% ls
total 8
drwxr-xr-x   3 tamird  staff    96B Jul 17 01:51 .
drwxr-xr-x  14 tamird  staff   448B Jul 17 01:47 ..
-rw-r--r--   1 tamird  staff   141B Jul 17 01:49 Dockerfile
% cat Dockerfile
FROM busybox:latest AS build
RUN echo "hello from $(date -u +%FT%TZ)" > /hello.txt

FROM scratch AS artifact
COPY --from=build /hello.txt /

% container build . --target artifact --progress plain --output type=tar,dest=container-out
#1 [resolver] fetching image...docker.io/library/busybox:latest
#1 DONE 0.0s

#2 [resolver] fetching image...docker.io/library/scratch
#2 DONE 0.0s

#3 [internal] load .dockerignore
#3 transferring context: 2B 0.0s done
#3 DONE 0.0s

#4 oci-layout://docker.io/library/busybox:latest@sha256:f85340bf132ae937d2c2a763b8335c9bab35d6e8293f70f606b9c6178d84f42b
#4 resolve docker.io/library/busybox:latest@sha256:f85340bf132ae937d2c2a763b8335c9bab35d6e8293f70f606b9c6178d84f42b done
#4 DONE 0.0s

#5 [linux/arm64 build 1/2] RUN echo "hello from $(date -u +%FT%TZ)" > /hello.txt
#5 CACHED

#6 [linux/arm64/v8 artifact 1/1] COPY --from=build /hello.txt /
#6 CACHED

#7 exporting to client tarball
#7 sending tarball done
#7 DONE 0.0s
Successfully built b0664c8b-5859-4444-8e97-e1c3496bbd52:latest
% ls
total 8
drwxr-xr-x   4 tamird  staff   128B Jul 17 01:51 .
drwxr-xr-x  14 tamird  staff   448B Jul 17 01:47 ..
-rw-r--r--   1 tamird  staff     0B Jul 17 01:51 container-out
-rw-r--r--   1 tamird  staff   141B Jul 17 01:49 Dockerfile
% rm container-out
% docker buildx build . --target artifact --progress plain --output type=tar,dest=container-out
#0 building with "default" instance using docker-container driver

#1 [internal] booting buildkit
#1 starting container buildx_buildkit_default
#1 starting container buildx_buildkit_default 0.6s done
#1 DONE 0.6s

#2 [internal] load build definition from Dockerfile
#2 transferring dockerfile: 180B done
#2 DONE 0.0s

#3 [internal] load metadata for docker.io/library/busybox:latest
#3 DONE 0.5s

#4 [internal] load .dockerignore
#4 transferring context: 2B done
#4 DONE 0.0s

#5 [build 1/2] FROM docker.io/library/busybox:latest@sha256:f85340bf132ae937d2c2a763b8335c9bab35d6e8293f70f606b9c6178d84f42b
#5 resolve docker.io/library/busybox:latest@sha256:f85340bf132ae937d2c2a763b8335c9bab35d6e8293f70f606b9c6178d84f42b done
#5 sha256:189fdd1508372905e80cc3edcdb56cdc4fa216aebef6f332dd3cba6e300238ea 1.84MB / 1.84MB 0.1s done
#5 extracting sha256:189fdd1508372905e80cc3edcdb56cdc4fa216aebef6f332dd3cba6e300238ea 0.0s done
#5 DONE 0.2s

#6 [build 2/2] RUN echo "hello from $(date -u +%FT%TZ)" > /hello.txt
#6 DONE 0.1s

#7 [artifact 1/1] COPY --from=build /hello.txt /
#7 DONE 0.0s

#8 exporting to client tarball
#8 sending tarball done
#8 DONE 0.0s
% ls
total 16
drwxr-xr-x   4 tamird  staff   128B Jul 17 01:52 .
drwxr-xr-x  14 tamird  staff   448B Jul 17 01:47 ..
-rw-r--r--   1 tamird  staff   3.0K Jul 17 01:52 container-out
-rw-r--r--   1 tamird  staff   141B Jul 17 01:49 Dockerfile