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Building Container Images

Finch leverages Moby's BuildKit to build container images defined in a Dockerfile. To interact with BuildKit you use the finch build command.

Building a Container Image

A sample application called hello-finch is included in the Finch Repository. In this guide we will clone this Finch repository, and build hello-finch.

  1. Clone the Finch repository.

    git clone https://github.com/runfinch/finch.git

  2. Navigate to the hello-finch application.

    cd finch/contrib/hello-finch

  3. Build hello-finch with the finch build. Here we specifying the tag that we want to use for the image, as well as where the build context can be found.

    finch build --tag hello-finch .

  4. You can see the newly build container image in the image store using the finch image list command.

    finch image list

    The output shows your new container image, the platform it was built for and the uncompressed size.

    REPOSITORY     TAG       IMAGE ID        CREATED        PLATFORM       SIZE       BLOB SIZE
hello-finch    latest    69b2528740fe    2 weeks ago    linux/arm64    1.8 MiB    1008.4 KiB

Building a Multi Architecture Container Image

By default Finch will build a container image that corresponds to your local machine, i.e. an x86 container image when running on an Intel machine, an arm64 when running on a Apple Silicon machine. If you wish to build a container image for an alternative architecture, or multiple architectures at the same time, then you can use the --platform flag with finch build.

  1. Once again we will build the hello-finch demo application. If you haven't already, clone the Finch repository.

    git clone https://github.com/runfinch/finch.git

  2. Navigate to the hello-finch application.

    cd finch/contrib/hello-finch

  3. Build hello-finch with the finch build. Here we specify an alternative architecture with the --platform flag. Here you could specify a single architecture --platform linux/amd64 or multiple architectures --platform linux/arm64,linux/amd64.

    finch build \
  --platform linux/arm64,linux/amd64 \
  --tag hello-finch \
  .

    finch build `
  --platform linux/arm64,linux/amd64 `
  --tag hello-finch `
  .

  4. You can see both container images in the local image store, with the finch image list command.

    finch image list

    Notice how there are 2 images, one for each architecture.

    REPOSITORY     TAG       IMAGE ID        CREATED        PLATFORM       SIZE       BLOB SIZE
hello-finch    latest    5874669344b3    2 weeks ago    linux/arm64    1.8 MiB    1009.0 KiB
hello-finch    latest    5874669344b3    2 weeks ago    linux/amd64    0.0 B      1.0 MiB

Next Steps

In this short section, you learned how to build container images on finch.