优化 .net core 应用的 dockerfile

Intro

在给 .net core 应用的写 dockerfile 的时候一直有个苦恼，就是如果有很多个项目，在 dockerfile 里写起来就会很繁琐，有很多项目文件要 copy，dockerfile 还不支持直接批量复制项目文件，今天要改的一个项目也是有好多个项目文件，不想再一个一个复制，于是 google 一下看有没有比较好的解决方案，找到一个折中的解决方案，分享一下

Solution

1. 首先把所有的项目文件拷贝到 docker 镜像内 COPY */*.csproj ./
2. 然后根据项目文件名称创建项目文件夹，并移动项目文件到对应的项目目录下

原来的 dockerfile

FROM mcr.microsoft.com/dotnet/core/sdk:3.0-alpine AS build-env
WORKDIR /src

# Copy csproj and restore as distinct layers
COPY ActivityReservation.Common/*.csproj ActivityReservation.Common/
COPY ActivityReservation.Models/*.csproj ActivityReservation.Models/
COPY ActivityReservation.DataAccess/*.csproj ActivityReservation.DataAccess/
COPY ActivityReservation.Business/*.csproj ActivityReservation.Business/
COPY ActivityReservation.Helper/*.csproj ActivityReservation.Helper/
COPY ActivityReservation.WechatAPI/*.csproj ActivityReservation.WechatAPI/
COPY ActivityReservation.AdminLogic/*.csproj ActivityReservation.AdminLogic/
COPY ActivityReservation.API/*.csproj ActivityReservation.API/
COPY ActivityReservation/ActivityReservation.csproj ActivityReservation/

# RUN dotnet restore ActivityReservation/ActivityReservation.csproj
## diff between netcore2.2 and netcore3.0
WORKDIR /src/ActivityReservation
RUN dotnet restore

# copy everything and build
COPY . .
RUN dotnet publish -c Release -o out ActivityReservation/ActivityReservation.csproj

# build runtime image
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0-alpine

LABEL Maintainer="WeihanLi"
WORKDIR /app
COPY --from=build-env /src/ActivityReservation/out .
EXPOSE 80
ENTRYPOINT ["dotnet", "ActivityReservation.dll"]

修改之后的 dockerfile

FROM mcr.microsoft.com/dotnet/core/sdk:3.0-alpine AS build-env
WORKDIR /src

# Copy csproj and restore as distinct layers
# https://andrewlock.net/optimising-asp-net-core-apps-in-docker-avoiding-manually-copying-csproj-files-part-2/
COPY */*.csproj ./
RUN for file in $(ls *.csproj); do mkdir -p ${file%.*}/ && mv $file ${file%.*}/; done

## diff between netcore2.2 and netcore3.0
WORKDIR /src/ActivityReservation
RUN dotnet restore

# copy everything and build
COPY . .
RUN dotnet publish -c Release -o out ActivityReservation/ActivityReservation.csproj

# build runtime image
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0-alpine

LABEL Maintainer="WeihanLi"
WORKDIR /app
COPY --from=build-env /src/ActivityReservation/out .
EXPOSE 80
ENTRYPOINT ["dotnet", "ActivityReservation.dll"]

是不是精简了许多，来看一下修改前后的对比，更明显的对比一下：

核心代码：

 # 拷贝所有的二级目录下的项目文件
COPY */*.csproj ./
# 根据项目文件名称创建项目文件夹，并移动项目文件到对应的项目目录下
RUN for file in $(ls *.csproj); do mkdir -p ${file%.*}/ && mv $file ${file%.*}/; done 

More

注：上面的方法适用于项目文件目录名称和项目文件名称一致的情况，默认创建的项目应该都会符合这样的要求，如果你的项目文件是三级目录，如 src/*/*.csproj 的，需要自己根据项目情况调整 dockerfile

有没有学到呢~~

Reference

• https://stackoverflow.com/questions/51372791/is-there-a-more-elegant-way-to-copy-specific-files-using-docker-copy-to-the-work
• https://andrewlock.net/optimising-asp-net-core-apps-in-docker-avoiding-manually-copying-csproj-files-part-2/
• https://github.com/WeihanLi/ActivityReservation/blob/dev/Dockerfile