Dockerfileにパッケージマネージャ経由で拡張してイメージをつくる

実際のところ

前回と同様alpineから。
これにはbashが入っていないので、パッケージマネージャapkを更新してbashを導入。

FROM alpine:latest
RUN apk update
RUN apk add bash
ENTRYPOINT ["/bin/bash"]

EntryPointをbashに設定することで起動するのもbashに

docker.exe build -t bashman .
[+] Building 3.8s (7/7) FINISHED
 => [internal] load build definition from Dockerfile                                                               0.0s
 => => transferring dockerfile: 113B                                                                               0.0s
 => [internal] load .dockerignore                                                                                  0.0s
 => => transferring context: 2B                                                                                    0.0s
 => [internal] load metadata for docker.io/library/alpine:3.14                                                     1.7s
 => CACHED [1/3] FROM docker.io/library/alpine:3.14@sha256:06b5d462c92fc39303e6363c65e074559f8d6b1363250027ed5053  0.0s
 => [2/3] RUN apk update                                                                                           1.2s
 => [3/3] RUN apk add bash                                                                                         0.7s
 => exporting to image                                                                                             0.0s
 => => exporting layers                                                                                            0.0s
 => => writing image sha256:fceffbd277afb5c6723991fd727cd077a4ac264476b4523158edf04efbd61f48                       0.0s
 => => naming to docker.io/library/bashman                                                                         0.0s
PS C:\Users\user\dockerbuild> docker run --name rich_cat -it bashman
bash-5.1#