When running a docker container, what's the point of -idt option ?

Mhd Tahawi

For example, in Lab2 of DebOps and SRE fundametals course:
docker container run -idt --name redis redis:alpine

What's the point of i (interactive) and t (attach a pseudo TTY) if we are also running in d (detached mode) ?

luisviveropena

Hi @Mhd Tahawi ,

It wasn't easy to find an answer, but it's useful, as explained in the official documentation:

https://docs.docker.com/reference/cli/docker/container/run/#tty

Please take a look at this.

Regards,
Luis.

luisviveropena

Moved to the correct forum.

luisviveropena

Hi @Mhd Tahawi ,

The idea of this is to have the container running in background mode. The default action is to run it on foreground. So whenever you want, you can close the terminal, or perform any other stuff in the terminal, and when you need you can connect to the container -running a binary as sh:

For example:

docker exec -it 6782576441fe sh

And you will get into the container, by running a sh shell.

You can have more information in the official documentation:

https://docs.docker.com/engine/reference/run/

==>Foreground and background

Regards,
Luis.

Mhd Tahawi

Hello @luisviveropena

Thanks for answering (and for moving the question to the right forum).

I do understand foreground and background, detached mode and accessing the container in interactive mode.

Let me phrase my question differently:
What difference in behavior would I get if I use:
docker container run -idt --name redis redis:alpine // interactive tty and detached
over
docker container run -d --name redis redis:alpine // just detached

In both cases, I will end up running in detached mode, and in both cases, I will need to run
docker exec -it <containerName/Id>
for an interactive shell. So what extra functionality do I get from adding "-it" with "-d" ?

I can think of one use case for "-i", running a container in detached mode while handling input from stdin, something like:
echo "some input" | docker run -id myFancyImage

but for "t" option, I don't see any point, and it feels redundant.

Thanks for your help,
Mohamad