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ENV_VARS.md

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Environment Variables

Version: 0.7.1 Updated: 2026-02-08

Overview

glcmd is configured via environment variables for flexibility across different deployment environments (development, production, containers). All variables have sensible defaults.

The daemon (glcore) uses authentication, daemon, and database variables. The CLI client (glcli) uses only GLCMD_API_URL.

Authentication Configuration

GLCMD_EMAIL

  • Description: LibreView follower account email
  • Required: Yes
  • Example: GLCMD_EMAIL=follower@example.com
  • Note: Must be a LibreLinkUp follower account, not the primary patient account

GLCMD_PASSWORD

  • Description: LibreView follower account password
  • Required: Yes
  • Example: GLCMD_PASSWORD=your_secure_password
  • Security: Use strong passwords. Consider using secrets management in production.

Daemon Configuration

GLCMD_API_PORT

  • Description: HTTP port for unified API server (health, metrics, glucose endpoints)
  • Default: 8080
  • Example: GLCMD_API_PORT=9090
  • Used by: glcore
  • Endpoints:
    • GET /health - Health status (returns 200 if healthy, 503 if degraded/unhealthy)
    • GET /metrics - Runtime metrics (memory, goroutines, uptime)
    • GET /v1/measurements/latest - Latest glucose measurement
    • GET /v1/measurements - Paginated measurements
    • GET /v1/measurements/stats - Statistics with time-in-range
    • GET /v1/sensors - Current sensor information
    • GET /v1/sensors/history - Sensor history
    • GET /v1/sensors/stats - Sensor lifecycle statistics

Usage:

# Default port
GLCMD_API_PORT=8080

# Custom port
GLCMD_API_PORT=9090

# Check health
curl http://localhost:8080/health
curl http://localhost:8080/metrics

GLCMD_API_URL

  • Description: Base URL for the glcore API server
  • Default: http://localhost:8080
  • Example: GLCMD_API_URL=http://192.168.1.100:8080
  • Used by: glcli
  • Note: Can also be set per-command with the --api-url flag

Usage:

# Default (local daemon)
GLCMD_API_URL=http://localhost:8080

# Remote daemon
GLCMD_API_URL=http://remote-server:8080

# Or use the flag
glcli --api-url http://remote-server:8080 stats

Logging Configuration

GLCMD_LOG_FORMAT

  • Description: Output format for console logging
  • Values: text | json
  • Default: text
  • Example: GLCMD_LOG_FORMAT=json
  • Note: JSON format is useful for log aggregation systems (ELK, Loki, etc.)

Usage:

# Human-readable text output (default)
GLCMD_LOG_FORMAT=text
# Output: time=2026-02-07T10:30:00Z level=INFO msg="authenticated" duration=1.2s

# JSON output for log aggregation
GLCMD_LOG_FORMAT=json
# Output: {"time":"2026-02-07T10:30:00Z","level":"INFO","msg":"authenticated","duration":"1.2s"}

GLCMD_LOG_LEVEL

  • Description: Minimum log level to output
  • Values: debug | info | warn | error
  • Default: info
  • Example: GLCMD_LOG_LEVEL=debug
  • Note: Logs are output to stderr

Log Levels:

  • debug: Verbose output including API requests and internal operations
  • info: Standard operational messages (startup, fetch cycles, measurements)
  • warn: Warning conditions that may require attention
  • error: Error conditions only

Usage:

# Production (recommended)
GLCMD_LOG_LEVEL=info

# Development/debugging
GLCMD_LOG_LEVEL=debug

# Minimal output
GLCMD_LOG_LEVEL=warn

Database Configuration

GLCMD_DB_PATH

  • Description: Path to SQLite database file
  • Default: ./data/glcmd.db
  • Example: GLCMD_DB_PATH=/var/lib/glcmd/glcmd.db
  • Note: Directory must exist before starting the application

Usage:

# Default location
GLCMD_DB_PATH=./data/glcmd.db

# Custom location
GLCMD_DB_PATH=/home/user/.glcmd/database.db

Directory Creation:

mkdir -p ./data  # Create directory if it doesn't exist

GLCMD_DB_MAX_OPEN_CONNS

  • Description: Maximum number of open database connections
  • Default: 1
  • Example: GLCMD_DB_MAX_OPEN_CONNS=1
  • Note: SQLite should always use 1 (single writer limitation)

GLCMD_DB_MAX_IDLE_CONNS

  • Description: Maximum number of idle connections in the pool
  • Default: 1
  • Example: GLCMD_DB_MAX_IDLE_CONNS=1
  • Recommendation: Set to same as MAX_OPEN_CONNS for consistent pool size

GLCMD_DB_LOG_LEVEL

  • Description: GORM logging level
  • Values: silent | error | warn | info
  • Default: warn
  • Example: GLCMD_DB_LOG_LEVEL=info

Log Levels:

  • silent: No logging (production)
  • error: Only errors (production)
  • warn: Errors + slow queries (recommended for production)
  • info: All queries (development/debugging)

Usage:

# Production
GLCMD_DB_LOG_LEVEL=warn

# Development/debugging
GLCMD_DB_LOG_LEVEL=info

Configuration Examples

Development

# Authentication
GLCMD_EMAIL=dev@example.com
GLCMD_PASSWORD=dev_password

# Database
GLCMD_DB_PATH=./data/glcmd.db
GLCMD_DB_LOG_LEVEL=info

# Logging
GLCMD_LOG_LEVEL=debug
GLCMD_LOG_FORMAT=text

# Application
GLCMD_API_PORT=8080

Production

# Authentication
GLCMD_EMAIL=user@example.com
GLCMD_PASSWORD=secure_password

# Database
GLCMD_DB_PATH=/var/lib/glcmd/glcmd.db
GLCMD_DB_LOG_LEVEL=warn
GLCMD_DB_MAX_OPEN_CONNS=1
GLCMD_DB_MAX_IDLE_CONNS=1

# Logging
GLCMD_LOG_LEVEL=info
GLCMD_LOG_FORMAT=text

# Application
GLCMD_API_PORT=8080

Docker Compose Example

version: '3.8'

services:
  glcore:
    build: .
    environment:
      # Authentication
      GLCMD_EMAIL: ${LIBREVIEW_EMAIL}
      GLCMD_PASSWORD: ${LIBREVIEW_PASSWORD}

      # Database
      GLCMD_DB_PATH: /data/glcmd.db
      GLCMD_DB_LOG_LEVEL: warn

      # Logging
      GLCMD_LOG_LEVEL: info
      GLCMD_LOG_FORMAT: json

      # Application
      GLCMD_API_PORT: 8080
    volumes:
      - glcmd_data:/data
    ports:
      - "8080:8080"
    restart: unless-stopped

volumes:
  glcmd_data:

Environment Variable Loading

Order of Precedence

  1. Environment variables (highest priority)
  2. Default values in code (lowest priority)

Loading via .env File

While glcmd doesn't natively support .env files, you can load them before starting:

# Install godotenv (optional)
go install github.com/joho/godotenv/cmd/godotenv@latest

# Run with .env
godotenv -f .env ./bin/glcore

Example .env file:

GLCMD_EMAIL=user@example.com
GLCMD_PASSWORD=password
GLCMD_DB_PATH=./data/glcmd.db
GLCMD_DB_LOG_LEVEL=info
GLCMD_LOG_LEVEL=info
GLCMD_LOG_FORMAT=text
GLCMD_API_PORT=8080

Systemd Service Example

[Unit]
Description=glcmd glucose monitoring daemon
After=network.target

[Service]
Type=simple
User=glcmd
Group=glcmd
WorkingDirectory=/opt/glcmd

# Environment variables
Environment="GLCMD_EMAIL=user@example.com"
Environment="GLCMD_PASSWORD=password"
Environment="GLCMD_DB_PATH=/var/lib/glcmd/glcmd.db"
Environment="GLCMD_DB_LOG_LEVEL=warn"
Environment="GLCMD_LOG_LEVEL=info"
Environment="GLCMD_LOG_FORMAT=text"
Environment="GLCMD_API_PORT=8080"

ExecStart=/opt/glcmd/glcore
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

Security Best Practices

Sensitive Variables

The GLCMD_PASSWORD variable contains sensitive information.

Recommendations:

  1. Never commit to version control
  2. Use secrets management (Vault, AWS Secrets Manager, etc.)
  3. Restrict file permissions if using .env files (chmod 600 .env)
  4. Use environment-specific values (different passwords per environment)

Example: Docker Secrets

version: '3.8'

services:
  glcore:
    image: glcmd:latest
    environment:
      GLCMD_EMAIL: user@example.com
      GLCMD_DB_PATH: /data/glcmd.db
      GLCMD_LOG_LEVEL: info
      # Password from secret
      GLCMD_PASSWORD_FILE: /run/secrets/libreview_password
    secrets:
      - libreview_password

secrets:
  libreview_password:
    external: true

Validation

The application validates configuration on startup and will exit with an error if:

  • Database connection fails
  • Invalid duration formats
  • Invalid enum values (GLCMD_DB_LOG_LEVEL, GLCMD_LOG_LEVEL, etc.)
  • Missing required credentials (email/password)

Example Error Messages:

Error: failed to connect to database: unable to open database file
Error: invalid GLCMD_LOG_LEVEL value: 'verbose' (must be 'debug', 'info', 'warn', or 'error')

Troubleshooting

Database Connection Issues

Problem: failed to connect to database

Solutions:

  1. Check GLCMD_DB_PATH directory exists
  2. Verify file permissions on database file
  3. Check database logs for connection errors

Lock/Busy Errors

Problem: database is locked or SQLITE_BUSY

Solutions:

  1. Ensure GLCMD_DB_MAX_OPEN_CONNS=1 for SQLite
  2. Check for long-running queries blocking writes
  3. Ensure only one glcore instance is running

Performance Issues

Problem: Slow database operations

Solutions:

  1. Set GLCMD_DB_LOG_LEVEL=info to see slow queries
  2. Check WAL mode enabled (SQLite)

Upgrading from v0.4.x to v0.5.0

Removed Environment Variables

The following environment variables have been removed:

  • GLCMD_DISPLAY_INTERVAL - Periodic display feature removed
  • GLCMD_ENABLE_EMOJIS - Emoji display feature removed

If these variables are set, they will be ignored.

New Environment Variables

  • GLCMD_LOG_FORMAT: Log output format (text or json)
  • GLCMD_LOG_LEVEL: Log verbosity (debug, info, warn, error)

Behavioral Changes

  • The daemon no longer displays periodic glucose readings to the console
  • All glucose data is accessed via the REST API or CLI client (glcli)
  • Logs are output to stderr instead of files

Reference: Default Values Summary

Variable Default Type
GLCMD_EMAIL (required) string
GLCMD_PASSWORD (required) string
GLCMD_API_PORT 8080 int
GLCMD_API_URL http://localhost:8080 string
GLCMD_LOG_FORMAT text string
GLCMD_LOG_LEVEL info string
GLCMD_DB_PATH ./data/glcmd.db string
GLCMD_DB_MAX_OPEN_CONNS 1 int
GLCMD_DB_MAX_IDLE_CONNS 1 int
GLCMD_DB_LOG_LEVEL warn string