Multi Stage Builds - Concurrency

Multi Stage Builds - Concurrency

Stages can be built in parallel when using BuildKit

build1 and build2 are built at the same time

FROM alpine AS build1
RUN touch /opt/binary1

FROM alpine AS build2
RUN touch /opt/binary2

FROM alpine AS final
COPY --from=build1 /opt/binary1 /opt/
COPY --from=build2 /opt/binary2 /opt/

Concurrency is determined based on the dependency graph

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Demo: Multi Stage Builds - Concurrency

Stages have a delay

Build sequentially using the legacy build engine:

time docker build .

Build in parallel using BuildKit:

DOCKER_BUILDKIT=1 docker build .

Sequential build will take double the time

Parallel builds reduce the waiting time