3

Is it possible to get host's info from within docker, for example

  1. HOST Machine's IP (eth0's IP not docker0's)
  2. Available RAM in HOST machine

etc.,

Thanks in advance

Improve this question

1 Answer 1

Reset to default
4

It's not generally possible - it would break the isolation which Docker provides.

In this article, you can see how, any breakout from the Docker container is actually a serious security issue.

https://blog.docker.com/2014/06/docker-container-breakout-proof-of-concept-exploit/

However, there are various workarounds:

http://blog.michaelhamrah.com/2014/06/accessing-the-docker-host-server-within-a-container/

Suggests that the following approach:

"Although there’s no way to introspect the host’s ip address (AFAIK) you can pass this in via an environment variable:"

docker@boot2docker:~$ docker run -i -t -e DOCKER_HOST=192.168.59.103 ubuntu /bin/bash root@07561b0607f4:/# env HOSTNAME=07561b0607f4 DOCKER_HOST=192.168.59.103 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PWD=/

On EC2, specifically, you can access the instance's metadata:

See

Fetching AWS instance metadata from within Docker container?

In particular:

$ curl http://169.254.169.254/latest/meta-data/hostname ec2-203-0-113-25.compute-1.amazonaws.com

Other metadata options are listed here:

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

Improve this answer
Sign up to request clarification or add additional context in comments.

5 Comments

Thank you, Donald I'm currently using the same method on EC2. docker run -it -p 9200:9200 -p 9300:9300 -e HOST_IP=$(hostname --ip-address) shan/elk:latest My use case is, I'm running elasticsearch inside docker and i need to pass the IP of the host machine to network.publish_host: parameter in elasticsearch Without passing the HOST_IP, auto discovery is not working Thank you very much Donald.
I'm afraid you have'll to pass it in - it's just not possible to break out of the container otherwise.
Have to live with it, as security is more important
Donald's answer is true in general, but on EC2, you could query instance metadata to get the IP address.
Thanks both of you @Donald_W and @NathanielWaisbrot, it working fine. I'm able to get the instance IP using curl http://169.254.169.254/latest/meta-data/local-ipv4.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.