Note 1: These instructions will also work for a "network" with only one node.
Note 2: You might not need to set up your own network yet. You should start by creating a proof-of-concept app that writes to [the BigchainDB Testnet](https://testnet.bigchaindb.com/), and if that goes well, then you can look into setting up your own network.
Note 3: If you want to set up a node or network so that you can contribute to developing and testing the BigchainDB code, then see [the docs about contributing to BigchainDB](https://docs.bigchaindb.com/projects/contributing/en/latest/index.html).
The process to create a network is both *social* and *technical*: *social* because someone (that we will call **Coordinator**) needs to find at least three other **Members** willing to join the network, and coordinate the effort; *technical* because each member of the network needs to set up a machine running BigchainDB. (Note: a Coordinator is a Member as well.)
A **BigchainDB Network** (or just *Network*) is a set of **4 or more BigchainDB Nodes** (or *Nodes*). Every Node is independently managed by a Member, and runs an instance of the [BigchainDB Server software][bdb:software]. At the **Genesis** of a Network, there **MUST** be at least **4** Nodes ready to connect. After the Genesis, a Network can dynamically add new Nodes or remove old Nodes.
A Network will stop working if more than one third of the Nodes are down or faulty _in any way_. The bigger a Network, the more failures it can handle. A Network of size 4 can tolerate only 1 failure, so if 3 out of 4 Nodes are online, everything will work as expected. Eventually, the Node that was offline will automatically sync with the others.
This tutorial assumes you have basic knowledge on how to manage a GNU/Linux machine. The commands are tailored for an up-to-date *Debian-like* distribution. (We use an **Ubuntu 18.04 LTS** Virtual Machine on Microsoft Azure.) If you are on a different Linux distribution then you might need to adapt the names of the packages installed.
We don't make any assumptions about **where** you run the Node.
You can run BigchainDB Server on a Virtual Machine on the cloud, on a machine in your data center, or even on a Raspberry Pi. Just make sure that your Node is reachable by the other Nodes. Here's a **non-exhaustive list of examples**:
- **good**: all Nodes running in the cloud using public IPs.
- **bad**: some Nodes running in the cloud using public IPs, some Nodes in a private network.
- **good**: all Nodes running in a private network.
The rule of thumb is: if Nodes can ping each other, then you are good to go.
The next sections are labelled with **Member** or **Coordinator**, depending on who should follow the instructions. Remember, a Coordinator is also a Member.
Every Member in the Network **must** set up its own Node. The process consists of installing three components, BigchainDB Server, Tendermint Core, and MongoDB, and configuring the firewall.
Now install the latest version of BigchainDB. Check the [project page on PyPI][bdb:pypi] for the last version (which was `2.0.0a6` at the time of writing) and install it:
If you install MongoDB using the above command (which installs the `mongodb` package), it also configures MongoDB, starts MongoDB (in the background), and installs a MongoDB startup script (so that MongoDB will be started automatically when the machine is restarted).
Note: The `mongodb` package is _not_ the official MongoDB package from MongoDB the company. If you want to install the official MongoDB package, please see [the MongoDB documentation](https://docs.mongodb.com/manual/installation/). Note that installing the official package _doesn't_ also start MongoDB.
Make sure to accept inbound connections on ports `9984`, `9985`, and `26656`. You might also want to add port `22` so that you can continue to access the machine via SSH.
Some cloud providers, like Microsoft Azure, require you to change "security groups" (virtual firewalls) using their portal or other APIs (such as their CLI).
The first question is ``API Server bind? (default `localhost:9984`)``. To expose the API to the public, bind the API Server to `0.0.0.0:9984`. Unless you have specific needs, you can keep the default value for all other questions.
A Node is identified by the triplet `<hostname, node_id, public_key>`.
As a Member, it's your duty to create and store securely your private key, and share your `hostname`, `node_id`, and `public_key` with the other members of the network.
To generate all of that, run:
```
tendermint init
```
The `public_key` is stored in the file `.tendermint/config/priv_validator.json`, and it should look like:
An example `node_id` is `9b989cd5ac65fec52652a457aed6f5fd200edc22`.
An example hostname is `charlie5.cloudservers.company.com`. You can also use a public IP addres, like `46.145.17.32`, instead of a hostname, but make sure that IP address won't change.
**Important note on security: each Member should take extra steps to verify the public keys they receive from the other Members have not been tampered with, e.g. a key signing party would be one way.**
At this point the Coordinator should have received the data from all the Members, and should combine them in the `.tendermint/config/genesis.json` file:
The new `genesis.json` file contains the data that describes the Network. The key `name` is the Member's moniker; it can be any valid string, but put something human-readable like `"Alice's Node Shop"`.
At this point the Member should have received the `genesis.json` file.
**Important note on security: each Member should verify that the `genesis.json` file contains the correct public keys.**
The Member must copy the `genesis.json` file in the local `.tendermint/config` directory. Every Member now shares the same `chain_id`, `genesis_time`, used to identify the Network, and the same list of `validators`.
The Member must edit the `.tendermint/config/config.toml` file and make the following changes:
## Member: Start MongoDB, BigchainDB and Tendermint
If you installed MongoDB using `sudo apt install mongodb`, then MongoDB should already be running in the background. You can check using `systemctl status mongodb`.
If MongoDB isn't running, then you can start it using the command `mongod`, but that will run it in the foreground. If you want to run it in the background (so it will continue running after you logout), you can use `mongod --fork --logpath /var/log/mongodb.log`. (You might have to create the `/var/log` directory if it doesn't already exist.)
If you installed MongoDB using `sudo apt install mongodb`, then a MongoDB startup script should already be installed (so MongoDB will start automatically when the machine is restarted). Otherwise, you should install a startup script for MongoDB.
To start BigchainDB, one uses the command `bigchaindb start` but that will run it in the foreground. If you want to run it in the background (so it will continue running after you logout), you can use `nohup`, `tmux`, or `screen`. For example, `nohup bigchaindb start 2>&1 > bigchaindb.log &`
The _recommended_ approach is to create a startup script for BigchainDB, so it will start right after the boot of the operating system. (As mentioned earlier, MongoDB should already have a startup script.)
To start Tendermint, one uses the command `tendermint node` but that will run it in the foreground. If you want to run it in the background (so it will continue running after you logout), you can use `nohup`, `tmux`, or `screen`. For example, `nohup tendermint node 2>&1 > tendermint.log &`
The _recommended_ approach is to create a startup script for Tendermint, so it will start right after the boot of the operating system.
Note: We'll share some example startup scripts in the future. This document is a work in progress.
If you followed the recommended approach and created startup scripts for BigchainDB and Tendermint, then you can reboot the machine now. MongoDB, BigchainDB and Tendermint should all start.
## How Others Can Access Your Node
If you followed the above instructions, then your node should be publicly-accessible with BigchainDB Root URL `http://hostname:9984` (where hostname is something like `bdb7.canada.vmsareus.net` or `17.122.200.76`). That is, anyone can interact with your node using the [BigchainDB HTTP API](http-client-server-api.html) exposed at that address. The most common way to do that is to use one of the [BigchainDB Drivers](./drivers-clients/index.html).
## Refreshing Your Node
If you want to refresh your node back to a fresh empty state, then your best bet is to terminate it and deploy a new virtual machine, but if that's not an option, then you can:
