Michal Čihař - Running Bitcoin node on Turris Omnia

Running Bitcoin node on Turris Omnia

For quite some I'm happy user of Turris Omnia router. The router has quite good hardware, so I've decided to try if I can run Bitcoin node on that and ElectrumX server.

To make the things easier to manage, I've decided to use LXC and run all these in separate container. First of all you need LXC on the router. This is the default setup, but in case you've removed it, you can add it back in the Updater settings.

Now we will create Debian container. There is basic information on using in Turris Documentation on how to create the container, in latter documentation I assume it is called debian.

It's also good idea to enable LXC autostart, to do so add your container to cat /etc/config/lxc-auto on :

config container
    option name debian

You might also want to edit lxc container configration to enable clean shutdown:

# Send SIGRTMIN+3 to shutdown systemd (37 on Turris Omnia)
lxc.haltsignal = SIGRTMIN+3

To make the system more recent, I've decided to use Debian Stretch (one of reasons was that ElectrumX needs Python 3.5.3 or newer). Which is anyway probably sane choice right now given that it's already frozen and will be soon stable. As Stretch is not available as a download option in Omnia, I've chosen to use Debian Jessie and upgrate it later:

$ lxc-attach  --name debian
$ sed -i s/jessie/stretch/ /etc/apt/sources.list
$ apt update
$ apt full-upgrade

Now you have up to date system and we can start installing dependencies. First thing to install is Bitcoin Core. Just follow the instructions on their website to do that. Now it's time to set it up and wait for downloading full blockchain:

$ adduser bitcoin
$ su - bitcoin
$ bitcoind -daemon

Depending on your connection speed, the download will take few hours. You can monitor the progress using bitcoin-cli, you're waiting for 450k blocks:

$ bitcoin-cli getinfo
{
  "version": 140000,
  "protocolversion": 70015,
  "walletversion": 130000,
  "balance": 0.00000000,
  "blocks": 301242,
  "timeoffset": -1,
  "connections": 8,
  "proxy": "",
  "difficulty": 8853416309.1278,
  "testnet": false,
  "keypoololdest": 1490267950,
  "keypoolsize": 100,
  "paytxfee": 0.00000000,
  "relayfee": 0.00001000,
  "errors": ""
}

Depending how much memory you have (mine has 2G) and what all you run on the router, you will have to tweak bitcoind configuration to consume less memory. This can be done by editing .bitcoin/bitcoin.conf, I've ended up with following settings:

par=1
dbcache=150
maxmempool=150

You can also create startup unit for Bitcoin daemon (place that as /etc/systemd/system/bitcoind.service):

[Unit]
Description=Bitcoind
After=network.target

[Service]
ExecStart=/opt/bitcoin/bin/bitcoind
User=bitcoin
TimeoutStopSec=30min
Restart=on-failure
RestartSec=30

[Install]
WantedBy=multi-user.target

Now we can enable services to start on container start:

systemctl enable bitcoind.service

Then I wanted to setup ElectrumX as well, but I've quickly realized that it uses way more memory that my router has, so there is no option to run it without using swap, what will probably make it quite slow (I haven't tried that).