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Version: v1.0.1 (stable)

Validators

Nym validators secure the network with a staking token, defending the network from Sybil attacks.

Validators also provide privacy-enhanced credentials based on the testimony of a set of decentralized, blockchain-based issuing authorities. Nym validators use a signature scheme called Coconut to issue credentials. This allows privacy apps to generate anonymous resource claims through decentralised authorities, then use them with Service Providers.

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 the Nym validator​

Prerequisites​

  • git
sudo apt update
sudo apt install git

Verify git is installed with:

git version
# Should return: git version X.Y.Z
  • 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/go1.17.5.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: go version go1.17.5 linux/amd64
  • gcc

gcc can be installed with:

sudo apt install build-essential
# Optional additional manual pages can be installed with:
sudo apt-get install manpages-dev

Verify gcc is installed with:

gcc --version

Which should return something like:

gcc (Ubuntu 7.4.0-1ubuntu1~18.04) 7.4.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Building your validator​

We use the wasmd version of the Cosmos validator to run our blockchain. First define the correct variables by selecting the correct network below, as the instructions, files, and endpoints differ in the instructions from here on in:

BECH32_PREFIX=nymt
WASMD_VERSION=v0.21.0
NYM_APP_NAME=nymd

Then run this to clone, compile, and build your validator:

git clone https://github.com/CosmWasm/wasmd.git
cd wasmd
git checkout ${WASMD_VERSION}
mkdir build
go build -o ./build/${NYM_APP_NAME} -mod=readonly -tags "netgo,ledger" -ldflags "-X github.com/cosmos/cosmos-sdk/version.Name=${NYM_APP_NAME} -X github.com/cosmos/cosmos-sdk/version.AppName=${NYM_APP_NAME} -X github.com/CosmWasm/wasmd/app.NodeDir=.${NYM_APP_NAME} -X github.com/cosmos/cosmos-sdk/version.Version=${WASMD_VERSION} -X github.com/cosmos/cosmos-sdk/version.Commit=dc5ef6fe84f0a5e3b0894692a18cc48fb5b00adf -X github.com/CosmWasm/wasmd/app.Bech32Prefix=${BECH32_PREFIX} -X \"github.com/cosmos/cosmos-sdk/version.BuildTags=netgo,ledger\"" -trimpath ./cmd/wasmd

At this point, you will have a copy of the nymd (for sandbox) or nyxd (for mainnet) binary in your build/ directory. Test that it's compiled properly by running:

./build/${NYM_APP_NAME}

You should see help text print out.

Both the nymd or 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.

caution

If you have compiled these files locally you need to upload both of them to the server on which the validator will run. If you have instead compiled them on the server skip to the step outlining setting LD_LIBRARY PATH below.

To locate these files on your local system run:

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

This will output something like:

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

When you upload your nymd/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 nymd/nyxd already has access to libwasmvm.so.

Upload both nymd/nyxd and libwasmvm.so to your validator machine. If nymd/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 nymd 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/nym/binaries
# 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:

nymd

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 yourname in the following command:

nymd init YOUR_NAME --chain-id=nym-sandbox
caution

init generates priv_validator_key.json and node_key.json.

If you have already set up a validator on a previous testnet, make sure to back up the key located at ~/.nymd/config/priv_validator_key.json.

If you don't save the validator key, then it can't sign blocks and will be jailed all the time, and there is no way to deterministically (re)generate this key.

At this point, you have a new validator, with its own genesis file located at $HOME/.nymd/config/genesis.json. You will need to replace the contents of that file that with the Sandbox Testnet genesis file. You can use the following command to download the one for the Sandbox testnet:
wget  -O $HOME/.nymd/config/genesis.json https://nymtech.net/testnets/sandbox/genesis.json

config.toml configuration​

Add the Nym validator as a persistent peer so that your validator can start pulling blocks from the rest of the network, by editing the following config options in $HOME/.nymd/config/config.toml to match the information below:
cors_allowed_origins = ["*"]
persistent_peers = "d24ee58d85a65d34ad5adfc3302c3614b36e8b14@sandbox-validator.nymtech.net:26656"
create_empty_blocks = false
laddr = "tcp://0.0.0.0:26656"

These affect the following:

  • cors_allowed_origins = ["*"] allows the wallet to make HTTPS requests to your validator.
  • persistent_peers = "<PEER_ADDRESS>@<DOMAIN>.nymtech.net:26656" allows your validator to start pulling blocks from other validators
  • 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"
tip

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 $HOME/.${NYM_APP_NAME}/config/app.toml, set the following values:

minimum-gas-prices = "0.025unymt"
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:

nymd keys add nymd-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:

nymd keys show nymd-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:

nymd 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:

nymd 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.

If you are having trouble upgrading your validator binary, try replacing (or re-compile) the libwasmvm.so file and replace it on your validator server.

warning

When joining consensus, make sure that you do not disrupt (or worse - halt) the network by coming in with a disproportionately large amount of staked tokens.

Please initially stake a small amount of tokens compared to existing validators, then delegate to yourself in tranches over time.

nymd tx staking create-validator --amount=10000000unyxt --fees=5000unyxt --pubkey=$(/home/youruser/path/to/nym/binaries/nymd tendermint show-validator) --moniker="whatever you called your validator" --chain-id=nym-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="KEYCHAIN NAME" --node https://sandbox-validator.nymtech.net:443

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

Note: 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:

nymd tx staking edit-validator --chain-id=nym-sandbox --moniker="whatever you called your validator" --details="Nym validator" --security-contact="your email" --identity="your identity" --gas="auto" --gas-adjustment=1.15 --from="KEYCHAIN 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=Nymd (1.0.0-rc.1)
StartLimitInterval=350
StartLimitBurst=10

[Service]
User=nym # change to your user
Type=simple
Environment="LD_LIBRARY_PATH=/home/youruser/path/to/nym/binaries" # change to correct path
ExecStart=/home/youruser/path/to/nym/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
β”œβ”€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 }}";

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
caution

If using a VPS running Ubuntu 20: replace certbot nginx python3 with python3-certbot-nginx

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', and look something like this:

# 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.

Unjailing your validator​

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

nymd tx slashing unjail --broadcast-mode=block --from="KEYCHAIN NAME" --chain-id=nym-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!

nymd tx staking delegate VALOPERADDRESS AMOUNTunymt --from="KEYCHAIN NAME" --keyring-backend=os --chain-id=nym-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.

Default portUse
1317REST API server endpoint
26656Listen for incoming peer connections
26660Listen for Prometheus connections