Switch from IPs to local address resolving

[Timple]

Proposal Get rid of all the fixed ip's on dev-pcs etc and switch to local address resolving.

Examples ping amigo1.local ssh amigo@amigo2.local export ROS_MASTER_URI=http://amigo1.local:11311

Rationale The custom /etc/hosts files are a hassle to maintain. Also every tournament our subnet changes which makes everything difficult.

How does it work If an avahi client and deamon is installed on every PC (simple apt-gettie) then every PC acts as a DNS resolver for only it's own hostname.local. So a ping amigo1.local results in the user PC broadcasting the question who amigo1.local is. ONLY amigo1 responds with the answer: I am here with this IP. Then the action ping starts. If a computer has multiple IP addresses this still works

Pros

• DHCP can be used for most PCs
• Internet access and standard DNS resolving becomes easier because of DHCP
• We don't need to be in control of the router
• Swapping between cable and wifi on laptops is easier as ever
• Roll-out can be incremental, minimizing risks

Cons

• DHCP server required in the network, so a workaround is needed for amigo itself

Why now

• Got a call about networking, really needs to be easier!
• Newly gained knowledge about (local) dns resolution ;-)
• Can be part of the 'we need to be more robust' plan

Todo

• [x] Install and configure avahi deamons on every PC
• [x] Investigate how to do DHCP and a static IP on amigo PCs Done
• [x] Check windows support
• [ ] Configure static IPs on amigo PCs -> This seems to be done already once avahi is configured link, to be tested
• [ ] export ROS_HOSTNAME=`hostname`.local either always or when running amigo-core

NB: Of course for amigo you can read Sergio / HSR / Pico / Pepper / Whatever we buy next

[Rayman]

The last point (export ROS_HOSTNAME=`hostname`.local) looks to me like a hack so you don't have to change a lot of code.

[Timple]

You realize we now do:

export ROS_IP=`hostname -I | sed 's/.*\(192\.168\.44\.[0-9]\+\).*/\1/'`

Talking about hacks :P

But seriously, why does setting the ROS_HOSTNAME look like a hack? You are simply telling the other ROS nodes on other PCs that this is the address where you can be found.

[Rayman]

Yeah that's true, its way better then what we had before