How to check if running inside Docker?

To check if you are inside a docker container, run the command

cat /proc/1/cgroup | grep --color  docker

If you get some result with docker in it, you are inside a docker container.

Example

identify docker container

See Docker

Comments

One response to “How to check if running inside Docker?”

  1. Ron Avatar
    Ron

    This doesn’t work with cgroup 2.0, and it doesn’t work inside Docker Desktop on Mac.

    root@8a1d175a0b6c:/# cat /proc/self/cgroup
    0::/

    The presence of a /.dockerenv file on the root filesystem in Linux is probably a more reliable way to know that you’re running inside a Docker container, but that doesn’t give you your container Id; it’s just an empty file.

    There needs to be a less fragile way to 1) detect when you’re running in a container, and 2) get your own container Id. The Docker team really dropped the ball on this. At a minimum, they should have put the container Id inside /.dockerenv.

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