- Create a simple Dockerfile to build an apline image.
- Use
build and buildx build to build the same Dockerfile.
- Examine the image layer.
FROM alpine
RUN apk add --no-cache bash
COPY . /app
RUN chmod +x /app/hello.sh
CMD /app/hello.sh
$ docker build -t img0 .
Sending build context to Docker daemon 3.072kB
Step 1/5 : FROM alpine
latest: Pulling from library/alpine
2408cc74d12b: Pull complete
Digest: sha256:686d8c9dfa6f3ccfc8230bc3178d23f84eeaf7e457f36f271ab1acc53015037c
Status: Downloaded newer image for alpine:latest
---> e66264b98777
Step 2/5 : RUN apk add --no-cache bash
---> Running in 8d4bb9012c59
fetch https://dl-cdn.alpinelinux.org/alpine/v3.16/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.16/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ncurses-terminfo-base (6.3_p20220521-r0)
(2/4) Installing ncurses-libs (6.3_p20220521-r0)
(3/4) Installing readline (8.1.2-r0)
(4/4) Installing bash (5.1.16-r2)
Executing bash-5.1.16-r2.post-install
Executing busybox-1.35.0-r13.trigger
OK: 8 MiB in 18 packages
Removing intermediate container 8d4bb9012c59
---> c30c4ade8d67
Step 3/5 : COPY . /app
---> 14ab7c71e803
Step 4/5 : RUN chmod +x /app/hello.sh
---> Running in 8fc8c2d9a28e
Removing intermediate container 8fc8c2d9a28e
---> f11502e3c083
Step 5/5 : CMD /app/hello.sh
---> Running in 3f00d75f1bd4
Removing intermediate container 3f00d75f1bd4
---> a7323ea78a43
Successfully built a7323ea78a43
Successfully tagged img0:latest
$ docker buildx build -t img1 .
[+] Building 4.6s (9/9) FINISHED
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 137B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/alpine:latest 0.0s
=> [1/4] FROM docker.io/library/alpine 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 212B 0.0s
=> [2/4] RUN apk add --no-cache bash 3.9s
=> [3/4] COPY . /app 0.0s
=> [4/4] RUN chmod +x /app/hello.sh 0.4s
=> exporting to image 0.1s
=> => exporting layers 0.1s
=> => writing image sha256:c6cfc6f9688fb5aca23bfc128cb326c90d07ae420456f3c3a0b558ec7f0bfc6c 0.0s
=> => naming to docker.io/library/img1
$ docker image history img0
IMAGE CREATED CREATED BY SIZE COMMENT
a7323ea78a43 2 minutes ago /bin/sh -c #(nop) CMD ["/bin/sh" "-c" "/app… 0B
f11502e3c083 2 minutes ago /bin/sh -c chmod +x /app/hello.sh 38B
14ab7c71e803 2 minutes ago /bin/sh -c #(nop) COPY dir:d7e62b3bbd2c3347c… 138B
c30c4ade8d67 2 minutes ago /bin/sh -c apk add --no-cache bash 2.15MB
e66264b98777 6 weeks ago /bin/sh -c #(nop) CMD ["/bin/sh"] 0B
<missing> 6 weeks ago /bin/sh -c #(nop) ADD file:8e81116368669ed3d… 5.53MB
$ docker image history img1
IMAGE CREATED CREATED BY SIZE COMMENT
c6cfc6f9688f 38 seconds ago CMD ["/bin/sh" "-c" "/app/hello.sh"] 0B buildkit.dockerfile.v0
<missing> 38 seconds ago RUN /bin/sh -c chmod +x /app/hello.sh # buil… 38B buildkit.dockerfile.v0
<missing> 39 seconds ago COPY . /app # buildkit 138B buildkit.dockerfile.v0
<missing> 39 seconds ago RUN /bin/sh -c apk add --no-cache bash # bui… 2.15MB buildkit.dockerfile.v0
<missing> 6 weeks ago /bin/sh -c #(nop) CMD ["/bin/sh"] 0B
<missing> 6 weeks ago /bin/sh -c #(nop) ADD file:8e81116368669ed3d… 5.53MB
$ docker image inspect a7323ea78a43
[
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"RepoTags": [
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],
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],
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"WorkDir": "/var/lib/docker/overlay2/11d90a52784c4bfe1405fa6d3fd5bcaacf47365354dd56e887d3b16413144b86/work"
},
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},
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$ docker image inspect c6cfc6f9688f
[
{
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],
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},
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},
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},
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]
