Is there any way to set default computing env for all future container?
Use case:
I have build infrastructure and want to set machine-specific env for all containers that will be started on machine.
While you can’t directly set ENV variable values when running docker build, you can use ARG to pass through --build-arg values right into your ENV instructions.
First, you’ll need to define an additional ARG variable, which is only there to pass through the value to your environment variable:
ARG buildtime_variable=default_value # <- this one’s new
ENV env_var_name=$buildtime_variable # we reference it directly
Almost done! Now, when you’re building your image you can override the default_value of “buildtime_variable” any time you like:
$ docker build --build-arg buildtime_variable=a_value # … the rest of the build command is omitted
Try an environment variable file
–env-file /path/to/envfiles.
Use the -e , --env , and --env-file flags to set simple (non-array) environment variables in the container you’re running, or overwrite variables that are defined in the Dockerfile of the image you’re running.
Don’t knew about build-arg trick. Thanks.
But, unfortunately, I don’t have possibilities to rebuild all images. Also, they can be external.
And I really want to do such things on the docker engine layer. And don’t want to any affect on the run/start container usage for users.