Installation

Connect your serial adapter (usbcom1a works well if you don’t have one already) to the apu2c4 and start a program to use it, e.g. screen /dev/ttyUSB0 115200. Then, power on the apu2c4 and configure it to do PXE boot:

Press F10 to enter the boot menu
Press 3 to enter setup
Press n to enable network boot
Press c to move mSATA to the top of the boot order
Press e to move iPXE to the top of the boot order
Press s to save configuration and exit

Connect a network cable on net0, the port closest to the serial console port:

router7 development setup

Next, build a router7 image:

go get -u github.com/gokrazy/tools/cmd/gokr-packer github.com/rtr7/tools/cmd/...
go get -u -d github.com/rtr7/router7
mkdir /tmp/recovery
GOARCH=amd64 gokr-packer \
	-hostname=router7 \
	-overwrite_boot=/tmp/recovery/boot.img \
	-overwrite_mbr=/tmp/recovery/mbr.img \
	-overwrite_root=/tmp/recovery/root.img \
	-kernel_package=github.com/rtr7/kernel \
	-firmware_package=github.com/rtr7/kernel \
	-gokrazy_pkgs=github.com/gokrazy/gokrazy/cmd/ntp \
	-serial_console=ttyS0,115200n8 \
	github.com/rtr7/router7/cmd/...

Run rtr7-recover -boot=/tmp/recovery/boot.img -mbr=/tmp/recovery/mbr.img -root=/tmp/recovery/root.img to:

trigger a reset if a Teensy with the rebootor firmware is attached
serve a DHCP lease to all clients which request PXE boot (i.e., your apu2c4)
serve via TFTP:
- the PXELINUX bootloader
- the router7 kernel
- an initrd archive containing the rtr7-recovery-init program and mke2fs
serve via HTTP the boot and root images
optionally serve via HTTP a backup.tar.gz image containing files for /perm (e.g. for moving to new hardware, rolling back corrupted state, or recovering from a disk failure)
exit once the router successfully wrote the images to disk

Updates

Run e.g. rtr7-safe-update -updates_dir=$HOME/router7/updates to:

verify the router currently has connectivity, abort the update otherwise
download a backup archive of /perm
build a new image
update the router
wait until the router restored connectivity, roll back the update using rtr7-recover otherwise

The update step uses kexec to reduce the downtime to approximately 15 seconds.

Manual Recovery

Given rtr7-safe-update’s safeguards, manual recovery should rarely be required.

To manually roll back to an older image, invoke rtr7-safe-update via the recover.bash script in the image directory underneath -updates_dir, e.g.:

% cd ~/router7/updates/2018-07-03T17:33:52+02:00
% ./recover.bash

Teensy rebootor

The cheap and widely-available Teensy++ USB development board comes with a firmware called rebootor, which is used by the teensy_loader_cli program to perform hard resets.

This setup can be used to programmatically reset the apu2c4 (from rtr7-recover) by connecting the Teensy++ to the apu2c4’s reset pins:

connect the Teensy++’s GND pin to the apu2c4 J2’s pin 4 (GND)
connect the Teensy++’s B7 pin to the apu2c4 J2’s pin 5 (3.3V, resets when pulled to GND)

You can find a working rebootor firmware .hex file at https://github.com/PaulStoffregen/teensy_loader_cli/issues/38

Prometheus

See https://github.com/rtr7/router7/tree/master/contrib/prometheus for example configuration files, and install the router7 Grafana Dashboard.