Validators

The validator is built using Cosmos SDK and Tendermint, with a CosmWasm smart contract controlling the directory service, node bonding, and delegated mixnet staking.

Building your validator

Prerequisites

git, gcc, jq

• Debian-based systems:

apt install git build-essential jq

# optional additional manual pages can be installed with:
apt-get install manpages-dev

• Arch-based systems: Install git, gcc and jq with the following:

pacman -S git gcc jq

Go

Go can be installed via the following commands (taken from the Agoric SDK docs):

# First remove any existing old Go installation
sudo rm -rf /usr/local/go

# Install correct Go version
curl https://dl.google.com/go/go1.20.4.linux-amd64.tar.gz | sudo tar -C/usr/local -zxvf -

# Update environment variables to include go
cat <<'EOF' >>$HOME/.profile
export GOROOT=/usr/local/go
export GOPATH=$HOME/go
export GO111MODULE=on
export PATH=$PATH:/usr/local/go/bin:$HOME/go/bin
EOF
source $HOME/.profile

Verify Go is installed with:

go version
# Should return something like:
go version go1.20.4 linux/amd64

Download a precompiled validator binary

You can find pre-compiled binaries for Ubuntu 22.04 and 20.04 here.

Manually compiling your validator binary

The codebase for the Nyx validators can be found here.

The validator binary can be compiled by running the following commands:

git clone https://github.com/nymtech/nyxd.git
cd nyxd

# Mainnet
make build

# Sandbox testnet
BECH32_PREFIX=nymt make build

At this point, you will have a copy of the nyxd binary in your build/ directory. Test that it’s compiled properly by running:

./build/nyxd

You should see help text print out.

The nyxd binary and the libwasmvm.so shared object library binary have been compiled. libwasmvm.so is the wasm virtual machine which is needed to execute smart contracts.

To locate these files on your system if you downloaded a pre-compiled binary from Github run:

WASMVM_SO=$(ldd path/to/nyxd/binary | grep libwasmvm.so | awk '{ print $3 }')
ls ${WASMVM_SO}

e.g. if you downloaded your nyxd binary to /root then you would replace ldd path/to/nyxd/binary with ldd nyxd in the above command.

To locate these files on your system if you uploaded your validator after compiling it on a local machine run:

WASMVM_SO=$(ldd build/nyxd | grep libwasmvm.so | awk '{ print $3 }')
ls ${WASMVM_SO}

The above commands will output something like:

'/home/username/go/pkg/mod/github.com/!cosm!wasm/wasmvm@v0.13.0/api/libwasmvm.so'

When you upload your nyxd binary, you’ll need to tell it where libwasmvm.so is when you start your validator, or it will not run. If you have compiled them on your server then this is not necessary, as the compiled nyxd already has access to libwasmvm.so.

Upload both nyxd and libwasmvm.so to your validator machine. If nyxd can’t find libwasmvm.so you will see an error like the following:

./nyxd: error while loading shared libraries: libwasmvm.so: cannot open shared object file: No such file or directory

You’ll need to set LD_LIBRARY_PATH in your user’s ~/.bashrc file, and add that to our path. Replace /home/youruser/path/to/nym/binaries in the command below to the locations of nyxd and libwasmvm.so and run it. If you have compiled these on the server, they will be in the build/ folder:

NYX_BINARIES=/home/youruser/path/to/validator/binary

# if you are using another shell like zsh replace '.bashrc' with the relevant config file
echo 'export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:'NYX_BINARIES >> ~/.bashrc
echo 'export PATH=$PATH:'${NYX_BINARIES} >> ~/.bashrc
source ~/.bashrc

Test everything worked:

nyxd

This should return the regular help text.

Initialising your validator

Prerequisites:

• FQDN Domain name
• IPv4 and IPv6 connectivity

Choose a name for your validator and use it in place of <ID> in the following command:

# Mainnet
nyxd init <ID> --chain-id=nyx

# Sandbox testnet
nyxd init <ID> --chain-id=sandbox

At this point, you have a new validator, with its own genesis file located at $HOME/.nyxd/config/genesis.json. You will need to replace the contents of that file that with either the Nyx Mainnet or Sandbox Testnet genesis file.

You can use the following command to download them for the correct network:

# Mainnet
wget  -O $HOME/.nyxd/config/genesis.json https://nymtech.net/genesis/genesis.json

# Sandbox testnet
wget -O $HOME/.nyxd/config/genesis.json https://sandbox-validator1.nymtech.net/snapshots/genesis.json

config.toml configuration

Edit the following config options in $HOME/.nyxd/config/config.toml to match the information below for your network:

# Mainnet
persistent_peers = "ee03a6777fb76a2efd0106c3769daaa064a3fcb5@51.79.21.187:26656"
create_empty_blocks = false
laddr = "tcp://0.0.0.0:26656"

# Sandbox testnet
cors_allowed_origins = ["*"]
persistent_peers = "8421c0a3d90d490e27e8061f2abcb1276c8358b6@sandbox-validator1.nymtech.net:26666"
create_empty_blocks = false
laddr = "tcp://0.0.0.0:26656"

These affect the following:

• persistent_peers = "<PEER_ADDRESS>@<DOMAIN>.nymtech.net:26666" allows your validator to start pulling blocks from other validators. The main sandbox validator listens on 26666 instead of the default 26656 for debugging. It is recommended you do not change your port from 26656.
• create_empty_blocks = false will save space
• laddr = "tcp://0.0.0.0:26656" is in your p2p configuration options

Optionally, if you want to enable Prometheus metrics then the following must also match in the config.toml:

• prometheus = true
• prometheus_listen_addr = ":26660"

Remember to enable metrics in the ‘Configuring Prometheus metrics’ section below as well.

And if you wish to add a human-readable moniker to your node:

• moniker = "yourname"

Finally, if you plan on using Cockpit on your server, change the grpc port from 9090 as this is the port used by Cockpit.

app.toml configuration

In the file $HOME/nyxd/config/app.toml, set the following values:

# Mainnet
minimum-gas-prices = "0.025unym,0.025unyx"
enable = true in the `[api]` section to get the API server running

# Sandbox Testnet
minimum-gas-prices = "0.025unymt,0.025unyxt"
enable = true` in the `[api]` section to get the API server running

Setting up your validator’s admin user

You’ll need an admin account to be in charge of your validator. Set that up with:

nyxd keys add nyxd-admin

This will add keys for your administrator account to your system’s keychain and log your name, address, public key, and mnemonic. As the instructions say, remember to write down your mnemonic.

You can get the admin account’s address with:

nyxd keys show nyxd-admin -a

Type in your keychain password, not the mnemonic, when asked.

Starting your validator

Everything should now be ready to go. You’ve got the validator set up, all changes made in config.toml and app.toml, the Nym genesis file copied into place (replacing the initial auto-generated one). Now let’s validate the whole setup:

nyxd validate-genesis

If this check passes, you should receive the following output:

File at /path/to/genesis.json is a valid genesis file

If this test did not pass, check that you have replaced the contents of /path/to/.nymd/config/genesis.json with that of the correct genesis file.

Before starting the validator, we will need to open the firewall ports:

# if ufw is not already installed:
sudo apt install ufw
sudo ufw enable
sudo ufw allow 1317,26656,26660,22,80,443/tcp
# to check everything worked
sudo ufw status

Ports 22, 80, and 443 are for ssh, http, and https connections respectively. The rest of the ports are documented here.

For more information about your validator’s port configuration, check the validator port reference table below.

If you are planning to use Cockpit on your validator server then you will have defined a different grpc port in your config.toml above: remember to open this port as well.

Start the validator:

nyxd start

Once your validator starts, it will start requesting blocks from other validators. This may take several hours. Once it’s up to date, you can issue a request to join the validator set with the command below.

Syncing from a snapshot

If you wish to sync from a snapshot on mainnet use Polkachu’s mainnet resources.

If you wish to sync from a snapshot on Sandbox testnet use the below commands, which are a modified version of Polkachu’s excellent resources. These commands assume you are running an OS with apt as the package manager:

# install lz4 if necessary
sudo apt install snapd -y
sudo snap install lz4

# download the snapshot
wget -O nyxd-sandbox-snapshot-data.tar.lz4 https://sandbox-validator1.nymtech.net/snapshots/nyxd-sandbox-snapshot-data.tar.lz4

# reset your validator state
nyxd tendermint unsafe-reset-all

# unpack the snapshot
lz4 -c -d nyxd-sandbox-snapshot-data.tar.lz4 | tar -x -C $HOME/.nyxd

You can then restart nyxd - it should start syncing from a block > 2000000.

Joining Consensus

Once your validator has synced and you have received tokens, you can join consensus and produce blocks.

# Mainnet
nyxd tx staking create-validator
  --amount=10000000unyx
  --fees=0unyx
  --pubkey=$(/home/youruser/path/to/nyxd/binaries/nyxd tendermint show-validator)
  --moniker="whatever you called your validator"
  --chain-id=nyx
  --commission-rate="0.10"
  --commission-max-rate="0.20"
  --commission-max-change-rate="0.01"
  --min-self-delegation="1"
  --gas="auto"
  --gas-adjustment=1.15
  --from="KEYRING_NAME"
  --node https://rpc-1.nyx.nodes.guru:443

# Sandbox Testnet
nyxd tx staking create-validator
  --amount=10000000unyxt
  --fees=5000unyxt
  --pubkey=$(/home/youruser/path/to/nym/binaries/nyxd tendermint show-validator)
  --moniker="whatever you called your validator"
  --chain-id=sandbox
  --commission-rate="0.10"
  --commission-max-rate="0.20"
  --commission-max-change-rate="0.01"
  --min-self-delegation="1"
  --gas="auto"
  --gas-adjustment=1.15
  --from="KEYRING_NAME"
  --node https://sandbox-validator1.nymtech.net:443

You’ll need either unyxt tokens on Sandbox, or unyx tokens on mainnet to perform this command.

We are currently working towards building up a closed set of reputable validators. You can ask us for coins to get in, but please don’t be offended if we say no - validators are part of our system’s core security and we are starting out with people we already know or who have a solid reputation.

If you want to edit some details for your node you will use a command like this:

# Mainnet
nyxd tx staking edit-validator
  --chain-id=nyx
  --moniker="whatever you called your validator"
  --details="Nyx validator"
  --security-contact="your email"
  --identity="your identity"
  --gas="auto"
  --gas-adjustment=1.15
  --from="KEYRING_NAME"
  --fees 2000unyx

# Sandbox testnet
nyxd tx staking edit-validator
  --chain-id=sandbox
  --moniker="whatever you called your validator"
  --details="Sandbox testnet validator"
  --security-contact="your email"
  --identity="your identity"
  --gas="auto"
  --gas-adjustment=1.15
  --from="KEYRING_NAME"
  --fees 2000unyxt

With above command you can specify the gpg key last numbers (as used in keybase) as well as validator details and your email for security contact.

Automating your validator with systemd

You will most likely want to automate your validator restarting if your server reboots. Below is a systemd unit file to place at /etc/systemd/system/nymd.service:

[Unit]
Description=Nyxd
StartLimitInterval=350
StartLimitBurst=10

[Service]
User=nyx                                                          # change to your user
Type=simple
Environment="LD_LIBRARY_PATH=/home/youruser/path/to/nyx/binaries" # change to correct path
ExecStart=/home/youruser/path/to/nyx/binaries/nymd start          # change to correct path
Restart=on-failure
RestartSec=30
LimitNOFILE=infinity

[Install]
WantedBy=multi-user.target

Proceed to start it with:

systemctl daemon-reload # to pickup the new unit file
systemctl enable nymd   # to enable the service
systemctl start nymd    # to actually start the service
journalctl -f           # to monitor system logs showing the service start

Installing and configuring nginx for HTTPS

Setup

Nginx is an open source software used for operating high-performance web servers. It allows us to set up reverse proxying on our validator server to improve performance and security.

Install nginx and allow the ‘Nginx Full’ rule in your firewall:

sudo ufw allow 'Nginx Full'

Check nginx is running via systemctl:

systemctl status nginx

Which should return:

● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2018-04-20 16:08:19 UTC; 3 days ago
     Docs: man:nginx(8)
 Main PID: 2369 (nginx)
    Tasks: 2 (limit: 1153)
   CGroup: /system.slice/nginx.service
           ├─2369 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
           └─2380 nginx: worker process

Configuration

Proxying your validator’s port 26657 to nginx port 80 can then be done by creating a file with the following at /etc/nginx/conf.d/validator.conf:

server {
  listen 80;
  listen [::]:80;
  server_name "domain_name";

  location / {
    proxy_pass http://127.0.0.1:26657;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}

Followed by:

sudo apt install certbot nginx python3
certbot --nginx -d nym-validator.yourdomain.com -m you@yourdomain.com --agree-tos --noninteractive --redirect

These commands will get you an https encrypted nginx proxy in front of the API.

Configuring Prometheus metrics (optional)

Configure Prometheus with the following commands (adapted from NodesGuru’s Agoric setup guide):

echo 'export OTEL_EXPORTER_PROMETHEUS_PORT=9464' >> $HOME/.bashrc
source ~/.bashrc
sed -i '/\[telemetry\]/{:a;n;/enabled/s/false/true/;Ta}' $HOME/.nymd/config/app.toml
sed -i "s/prometheus-retention-time = 0/prometheus-retention-time = 60/g" $HOME/.nymd/config/app.toml
sudo ufw allow 9464
echo 'Metrics URL: http://'$(curl -s ifconfig.me)':26660/metrics'

Your validator’s metrics will be available to you at the returned ‘Metrics URL’.

# HELP go_gc_duration_seconds A summary of the pause duration of garbage collection cycles.
# TYPE go_gc_duration_seconds summary
go_gc_duration_seconds{quantile="0"} 6.7969e-05
go_gc_duration_seconds{quantile="0.25"} 7.864e-05
go_gc_duration_seconds{quantile="0.5"} 8.4591e-05
go_gc_duration_seconds{quantile="0.75"} 0.000115919
go_gc_duration_seconds{quantile="1"} 0.001137591
go_gc_duration_seconds_sum 0.356555301
go_gc_duration_seconds_count 2448
# HELP go_goroutines Number of goroutines that currently exist.
# TYPE go_goroutines gauge
go_goroutines 668
# HELP go_info Information about the Go environment.
# TYPE go_info gauge
go_info{version="go1.15.7"} 1
# HELP go_memstats_alloc_bytes Number of bytes allocated and still in use.
# TYPE go_memstats_alloc_bytes gauge
go_memstats_alloc_bytes 1.62622216e+08
# HELP go_memstats_alloc_bytes_total Total number of bytes allocated, even if freed.
# TYPE go_memstats_alloc_bytes_total counter
go_memstats_alloc_bytes_total 2.09341707264e+11
# HELP go_memstats_buck_hash_sys_bytes Number of bytes used by the profiling bucket hash table.
# TYPE go_memstats_buck_hash_sys_bytes gauge
go_memstats_buck_hash_sys_bytes 5.612319e+06
# HELP go_memstats_frees_total Total number of frees.
# TYPE go_memstats_frees_total counter
go_memstats_frees_total 2.828263344e+09
# HELP go_memstats_gc_cpu_fraction The fraction of this program's available CPU time used by the GC since the program started.
# TYPE go_memstats_gc_cpu_fraction gauge
go_memstats_gc_cpu_fraction 0.03357798610671518
# HELP go_memstats_gc_sys_bytes Number of bytes used for garbage collection system metadata.
# TYPE go_memstats_gc_sys_bytes gauge
go_memstats_gc_sys_bytes 1.3884192e+07

Setting the ulimit

Linux machines limit how many open files a user is allowed to have. This is called a ulimit.

ulimit is 1024 by default on most systems. It needs to be set higher, because validators make and receive a lot of connections to other nodes.

If you see errors such as:

Failed to accept incoming connection - Os { code: 24, kind: Other, message: "Too many open files" }

This means that the operating system is preventing network connections from being made.

Set the ulimit via systemd service file

Query the ulimit of your validator with:

grep -i "open files" /proc/$(ps -A -o pid,cmd|grep nymd | grep -v grep |head -n 1 | awk '{print $1}')/limits

You’ll get back the hard and soft limits, which looks something like this:

Max open files            65536                65536                files

If your output is the same as above, your node will not encounter any ulimit related issues.

However if either value is 1024, you must raise the limit via the systemd service file. Add the line:

LimitNOFILE=65536

Reload the daemon:

systemctl daemon-reload

or execute this as root for system-wide setting of ulimit:

echo "DefaultLimitNOFILE=65535" >> /etc/systemd/system.conf

Reboot your machine and restart your node. When it comes back, use cat /proc/$(pidof nym-validator)/limits | grep "Max open files" to make sure the limit has changed to 65535.

Set the ulimit on non-systemd based distributions

Edit etc/security/conf and add the following lines:

# Example hard limit for max opened files
username        hard nofile 4096
# Example soft limit for max opened files
username        soft nofile 4096

Then reboot your server and restart your validator.

Using your validator

Unjailing your validator

If your validator gets jailed, you can fix it with the following command:

# Mainnet
nyxd tx slashing unjail
  --broadcast-mode=block
  --from="KEYRING_NAME"
  --chain-id=nyx
  --gas=auto
  --gas-adjustment=1.4
  --fees=7000unyx

# Sandbox Testnet
nyxd tx slashing unjail
  --broadcast-mode=block
  --from="KEYRING_NAME"
  --chain-id=sandbox
  --gas=auto
  --gas-adjustment=1.4
  --fees=7000unyxt

Common reasons for your validator being jailed

The most common reason for your validator being jailed is that your validator is out of memory because of bloated syslogs.

Running the command df -H will return the size of the various partitions of your VPS.

If the /dev/sda partition is almost full, try pruning some of the .gz syslog archives and restart your validator process.

Day 2 operations with your validator

You can check your current balances with:

nymd query bank balances ${ADDRESS}

For example, on the Sanbox testnet this would return:

balances:
- amount: "919376"
denom: unymt
pagination:
next_key: null
total: "0"

You can, of course, stake back the available balance to your validator with the following command.

Remember to save some tokens for gas costs!

# Mainnet
nyxd tx staking delegate VALOPERADDRESS AMOUNTunym
  --from="KEYRING_NAME"
  --keyring-backend=os
  --chain-id=nyx
  --gas="auto"
  --gas-adjustment=1.15
  --fees 5000unyx

# Sandbox Testnet
nyxd tx staking delegate VALOPERADDRESS AMOUNTunymt
  --from="KEYRING_NAME"
  --keyring-backend=os
  --chain-id=sandbox
  --gas="auto"
  --gas-adjustment=1.15
  --fees 5000unyxt

Validator port reference

All validator-specific port configuration can be found in $HOME/.nymd/config/config.toml. If you do edit any port configs, remember to restart your validator.