Course outline

01 · HTTP & REST APIs

02 · Databases & Persistence

03 · Authentication & Authorization

04 · API Design & gRPC

05 · Caching, Queues & Background Jobs

06 · Production-Ready Services

07 · Advanced Auth & Tenant Security

08 · Performance & Caching at Scale

09 · Testing & Release Confidence

Stage 3 · Build

Production-Ready Services

Configuration

Load environment variables, config files, secrets, and defaults with Viper, envconfig, or clean structs.

7 min readBuilding Backend ApplicationsBuild

Why Configuration Management

Hardcoded values break when you move from development to production. Configuration management separates values from code, letting you run the same binary in different environments with different settings.

Environment Variables

Goclean-struct-based-config.go

18 linesLn 1, Col 1Go

kelseyhightightire/envconfig reads environment variables into struct fields. The env tag specifies the variable name. envDefault provides fallback values. No external dependencies.

Config Files

Goviper-config-file-loading.go

29 linesLn 1, Col 1Go

Viper reads from config files, environment variables, and defaults. Environment variables override config files. AutomaticEnv() maps env vars to config keys.

Secrets Management

Secrets like database passwords and API keys should never be in config files or git. Use environment variables, secret managers (Vault, AWS SSM), or Kubernetes secrets.

Gosecret-validation.go

13 linesLn 1, Col 1Go

Fail fast on startup if required secrets are missing. Never log secrets. Never include secrets in error messages. Validate secret strength for security-critical values.

Validation

Goconfig-validation-on-startup.go

23 linesLn 1, Col 1Go

Validate all configuration on startup. Log non-sensitive values for debugging. Mask sensitive values in logs. This catches configuration errors before the server starts accepting traffic.

12-Factor Config

Store config in environment variables, not in code.
Separate config from code — same binary, different environments.
Use defaults for non-critical settings.
Validate all config on startup.
Never log secrets or config file paths in production.
Use typed config structs, not string maps.

Use .env for local development

Create a .env.example file with all required variables and placeholder values. Developers copy it to .env and fill in local values. Never commit .env to git.

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