<p>Connect your serial adapter (<ahref="https://pcengines.ch/usbcom1a.htm">usbcom1a</a> works well if you don’t have one already) to the apu2c4 and start a program to use it, e.g. <code>screen /dev/ttyUSB0 115200</code>. Then, power on the apu2c4 and configure it to do PXE boot:</p>
<ul>
<li>Press <code>F10</code> to enter the boot menu</li>
<li>Press <code>3</code> to enter setup</li>
<li>Press <code>n</code> to enable network boot</li>
<li>Press <code>c</code> to move mSATA to the top of the boot order</li>
<li>Press <code>e</code> to move iPXE to the top of the boot order</li>
<li>Press <code>s</code> to save configuration and exit</li>
</ul>
<p>Connect a network cable on <code>net0</code>, the port closest to the serial console port:</p>
<divclass="highlight"><prestyle="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><codeclass="language-shell"data-lang="shell">go get -u github.com/gokrazy/tools/cmd/gokr-packer github.com/rtr7/tools/cmd/...
<li>trigger a reset <ahref="#rebootor">if a Teensy with the rebootor firmware is attached</a></li>
<li>serve a DHCP lease to all clients which request PXE boot (i.e., your apu2c4)</li>
<li>serve via TFTP:
<ul>
<li>the PXELINUX bootloader</li>
<li>the router7 kernel</li>
<li>an initrd archive containing the rtr7-recovery-init program and mke2fs</li>
</ul>
</li>
<li>serve via HTTP the boot and root images</li>
<li>optionally serve via HTTP a backup.tar.gz image containing files for <code>/perm</code> (e.g. for moving to new hardware, rolling back corrupted state, or recovering from a disk failure)</li>
<li>exit once the router successfully wrote the images to disk</li>
</ul>
<h2id="updates">Updates</h2>
<p>Run e.g. <code>rtr7-safe-update -updates_dir=$HOME/router7/updates</code> to:</p>
<ul>
<li>verify the router currently has connectivity, abort the update otherwise</li>
<li>download a backup archive of <code>/perm</code></li>
<li>build a new image</li>
<li>update the router</li>
<li>wait until the router restored connectivity, roll back the update using <code>rtr7-recover</code> otherwise</li>
</ul>
<p>The update step uses kexec to reduce the downtime to approximately 15 seconds.</p>
<h2id="manual-recovery">Manual Recovery</h2>
<p>Given <code>rtr7-safe-update</code>’s safeguards, manual recovery should rarely be required.</p>
<p>To manually roll back to an older image, invoke <code>rtr7-safe-update</code> via the
<code>recover.bash</code> script in the image directory underneath <code>-updates_dir</code>, e.g.:</p>
<divclass="highlight"><prestyle="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><codeclass="language-shell"data-lang="shell">% cd ~/router7/updates/2018-07-03T17:33:52+02:00
<p>The cheap and widely-available <ahref="https://www.pjrc.com/store/teensypp.html">Teensy++ USB development board</a> comes with a firmware called rebootor, which is used by the <ahref="https://www.pjrc.com/teensy/loader_cli.html"><code>teensy_loader_cli</code></a> program to perform hard resets.</p>
<p>This setup can be used to programmatically reset the apu2c4 (from <code>rtr7-recover</code>) by connecting the Teensy++ to the <ahref="http://pcengines.ch/pdf/apu2.pdf">apu2c4’s reset pins</a>:</p>
<ul>
<li>connect the Teensy++’s <code>GND</code> pin to the apu2c4 J2’s pin 4 (<code>GND</code>)</li>
<li>connect the Teensy++’s <code>B7</code> pin to the apu2c4 J2’s pin 5 (<code>3.3V</code>, resets when pulled to <code>GND</code>)</li>
</ul>
<p>You can find a working rebootor firmware .hex file at <ahref="https://github.com/PaulStoffregen/teensy_loader_cli/issues/38">https://github.com/PaulStoffregen/teensy_loader_cli/issues/38</a></p>
<h2id="prometheus">Prometheus</h2>
<p>See <ahref="https://github.com/rtr7/router7/tree/master/contrib/prometheus">https://github.com/rtr7/router7/tree/master/contrib/prometheus</a> for example
configuration files, and install the <ahref="https://grafana.com/dashboards/8288">router7 Grafana
