Dockerfile ONBUILD build output

$ docker build --no-cache -t demo-onbuild .

### REMOVED ###
Step 6/11 : RUN echo "First stage build time:"; env | grep VAR_
 ---> Running in 2059bd2e7860
First stage build time:
VAR_ARG=arg_value
VAR_ENV=env_value
Removing intermediate container 2059bd2e7860
 ---> ec2a853d2c02
### REMOVED ###
Step 8/11 : RUN echo "Second stage build time:"; env | grep VAR_
 ---> Running in c6002665e972
Second stage build time:
VAR_ARG_ONBUILD=onbuild_arg_value
VAR_ENV_ONBUILD=onbuild_env_value
VAR_ENV=env_value
Removing intermediate container c6002665e972
 ---> b8e8b99d65cd
### REMOVED ###
Step 10/11 : RUN echo "Third stage build time:"; env | grep VAR_
 ---> Running in c71c1773ee98
Third stage build time:
VAR_ARG_ONBUILD=onbuild_arg_value
VAR_ENV_ONBUILD=onbuild_env_value
VAR_ENV=env_value
Removing intermediate container c71c1773ee98
 ---> 005c9e64aeea
Step 11/11 : CMD ["bash", "-c", "echo At runtime; env | grep VAR_"]
 ---> Running in fbdd2385224a
Removing intermediate container fbdd2385224a
 ---> c96e28248334
Successfully built c96e28248334
Successfully tagged demo-onbuild:latest