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The Exchange platform is configured using environment variables. This guide documents all available configuration options.

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Environment file setup

The platform uses .env files for configuration. Two example files are provided:
  • Project root - .env.example for local development
  • Docker directory - docker/.env.example for containerized deployment

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Local development

cp .env.example .env

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Docker deployment

cd docker
cp .env.example .env

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Configuration categories

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Database configuration

PostgreSQL database connection settings.
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PG__USER
string
required
PostgreSQL username for authentication.Default: root
PG__USER=root
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PG__PASSWORD
string
required
PostgreSQL password for authentication.Default: root
Use a strong password in production!
PG__PASSWORD=your-secure-password
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PG__HOST
string
required
PostgreSQL server hostname.Local development: localhostDocker deployment: exchange-postgres
PG__HOST=localhost
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PG__PORT
number
required
PostgreSQL server port.Default: 5000 (local) or 5432 (Docker)
PG__PORT=5000
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PG__DBNAME
string
required
PostgreSQL database name.Default: exchange-db
PG__DBNAME=exchange-db
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PG__POOL_MAX_SIZE
number
default:"16"
Maximum number of connections in the database connection pool.Adjust based on expected load and server capacity.
PG__POOL_MAX_SIZE=16
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DATABASE_URL
string
required
Complete PostgreSQL connection string used by SQLx.Format: postgres://user:password@host:port/database
DATABASE_URL=postgres://${PG__USER}:${PG__PASSWORD}@${PG__HOST}:${PG__PORT}/${PG__DBNAME}
This variable uses variable substitution from the other PG__* variables.

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Docker-specific database variables

These variables are used in Docker Compose for PostgreSQL container setup:
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POSTGRES_HOST
string
PostgreSQL container hostname.
POSTGRES_HOST=exchange-postgres
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POSTGRES_DB
string
PostgreSQL database name (Docker container).
POSTGRES_DB=exchange-db
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POSTGRES_USER
string
PostgreSQL username (Docker container).
POSTGRES_USER=root
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POSTGRES_PASSWORD
string
PostgreSQL password (Docker container).
POSTGRES_PASSWORD=root
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POSTGRES_PORT
number
PostgreSQL internal port in Docker.
POSTGRES_PORT=5432

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Redis configuration

Redis is used for pub/sub messaging and caching.
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REDIS_URL
string
required
Complete Redis connection URL.Local development: redis://localhost:6380Docker deployment: redis://exchange-redis:6379
REDIS_URL=redis://exchange-redis:6379

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Service configuration

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SERVER_ADDR
string
default:"0.0.0.0:8080"
Router (REST API) server bind address and port.Format: host:port
SERVER_ADDR=0.0.0.0:8080
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WS_STREAM_URL
string
default:"0.0.0.0:4000"
WebSocket streaming service bind address and port.Format: host:port
WS_STREAM_URL=0.0.0.0:4000

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Build-time configuration

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SQLX_OFFLINE
boolean
default:"true"
Controls SQLx compile-time query verification.Values:
  • true - Skip compile-time query verification (faster builds)
  • false - Verify queries against database at compile time
SQLX_OFFLINE=true
In Dockerfiles, this is set to true to enable offline builds without database access.
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RUST_LOG
string
default:"info"
Rust logging level.Values: trace, debug, info, warn, error
RUST_LOG=info

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Configuration examples

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Local development

.env
# Database
PG__USER=root
PG__PASSWORD=root
PG__HOST=localhost
PG__PORT=5000
PG__DBNAME=exchange-db
PG__POOL_MAX_SIZE=16

DATABASE_URL=postgres://${PG__USER}:${PG__PASSWORD}@${PG__HOST}:${PG__PORT}/${PG__DBNAME}

# Redis
REDIS_URL=redis://localhost:6380

# Services
SERVER_ADDR=0.0.0.0:8080
WS_STREAM_URL=0.0.0.0:4000

# Logging
RUST_LOG=debug

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Docker deployment

docker/.env
# PostgreSQL Docker container
POSTGRES_HOST=exchange-postgres
POSTGRES_DB=exchange-db
POSTGRES_USER=root
POSTGRES_PASSWORD=root
POSTGRES_PORT=5432

# Service configuration
SERVER_ADDR=0.0.0.0:8080
WS_STREAM_URL=0.0.0.0:4000

# Redis
REDIS_URL=redis://exchange-redis:6379

# Database connection for services
PG__USER=root
PG__PASSWORD=root
PG__HOST=exchange-postgres
PG__PORT=5432
PG__DBNAME=exchange-db
PG__POOL_MAX_SIZE=16

DATABASE_URL=postgres://${PG__USER}:${PG__PASSWORD}@${PG__HOST}:${PG__PORT}/${PG__DBNAME}

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Production deployment

.env
# Database - use strong credentials!
PG__USER=exchange_prod_user
PG__PASSWORD=<STRONG_RANDOM_PASSWORD>
PG__HOST=production-db-host
PG__PORT=5432
PG__DBNAME=exchange_production
PG__POOL_MAX_SIZE=32

DATABASE_URL=postgres://${PG__USER}:${PG__PASSWORD}@${PG__HOST}:${PG__PORT}/${PG__DBNAME}

# Redis - consider Redis cluster for HA
REDIS_URL=redis://production-redis-host:6379

# Services
SERVER_ADDR=0.0.0.0:8080
WS_STREAM_URL=0.0.0.0:4000

# Logging - use warn or error in production
RUST_LOG=warn

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Environment validation

The Exchange platform uses the confik crate for configuration management with automatic validation. If required environment variables are missing, services will fail to start with clear error messages.

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Security considerations

Follow these security best practices:
  • Never commit .env files to version control
  • Use strong passwords in production (minimum 20 characters)
  • Rotate credentials regularly
  • Use secrets management tools (AWS Secrets Manager, HashiCorp Vault, etc.)
  • Restrict database access to application servers only
  • Enable SSL/TLS for database and Redis connections in production

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SQLx offline mode

The platform uses SQLx’s offline mode for Docker builds:

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Preparing the query cache

If you modify database queries, regenerate the query cache: 
SQLX_OFFLINE=false cargo sqlx prepare --workspace
This creates/updates files in the .sqlx directory.

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Building with offline mode

SQLX_OFFLINE=true cargo build
Or set it in your .env: 
SQLX_OFFLINE=true

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PostgreSQL tuning

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Max connections

In Docker Compose, PostgreSQL is configured with: 
command: -c 'max_connections=800'
Adjust based on:
  • Number of service instances
  • PG__POOL_MAX_SIZE setting
  • Expected concurrent load
Formula: max_connections >= (number_of_services × pool_size) + 10

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Shared memory

shm_size: 1gb
Increase for better performance with large datasets.

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Redis tuning

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Persistence settings

command: redis-server --save 20 1 --loglevel warning
Explanation:
  • --save 20 1 - Save to disk if at least 1 key changed in 20 seconds
  • --loglevel warning - Reduce log verbosity
For high-write workloads, consider: 
command: redis-server --save 60 1000 --loglevel warning

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Troubleshooting

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Database connection fails

Verify your configuration: 
# Check if variables are set
echo $DATABASE_URL

# Test connection
psql $DATABASE_URL -c "SELECT 1;"

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Redis connection fails

# Test Redis connection
redis-cli -u $REDIS_URL ping

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Environment variables not loading

Ensure you’re loading the .env file: 
# The project uses dotenvy to load .env automatically
# If using docker-compose, ensure env_file is specified
docker compose config  # Verify env vars are loaded

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Next steps

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