1、 树莓派安装Docker
$ curl -fsSL https://get.docker.com -o get-docker.sh $ sudo sh get-docker.sh
2、 在Visual Studio创建测试项目
3、 生成项目镜像。这部分坑比较多，需要多注意一下，我也会把步骤拆分的更细。
项目创建后VS会在项目目录下自动生成Docker镜像的描述文件Dockerfile，但是如果我们直接使用这个文件生成镜像就会提示下面的错误。
这是因为下面标黄的部分路径错误导致的，需要把前面标红的目录部分删掉就可以了。
#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/core/aspnet:3.1-buster-slim AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build
WORKDIR /src
COPY ["RaspberryDockerDemo/RaspberryDockerDemo.csproj", "RaspberryDockerDemo/"]
RUN dotnet restore "RaspberryDockerDemo/RaspberryDockerDemo.csproj"
COPY . .
WORKDIR "/src/RaspberryDockerDemo"
RUN dotnet build "RaspberryDockerDemo.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "RaspberryDockerDemo.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "RaspberryDockerDemo.dll"]
再次执行生成命令，你会发现又出错了 -_-!
根据错误提示我们注意到是没找到入口的静态main方法，事实上这个方法是有的，问题出在以下标黄的COPY命令部分，路径又错了，我们加上子目录修改为正确的路径。
#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/core/aspnet:3.1-buster-slim AS base WORKDIR /app EXPOSE 80 EXPOSE 443 FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build WORKDIR /src COPY ["RaspberryDockerDemo.csproj", "RaspberryDockerDemo/"] RUN dotnet restore "RaspberryDockerDemo/RaspberryDockerDemo.csproj"
COPY . ./RaspberryDockerDemo
WORKDIR "/src/RaspberryDockerDemo" RUN dotnet build "RaspberryDockerDemo.csproj" -c Release -o /app/build FROM build AS publish RUN dotnet publish "RaspberryDockerDemo.csproj" -c Release -o /app/publish FROM base AS final WORKDIR /app COPY --from=publish /app/publish . ENTRYPOINT ["dotnet", "RaspberryDockerDemo.dll"]
经过各种路径问题，我们终于成功生成了镜像。
使用docker ps命令我们可以看到我们刚生成的镜像
后来我发现这个镜像部署到树莓派无法启动，会提示如下错误
exec user process caused "exec format error"
这是因为树莓派是基于ARM的CPU架构的，我们的开发机是普通的x86/64平台，导致生成的镜像无法在ARM平台启动，我们需要把Dockerfile中的配置修改为arm使用的环境。
同时也需要修改publish命令，增加-r参数来指定应用程序的目标平台为debian-arm。
-r参数说明参见文档 https://docs.microsoft.com/zh-cn/dotnet/core/rid-catalog， https://github.com/dotnet/runtime/blob/master/src/libraries/pkg/Microsoft.NETCore.Platforms/runtime.json
修改后最终的文件如下:
#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/core/aspnet:3.1.3-buster-slim-arm32v7 AS base WORKDIR /app EXPOSE 80 EXPOSE 443 FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build WORKDIR /src COPY ["RaspberryDockerDemo.csproj", "RaspberryDockerDemo/"] RUN dotnet restore "RaspberryDockerDemo/RaspberryDockerDemo.csproj" COPY . ./RaspberryDockerDemo WORKDIR "/src/RaspberryDockerDemo" RUN dotnet build "RaspberryDockerDemo.csproj" -c Release -o /app/build FROM build AS publish RUN dotnet publish "RaspberryDockerDemo.csproj" -r debian-arm -c Release -o /app/publish FROM base AS final WORKDIR /app COPY --from=publish /app/publish . ENTRYPOINT ["dotnet", "RaspberryDockerDemo.dll"]
接下就很简单了，我们再次运行docker build命令生成镜像，直接用docker save命令把镜像导出到本地
docker save -o e:/raspdockerdemo.tar rasp/raspdockerdemo:v1
4、 部署镜像到树莓派
上传文件到树莓派，我使用的是WinSCP上传的。然后使用 docker load命令导入我们的镜像。
现在就可以使用docker run命令来启动我们的镜像了。
使用docker ps命令可以看到我们的镜像已经成功在docker上跑起来了。
使用浏览器访问 http://树莓派IP:7000，就可以看到我们的测试项目已经可以访问了。
