I. Use smaller image base

 

Consider using an alpine OS as base image, it’s only about 50MB

 

FROM alpine

 

II. Don’t install unnecessary library

 

We don’t need install any debug tool as nano, curl, telnet, vim . Developers will install it on demand when they need it

 

 

 

III. Minimize your layer

 

We need to merge any possible command into 1 layer to help smaller layer size. Instead of

 

RUN apt-get update
RUN apt-get install -y nodejs

 

We use

 

RUN apt-get update && apt-get install -y nodejs

 

 

 

IV. Not cache repository when install packages

 

With ubuntu

 

RUN apt-get install -- no-install-recommends

 

With alpine

 

apk add --no-cache

 

V. Remove repository list or source after setup

 

After install everything in docker, we should remove package list/repository list & source code.

 

With ubuntu, we can run following layer

 

RUN rm -rf /var/lib/apt/lists/*

 

With CentOS or Redhat core, run following layer

 

RUN yum clean all

 

V. Using multiple environment for purpose

 

We can use multiple with Docker FROM to reduce unnecessary lib

 

FROM mcr.microsoft.com/dotnet/aspnet:5.0 AS base
...
FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
...
FROM build AS publish
RUN dotnet publish "ZDN.Web.Api.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENV ASPNETCORE_ENVIRONMENT=Internal
ENTRYPOINT ["dotnet", "ZDN.Web.Api.dll"]