问docker构建跳过Dockerfile CMD

EN

FROM node:12-alpine
WORKDIR /app
COPY package.json yarn.lock ./
RUN yarn install --production
COPY . .
CMD ["node", "src/index.js"]

user$ docker build -t getting-started .
[+] Building 17.5s (10/10) FINISHED
 => [internal] load build definition from Dockerfile                                          0.0s
 => => transferring dockerfile: 175B                                                          0.0s
 => [internal] load .dockerignore                                                             0.0s
 => => transferring context: 52B                                                              0.0s
 => [internal] load metadata for docker.io/library/node:12-alpine                             0.0s
 => [1/5] FROM docker.io/library/node:12-alpine                                               0.0s
 => [internal] load build context                                                             0.3s
 => => transferring context: 7.32kB                                                           0.3s
 => CACHED [2/5] WORKDIR /app                                                                 0.0s
 => [3/5] COPY package.json yarn.lock ./                                                      0.1s
 => [4/5] RUN yarn install --production                                                      15.1s
 => [5/5] COPY . .                                                                            0.1s
 => exporting to image                                                                        1.8s
 => => exporting layers                                                                       1.8s
 => => writing image sha256:65d56e5aebc4c0124f8342083c9df76692d58d8c1fa46a41eaf92a214eefab99  0.0s
 => => naming to docker.io/library/getting-started

Sending build context to Docker daemon  219.1kB
Step 1/6 : FROM node:12-alpine
---> b0dc3a5e5e9e
Step 2/6 : WORKDIR /app
---> Using cache
---> 9577ae713121
Step 3/6 : COPY package.json yarn.lock ./
---> Using cache
---> bd5306f49fc8
Step 4/6 : RUN yarn install --production
---> Using cache
---> 4e68fbc2d704
Step 5/6 : COPY . .
---> cccde25a3d9a
Step 6/6 : CMD ["node", "src/index.js"]
---> Running in 2be75662c150
Removing intermediate container 2be75662c150
---> 458e5c6f080c
Successfully built 458e5c6f080c
Successfully tagged getting-started:latest