One of the most anticipated announcements in the Docker space when it comes to building images is Multi-Stage builds because of the huge benefits it gives to CI/CD pipelines in DevOps. Before this announcement, building software in a container usually involved creating a container with all the SDK’s and compilers in the container, uploading code into the container, compiling it, creating a drop, then building another container with just the runtime that sucks in the compiled code to run. This pattern required an external tool and storage to build the container image so it was more burdensome.
Multi-Stage builds on Docker though provide a mechanism for moving the output of a build from a builder container into another container that can be used for running. Consider the following the example. This Dockerfile builds a .NET core app in one container then packages it in another.
#Builder FROM microsoft/dotnet:1.1.2-sdk-jessie COPY /myapp /myapp RUN dotnet restore ./myapp && dotnet build -c release ./myapp && dotnet publish -c release -o pubdir ./myapp #Final Build FROM microsoft/dotnet:1.1.2-runtime COPY --from=0 /myapp/pubdir /myapp ENV ASPNETCORE_URLS http://+:80 ENTRYPOINT ["dotnet", "/myapp/myapp.dll"] EXPOSE 80
This file has two FROM instructions, which in a traditional Dockerfile only one is a allowed. The first one in the file Dockerfile points to an image on Docker Hub for .NET Core on Linux with the SDK already installed. This instructions are quite simple: upload the code and compile it. In classic Dockerfiles, additional steps would be required to move the binaries out of the build container into a share to be picked up.
Notice the COPY the command after the second FROM. This copy now has a parameter, –from= that allows artifacts to be copied out of a builder container into the respective container. The integer refers to a 0-based array, with 0 referring to the first container being used in the Dockerfile.
Chaining build containers with the final container as the final artifact allows users to implement better CI and CD with Docker without having to use external tools to have separate build/test and deployment containers.
Stay in Good Standing
- Meet HIPAA/HITECH, HITRUST and PCI DSS compliance: >> Managed Compliance.
- Ensure you are secure from design through deployment: >> Managed InfoSec.
- Eliminate concerns about exposing your PHI and Non-PHI data when using the public cloud.
- Define your objectives and build the right foundation using best practices and then execute it.
- You gain the peace of mind that comes from knowing we have planned out your cloud to the smallest details and then made sure it delivers on your needs.
Collaborate with Experts
- Plan out your cloud strategy without having to commit all your applications to the public cloud: >> Hybrid Approach.
- Microsoft has the only viable hybrid strategy and expected to surpass AWS in market share by 2019.
- We specialize in engineering, deploying and operating the right solution for your business by combining public and private Azure.
- As one of the world’s five largest Microsoft cloud solution providers (CSP), we help you identify the optimal environment to run each application including you database and storage.
Migrate Existing Environments
- We have expertise which minimizes redevelopment to move applications and data without recoding.
- We leverage Microsoft Azure Site Recovery (ASR) which provides a simple way to move applications and data without having to redevelop the underlying cloud infrastructure.
- We implement your new environment on a public or private cloud depending on your preferences and business requirements.
- We enable access to complete and accurate PHI for better medical care.