Configuration

A craftgo project has two configuration files. They live in different places and serve different stages.

At a glance

File	Read by	When	Controls
<design>/craftgo.design.yaml	craftgo CLI	At gen time	Where generated files land + OpenAPI metadata
<project>/config/config.yaml	main.go	At boot	Server addr, OTel, metrics, your own custom fields

The first is read once when you run craftgo gen. The second is read every time the binary starts. Both are gen-once - craftgo writes them when missing and never overwrites your edits.

Codegen config (craftgo.design.yaml)

Lives inside the design folder. The directory containing this file is the design root; its parent is the project root (the directory that holds go.mod).

myproject/
├── design/                          design root
│   ├── craftgo.design.yaml          ← this file
│   └── users/service.craftgo
├── go.mod
└── internal/                        generated, sits at project root

craftgo init creates a starter file. Default content matches every key's default, so an empty manifest works:

output:
  types:      ./internal/types
  transport:  ./internal/transport
  routes:     ./internal/routes
  service:    ./internal/service
  middleware: ./internal/middleware
  svccontext: ./svccontext/svccontext.go
  openapi:    ./docs/openapi.yaml
  config:     ./config
  main:       ./main.go

openapi:
  title:    My API
  version:  1.0.0
  basePath: /api
  securitySchemes:
    bearer:
      type: http
      scheme: bearer
      bearerFormat: JWT

output.* paths

All paths are relative to the project root (the parent of the design folder, the directory holding go.mod). Override any of them to relocate the corresponding artifact.

Key	Default	Kind	Holds
types	./internal/types	directory	One subfolder per design package; types.go, validate.go, enums.go, errors.go
transport	./internal/transport	directory	One subfolder per service; <method>.go per method
routes	./internal/routes	directory	Per-service routes.go plus an umbrella routes.go
service	./internal/service	directory	One subfolder per service; <method>.go per method (gen-once)
middleware	./internal/middleware	directory	One file per declared middleware Name (gen-once)
svccontext	./svccontext/svccontext.go	file path	Single Go file with the dependency container (gen-once); middlewares.go lands beside it
openapi	./docs/openapi.yaml	file path	The generated OpenAPI 3.1 spec
config	./config	directory	config.go, config.yaml, example.config.yaml (all gen-once)
main	./main.go	file path	The project entry point (gen-once)

The four "file path" entries point at exact files. The rest are directories where craftgo writes one subfolder per package or service.

Customizing paths

A common use is to put generated artifacts at the project root instead of under internal/:

output:
  types:     ./types
  transport: ./transport
  routes:    ./routes
  service:   ./service

Or split off the spec to a separate api/ folder:

output:
  openapi: ./api/openapi.yaml

Or skip generating an artifact entirely with -:

output:
  main: -          # do not generate main.go

When main: - is set, craftgo also skips config/, svccontext, and middleware since those exist to support main.go. Useful for projects that import the generated types as a library and run their own server.

Module path is auto-resolved

The craftgo.design.yaml does not carry a Go module / package field. craftgo reads module <path> from go.mod (walking up from the project root) at gen time and uses that for every Go import in generated files.

If go.mod is missing, craftgo gen fails with a clear error. Run go mod init <module> first.

openapi.* block

Metadata that flows into the generated openapi.yaml.

Key	Type	Effect
title	string	OpenAPI document title
version	string	OpenAPI document version
basePath	string	Path prefix prepended to every operation path
securitySchemes	map	Named OpenAPI security schemes (see below)

version can also be set per-file via @version("...") - file-level decorator wins when present. title is manifest-only.

basePath rides into the servers[0].url field of the generated spec. If you need multiple servers or richer descriptions, edit the generated openapi.yaml after gen (it is committed; craftgo regenerates it on every run).

openapi.securitySchemes

Each entry is a named scheme referenced from the DSL with @security(<name>). Schemes:

openapi:
  securitySchemes:
    bearer:                    # @security(bearer)
      type: http
      scheme: bearer
      bearerFormat: JWT

    apiKeyHeader:              # @security(apiKeyHeader)
      type: apiKey
      in: header
      name: X-API-Key

    oauth2:                    # @security(oauth2)
      type: oauth2

    openIdConnect:
      type: openIdConnect
      openIdConnectUrl: https://issuer.example.com/.well-known/openid-configuration

Supported type values: http, apiKey, oauth2, openIdConnect, mutualTLS. Per-type extra fields:

• http: scheme (e.g. bearer, basic), optional bearerFormat
• apiKey: in (header / query / cookie), name
• oauth2: scopes are application-defined - validated as strings, not against a fixed set
• openIdConnect: openIdConnectUrl

The semantic analyzer cross-checks every @security(<name>) reference against this map. Unknown names fail at gen time, not at deploy.

Runtime config (config/config.yaml)

Generated by craftgo gen on first run alongside config.go. Read by main.go via config.Load(). Default content:

server:
  addr: ":8080"
  handlerTimeout: 0s
  maxBodySize: 0
  compression:
    enabled: false
    minSize: 0
    level: 0

otel:
  enabled: true
  serviceName: my-app
  exporter: none
  endpoint: ""

metrics:
  enabled: true
  exporter: prometheus
  endpoint: ""
  adminAddr: ":9090"
  path: /metrics

server

Key	Type	Effect
addr	string	Listen address. ":8080", "127.0.0.1:8080", etc.
handlerTimeout	duration	Global per-handler deadline. 0s = no global cap; per-method @timeout overrides.
maxBodySize	int	Global request body cap in bytes. 0 = no cap.
compression.enabled	bool	Toggle gzip / deflate response compression.
compression.minSize	int	Skip compression when body is smaller. 0 falls back to 1024.
compression.level	int	Compression level (1-9). 0 falls back to default.

Compression is off by default. Turn it on only when not behind a compressing reverse proxy (Nginx, Envoy, CloudFront).

otel

Key	Effect
enabled	Toggle the OTel HTTP middleware.
serviceName	service.name resource attribute on every span.
exporter	none / stdout / otlp_grpc / otlp_http.
endpoint	OTLP collector address. Ignored for none / stdout.

Setting enabled: true with exporter: none produces in-process spans whose IDs flow into log lines but are not exported.

metrics

Key	Effect
enabled	Toggle the meter provider and admin scrape listener.
exporter	prometheus / otlp_grpc / otlp_http / none.
endpoint	OTLP collector address (ignored for prometheus / none).
adminAddr	Listen address for /metrics scrape (prometheus only).
path	URL path for the scrape (default /metrics).

The admin listener runs separately from the public API listener.

Adding custom fields

Edit config/config.go (gen-once - your edits stick):

type Config struct {
    Server  ServerConfig  `yaml:"server"`
    OTel    OTelConfig    `yaml:"otel"`
    Metrics MetricsConfig `yaml:"metrics"`

    DB struct {
        DSN string `yaml:"dsn"`
    } `yaml:"db"`
}

Then add the matching block to config.yaml:

db:
  dsn: postgres://localhost/myapp

Read from your service via svcCtx.Config.DB.DSN.

File location at runtime

main.go reads config/config.yaml by default. Pass a different path by editing the call:

cfg, err := config.Load("/etc/myapp/config.yaml")

craftgo does not read environment variables. The YAML file is the single source of runtime configuration. Mount the right file per environment:

deploy/
├── config.dev.yaml
├── config.staging.yaml
└── config.production.yaml

CI / your deployer copies the right file to config/config.yaml before the binary starts.