nimbus-eth2/README.md

# Ethereum Beacon Chain
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Nimbus beacon chain is a research implementation of the beacon chain component of the upcoming Ethereum Serenity upgrade, aka Eth2. See the main [Nimbus](https://github.com/status-im/nimbus/) project for the bigger picture.


## Interop (for other Eth2 clients)

Nimbus is currently going through interoperability testing with several other beacon chain implementations - several tools are available to make this testing easier:

* [multinet](https://github.com/status-im/nim-beacon-chain/tree/master/multinet) - a set of scripts to build and run several Eth2 clients locally
* [ncli](https://github.com/status-im/nim-beacon-chain/tree/master/multinet) - command line tools for working with SSZ files and state transitions

⚠️ Important: To save bandwith `export GIT_LFS_SKIP_SMUDGE=1` before cloning the repo.
This prevents LFS during unusual clones (i.e. when you add `--recurse-submodules` without being instructed to do so).

## Related

* [status-im/nimbus](https://github.com/status-im/nimbus/): main Nimbus repository - start here to learn more about the Nimbus eco-system
* [ethereum/eth2.0-specs](https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md): Serenity specification that this project implements
* [ethereum/beacon\_chain](https://github.com/ethereum/beacon_chain): reference implementation from the Ethereum foundation

You can check where the beacon chain fits in the Ethereum research ecosystem in the [Status Athenaeum](https://github.com/status-im/athenaeum/blob/b465626cc551e361492e56d32517b2cdadd7493f/ethereum_research_records.json#L38).

## Building and Testing

### Prerequisites

* [RocksDB](https://github.com/facebook/rocksdb/)
* PCRE
* Go 1.12 (for compiling libp2p daemon - being phased out)
* GNU Make, Bash and the usual POSIX utilities. Git 2.9.4 or newer.

On Windows, a precompiled DLL collection download is available through the `fetch-dlls` Makefile target: ([Windows instructions](#windows)).

```bash
# MacOS with Homebrew
brew install rocksdb pcre

# Fedora
dnf install rocksdb-devel pcre

# Debian and Ubuntu
sudo apt-get install librocksdb-dev libpcre3-dev

# Arch (AUR)
pakku -S rocksdb pcre-static
```

`rocksdb` can also be installed by following [their instructions](https://github.com/facebook/rocksdb/blob/master/INSTALL.md).

### Build & Develop

#### POSIX-compatible OS

```bash
make # The first `make` invocation will update all Git submodules and prompt you to run `make` again.
     # It's only required once per Git clone. You'll run `make update` after each `git pull`, in the future,
     # to keep those submodules up to date.

# Run tests
make test

# Update to latest version
git pull
make update
```

To run a command that might use binaries from the Status Nim fork:
```bash
./env.sh bash # start a new interactive shell with the right env vars set
which nim
nim --version

# or without starting a new interactive shell:
./env.sh which nim
./env.sh nim --version
```

#### Windows

_(Experimental support!)_

Install Mingw-w64 for your architecture using the "[MinGW-W64 Online
Installer](https://sourceforge.net/projects/mingw-w64/files/)" (first link
under the directory listing). Run it and select your architecture in the setup
menu ("i686" on 32-bit, "x86\_64" on 64-bit), set the threads to "win32" and
the exceptions to "dwarf" on 32-bit and "seh" on 64-bit. Change the
installation directory to "C:\mingw-w64" and add it to your system PATH in "My
Computer"/"This PC" -> Properties -> Advanced system settings -> Environment
Variables -> Path -> Edit -> New -> C:\mingw-w64\mingw64\bin (it's "C:\mingw-w64\mingw32\bin" on 32-bit)

Install [Git for Windows](https://gitforwindows.org/) and use a "Git Bash" shell to clone and build nim-beacon-chain.

If you don't want to compile RocksDB and SQLite separately, you can fetch pre-compiled DLLs with:
```bash
mingw32-make # this first invocation will update the Git submodules
mingw32-make fetch-dlls # this will place the right DLLs for your architecture in the "build/" directory
```

You can now follow those instructions in the previous section by replacing `make` with `mingw32-make` (regardless of your 32-bit or 64-bit architecture):

```bash
mingw32-make test # run the test suite
```


#### Raspberry PI

Raspberry Pi support is experimental.

We recommend you remove any cover or use a fan as the Raspberry Pi will get hot (85°C) and throttle.

* Raspberry PI 3b+ or Raspberry Pi 4b.
* 64gb SD Card (less might work too, but the default recommended 4-8GB will probably be too small)
* [Rasbian Buster Lite](https://www.raspberrypi.org/downloads/raspbian/) - Lite version is enough to get going and will save some disk space!

Assuming you're working with a freshly written image:

```bash

# Start by increasing swap size to 2gb:
sudo vi /etc/dphys-swapfile
# Set CONF_SWAPSIZE=2048
# :wq
sudo reboot

# Install prerequisites
sudo apt-get install git libgflags-dev libsnappy-dev libpcre3-dev

mkdir status
cd status

# Install rocksdb
git clone https://github.com/facebook/rocksdb.git
cd rocksdb
make shared_lib
sudo make install
cd ..

# Raspberry pi doesn't include /usr/local/lib in library search path
# Add it to your profile
echo '# Local compiles (nimbus - rocksdb)' >> ~/.profile
echo 'export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH' >> ~/.profile
echo '' >> ~/.profile

# Install Go at least 1.12 (Buster only includes up to 1.11)
# Raspbian is 32-bit, so the package is go1.XX.X.linux-armv6l.tar.gz (and not arm64)
curl -O https://storage.googleapis.com/golang/go1.13.3.linux-armv6l.tar.gz
sudo tar -C /usr/local -xzf go1.13.3.linux-armv6l.tar.gz

echo '# Go install' >> ~/.profile
echo 'export PATH=$PATH:/usr/local/go/bin' >> ~/.profile

# Reload the environment variable changes
source ~/.profile

git clone https://github.com/status-im/nim-beacon-chain.git

cd nim-beacon-chain
# Follow instructions above!
```

## Connecting to testnets

Nimbus should be able to connect to any of the testnets published in the [eth2-testnets repo](https://github.com/zah/eth2-testnets).
For example, connecting to our testnet0 is done with the following commands:

```bash
cd nim-beacon-chain
source env.sh
nim scripts/connect_to_testnet.nims nimbus/testnet0
```

## Beacon node simulation

The beacon node simulation will create a full peer-to-peer network of beacon nodes and validators, and run the beacon chain in real time. To change network parameters such as shard and validator counts, see [start.sh](tests/simulation/start.sh).

```bash
# Clear data files from your last run and start the simulation with a new genesis block:
make VALIDATORS=192 NODES=6 MISSING_NODES=1 eth2_network_simulation

# In another terminal, get a shell with the right environment variables set:
./env.sh bash

# In the above example, the network is prepared for 7 beacon nodes but one of
# them is not started by default (`MISSING_NODES`) - you can start it separately
# by running:
./tests/simulation/run_node.sh 6 # (or the 0-based node number of the missing node)

# Running a separate node allows you to test sync as well as see what the action
# looks like from a single nodes' perspective.
```

You can also separate the output from each beacon node in its own panel, using [multitail](http://www.vanheusden.com/multitail/):

```bash
make USE_MULTITAIL="yes" eth2_network_simulation
```

You can find out more about it in the [development update](https://our.status.im/nimbus-development-update-2018-12-2/).

_Alternatively, fire up our [experimental Vagrant instance with Nim pre-installed](https://our.status.im/setting-up-a-local-vagrant-environment-for-nim-development/) and give us yout feedback about the process!_

### Visualising simulation metrics

Those [generic instructions from the Nimbus repo](https://github.com/status-im/nimbus/#metric-visualisation) apply here as well.

Specific steps:

```bash
# This will generate the Prometheus config and the Grafana dashboard on the fly,
# based on the number of nodes (which you can control by passing something like NODES=6 to `make`).
make VALIDATORS=192 NODES=6 MISSING_NODES=0 eth2_network_simulation

# In another terminal tab, after the sim started:
cd tests/simulation/prometheus
prometheus
```

The dashboard you need to import in Grafana is "tests/simulation/beacon-chain-sim-all-nodes-Grafana-dashboard.json".

[Obligatory screenshot.](https://i.imgur.com/pLvLhID.png)

### Makefile tips and tricks for developers

- build all those tools known to the Makefile:

```bash
# (assuming you have 4 CPU cores and want to take advantage of them):
make -j4
```

- build a specific tool:

```bash
make state_sim
```

- you can control the Makefile's verbosity with the V variable (defaults to 0):

```bash
make V=1 # verbose
make V=2 test # even more verbose
```

- same for the [Chronicles log level](https://github.com/status-im/nim-chronicles#chronicles_log_level):

```bash
make LOG_LEVEL=DEBUG bench_bls_sig_agggregation # this is the default
make LOG_LEVEL=TRACE beacon_node # log everything
```

- pass arbitrary parameters to the Nim compiler:

```bash
make NIMFLAGS="-d:release"
```

- you can freely combine those variables on the `make` command line:

```bash
make -j8 NIMFLAGS="-d:release" USE_MULTITAIL=yes eth2_network_simulation
```

## State transition simulation

The state transition simulator can quickly run the Beacon chain state transition function in isolation and output JSON snapshots of the state. The simulation runs without networking and blocks are processed without slot time delays.

```bash
# build and run the state simulator, then display its help ("-d:release" speeds it
# up substantially, allowing the simulation of longer runs in reasonable time)
make NIMFLAGS="-d:release" state_sim
build/state_sim --help
```

## Testnet

The beacon chain now has a public testnet available. Connect to it with:

```bash
make testnet0
scripts/testnet0.sh # this launches the testnet0-specific node you just built
```

For more information about the testnet and to find out how to launch your own, see [this announcement](https://our.status.im/the-nimbus-mvp-testnet-is-here/) and the [official docs on launching the testnets](https://nimbus.status.im/docs/t0.html).

## Convention

Ethereum Foundation uses:
  - snake_case for fields and procedure names
  - MACRO_CASE for constants
  - PascalCase for types

Nim NEP-1 recommends:
  - camelCase for fields and procedure names
  - PascalCase for constants
  - PascalCase for types

To facilitate collaboration and comparison, nim-beacon-chain uses the Ethereum Foundation convention.

## License

Licensed and distributed under either of

* MIT license: [LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT

or

* Apache License, Version 2.0, ([LICENSE-APACHEv2](LICENSE-APACHEv2) or http://www.apache.org/licenses/LICENSE-2.0)

at your option. These files may not be copied, modified, or distributed except according to those terms.