CODEWITHSUNDEEP
dockerfile
Pessoa
Pessoa

Reputation: 1

How to define an environmental variable to hold current time in Dockerfile

What I'm trying is to define an ENV variable that will hold current time inside a docker container. Using bash, I can simply state timenow=$(date+"%y%m%d") and voila, if I echo $timenow I see the captured time in the specified format print to the console.

Here goes my Dockerfile: What is written below does not work, any tips on how to do it will be very much appreciated sirs.

FROM ubuntu
MAINTAINER Me
ENV timenow ""
RUN /bin/bash -c "timenow=$(date +'%y-%m-%d')"
CMD ["sh", "-c", "echo $timenow"]

Upvotes: 0

Views: 1929

Answers (1)

Konrad Botor
Konrad Botor

Reputation: 5063

I'd go with

FROM ubuntu
LABEL maintainer="Me"
ARG TIMENOW
ENV TIMENOW $TIMENOW
CMD ["sh", "-c", "echo $TIMENOW"]

and then

docker build --build-arg TIMENOW=$(date +'%y-%m-%d') --tag my_image:latest .
docker run -it --rm my_image:latest

which should display the time the image was built, which is what I belive you want.

Edit:

If you want the current time at the moment the contaier was executed, then the following should work

FROM ubuntu
LABEL maintainer="Me"
CMD TIMENOW=$(date+"%y%m%d") && echo $TIMENOW

and then

docker build --tag my_image:latest .
docker run -it --rm my_image:latest

Upvotes: 1

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