Startup script doesn't grab IP addresses correctly

[mmcc-xx]

This is a...

• Request for a new or modified feature
• [X ] Issue trying to run the docker image
• Issue trying to build / test / develop the docker image

Description

The startup script found here: https://github.com/diginc/docker-pi-hole/blob/master/docker_run.sh
doesn't seem to be able to grab IP addresses correctly

Expected Behavior

Script determines correct current IPv4 and IPv6 addresses

Actual Behavior

When I execute the following command
echo "${IP:-$(ip route get 8.8.8.8 | awk '{ print $NF; exit }')}"
the returned value is "1000"

When I execute the following command from the script
echo "${IPv6:-$(ip -6 route get 2001:4860:4860::8888 | awk '{ print $10; exit }')}"
the returned value is "src"

Possible Fix

I'm using Ubuntu Bionic - perhaps the return format of the route command changed

Steps to Reproduce and debugging done

1. echo "${IP:-$(ip route get 8.8.8.8 | awk '{ print $NF; exit }')}"
2. echo "${IPv6:-$(ip -6 route get 2001:4860:4860::8888 | awk '{ print $10; exit }')}"

Debug steps I have tried

• I have tried destroying my container instance, pulling the newest image version, and re-creating a new container
• I have tried running the nearly stock docker run example in the readme (removing any customizations I added)
• I have tried running without my volume data mounts to eliminate volumes as the cause
• I have searched this repository for existing issues and pull requests that look similar

Context and extra information

Your Environment

• Docker Host Operating System and OS Version: Ubuntu Bionic
• Docker Version: 18.05.0-ce
• Hardware architecture: amd64

[eku]

Well, output of ip route depends on system and version.
Try

ip route get 8.8.8.8 |sed '/src/!d;s/^.*src \([^ ]*\).*$/\1/'
ip route get 8.8.8.8 |grep -oP 'src \K\S+'

[diginc]

When the auto lookup fails please just delete the whole first 4 IP lines and type in your IP to the variables like so:

IP="MyIP"
IPv6="MyIPv6"

The Lookup of IPs is a convenience thing for the majority of users. Like eku said it varies by platform. To make it 100% we'd need to know all the various platforms/network variants' outputs for the route get command.

[mikma]

Auto detection of the IPv4 address in the script on docker hub didn't work for me, since uid is the field of the ip route result. I solved it by using the same awk program as for IPv6:

$(ip route get 8.8.8.8 | awk '{for(i=1;i<=NF;i++) if ($i=="src") print $(i+1)}')

https://hub.docker.com/r/pihole/pihole/