Nimbus Eth2 (Beacon Chain)

Nimbus beacon chain is a research implementation of the beacon chain component of the upcoming Ethereum Serenity upgrade, aka Eth2.

• Nimbus Eth2 (Beacon Chain)
  • Documentation
  • Related projects
  • Prerequisites for everyone
    • Linux
    • MacOS
    • Windows
    • Android
  • For users
    • Connecting to testnets
    • Getting metrics from a local testnet client
    • Stress-testing the client by limiting the CPU power
  • Interop (for other Eth2 clients)
  • For researchers
    • State transition simulation
    • Local network simulation
    • Visualising simulation metrics
    • Network inspection
  • For developers
    • Windows dev environment
    • Linux, MacOS
    • Raspberry Pi
    • Makefile tips and tricks for developers
    • CI setup
  • License

Documentation

You can find the information you need to run a beacon node and operate as a validator in The Book.

See this page for how to become a validator on Medalla.

Related projects

• status-im/nimbus: Nimbus for Ethereum 1
• ethereum/eth2.0-specs: Serenity specification that this project implements

You can check where the beacon chain fits in the Ethereum ecosystem our Two-Point-Oh series: https://our.status.im/tag/two-point-oh/

Prerequisites for everyone

At the moment, Nimbus has to be built from source.

Nimbus has the following external dependencies:

• Developer tools (C compiler, Make, Bash, Git)
• PCRE

Nim is not an external dependency, Nimbus will build its own local copy.

Linux

On common Linux distributions the dependencies can be installed with:

# Debian and Ubuntu
sudo apt-get install build-essential git libpcre3-dev

# Fedora
dnf install @development-tools pcre

# Archlinux, using an AUR manager for pcre-static
yourAURmanager -S base-devel pcre-static

MacOS

Assuming you use Homebrew to manage packages:

brew install pcre cmake

Make sure you have CMake installed, to be able to build libunwind (used for lightweight stack traces).

Windows

You can install the developer tools by following the instruction in our Windows dev environment section. It also provides a downloading script for prebuilt PCRE.

Android

• Install the Termux app from FDroid or the Google Play store
• Install a PRoot of your choice following the instructions for your preferred distribution. Note, the Ubuntu PRoot is known to contain all Nimbus prerequisites compiled on Arm64 architecture (common architecture for Android devices).

Assuming Ubuntu PRoot is used

apt install build-essential git libpcre3-dev

For users

Connecting to testnets

Once the prerequisites are installed you can connect to the Medalla testnet with the following commands:

git clone https://github.com/status-im/nim-beacon-chain
cd nim-beacon-chain
make medalla           # This will build Nimbus and all other dependencies
                      # and connect you to Medalla

You can also start multiple local nodes, in different terminal windows/tabs, by specifying their numeric IDs:

make medalla NODE_ID=0 # the default
make medalla NODE_ID=1
make medalla NODE_ID=2

To change the TCP and UDP ports from the default value of 9000:

make BASE_PORT=9100 medalla

If you wish to make a deposit, execute the following command:

make medalla-deposit VALIDATORS=2 # The default is just 1 deposit

Getting metrics from a local testnet client

# the primitive HTTP server started to serve the metrics is considered insecure
make NIMFLAGS="-d:insecure" medalla

Now visit http://127.0.0.1:8008/metrics to see the raw metrics. You should see a plaintext page that looks something like this:

# HELP nim_runtime_info Nim runtime info
# TYPE nim_runtime_info gauge
nim_gc_mem_bytes 6275072.0
nim_gc_mem_occupied_bytes 1881384.0
nim_gc_heap_instance_occupied_bytes{type_name="KeyValuePairSeq[digest.Eth2Digest, block_pools_types.BlockRef]"} 25165856.0
nim_gc_heap_instance_occupied_bytes{type_name="BlockRef"} 17284608.0
nim_gc_heap_instance_occupied_bytes{type_name="string"} 6264507.0
nim_gc_heap_instance_occupied_bytes{type_name="seq[SelectorKey[asyncdispatch.AsyncData]]"} 409632.0
nim_gc_heap_instance_occupied_bytes{type_name="OrderedKeyValuePairSeq[Labels, seq[Metric]]"} 122720.0
nim_gc_heap_instance_occupied_bytes{type_name="Future[system.void]"} 79848.0
nim_gc_heap_instance_occupied_bytes{type_name="anon ref object from /Users/hackingresearch/nimbus/clone/nim-beacon-chain/vendor/nimbus-build-system/vendor/Nim/lib/pure/asyncmacro.nim(319, 33)"} 65664.0
nim_gc_heap_instance_occupied_bytes{type_name="anon ref object from /Users/hackingresearch/nimbus/clone/nim-beacon-chain/vendor/nimbus-build-system/vendor/Nim/lib/pure/asyncnet.nim(506, 11)"} 43776.0
nim_gc_heap_instance_occupied_bytes{type_name="seq[byte]"} 37236.0
nim_gc_heap_instance_occupied_bytes{type_name="seq[TrustedAttestation]"} 29728.0

...

Unfortunately, this simple method only offers one snapshot in time (you'll need to keep refreshing to see the data update) which means it's impossible to see a useful history of the metrics. In short, it's far from optimal from an information design point of view.

In order to settle on a better solution, we'll need the help of two external projects -- Prometheus and Grafana.

See this page from our Nimbus book for a step-by-step guide on how to use Prometheus and Grafana to spin up a beautiful and useful monitoring dashboard for your validator.

---

For those of you who are already familiar with Prometheus and Grafana

To feed the data into a Prometheus instance, run:

cd build/data/shared_medalla_0
prometheus --config.file=./prometheus.yml --storage.tsdb.path=./prometheus
# when starting multiple nodes at the same time, just use the config file from the one with the highest ID

You can then visualise the data by getting Grafana up and running with the dashboard definition found in grafana/beacon\_nodes\_Grafana\_dashboard.json.

Stress-testing the client by limiting the CPU power

make medalla CPU_LIMIT=20

The limiting is provided by the cpulimit utility, available on Linux and macOS. The specified value is a percentage of a single CPU core. Usually 1 - 100, but can be higher on multi-core CPUs.

Interop (for other Eth2 clients)

After installing the prerequisites

To run the Nimbus state transition, we provide the ncli tool:

• ncli

The interop scripts have been moved in a common repo, the interop relied on 0.8.3 specs which had seen significant changes. The interop branch still exist but is unmaintained.

• multinet - a set of scripts to build and run several Eth2 clients locally
• interop branch (unmaintained)

For researchers

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.

# 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

Local network simulation

The local network simulation will create a full peer-to-peer network of beacon nodes and validators on a single machine, and run the beacon chain in real time.

Parameters such as shard, validator counts, and data folders are configured vars.sh. They can be set in as environment variables before launching the simulation.

# Clear data files from your last run and start the simulation with a new genesis block:
make VALIDATORS=192 NODES=6 USER_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 (`USER_NODES`) - this is useful to test
# catching up to the consensus. The following command will start the missing node.
./tests/simulation/run_node.sh 0 # (or the index (0-based) 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.

By default, validators will be split in half between beacon node and validator client processes (50/50), communicating through the official validator API (for example with 192 validators and 6 nodes you will roughly end up with 6 beacon node and 6 validator client processes, where each of them will handle 16 validators), but if you don't want to use external validator clients and instead want to have all the validators handled by the beacon nodes you may use BN_VC_VALIDATOR_SPLIT=no as an additional argument to make eth2_network_simulation.

By default, the simulation will start from a pre-generated genesis state. If you wish to simulate the bootstrap process with a Ethereum 1.0 validator deposit contract, start the simulation with WAIT_GENESIS=yes

make eth2_network_simulation WAIT_GENESIS=yes

You can also separate the output from each beacon node in its own panel, using multitail:

make eth2_network_simulation USE_MULTITAIL="yes"

You can find out more about it in the development update.

Alternatively, fire up our experimental Vagrant instance with Nim pre-installed and give us yout feedback about the process!

Visualising simulation metrics

The generic instructions from the Nimbus repo apply here as well.

Specific steps:

# This will generate the Prometheus config on the fly, based on the number of
# nodes (which you can control by passing something like NODES=6 to `make`).
# The `-d:insecure` flag starts an HTTP server from which the Prometheus daemon will pull the metrics.
make VALIDATORS=192 NODES=6 USER_NODES=0 NIMFLAGS="-d:insecure" 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 "grafana/beacon_nodes_Grafana_dashboard.json".

Network inspection

The inspector tool can help monitor the libp2p network and the various channels where blocks and attestations are being transmitted, showing message and connectivity metadata. By default, it will monitor all ethereum 2 gossip traffic.

. ./env.sh
# Build inspector for minimal config:
./env.sh nim c -d:const_preset=minimal -o:build/inspector_minimal beacon_chain/inspector.nim

# Build inspector for mainnet config:
./env.sh nim c -d:const_preset=mainnet -o:build/inspector_mainnet beacon_chain/inspector.nim

# See available options
./env.sh build/inspector_minimal --help

# Connect to a network from eth2 testnet repo bootstrap file - --decode option attempts to decode the messages as well
./env.sh build/inspector_minimal --decode -b:$(curl -s https://raw.githubusercontent.com/eth2-clients/eth2-testnets/master/nimbus/testnet0/bootstrap_nodes.txt | head -n1)

For developers

Latest updates happen in the devel branch which is merged into master every week on Tuesday before deploying new testnets.

Interesting Make variables and targets are documented in the nimbus-build-system repo.

The following sections explain how to set up your build environment on your platform.

Windows dev environment

Install Mingw-w64 for your architecture using the "MinGW-W64 Online Installer" (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 and use a "Git Bash" shell to clone and build nim-beacon-chain.

Install CMake to be able to build libunwind (used for lightweight stack traces).

When running the tests, you might hit some Windows path length limits. Increase them by editing the Registry in a PowerShell instance with administrator privileges:

Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -Value 1

and run this in a "Git Bash" terminal:

git config --global core.longpaths true

If you don't want to compile PCRE separately, you can fetch pre-compiled DLLs with:

mingw32-make fetch-dlls # this will place the right DLLs for your architecture in the "build/" directory

If you were following the Windows testnet instructions, you can jump back to Connecting to testnets now

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):

mingw32-make test # run the test suite

Linux, MacOS

After cloning the repo:

# The first `make` invocation will update all Git submodules.
# You'll run `make update` after each `git pull`, in the future, to keep those submodules up to date.

# Build beacon_node and all the tools, using 4 parallel Make jobs
make -j4

# 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:

./env.sh bash # start a new interactive shell with the right env vars set
which nim
nim --version # Nimbus is tested and supported on 1.0.2 at the moment

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

Raspberry Pi

We recommend you remove any cover or use a fan; 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 - Lite version is enough to get going and will save some disk space!

Assuming you're working with a freshly written image:

# 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

# Then you can follow instructions for Linux.

Makefile tips and tricks for developers

• build all those tools known to the Makefile:

# $(nproc) corresponds to the number of cores you have
make -j$(nproc)

• build a specific tool:

make state_sim

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

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

• same for the Chronicles log level:

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:

make NIMFLAGS="-d:release"

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

make -j$(nproc) NIMFLAGS="-d:release" USE_MULTITAIL=yes eth2_network_simulation

• don't use the lightweight stack tracing implementation from nim-libbacktrace:

make USE_LIBBACKTRACE=0 # expect the resulting binaries to be 2-3 times slower

• disable -march=native because you want to run the binary on a different machine than the one you're building it on:

make NIMFLAGS="-d:disableMarchNative" beacon_node

• disable link-time optimisation (LTO):

make NIMFLAGS="-d:disableLTO" beacon_node

• build a static binary

make NIMFLAGS="--passL:-static" beacon_node

• publish a book using mdBook from sources in "docs/" to GitHub pages:

make publish-book

CI setup

Local testnets run for 4 epochs each, to test finalization. That happens only on Jenkins Linux hosts, and their logs are available for download as artifacts, from the job's page. Don't expect these artifacts to be kept more than a day after the corresponding branch is deleted.

License

Licensed and distributed under either of

• MIT license: LICENSE-MIT or http://opensource.org/licenses/MIT

or

• Apache License, Version 2.0, (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.