ce251661188"}~ 
root@Server218 /h/d/g/d/httpserver# curl http://localhost:8000/ping
{"message":"当前为您服务的主机为:a5419e3d3f9c"}~ 
root@Server218 /h/d/g/d/httpserver#

4. 实例弹性变化
   具体的操作只需要修改docker-compose.yml中的replicas的数量即可。然后重新使用:

docker stack deploy -c docker-compose.yml httpserver

发布就可以了,可以看出swarm管理下的实例会进行自动的负载均衡。

5. 关停服务

root@Server218 /h/d/g/d/httpserver# docker stack ls
NAME SERVICES
httpserver 1
root@Server218 /h/d/g/d/httpserver# docker stack rm httpserver
Removing service httpserver_web
Removing network httpserver_webnet
root@Server218 /h/d/g/d/httpserver# docker stack ls
NAME SERVICES
root@Server218 /h/d/g/d/httpserver#

6. 关掉swarm

root@Server218 /h/d/g/d/httpserver# docker swarm leave --force
Node left the swarm.
root@Server218 /h/d/g/d/httpserver#

总结

最后,回头看看这个目录。

root@Server218 /h/d/g/d/httpserver# ls -al
total 16688
drwxr-xr-x 2 root root 4096 Oct 14 12:20 ./
drwxr-xr-x 5 root root 4096 Oct 14 12:00 ../
-rw-r--r-- 1 root root 121 Oct 14 12:11 Dockerfile
-rw-r--r-- 1 root root 362 Oct 14 12:01 Makefile
-rw-r--r-- 1 root root 682 Oct 14 12:01 app.go
-rw-r--r-- 1 root root 385 Oct 14 12:27 docker-compose.yml
-rwxr-xr-x 1 root root 17063672 Oct 14 12:03 httpserver*
root@Server218 /h/d/g/d/httpserver#

基本上,在docker中弹性部署自己的服务就结束了,基本上也能满足需要。

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