02 / 06Intermediate

Set up your project

Prerequisites

You can write basic Python.
You know the core ideas behind blockchains.
You have a basic grasp of PySpark and Big Data processing.
You have Python 3.8 or later and the related libraries.
You work inside a Python virtual environment.

Set up the Chromia development environment

Complete the following setup steps before you start:

Set up PostgreSQL database

Rell needs PostgreSQL 16.3. You can use the IDE without a database, but you can't run a node. A console or a remote postchain app runs without a database.

By default, Rell expects these database settings:

database: postchain
user: postchain
password: postchain

Install

Install Homebrew by following the Homebrew installation guide.

Install PostgreSQL:

shell

brew install postgresql@16brew services start postgresql@16createuser -s postgres

Create and configure the database:

plsql

psql -U postgres -c "CREATE DATABASE postchain WITH TEMPLATE = template0 LC_COLLATE = 'C.UTF-8' LC_CTYPE = 'C.UTF-8' ENCODING 'UTF-8';" -c "CREATE ROLE postchain LOGIN ENCRYPTED PASSWORD 'postchain'; GRANT ALL ON DATABASE postchain TO postchain;"

Install PostgreSQL:
bash
```
sudo apt install postgresql-16
```

Create and configure the database:

bash

sudo -u postgres psql -c "CREATE DATABASE postchain WITH TEMPLATE = template0 LC_COLLATE = 'C.UTF-8' LC_CTYPE = 'C.UTF-8' ENCODING 'UTF-8';" -c "CREATE ROLE postchain LOGIN ENCRYPTED PASSWORD 'postchain'; GRANT ALL ON DATABASE postchain TO postchain;"

Install Docker by following the Docker installation guide.
Create and configure the database:
dockerfile
```
docker run --name postgres -e POSTGRES_USER=postchain -e POSTGRES_PASSWORD=postchain -p 5432:5432 -d postgres:16.3-alpine3.20
```
note
The Alpine image of PostgreSQL is used here because its default collation settings are correct. You can also set the collation explicitly with this environment variable:
bash
```
POSTGRES_INITDB_ARGS="--lc-collate=C.UTF-8 --lc-ctype=C.UTF-8 --encoding=UTF-8"
```

Get the PostgreSQL installer from the PostgreSQL download page.
Run the installer, then add the PostgreSQL folder that holds the binaries to your environment variables. In the Command Prompt (CMD), run the command below. Check that the path to your binaries is correct and substitute the real version number for the <version> placeholder:
shell
```
setx POSTGRESQL "C:\Program Files\PostgreSQL\<version>\bin"
```
Close and reopen the Command Prompt (CMD) so the new environment variables take effect. Then run these two commands, one after the other, to prepare the database:
plsql
```
psql -U postgres -c "CREATE DATABASE postchain WITH TEMPLATE = template0 LC_COLLATE = 'en_US.UTF-8' LC_CTYPE = 'en_US.UTF-8' ENCODING 'UTF-8';"psql -U postgres -c "CREATE ROLE postchain LOGIN ENCRYPTED PASSWORD 'postchain'; GRANT ALL ON DATABASE postchain TO postchain;"
```
note
Some Windows versions produce permission errors or faulty PostgreSQL installations. If you hit these problems, install Docker and run PostgreSQL in a container instead.

Install Chromia CLI

Follow these steps to install and update the Chromia CLI.

Prerequisite

Check that you have the following in place first:

PostgreSQL database: Follow the PostgreSQL setup guide.
RELL_JAVA environment: Chromia CLI runs on a Java runtime, version 21 or later. The package managers handle this dependency, so you normally don't configure it yourself. To choose a specific Java runtime for Chromia CLI, set the RELL_JAVA environment variable to the location of a valid Java installation.

Installation

Install Chromia CLI through a package manager, or download it from the Chromia CLI package registry.

On macOS, install Chromia CLI (chr) as follows:

Install Homebrew if you don't have it yet:

bash

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

bash

brew tap chromia/core https://gitlab.com/chromaway/core-tools/homebrew-chromia.git

Install Chromia CLI:
bash
```
brew install chromia/core/chr
```
info
To pin a particular Chromia CLI version, run:
shell
```
brew install chromia/core/chr@<version>brew unlink chrbrew link chr@<version>
```
To see which versions are available, run brew search chr.
Confirm the installation by printing the version:
bash
```
chr --version
```

On Linux or WSL (Windows Subsystem for Linux), install Chromia CLI (chr) as follows:

Fetch Chromia's apt-repo public key and add it to your system's trusted keyrings:

bash

curl -fsSL https://apt.chromia.com/chromia.gpg | sudo tee /usr/share/keyrings/chromia.gpg

Add the Chromia repository to your package sources:

bash

echo "deb [arch=amd64 signed-by=/usr/share/keyrings/chromia.gpg] https://apt.chromia.com stable main" | sudo tee /etc/apt/sources.list.d/chromia.list

Refresh your package sources:
bash
```
sudo apt-get update
```
info
If you added apt.chromia.com before Chromia CLI version 0.16.0, run this command so the repository can update:
bash
```
sudo apt-get --allow-releaseinfo-change update
```
After the update finishes, install Chromia CLI:
bash
```
sudo apt-get install chr
```
Confirm the installation by printing the version:
bash
```
chr --version
```

On Windows, install Chromia CLI (chr) with Scoop:

Install Scoop if you don't have it yet. Run this in PowerShell as Administrator:
powershell
```
iwr -useb get.scoop.sh | iex
```

Add the Chromia bucket to Scoop:

powershell

scoop bucket add chromia https://gitlab.com/chromaway/core-tools/scoop-chromia/

Add the Java bucket to Scoop:
powershell
```
scoop bucket add java
```
With this bucket, Scoop can fetch openjdk21, which chromia-cli needs during installation.
Install Chromia CLI:
powershell
```
scoop install chr
```
Confirm the installation by printing the version:
powershell
```
chr --version
```

Updating Chromia CLI

Get the newest Chromia CLI from the package registry. If a package manager installed it, update it with the command for your platform:

shell

brew updatebrew upgrade chr

shell

sudo apt-get updatesudo apt-get install chr

shell

scoop updatescoop update chr

Docker

You can run Chromia CLI inside a standalone Linux container where it is already installed. Set up the PostgreSQL database first.

The published images require Docker to be installed and configured on your host. The Docker documentation explains how to install Docker on Windows, Mac, and Linux.

Start the Docker container with Chromia CLI pre-installed

To run the latest Chromia CLI, pass the CLI image name and chr to the docker run command.

shell

docker run --rm -v $(pwd):/usr/app registry.gitlab.com/chromaway/core-tools/chromia-cli/chr:<latest version> chr

Windows Command Prompt Users

The $(pwd) syntax doesn't work in Windows Command Prompt (cmd). Use one of these instead:

PowerShell: $(Get-Location) or $(pwd)
Command Prompt: %CD%

Command Prompt example:

cmd

docker run --rm -v %CD%:/usr/app registry.gitlab.com/chromaway/core-tools/chromia-cli/chr:<latest version> chr

To update or remove the Docker image, consult the Docker command line reference.

bash

#!/bin/bash# Allocate a pseudo-TTY one when run in interactive modeif [ -t 0 ] && [ -t 1 ] ; then TTY="--tty"; else TTY=""; fidocker run \  # Sets the network to host to not need to change the database hostname (linux only)  --network=host \  # Set timezone based on system settings (linux only)  -e TZ=$(cat /etc/timezone) \  # Sets process ownership to current user  --user $(id -u):$(id -g) \  --mount type=bind,source="/etc/passwd",target=/etc/passwd,readonly \  --mount type=bind,source="/etc/group",target=/etc/group,readonly \  # Configures ssh-agent (only needed if chr install is called on non-public repositores)  -e SSH_AUTH_SOCK=$SSH_AUTH_SOCK \  --volume "$SSH_AUTH_SOCK:$SSH_AUTH_SOCK" \  --mount type=bind,source="${HOME}/.ssh",target=${HOME}/.ssh,readonly \  --mount type=bind,source="${HOME}/.config/jgit",target=${HOME}/.config/jgit \  # Mounts current folder into the container (Use `Get-Location` on PowerShell)  --mount type=bind,source="$(pwd)",target=/usr/app \  --interactive ${TTY} \  --rm \  registry.gitlab.com/chromaway/core-tools/chromia-cli/chr:${CHR_VERSION:-latest} chr "$@"

Windows Command Prompt Users

This bash script relies on $(pwd), which Windows Command Prompt doesn't support. On Windows:

PowerShell: run the command unchanged; PowerShell also understands $(pwd)
Command Prompt: swap $(pwd) for %CD% in the mount command

Mount line adjusted for Command Prompt:

cmd

--mount type=bind,source="%CD%",target=/usr/app \

Clone the project repository

shell

git clone https://bitbucket.org/chromawallet/big-data-spark/src/main/

Navigate to blockchain components

shell

cd main/rell/

Install Rell dependencies

shell

chr install

Navigate to PySpark components

shell

cd pyspark

Install PySpark dependencies

Set up a virtual environment

Linux/WSL:

shell

# Create virtual environmentpython3 -m venv venv# Activate virtual environmentsource venv/bin/activate# Install dependenciespip install -r requirements.txt

Windows:

shell

# Create virtual environmentpython -m venv venv# Activate virtual environmentvenv\Scripts\activate# Install dependenciespip install -r requirements.txt

Note: Activate your virtual environment before you run any of the project's Python scripts.

Written for this site from Chromia’s public course. Code samples are the course’s own.