Andrei-Dolgolev / testnet.bash

Bash script that sets up a private Ethereum network for development and testing.

testnet.bash

Bash script that sets up a private Ethereum network for development and testing.

Setup

This bash script uses:

1. bash
2. geth
3. jq

Creating a test network

To bring up a test network, run the testnet.bash script from the root of this repository as follows:

mkdir -p testnet
TESTNET_BASE_DIR=testnet/ ./testnet.bash

You can run the same command to restart the testnet after shutting it down using CTRL+C.

All the account passwords (by default) are peppercat.

Inputs

Accepts inputs through environment variables:

TESTNET_BASE_DIR

Directory in which all data is stored. This is where you will find your node data directories, dag directories, and more.

If this is not set, will create a temporary directory in which to store all data.

GETH

Set this environment variable to specify a path to a custom geth. If not set, will use the first geth available in your $PATH.

Customization

Just copy the bash script and edit it, my friend.

FAQ

Why not Ganache?

Ganache is pretty heavy-duty and I wanted something light-weight that I could use to spin up a private network, set up a scenario, and then run a series of tests.

Ganache is also a completely independent implementation of the Ethereum interfaces. I wanted to be able to test against (different versions of) geth because that's what we currently use in Moonstream. Moonstream crawlers crawl data from geth nodes and any reasonable test of those crawlers should use geth nodes.

Why bash?

Because bash is ubiquitous, especially in continuous integration environments.

I have experimented in the past with similar setups in docker-compose (link). This bash script does the job just as well, is much simpler to understand, and is much easier to customize.

How do I change the genesis parameters?

Copy the bash script and edit the definition of the GENESIS_JSON variable.

How do I add more nodes?

The vanilla script sets up 2 mining nodes. Any less and chain data will not be persisted to disk between runs. If you wanted to add a third node, you would modify the bash script to add a run_miner call:

MINER_0=$(run_miner 0)
MINER_1=$(run_miner 1)
MINER_2=$(run_miner 2)

If you wanted to print metadata about this new miner, you would add a new echo statement near where the miner metadata is printed:

echo "Running testnet. Miner info:"
echo "$MINER_0" | jq .
echo "$MINER_1" | jq .
echo "$MINER_2" | jq .
echo
echo "Press CTRL+C to exit."

Finally, you would probably want to add the new miner's logs to the tail command:

tail -f $(echo "$MINER_0" | jq -r ".logfile") $(echo "$MINER_1" | jq -r ".logfile")

Why geth?

If you would like to add support for another Ethereum client, I would welcome a pull request.

Why does this script fail when I try to use a temporary testnet base directory on my Mac?

This script uses mktemp -d when you don't specify a testnet directory.

The BSD version of mktemp has a different signature than the GNU version. Relevant StackExchange thread: https://unix.stackexchange.com/questions/30091/fix-or-alternative-for-mktemp-in-os-x

If you want to run this script on a Mac with a temporary base directory, please let me know and I will add support. At that time, I would appreciate your help in testing the change.

In the meantime, you can get around the issue by explicitly creating a base directory and setting it as the TESTNET_BASE_DIR environment variable.

Where have you tested testnet.bash?

So far, it has been tested on:

• Debian Buster VM image on WSL2 (Windows 10), bash 5.0.3(1)-release

If you have run this script successfully, I would appreciate it if you submit an edit to this README describing your environment. Thank you.

peppercat?

Contributing

Your contributions are welcome:

• Create an issue
• Open a pull request