[](https://travis-ci.org/status-im/nim-beacon-chain)
[](https://dev.azure.com/nimbus-dev/nim-beacon-chain/_build/latest?definitionId=3&branchName=master)
Make sure you have [CMake](https://cmake.org/) installed, to be able to build libunwind (used for [lightweight stack traces](https://github.com/status-im/nim-libbacktrace)).
Nimbus connects to any of the testnets published in the [eth2-clients/eth2-testnets repo](https://github.com/eth2-clients/eth2-testnets/tree/master/nimbus).
After installing the [prerequisites](#prerequisites)
To run the Nimbus state transition, we provide the `ncli` tool:
* [ncli](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](https://github.com/status-im/nim-beacon-chain/tree/master/multinet) - a set of scripts to build and run several Eth2 clients locally
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)
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](tests/simulation/vars.sh). They can be set in as environment variables before launching the 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.
```
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
The [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`).
The [inspector tool](./beacon_chain/inspector.nim) 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.
```bash
. ./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)
Install [CMake](https://cmake.org/) to be able to build libunwind (used for [lightweight stack traces](https://github.com/status-im/nim-libbacktrace)).
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:
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):
