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。

app.go

package mainimport ("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()
}

把服务跑起来

go run app.go

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：2018-10-14 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。

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 cleanbuild: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

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] 2018/10/14 - 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。

Dockerfile

FROM ubuntu:latestMAINTAINER guopu marksinoberg@gmail.comWORKDIR /appEXPOSE 8080ADD . /appCMD ["./httpserver"]

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#

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：2018-10-14 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。

docker-compose.yml

version: "3"
services:web:image: httpserver:latestdeploy:replicas: 5resources:limits:cpus: "0.1"memory: 50Mrestart_policy:condition: on-faliureports:- "8000:8080"networks:- webnet
networks:webnet:

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 \172.31.237.68:2377To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.root@Server218 /h/d/g/d/httpserver#

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#

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。

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#

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。