Fulcrum on a RaspiBlitz

• FAQ
  • Do I need to stop Electrs?
  • Database corrupted
• Automated setup
• Manual setup
  • Prepare bitcoind
  • Prepare the system and directories
  • Create a config file
  • Create a systemd service
  • Start
  • Monitor
  • Open the firewall
  • Set up SSL
  • Create a Tor .onion service
  • Remove the Fulcrum user and installation (not the database)
• Docker setup
  • Generate TLS credentials
  • Start the image
  • Docker compose snippet
• Sources:

This is a rough overview, the guide is a work in progress.

Tested environments:

• Raspberry Pi4 8GB 64bit RaspberryOS with SSD and ZRAM
  First sync took 48h. Can expect 2 - 2.5 days.

• Raspberry Pi4 4GB 64bit RaspberryOS with SSD and 10GB ZRAM
  First sync took 3 days.

• See RPi-specific settings under heading “Create a config file”.

  FAQ

  Do I need to stop Electrs?

• Don’t really need to, Electrs (and also Fulcrum) are very light once synched. Chugging through the 450GB transaction history poses the challenge for the RPi. Best is to stop all services you don’t use, but testing is valuable in any circumstance.

  Database corrupted

• Received an error like:

  FATAL: Caught exception: It appears that Fulcrum was forcefully killed in the middle of committing a block to the db.
  We cannot figure out where exactly in the update process Fulcrum was killed, so we cannot undo the inconsistent state caused by the unexpected shutdown. Sorry!
  The database has been corrupted. Please delete the datadir and resynch to bitcoind.
  

• Delete the database and restart Fulcrum to start the sync from scratch

  sudo rm -rf /mnt/hdd/app-storage/fulcrum/db
  sudo systemctl restart fulcrum
  

Automated setup

• Issue: https://github.com/rootzoll/raspiblitz/issues/2924
• PR: https://github.com/rootzoll/raspiblitz/pull/2966
• Install script https://github.com/rootzoll/raspiblitz/blob/dev/home.admin/config.scripts/bonus.fulcrum.sh : ```

  download

  wget -O bonus.fulcrum.sh https://raw.githubusercontent.com/rootzoll/raspiblitz/dev/home.admin/config.scripts/bonus.fulcrum.sh

check

cat bonus.fulcrum.sh

run with debug

bash -x bonus.fulcrum.sh on

* if running RaspiBlitz v1.7.2 the script is part of the image:

config.scripts/bonus.fulcrum.sh on

## Manual setup

### Prepare bitcoind
* To avoid errors like

503 (content): Work queue depth exceeded

set in the `/mnt/hdd/bitcoin/bitcoin.conf`:

txindex=1 whitelist=download@127.0.0.1 rpcworkqueue=512 rpcthreads=128 zmqpubhashblock=tcp://0.0.0.0:8433

* Restart bitcoind

sudo systemctl bitcoind restart

* If the txindex was not built before WAIT until it finishes (takes ~7 hours).  
  Monitor the bitcoin `debug.log`).

sudo tail -n 100 -f /mnt/hdd/bitcoin/debug.log | grep txindex

### Prepare the system and directories

Create a dedicated user

sudo adduser –disabled-password –gecos “” fulcrum cd /home/fulcrum

sudo -u fulcrum git clone https://github.com/cculianu/Fulcrum

cd fulcrum

Install dependencies

sudo apt install -y libzmq3-dev

sudo apt install -y libssl-dev # was needed on Debian Bullseye

Set the platform

if [ $(uname -m) = “aarch64” ]; then build=”arm64-linux” elif [ $(uname -m) = “x86_64” ]; then build=”x86_64-linux-ub16” fi

Download the prebuilt binary

sudo -u fulcrum wget https://github.com/cculianu/Fulcrum/releases/download/v1.7.0/Fulcrum-1.7.0-${build}.tar.gz sudo -u fulcrum wget https://github.com/cculianu/Fulcrum/releases/download/v1.7.0/Fulcrum-1.7.0-${build}.tar.gz.asc sudo -u fulcrum wget https://github.com/cculianu/Fulcrum/releases/download/v1.7.0/Fulcrum-1.7.0-${build}.tar.gz.sha256sum

Verify

Get the PGP key

curl https://raw.githubusercontent.com/Electron-Cash/keys-n-hashes/master/pubkeys/calinkey.txt | sudo -u fulcrum gpg –import

Look for ‘Good signature’

sudo -u fulcrum gpg –verify Fulcrum-1.7.0-${build}.tar.gz.asc

Look for ‘OK’

sudo -u fulcrum sha256sum -c Fulcrum-1.7.0-${build}.tar.gz.sha256sum

Decompress

sudo -u fulcrum tar -xvf Fulcrum-1.7.0-${build}.tar.gz

Create the database directory in /mnt/hdd/app-storage (on the disk)

sudo mkdir -p /mnt/hdd/app-storage/fulcrum/db sudo chown -R fulcrum:fulcrum /mnt/hdd/app-storage/fulcrum

Create a symlink to /home/fulcrum/.fulcrum

sudo ln -s /mnt/hdd/app-storage/fulcrum /home/fulcrum/.fulcrum sudo chown -R fulcrum:fulcrum /home/fulcrum/.fulcrum

### Create a config file
* <https://github.com/cculianu/Fulcrum/blob/master/doc/fulcrum-example-config.conf>
* Can paste the this as a block to create the config file, but fill in the PASSWORD_B (Bitcoin Core RPC password):

PASSWORD_B=”your-password-here”

echo “
datadir = /home/fulcrum/.fulcrum/db bitcoind = 127.0.0.1:8332 rpcuser = ${RPC_USER} rpcpassword = ${PASSWORD_B}

RPi optimizations

avoid ‘bitcoind request timed out’

bitcoind_timeout = 300

reduce load (4 cores only)

bitcoind_clients = 1 worker_threads = 1 db_mem=1024

for 4GB RAM

db_max_open_files=200 fast-sync = 1024

server connections

disable peer discovery and public server options

peering = false announce = false tcp = 0.0.0.0:50021

ssl via nginx

” | sudo -u fulcrum tee /home/fulcrum/.fulcrum/fulcrum.conf

* The ports 50021 and 50022 are used to not interfere with a possible Electrs or ElectrumX instance.
* Note the different settings for 4 and 8 GB RAM
* Edit afterwards with `sudo nano /home/fulcrum/.fulcrum/fulcrum.conf`

### Create a systemd service
* Can paste this as a block to create the fulcrum.service file:

echo “
[Unit] Description=Fulcrum After=network.target bitcoind.service

[Service] ExecStart=/home/fulcrum/Fulcrum-1.7.0-${build}/Fulcrum /home/fulcrum/.fulcrum/fulcrum.conf User=fulcrum LimitNOFILE=8192 TimeoutStopSec=30min Restart=on-failure

[Install] WantedBy=multi-user.target “ | sudo tee /etc/systemd/system/fulcrum.service

### Start
* Depending on the available RAM it is a good idea to keep at least 10GB swap:
  <https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-debian-10>
  can consider ZRAM:  
  <https://haydenjames.io/raspberry-pi-performance-add-zram-kernel-parameters/>  
  <https://github.com/rootzoll/raspiblitz/issues/2905>

sudo systemctl enable fulcrum sudo systemctl start fulcrum

### Monitor

sudo journalctl -fu fulcrum sudo systemctl status fulcrum

### Open the firewall

sudo ufw allow 50021 comment ‘Fulcrum TCP’ sudo ufw allow 50022 comment ‘Fulcrum SSL’

### Set up SSL
* Paste this code as a block to make Fulcrum available on the port 50022 with SSL ncryption through Nginx

cd /home/fulcrum/.fulcrum

Create a self signed SSL certificate

sudo -u fulcrum openssl genrsa -out selfsigned.key 2048

echo “
[req] prompt = no default_bits = 2048 default_keyfile = selfsigned.key distinguished_name = req_distinguished_name req_extensions = req_ext x509_extensions = v3_ca

[req_distinguished_name] C = US ST = Texas L = Fulcrum O = RaspiBlitz CN = RaspiBlitz

[req_ext] subjectAltName = @alt_names

[v3_ca] subjectAltName = @alt_names

[alt_names] DNS.1 = localhost DNS.2 = 127.0.0.1 “ | sudo -u fulcrum tee localhost.conf

sudo -u fulcrum openssl req -new -x509 -sha256 -key selfsigned.key
-out selfsigned.cert -days 3650 -config localhost.conf

Setting up the nginx.conf

isConfigured=$(sudo cat /etc/nginx/nginx.conf 2>/dev/null | grep -c 'upstream fulcrum')
if [ ${isConfigured} -gt 0 ]; then
        echo "fulcrum is already configured with Nginx. To edit manually run \`sudo nano /etc/nginx/nginx.conf\`"

elif [ ${isConfigured} -eq 0 ]; then

        isStream=$(sudo cat /etc/nginx/nginx.conf 2>/dev/null | grep -c 'stream {')
        if [ ${isStream} -eq 0 ]; then

        echo " stream {
    upstream fulcrum {
            server 127.0.0.1:50021;
    }
    server {
            listen 50022 ssl;
            proxy_pass fulcrum;
            ssl_certificate /home/fulcrum/.fulcrum/selfsigned.cert;
            ssl_certificate_key /home/fulcrum/.fulcrum/selfsigned.key;
            ssl_session_cache shared:SSL-fulcrum:1m;
            ssl_session_timeout 4h;
            ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
            ssl_prefer_server_ciphers on;
    } }" | sudo tee -a /etc/nginx/nginx.conf

        elif [ ${isStream} -eq 1 ]; then
                sudo truncate -s-2 /etc/nginx/nginx.conf
                echo "
    upstream fulcrum {
            server 127.0.0.1:50021;
    }
    server {
            listen 50022 ssl;
            proxy_pass fulcrum;
            ssl_certificate /home/fulcrum/.fulcrum/selfsigned.cert;
            ssl_certificate_key /home/fulcrum/.fulcrum/selfsigned.key;
            ssl_session_cache shared:SSL-fulcrum:1m;
            ssl_session_timeout 4h;
            ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
            ssl_prefer_server_ciphers on;
    } }" | sudo tee -a /etc/nginx/nginx.conf

        elif [ ${isStream} -gt 1 ]; then
                echo " Too many \`stream\` commands in nginx.conf. Please edit manually: \`sudo nano /etc/nginx/nginx.conf\` and retry"
                exit 1
        fi
fi

Test nginx

sudo nginx -t

Restart nginx

sudo systemctl restart nginx

### Create a Tor .onion service
* On RaspiBlitz v1.7.2 run:

/home/admin/config.scripts/tor.onion-service.sh fulcrum 50021 50021 50022 50022

* Previous versions:

/home/admin/config.scripts/network.hiddenservice.sh fulcrum 50021 50021 50022 50022

* To set up manually see the guide [here](/bitcoin-tutorials/tor_hidden_service_example.html).

### Remove the Fulcrum user and installation (not the database)

sudo systemctl disable fulcrum sudo systemctl stop fulcrum sudo userdel -rf fulcrum

Remove Tor service

/home/admin/config.scripts/tor.onion-service.sh off electrs

Close ports on firewall

sudo ufw deny 50021 sudo ufw deny 50022

To remove the database directory

sudo rm -rf /mnt/hdd/app-storage/fulcrum/db

## Docker setup
The database persisted and serving on ports tcp: 50025, ssl: 50027.

Will mount the existing database from (can be any directory to sync new in < 10h on an SSD):

/mnt/hdd/hdd-snapshot-clone/app-storage/fulcrum/db

bitcoind is running on the localhost.

Adapted config in the `./fulcrum.conf`

bitcoind = 127.0.0.1:8332 rpcuser = RPCUSER rpcpassword = RPCPASSWORD bitcoind_timeout = 600 bitcoind_clients = 1 worker_threads = 1 db_mem=1024 db_max_open_files=200 fast-sync = 1024 peering = false announce = false tcp = 0.0.0.0:50025 ssl = 0.0.0.0:50027

### Generate TLS credentials

openssl req -newkey rsa:2048 -sha256 -nodes -x509 -days 3650 -subj “/O=Fulcrum” -keyout “tls.key” -out “tls.cert”

### Start the image
adapt the values as needed

docker image pull cculianu/fulcrum:latest docker run
–network=”host”
-p 50025:50025
-p 50027:50027
-v “$(pwd)”/fulcrum.conf:/fulcrum.conf
-v “$(pwd)”/tls.key:/tls.key
-v “$(pwd)”/tls.cert:/tls.cert
-v /mnt/hdd/hdd-snapshot-clone/app-storage/fulcrum/db:/db
-e DATA_DIR=/db
-e SSL_CERTFILE=/tls.cert
-e SSL_KEYFILE=/tls.key
openoms/fulcrum
Fulcrum /fulcrum.conf

### Docker compose snippet

fulcrum: image: cculianu/fulcrum:latest depends_on: [bitcoind] volumes: - ${PWD}/fulcrum.conf:/fulcrum.conf - ${PWD}/tls.key:/tls.key - ${PWD}/tls.cert:/tls.cert environment: - DATA_DIR=/db - SSL_CERTFILE=/tls.cert - SSL_KEYFILE=/tls.key command: [ “Fulcrum”, “/fulcrum.conf” ] ```

Sources:

• https://github.com/cculianu/Fulcrum
• https://sparrowwallet.com/docs/server-performance.html