![]() ![]() …you can invoke your build with docker buildx build –build-context app1=app1/src –build-context app2=app2/src. ![]() …with this Dockerfile: #syntax=docker/dockerfile:1.4 ![]() If your project has the following layout: project dockerignore file, or maybe you’d like each component to have its own Dockerfile. DIFFERENT CONTEXTS FULLThere’s a variety of issues: every component needs to be accessed by their full path, you can only have one. If your project contains multiple components that need to be built together, it’s sometimes tricky to load them with a single build context where everything needs to be contained in one directory. Probably the most requested use case for named contexts capability is the possibility to use multiple local source directories. You can also think about the previous examples as a way to create an alias for an image. Let’s say you built your app and pushed it to a staging repository, but now want to use it in your other builds that would usually use the release image.ĭocker buildx build -build-context myorg/myapp=docker-image:///registry/myapp. A common pattern could be that you haven’t released your image yet, and it’s only in the test registry or staging environment. When your Dockerfile uses alpine:3.15, even if it’s been updated with a newer version in the registry, your new build will still use the same exact image your previous build did.Īs another example, you may just want to try a different image or different version for debugging or developing your image. For example, you can use the new BuildInfo feature to capture all the build sources and run a build with the same dependencies as a previous build did, even if the image tags have been updated.ĭocker buildx imagetools inspect -format '' moby/buildkit "sources": [ Let’s start with an example of how you can use build contexts to pin an image used by a Dockerfile to a specific version. If no -from flag is set, files are loaded from the main build context. Stage defined with AS inside Dockerfile.Named build context defined with -build-context =.The value of is matched with the following priority order: Here’s how that might look: # syntax=docker/dockerfile:1.4 On the Dockerfile side, you can reference the build context on all commands that accept the “from” parameter. build-context alpine=docker-image://alpine:3.15 Docker image – Define with a docker-image:// prefix, e.g.build-context project2=./path/to/project2/src The key component defines the name for your build context and the value can be: You can now define additional build contexts when running the build command, give them a name, and then access them inside a Dockerfile the same way you previously did with build stages.Īdditional build contexts can be defined with a new -build-context = flag. The new named build context feature is an extension of this pattern. That’s why we added multi-stage builds where you can copy files from other parts of the Dockerfile by adding the -from flag and pointing it to the name of another Dockerfile stage or a remote image. Conquering Complex Buildsīut, as builds got more complicated, the ability to only access files from one location became quite limiting. In BuildKit, we also added build mounts with RUN -mount that allow accessing build context files directly - without copying them - for extra performance. Inside a Dockerfile you can use COPY and ADD commands to copy files from your build context and make them available to your build steps. making the current working directory the build context. When you invoke the docker build command, it takes one positional argument which is a path or URL to the build context. Let’s look at why it’s useful and how you can leverage it in your build pipelines. This means you can use files from different local directories as part of your build. The new releases of Dockerfile 1.4 and Buildx v0.8+ come with the ability to define multiple build contexts. ![]()
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