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Configuration Reference

Table of contents

  1. Server
  2. Logging
  3. gRPC Server
  4. gRPC TLS
  5. gRPC Keepalive
  6. HTTP Gateway
  7. Prometheus Metrics
  8. New Relic
  9. OpenTelemetry (OTLP)
  10. Error Tracking
  11. Graceful Shutdown
  12. Runtime
  13. Deprecated
  14. Example: Minimal Production Configuration
  15. Example: Local Development with Jaeger

ColdBrew is configured entirely through environment variables using envconfig. All fields have sensible defaults — you can run a service with zero configuration.

Access the config in code via:

cfg := config.GetColdBrewConfig()

Server

Variable Type Default Description
LISTEN_HOST string 0.0.0.0 Host address to listen on
GRPC_PORT int 9090 gRPC server port
HTTP_PORT int 9091 HTTP gateway port
APP_NAME string "" Application name (used in logs, metrics, New Relic)
ENVIRONMENT string "" Environment name (e.g., production, staging, development)
RELEASE_NAME string "" Release/version name

Logging

Variable Type Default Description
LOG_LEVEL string info Log level: debug, info, warn, error
JSON_LOGS bool true Emit logs in JSON format

gRPC Server

Variable Type Default Description
DISABLE_GRPC_REFLECTION bool false Disable gRPC server reflection (used by tools like grpcurl)
DO_NOT_LOG_GRPC_REFLECTION bool true Suppress logging of gRPC reflection API calls
GRPC_MAX_SEND_MSG_SIZE int 2147483647 Maximum send message size in bytes (default: ~2GB, unlimited)
GRPC_MAX_RECV_MSG_SIZE int 4194304 Maximum receive message size in bytes (default: 4MB)
DISABLE_VT_PROTOBUF bool false Disable vtprotobuf marshaller for gRPC. See vtprotobuf guide

gRPC TLS

Variable Type Default Description
GRPC_TLS_KEY_FILE string "" Path to TLS private key file. Both key and cert must be set to enable TLS
GRPC_TLS_CERT_FILE string "" Path to TLS certificate file. Both key and cert must be set to enable TLS
GRPC_TLS_INSECURE_SKIP_VERIFY bool false Skip TLS certificate verification (development only)

gRPC Keepalive

Variable Type Default Description
GRPC_SERVER_MAX_CONNECTION_IDLE_IN_SECONDS int 0 Close idle connections after this duration (0 = disabled)
GRPC_SERVER_MAX_CONNECTION_AGE_IN_SECONDS int 0 Maximum connection lifetime with ±10% jitter (0 = disabled)
GRPC_SERVER_MAX_CONNECTION_AGE_GRACE_IN_SECONDS int 0 Grace period after max connection age before force-closing

HTTP Gateway

Variable Type Default Description
DISABLE_SWAGGER bool false Disable Swagger UI at the swagger URL
SWAGGER_URL string /swagger/ URL path for Swagger UI
DISABLE_DEBUG bool false Disable pprof debug endpoints at /debug/
USE_JSON_BUILTIN_MARSHALLER bool false Use encoding/json instead of the default protojson marshaller for application/json
JSON_BUILTIN_MARSHALLER_MIME string application/json Content-Type for the JSON builtin marshaller
HTTP_HEADER_PREFIXES []string "" HTTP header prefixes to forward as gRPC metadata (comma-separated)
TRACE_HEADER_NAME string x-trace-id HTTP header name for trace ID propagation to log/trace contexts

Prometheus Metrics

Variable Type Default Description
DISABLE_PROMETHEUS bool false Disable Prometheus metrics endpoint at /metrics
ENABLE_PROMETHEUS_GRPC_HISTOGRAM bool true Enable gRPC request latency histograms
PROMETHEUS_GRPC_HISTOGRAM_BUCKETS []float64 "" Custom histogram buckets (comma-separated seconds, e.g., 0.005,0.01,0.025,0.05,0.1,0.25,0.5,1,2.5,5,10)

New Relic

Variable Type Default Description
NEW_RELIC_LICENSE_KEY string "" New Relic license key (required to enable New Relic)
NEW_RELIC_APPNAME string "" Application name in New Relic
DISABLE_NEW_RELIC bool false Disable all New Relic reporting
NEW_RELIC_DISTRIBUTED_TRACING bool true Enable New Relic distributed tracing
NEW_RELIC_OPENTELEMETRY bool true Enable New Relic via OpenTelemetry
NEW_RELIC_OPENTELEMETRY_SAMPLE float64 0.2 Trace sampling ratio for New Relic OpenTelemetry (0.0–1.0)

OpenTelemetry (OTLP)

When OTLP_ENDPOINT is set, it takes precedence over New Relic OpenTelemetry configuration.

Variable Type Default Description
OTLP_ENDPOINT string "" OTLP gRPC endpoint (e.g., localhost:4317, api.honeycomb.io:443)
OTLP_HEADERS string "" Custom headers as key=value pairs (comma-separated, e.g., x-honeycomb-team=your-key)
OTLP_COMPRESSION string gzip Compression type: gzip or none
OTLP_INSECURE bool false Disable TLS for OTLP connection (development only)
OTLP_SAMPLING_RATIO float64 0.2 Trace sampling ratio (0.0–1.0, where 1.0 = sample all)
OTLP_USE_OPENTRACING_BRIDGE bool true Enable OpenTracing compatibility bridge for existing instrumentation

Error Tracking

Variable Type Default Description
SENTRY_DSN string "" Sentry DSN for error notification

Graceful Shutdown

Variable Type Default Description
DISABLE_SIGNAL_HANDLER bool false Disable ColdBrew’s SIGINT/SIGTERM handler
SHUTDOWN_DURATION_IN_SECONDS int 15 Time to wait for in-flight requests to complete before forced shutdown
GRPC_GRACEFUL_DURATION_IN_SECONDS int 7 Time to wait for healthcheck failure to propagate before initiating shutdown. Should be less than SHUTDOWN_DURATION_IN_SECONDS

Runtime

Variable Type Default Description
DISABLE_AUTO_MAX_PROCS bool false Disable automatic GOMAXPROCS tuning (useful if your container runtime already sets it)

Deprecated

Variable Replacement Notes
HTTP_HEADER_PREFIX HTTP_HEADER_PREFIXES Single prefix replaced by comma-separated list

Example: Minimal Production Configuration 

export APP_NAME=myservice
export ENVIRONMENT=production
export LOG_LEVEL=info
export NEW_RELIC_LICENSE_KEY=your-key
export NEW_RELIC_APPNAME=myservice
export SENTRY_DSN=https://your-dsn@sentry.io/123

Example: Local Development with Jaeger 

export APP_NAME=myservice
export ENVIRONMENT=development
export LOG_LEVEL=debug
export OTLP_ENDPOINT=localhost:4317
export OTLP_INSECURE=true
export OTLP_SAMPLING_RATIO=1.0
export DISABLE_NEW_RELIC=true

Source: core/config/config.go