# Docker multi-stage builds all targets

**URL:** <https://forums.balena.io/t/docker-multi-stage-builds-all-targets/372772>\
**Category:** Product support\
**Tags:** docker\
**Created:** [January 10, 2025, 1:23am UTC](https://forums.balena.io/t/docker-multi-stage-builds-all-targets/372772 "2025-01-10T01:23:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sdowns](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@sdowns](https://forums.balena.io/u/sdowns)\
**Post date:** [January 10, 2025, 1:23am UTC](https://forums.balena.io/t/docker-multi-stage-builds-all-targets/372772/1 "2025-01-10T01:23:07Z")

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We have a project with a multi-stage dockerfile that includes targets for both our arm64 IoT devices and x86 tooling (cross compiler image).

When I submit this to Balena cloud builders using the balena CLI, it looks like all of the targets in the multi-stage dockerfile are being built - even if they are not a dependency of the target specified in our docker-compose file. This is both slow and actually fails due to an incompatibility with the target platform for our x86 cross compiler install scripts.

According to [docker](https://docs.docker.com/build/building/multi-stage/#differences-between-legacy-builder-and-buildkit), if you are using buildkit, then only the stages that the target stage depends on are built. Do the Balena cloud builders use buildkit?

The following is a simplified version of our dockerfile:

```auto
ARG BASE_OS=linux
ARG BASE_ARCH=aarch64

#-------------------------------------------------------------------------------
# Install the setup directory

FROM ubuntu:bionic AS tools
COPY . /setup
RUN /setup/download_some_stuff.sh

#-------------------------------------------------------------------------------
# Base Image

FROM --platform=$BASE_OS/$BASE_ARCH ubuntu:bionic AS base
COPY --from=tools /setup /setup
RUN /setup/install_base_packages.sh

#-------------------------------------------------------------------------------
# Target Sysroot (for cross compilation)

FROM base AS sysroot-tar
RUN /setup/scripts/balena/export-sysroot.sh
RUN /setup/blobs/tegra/extract-xavier-sysroot.sh /sysroot.tar /target-root

#-------------------------------------------------------------------------------
# Cross compiler image

FROM ubuntu:bionic AS crossbuild-x86
COPY --from=sysroot-tar /target-root /target-root
COPY --from=tools /setup /setup
RUN /setup/install_cross_compiler_stuff.sh

#-------------------------------------------------------------------------------
# Main Balena Application Image

FROM base AS application-base
RUN /setup/remove_unnecessary_files.sh && rm -rf /setup

#-------------------------------------------------------------------------------
# Much smaller final image

FROM scratch AS application
COPY --from=application-base / /
CMD ["/system-init"]

```

We specify “application” as our target in the docker-compose.yml file but the crossbuild-x86 target is also being built. If buildkit was being used I would expect that only the following should be built:

- tools
- base
- application-base
- application

Is there any way I can ensure that only the required targets are being built by the Balena cloud builders?

---

<div class="post-metadata">

**Author:** ![alexgg](https://avatars.discourse-cdn.com/v4/letter/a/7ab992/32.png) [@alexgg](https://forums.balena.io/u/alexgg)\
**Post date:** [January 10, 2025, 4:52pm UTC](https://forums.balena.io/t/docker-multi-stage-builds-all-targets/372772/2 "2025-01-10T16:52:10Z")

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Hi, unfortunately we don’t yet use buildkit on the builders - the balenaEngine does have the support enabled but until recently dockerode, which we use to interface with it, did not support it.