Hive consensus node - simple way

# Requirements:
Hardware: x86-64, 32GB RAM, 1TB fast storage (SSD / NVMe)
Software: Ubuntu 22.04 LTS

# Assumptions:
We act as user `hive` with uid `1000` and `HOME=/home/hive`
We use `screen` for convenience. 
We use `/home/hive/datadir` as a data dir for our node.

# Use cases:
Simple, yet versatile configuration that can be used to spawn a node that serves as a:
## seed
Take part in a P2P network. By default listen at publicly available TCP port 2001.
## witness
Witnesses, a.k.a. block producers play an essential role on Hive. In this case, you don’t want to open webserver ports to the public or enable non-essential plugins such as account_history. Make sure that you set values for `witness` and `private-key`.
## exchange
Exchanges need to track account history entries for a list of accounts they use for deposits and withdrawals. For that reason such accounts have to be specified in config files (see example entries). Each time you add a new account to be tracked, you have to perform a replay.
## personal wallet
You might want to have a node for personal needs to handle your accounts. Configure it just like the exchange, except you will track your own account(s).
## basic API
A consensus node has a basic, yet powerful API. It can return useful information about the current state of the blockchain, track the head block, return blocks with get_block API, and broadcast transactions, which might be just good enough to handle some bots or apps.

# Prepare directory tree
```bash
mkdir -pv ~/datadir/{blockchain,snapshot} ~/bin
```
# Use example config file 
```bash
wget https://gtg.openhive.network/get/snapshot/exchange/example-exchange-config.ini -O ~/datadir/config.ini
```

# Get `hived` and `cli_wallet` binaries
```bash
wget https://gtg.openhive.network/get/bin/hived-1.27.6 -nc -P ~/bin
wget https://gtg.openhive.network/get/bin/cli_wallet-1.27.6 -nc -P ~/bin
chmod u+x ~/bin/{hived,cli_wallet}-1.27.6
```
# Run `hived`
Of course you need to make sure it won’t be killed when you disconnect (use screen, or configure it as a service), make sure that the configuration fits your needs (tracking accounts, bind ports to public interfaces or to localhost, etc.)
```bash
~/bin/hived-1.27.6 -d /home/hive/datadir
```

That’s it.

It will start sync process during which `/home/hive/datadir/blockchain/block_log` and `/home/hive/datadir/blockchain/block_log.artifacts` will be created and updated as it will sync and process blocks coming from the Hive p2p network. As the blocks are processed the current state is being saved in the `/home/hive/datadir/blockchain/shared_memory.bin` file. If you track account history then there’s also `/home/hive/datadir/blockchain/account-history-rocksdb-storage` which is RocksDB storage with account history data.

# Optional steps and improvements

## Use tmpfs for shared_memory.bin file
It’s worth mentioning that `/home/hive/datadir/blockchain/shared_memory.bin` will be heavily accessed for read/write. Placing this file on tmpfs will speed up resync and replay, and will reduce I/O on the storage. The disadvantage is that it will not survive the reboot. You also need to have enough RAM / swap.
To use tmpfs, uncomment this line in `config.ini` file:
```
# shared-file-dir = "/run/hive"
```
And prepare that location for storing `shared_memory.bin` file:
```bash
sudo mkdir /run/hive
sudo chown -Rc hive:hive /run/hive
sudo mount -o remount,size=30G /run
```

## Use existing block_log
If you already have a block_log file you can use it to speed up the process. In such a case place it in `~/datadir/blockchain` and use `--replay`.
You can use a block_log from another instance you run or download from public sources (see: https://gtg.openhive.network/get/blockchain )
You can safely reuse block_log from older versions. 
```bash
wget https://gtg.openhive.network/get/blockchain/block_log -nc -P ~/datadir/blockchain
wget https://gtg.openhive.network/get/blockchain/block_log.artifacts -nc -P ~/datadir/blockchain
```
Please note that the block_log is roughly 500GB, downloading it could take a significant amount of time (6-12 hours even with a decent network connection) 

## Use a snapshot
Snapshot can apply the state of the blockchain that was generated on a different machine. It’s tightly bound to the version that was used to generate it and the exact configuration (used plugins, etc.). Make sure that you have `lbzip2` installed (`sudo apt install lbzip2`). Regular bzip2 will also work, but lbzip2 makes use of all available CPU threads. To use snapshot you also need a block_log that is at least as fresh at snapshot itself.

```bash
wget https://gtg.openhive.network/get/snapshot/exchange/latest.tar.bz2 -O - | lbzip2 -dc | tar xvC /home/hive/datadir/snapshot
```

When using snapshot use `--load-snapshot=latest` (where the ‘latest’ is the name of the snapshot)

<center>https://www.youtube.com/watch?v=vlW9lDE3DuI</center>

# TL;DR: Complete optimized recipe

```bash
screen -q # start the screen manager

mkdir -pv ~/datadir/{blockchain,snapshot} ~/bin

sudo mkdir /run/hive
sudo chown -Rc hive:hive /run/hive
sudo mount -o remount,size=30G /run

wget https://gtg.openhive.network/get/blockchain/block_log -nc -P ~/datadir/blockchain
wget https://gtg.openhive.network/get/blockchain/block_log.artifacts -nc -P ~/datadir/blockchain
wget https://gtg.openhive.network/get/snapshot/exchange/latest.tar.bz2 -O - | lbzip2 -dc | tar xvC /home/hive/datadir/snapshot
wget https://gtg.openhive.network/get/bin/hived-1.27.6 -nc -P ~/bin
wget https://gtg.openhive.network/get/bin/cli_wallet-1.27.6 -nc -P ~/bin
wget https://gtg.openhive.network/get/snapshot/exchange/example-exchange-config.ini -O ~/datadir/config.ini

sed -i '/^# shared-file-dir/s/^# //' ~/datadir/config.ini # enable tmpfs location
chmod u+x ~/bin/{hived,cli_wallet}-1.27.6

~/bin/hived-1.27.6 -d /home/hive/datadir --load-snapshot=latest
```

# Upgrading from previous version
If your instance is already configured this way, then upgrade is very easy:
```bash
rm -rf /home/hived/datadir/snapshot/latest
wget https://gtg.openhive.network/get/bin/hived-1.27.6 -nc -P ~/bin
wget https://gtg.openhive.network/get/bin/cli_wallet-1.27.6 -nc -P ~/bin
chmod u+x ~/bin/{hived,cli_wallet}-1.27.6
wget https://gtg.openhive.network/get/snapshot/exchange/latest.tar.bz2 -O - | lbzip2 -dc | tar xvC /home/hive/datadir/snapshot
```
Stop current instance and start with new binary:
```bash
~/bin/hived-1.27.6 -d /home/hive/datadir --load-snapshot=latest
```

# Estimated times:
Sync (from scratch) - 36h
Replay (if you already have a block_log) - 18h
Load from snapshot (if you already have a block_log) - 1h

# Congratulations, you have your Hive node running!