重新认识Docker Compose-Sidecar

什么是Docker Compose

在微服务盛行的今天,我们通常是这么定义Compose的:对容器的统一启动和关闭的编排工具。

但是我以前还是有个疑惑,谁会用Compose在一台服务器上部署多个服务呢?干脆直接用单体服务就行了!直到我遇到了以下的一个需求,让我明白了在一台服务器上不得不用多个服务的时候,Compose可以通过sidecar的模式,让服务很简单的通过127.0.0.1调用另一个服务

需求遇到不合适的语言

一个用golang开发的某个项目,希望根据学生信息打印学籍,学籍表其中一部分如下

重新认识Docker Compose-Sidecar

 go中并不是没有操作word的库,但是操作这样一个复杂的word,并且填好信息还是有很大难度。所以我们想到了一个实现方案。

实现方案

1.通过excel定义一个一样的模板

重新认识Docker Compose-Sidecar

2.golang往excel的指定cell里填值,这样相对往word里填值就简单很多,其中一部分代码

	xlsx.SetCellValue("Sheet1", "C3", student.Major.Name)
	xlsx.SetCellValue("Sheet1", "F3", student.ClassInfo.Name)
	xlsx.SetCellValue("Sheet1", "J3", student.SchoolSystem)

	xlsx.SetCellValue("Sheet1", "B4", student.Name)
	xlsx.SetCellValue("Sheet1", "D4", student.BeforName)
	xlsx.SetCellValue("Sheet1", "F4", student.Gender)
	xlsx.SetCellValue("Sheet1", "H4", student.Nation)

	xlsx.SetCellValue("Sheet1", "B5", student.IdCardNo)
	xlsx.SetCellValue("Sheet1", "F5", student.HomePlace)

	xlsx.SetCellValue("Sheet1", "B6", student.Birthday.Format("20060102"))
	xlsx.SetCellValue("Sheet1", "D6", student.EntranceTime.Format("20060102"))
	xlsx.SetCellValue("Sheet1", "F6", student.JoinTeamTime)

	xlsx.SetCellValue("Sheet1", "B7", student.FamilyAddress)
	xlsx.SetCellValue("Sheet1", "F7", student.HealthStatus)

3.最关键的一步,把excel转成pdf返给前端,供其展示或者打印

我在github了没找到golang把excel转成pdf的库(有推荐可以留言),于是想到了.net里的FreeSpire.Xls库可以很方便实现excel转pdf的功能,所以需要有个.net api把go生产并填好的excel转成pdf,于是我新建了一个.net webapi,项目名定义成pdfprocessor,其中定一个Controller

    [Route("[controller]")]
    public class PDFController : ControllerBase
    {
        private readonly ILogger<PDFController> _logger;
        public PDFController(ILogger<PDFController> logger)
        {
            _logger = logger;
        }

        [HttpPost]
        public async Task<IActionResult> HttpPostAsync()
        {
            try
            {
                Stream stream = Request.Body;
                byte[] buffer = new byte[Request.ContentLength.Value];
                stream.Position = 0L;
                stream.ReadAsync(buffer, 0, buffer.Length);
                Workbook wb = new Workbook();
                wb.LoadFromStream(stream);
                Worksheet ws = wb.Worksheets[0];
                var streamReturn = new MemoryStream();

                ws.SaveToPdfStream(streamReturn);
                return File(streamReturn, "application/octet-stream");
            }
            catch (Exception ex)
            {
                _logger.LogError("", ex);
                return BadRequest(ex.Message);
            }
        }
    }

4.部署go项目与.net项目,使go语言调用.net api实现excel转化pdf

因为这是一个很小的单体项目,那么如何使这个部署与调用相对简单就是我需要考虑的问题了,这时候我想到了Docker Compose。

我可以通过docker-compose同时启动go api和.net api,最重要的还是可以让go与.net项目使用同一个network的方式,使go api通过127.0.0.1:port来调用.net api,拓扑如下

重新认识Docker Compose-Sidecar

 5.go api通过127.0.0.1调用 .net api,这样.net api就成了go api的一个sidecar,为其服务

	response, err := http.Post("http://127.0.0.1:6081/PDF", "multipart/form-data;boundary="+multipart.NewWriter(bytes.NewBufferString("")).Boundary(), bytes.NewReader(byteA))
	if err != nil {
		c.Bad(err.Error())
		return
	}
	defer response.Body.Close()
	if response.StatusCode != 200 {
		data, _ := ioutil.ReadAll(response.Body)
		c.Bad(string(data))
		return
	}

	pdfFilePth := fmt.Sprintf("./templates/tmp/%s.pdf", uuid.New())
	f, err := os.Create(pdfFilePth)
	if err != nil {
		c.Bad(err.Error())
		return
	}
	io.Copy(f, response.Body)
	c.Ctx.Output.Download(pdfFilePth, "data.xlsx")

6.docker-compose部署

编写go的dockerfile

FROM library/golang

WORKDIR /app
RUN go env -w GO111MODULE=on
RUN go env -w GOPROXY=https://goproxy.cn,direct
ADD api/ /app
RUN cd /app
RUN go mod tidy
RUN go build main.go
ENTRYPOINT ["/app/main"]
EXPOSE 6080

编写.net的dockerfile

#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
RUN apt-get update
RUN apt-get install -y --no-install-recommends libgdiplus libc6-dev 
RUN apt-get install -y fontconfig xfonts-utils
COPY /pdfprocessor/fonts/  /usr/share/fonts/
RUN mkfontscale
RUN mkfontdir
RUN fc-cache -fv

WORKDIR /app
EXPOSE 6081

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["pdfprocessor/pdfprocessor.csproj", "pdfprocessor/"]
RUN dotnet restore "pdfprocessor/pdfprocessor.csproj"
COPY . .
WORKDIR "/src/pdfprocessor"
RUN dotnet build "pdfprocessor.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "pdfprocessor.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "pdfprocessor.dll"]

编写docker-compose.yaml,让goapi与.net api使用同一个network

version: '3.4'

services:
  pdfprocessor:
    image: pdfprocessor
    build:
      context: .
      dockerfile: pdfprocessor/Dockerfile
    depends_on:
      - eduadmin
    network_mode: "service:eduadmin"
  eduadmin:
    image: eduadmin
    build:
      context: .
      dockerfile: api/Dockerfile
    ports:
      - "6080:6080"
      - "6088:6088"

7.通过docker-compose up -d启动服务,查看pdf展示效果

重新认识Docker Compose-Sidecar

 

 重新认识Docker Compose-Sidecar

最后想说docker-compose真香!

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