https://hub.docker.com/repository/docker/meedamian/docker-ci/tags

buildx

$ cat Dockerfile
FROM alpine:3.12
RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cpuinfo; } > /root/me.txt
ENTRYPOINT [ "cat", "/root/me.txt" ]

$ TAG='meedamian/docker-ci:v12.7.2020'

$ docker manifest inspect alpine:3.12 | jq -r '.manifests[].platform | .os + "/" + .architecture + " " + .variant'
linux/amd64
linux/arm v6
linux/arm v7
linux/arm64 v8
linux/386
linux/ppc64le
linux/s390x

$ docker buildx build --no-cache --push  --tag="$TAG" --tag="${TAG%.*}" --tag="${TAG%%.*}" --tag="${TAG%:*}:latest" --platform=linux/amd64,linux/arm64,linux/386,linux/arm/v6  --progress=plain  .
#1 [internal] load .dockerignore
#1 transferring context: 2B 0.1s done
#1 DONE 0.2s

#2 [internal] load build definition from Dockerfile
#2 transferring dockerfile: 32B 0.1s done
#2 DONE 0.2s

#6 [linux/386 internal] load metadata for docker.io/library/alpine:3.12
#6 DONE 4.2s

#3 [linux/arm/v6 internal] load metadata for docker.io/library/alpine:3.12
#3 DONE 4.3s

#4 [linux/amd64 internal] load metadata for docker.io/library/alpine:3.12
#4 DONE 4.3s

#5 [linux/arm64 internal] load metadata for docker.io/library/alpine:3.12
#5 DONE 4.3s

#14 [linux/amd64 1/2] FROM docker.io/library/alpine:3.12@sha256:185518070891...
#14 resolve docker.io/library/alpine:3.12@sha256:185518070891758909c9f839cf4ca393ee977ac378609f700f60a771a2dfe321 done
#14 CACHED

#7 [linux/arm64 1/2] FROM docker.io/library/alpine:3.12@sha256:185518070891...
#7 CACHED

#9 [linux/386 1/2] FROM docker.io/library/alpine:3.12@sha256:18551807089175...
#9 CACHED

#11 [linux/arm/v6 1/2] FROM docker.io/library/alpine:3.12@sha256:18551807089...
#11 resolve docker.io/library/alpine:3.12@sha256:185518070891758909c9f839cf4ca393ee977ac378609f700f60a771a2dfe321 done
#11 CACHED

#12 [linux/arm/v6 2/2] RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cp...
#12 ...

#13 [linux/amd64 2/2] RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cpu...
#13 DONE 0.2s

#10 [linux/386 2/2] RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cpuin...
#10 DONE 0.3s

#12 [linux/arm/v6 2/2] RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cp...
#12 DONE 0.4s

#8 [linux/arm64 2/2] RUN { uname -a; uname -m; printf '\n\n'; cat /proc/cpu...
#8 DONE 0.4s

#15 exporting to image
#15 exporting layers
#15 exporting layers 0.3s done
#15 exporting manifest sha256:b559332ca9526b8bfeb39856d505d75c6600458d519b3f8d16aded7d1c55a464 0.0s done
#15 exporting config sha256:f708f3fd1054ae8648f6a02a9645c0c5d9f856e0d862b56787156f0900e71221 0.0s done
#15 exporting manifest sha256:3b61c60bbe1cfd70ec38d879f211828271e1bdea9a3e2859c0feb3ac9a1d1d8e 0.0s done
#15 exporting config sha256:4db558b7f3fe501157d2ff1305e451b814d8bc29025464a987994b56594d9717
#15 exporting config sha256:4db558b7f3fe501157d2ff1305e451b814d8bc29025464a987994b56594d9717 0.0s done
#15 exporting manifest sha256:755e1dbd3fb8a82da5e8395b175e7aaa0b3a4390c3110112742f5dad4026f720 0.0s done
#15 exporting config sha256:bd25fe75bd615254063c43c72ccaeca743fc7ca4e382cc13a5d88c4301efe247 0.0s done
#15 exporting manifest sha256:4b0791b0e7b84dcf271702956a05ac8c0d8064c885c8431966db688f7be95d03
#15 exporting manifest sha256:4b0791b0e7b84dcf271702956a05ac8c0d8064c885c8431966db688f7be95d03 0.1s done
#15 exporting config sha256:d8fa1dade0702f083f84b1ce356d042518e61ccc92ed3323dd10942396255e89 0.0s done
#15 exporting manifest list sha256:d45639fbb26fca5bf89fa73f7130b4373cb5a5417663074af96b2edbec8e253c 0.0s done
#15 pushing layers
#15 pushing layers 7.4s done
#15 pushing manifest for docker.io/meedamian/docker-ci:v12.7.2020
#15 pushing layers
#15 pushing manifest for docker.io/meedamian/docker-ci:v12.7.2020 11.5s done
#15 pushing layers 4.4s done
#15 pushing manifest for docker.io/meedamian/docker-ci:v12.7
#15 pushing layers
#15 pushing manifest for docker.io/meedamian/docker-ci:v12.7 10.7s done
#15 pushing layers 4.1s done
#15 pushing manifest for docker.io/meedamian/docker-ci:v12
#15 pushing layers
#15 pushing manifest for docker.io/meedamian/docker-ci:v12 10.7s done
#15 pushing layers 4.2s done
#15 pushing manifest for docker.io/meedamian/docker-ci:latest
#15 pushing manifest for docker.io/meedamian/docker-ci:latest 11.4s done
#15 DONE 64.8s