How can I create an environment variable that contains the IP address of an adapter that is set via DHCP?

Question

I am using docker and my scripts reference an environment variable that I'm manually setting in user's foo account /etc/environment like:

SERVER_IP=172.16.16.29

I'm using in my docker-compose file (which I'm running under as foo)

environment:
  - ServerIP=${SERVER_IP}

I would like to be able to have a variable DHCP_IP that will be populated when adapter enp0s3 has it's IP address set so that I can use DHCP_IP in place of SERVER_IP in the docker-compose above.

I'm not concerned about the IP address changing often as I'm using MAC address filtering in my router to assign the same IP. But I don't want to have to set the IP address manually in a file like I'm doing now.

So how can I put the value of the ip address of enp0s3 into a variable called DHCP_IP, and how can I reference that at the command line or in a file?

Or if you know of an alternative, I'm open to suggestions.

Solution 1

Add the following to /etc/bash.bashrc

The adapter in question is: enp0s3, so change that accordingly

IP="$(ip addr show enp0s3  | awk '$1 == "inet" { print $2 }' | cut -d/ -f1)"
export SERVER_IP=${IP}

Solution 2

I'm using the following approach:

Suppose that your ethernet name is ens160:

IP=http://"$(ifconfig ens160 | awk '/inet /{print $2}' | cut -f2 -d':')"

Or:

IP=http://"$(hostname -I | cut -f1 -d' ')"

Test:

echo $IP

http://192.168.100.146

Comments

[goo]

DHCP_IP="$(ip addr show enp0s3 | grep "inet " | awk '{print $2}' | cut -d/ -f1)"

[WhiskerBiscuit]

I can get the IP already. How do I put it to a variable?