LACP port bonding with DHCP on debian stretch

Finding information on LACP port bonding can be tricky.  It seems there's a decent guide published every couple years, but then the code changes and the information no longer really applies.

And creating a bonded interface with DHCP is even trickier.  You could solve it this way, if you wanted to cop out.  But copping out is for out coppers, and everyone knows that that ain't me.

So we're going to configure LACP port bonding (aka 802.3ad) on our brand new install of debian stretch (at the time of this writing, stretch is nearly identical to jessie, so this guide ought to work for jessie for a few years).

1. aptitude install ifenslave
   echo 'mii' >> /etc/modules
   modprobe bonding
   
   This gives us the ability to create bond interfaces.
   
   
2. vi /etc/network/interfaces
   
   And make sure the contents look something like this:
   
   source /etc/network/interfaces.d/*
   
   # Loopbackz
   auto lo
   iface lo inet loopback
   
   # Enslave these interfaces
   allow-hotplug eth0
   allow-hotplug eth1
   
   # The bonded interface
   auto bond0
   iface bond0 inet dhcp
       bond-slaves eth1 eth0 # order matters!  the first listed interface is the one whose mac is used
       bond-mode 802.3ad
       bond-miimon 100
       bond-downdelay 200
       bond-updelay 200
       bond-lacp-rate 1
       bond-xmit-hash-policy layer2+3
   
   
3. Reboot.  Or muck around with /etc/init.d/networking restart, ifconfig INTERFACE DOWN|UP, etc.
4. If the ifconfig output looks good, and the output from cat /proc/net/bonding/bond0 looks good, and you have network connectivity, then you've done it!

Go have a cold beer, you've earned it.