# Cosmovisor Setup

Setting up Cosmovisor is relatively straightforward. However, it does expect certain environment variables and folder structure to be set.

Cosmovisor allows you to download binaries ahead of time for chain upgrades, meaning that you can do zero (or close to zero) downtime chain upgrades. It's also useful if your local timezone means that a chain upgrade will fall at a bad time.

Rather than having to do stressful ops tasks late at night, it's always better if you can automate them away, and that's what Cosmovisor tries to do.

## Install

First, go and get cosmovisor (recommended approach):

```bash
go get github.com/cosmos/cosmos-sdk/cosmovisor/cmd/cosmovisor

# or, with go >= 1.15 you can do
go install github.com/cosmos/cosmos-sdk/cosmovisor/cmd/cosmovisor@latest

# to target a specific version:
go install github.com/cosmos/cosmos-sdk/cosmovisor/cmd/cosmovisor@v1.0.0
```

{% hint style="danger" %}
When using cosmovisor, make sure that you do not have auto download of binaries on.
{% endhint %}

Your installation can be confirmed with:

```bash
which cosmovisor
```

This will return something like:

```bash
/home/<your-user>/go/bin/cosmovisor
```

{% hint style="info" %}
Building from source allows you to target a specific version of Cosmovisor, in case you do not want to run 1.0.0 yet.
{% endhint %}

You can also build from source; cosmovisor is in the main `cosmos-sdk` repo on Github, so you can use Git tags to target a specific version. This example uses a tag, `v0.42.7` that refers to the Cosmos SDK, as Cosmovisor-specific tags did not exist before August 2021. The first of these was `cosmovisor/v0.1.0`, and the second is the current release, `cosmovisor/v1.0.0`.

```bash
git clone https://github.com/cosmos/cosmos-sdk
cd cosmos-sdk
git checkout v0.42.7
export PATH=$PATH:/usr/local/go/bin
export PATH=$PATH:$(go env GO cosmovisor/cosmovisor $GOPATH/bin/cosmovisor
cd $HOME
```

## Add environment variables to your shell

In the `.profile` file, usually located at `~/.profile`, add:

```bash
export DAEMON_NAME=kujirad
export DAEMON_HOME=$HOME/.kujira
```

Then source your profile to have access to these variables:

```bash
source ~/.profile
```

You can confirm success like so:

```
echo $DAEMON_NAME
```

It should return `kujirad`.

## Set up folder structure

Cosmovisor expects a certain folder structure:

```bash
.
├── current -> genesis or upgrades/<name>
├── genesis
│   └── bin
│       └── $DAEMON_NAME
└── upgrades
    └── <name>
        └── bin
            └── $DAEMON_NAME
```

Don't worry about `current` - that is simply a symlink used by Cosmovisor. The other folders will need setting up, but this is easy:

```bash
mkdir -p $DAEMON_HOME/cosmovisor/genesis/bin
mkdir -p $DAEMON_HOME/cosmovisor/upgrades
```

## Set up genesis binary

Cosmovisor needs to know which binary to use at genesis. We put this in `$DAEMON_HOME/cosmovisor/genesis/bin`.

First, find the location of the binary you want to use:

```bash
which kujirad
```

Then use the path returned to copy it to the directory Cosmovisor expects. Let's assume the previous command returned `/home/your-user/go/bin/ kujirad`:

```bash
cp /home/<your-user>/go/bin/kujirad $DAEMON_HOME/cosmovisor/genesis/bin
```

Once you're done, check the folder structure looks correct using a tool like `tree`.

## Set up service

Commands sent to Cosmovisor are sent to the underlying binary. For example, `cosmovisor version` is the same as typing `kujirad version`.

Nevertheless, just as we would manage `kujirad` using a process manager, we would like to make sure Cosmovisor is automatically restarted if something happens, for example an error or reboot.

First, create the service file:

```bash
sudo nano /etc/systemd/system/cosmovisor.service
```

Change the contents of the below to match your setup - `cosmovisor` is likely at `~/go/bin/cosmovisor` regardless of which installation path you took above, but it's worth checking.

```
[Unit]
Description=cosmovisor
After=network-online.target

[Service]
User=<your-user>
ExecStart=/home/<your-user>/go/bin/cosmovisor start
Restart=always
RestartSec=3
LimitNOFILE=4096
Environment="DAEMON_NAME=kujirad"
Environment="DAEMON_HOME=/home/<your-user>/.kujira"
Environment="DAEMON_ALLOW_DOWNLOAD_BINARIES=false"
Environment="DAEMON_RESTART_AFTER_UPGRADE=true"
Environment="DAEMON_LOG_BUFFER_SIZE=512"

[Install]
WantedBy=multi-user.target
```

{% hint style="info" %}
A description of what the environment variables do can be found [here](https://docs.cosmos.network/master/run-node/cosmovisor.html). Change them depending on your setup.
{% endhint %}

Note also that we set buffer size explicitly because of a [live bug in Cosmovisor](https://github.com/cosmos/cosmos-sdk/pull/8590) before version `v1.0.0`. If you are using `v1.0.0`, you may omit that line.

In addition, the same issue can be fixed by reducing the log via env variable. If you are unsure, ask on Discord.

## Start Cosmovisor

{% hint style="warning" %}
If syncing from a snapshot, do not start Cosmovisor yet.
{% endhint %}

Finally, enable the service and start it.

```bash
sudo -S systemctl daemon-reload
sudo -S systemctl enable cosmovisor
sudo systemctl start cosmovisor
```

Check it is running using:

```
sudo systemctl status cosmovisor
```

If you need to monitor the service after launch, you can view the logs using:

```bash
sudo journalctl -u cosmovisor -f
```