# Photon: the Indexer for ZK Compression on Solana
Photon is the core indexer for [ZK Compression](zkcompression.com) on the Solana blockchain. It offers rapid indexing capabilities, snapshot support, and flexible database options to cater to local and production deployments.
## 🚀 Quick Start
### Installation
1. Install dependencies:
```bash
sudo apt install -y build-essential pkg-config libssl-dev
```
2. Install `photon-indexer`:
```bash
cargo install photon-indexer
```
### 🔧 Usage
#### Basic Usage
* Run Photon with default settings against localnet:
```bash
photon
```
#### Configuration
* Connect to Devnet:
```bash
photon --rpc-url=https://api.devnet.solana.com
```
* Use gRPC for block streaming (requires GRPC_X_TOKEN env variable):
```bash
photon --rpc-url=https://api.devnet.solana.com --grpc-url=<grpc_url>
```
* Use a local Postgres database:
```bash
photon --db-url=postgres://postgres@localhost/postgres
```
* Specify a start slot:
```bash
photon --start-slot=123
```
* For more advanced options:
```bash
photon --help
```
## 📸 Snapshots
Photon supports snapshots for quick bootstrapping.
### Loading a Snapshot
1. Download a snapshot:
```bash
photon-snapshot-loader --snapshot-dir=~/snapshot --snapshot-server-url=https://photon-devnet-snapshot.helius-rpc.com
```
2. Run Photon with the snapshot:
```bash
photon --snapshot-dir=~/snapshot --rpc-url=https://api.devnet.solana.com --db-url=postgres://postgres@localhost/postgres
```
### Creating Snapshots
Create a local snapshot:
```bash
photon-snapshotter --snapshot-dir=~/snapshot
```
Store snapshots in an R2 bucket:
```bash
photon-snapshotter --r2-bucket=some-bucket --r2-prefix=prefix
```
Note: Set `R2_ACCESS_KEY`, `R2_ACCOUNT_ID`, and `R2_SECRET_KEY` environment variables when using R2.
## 🗄️ Database Management
Photon supports both Postgres and SQLite. By default, it uses an in-memory SQLite database.
To use a custom database:
```bash
export DATABASE_URL="postgres://postgres@localhost/postgres"
photon-migration up
photon --db-url=$DATABASE_URL
```
## 🛠️ Local Development
### Running Tests
1. Set up the environment:
```bash
export MAINNET_RPC_URL=https://api.mainnet-beta.solana.com
export DEVNET_RPC_URL=https://api.devnet.solana.com
export TEST_DATABASE_URL="postgres://postgres@localhost/postgres"
```
2. Install additional tools:
```bash
npm install -g @apidevtools/swagger-cli
wget https://dl.min.io/server/minio/release/linux-amd64/minio
chmod +x minio
docker run -p 3001:3001 docker.io/pmantica1/light-prover:1
```
3. Run tests:
```bash
cargo test
```
Note: All migrations run automatically during tests for both Postgres and SQLite.
### Database Model Generation
```bash
cargo install sea-orm-cli --version 0.10.6
sea-orm-cli generate entity -o src/dao/generated
```
### API Documentation
Generate OpenAPI schemas:
```bash
cargo run --bin=photon-openapi
```
## 📬 Support
For support or queries, please open an issue on Github or contact the [Helius discord](https://discord.gg/HjummjUXgq).