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Cosmovisor

Cosmovisor is a tool that automatically restarts the Empowerchain daemon and replaces it with the new version when an upgrade height is hit. The official documentation for Cosmovisor can be found in the Cosmos SDK docs

Installation

Go must be installed on the system before cosmovisor may be installed.

bash
go install cosmossdk.io/tools/cosmovisor/cmd/cosmovisor@latest

Ensure cosmovisor is installed and ready to be used by checking its version.

bash
cosmovisor version

Usage

Once cosmovisor is installed, the initial directory structure for it needs to be created.

bash
mkdir -p $HOME/.empowerd/cosmovisor/genesis/bin
mkdir -p $HOME/.empowerd/cosmovisor/upgrades

Copy the initial empowerd binary into $HOME/.empowerd/cosmovisor/genesis/bin. This should be the very first version used on the chain if syncing from genesis. If syncing from a snapshot or state sync, use the latest version of the empowerd binary.

bash
cp $(which empowerd) $HOME/.empowerd/cosmovisor/genesis/bin/empowerd

Once the initial binary has been copied, the current file must be created to point to the active binary.

bash
ln -s $HOME/.empowerd/cosmovisor/genesis/bin/empowerd $HOME/.empowerd/cosmovisor/current

It is recommended to setup a systemd service to manage Cosmovisor. A full list of environment variables that may be used can be found in the Cosmovisor docs.

bash
sudo tee /etc/systemd/system/empowerd.service > /dev/null <<EOF
[Unit]
Description=cosmovisor
After=network-online.target

[Service]
User=<username>
ExecStart=/home/<your-user>/go/bin/cosmovisor run start
Restart=always
RestartSec=3
LimitNOFILE=4096
Environment="DAEMON_NAME=empowerd"
Environment="DAEMON_HOME=/home/<username>/.nolus"
Environment="DAEMON_ALLOW_DOWNLOAD_BINARIES=false"
Environment="DAEMON_RESTART_AFTER_UPGRADE=true"
Environment="UNSAFE_SKIP_BACKUP=true"

[Install]
WantedBy=multi-user.target
EOF

Once the empowerd.service file is created, it can be started and enabled on system startup with the following commands:

bash
sudo systemctl start empowerd.service
sudo systemctl enable empowerd.service

To check the logs of the empowerd service while it is running, use journalctl:

bash
sudo journalctl -fu empowerd.service -o cat

Upgrades

When it comes time for empowerd to be upgraded, cosmovisor looks for the next binaries according to a specific directory structure.

All upgrades must be in the $HOME/.empowerd/cosmovisor/upgrades directory. The name of the upgrade must be a subdirectory in this location. For example, if an upgrade named v2 was released, the upgrade directory for this would be $HOME/.empowerd/cosmovisor/uprgades/v2. Within this directory should be another directory called bin. Finally, within this bin directory, the new empowerd binary should be present. Once the upgrade height is reached, cosmovisor stops the running empowerd binary and switches to the new one assuming that there is a properly created cosmovisor upgrade directory.

The following is a visual representation of cosmovisor's expected directory structure, starting at $HOME/empowerd/cosmovisor/:

.
├── current -> symlink to 'genesis' or 'upgrades/<upgrade_name>'
├── genesis
│   └── bin
│       └── empowerd
└── upgrades
    └── <upgrade_name>
        └── bin
            └── empowerd

It should not be necessary to change the current symlink unless Cosmovisor fails to handle the upgrade once the upgrade height is reached.