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Cratis

Configuration reference

Options go to use Arc.Application and are merged under config :my_app, MyApp.Arc, […], so deployment configuration wins.

defmodule MyApp.Arc do
  use Arc.Application, otp_app: :my_app, segments_to_skip: 1
end


# config/runtime.exs
config :my_app, MyApp.Arc, introspection: :authenticated

Application options

Section titled “Application options”
Option Default Meaning
otp_app required The OTP application scanned for commands and read models
artifacts scan otp_app An explicit list of modules instead of scanning
route_prefix "api" First segment of conventional routes
segments_to_skip 1 Leading module-name segments dropped from routes, slice locations and proxy folders
chronicle [] Options passed to every Chronicle call, for example [client: MyApp.Chronicle]
authentication [Arc.Authentication.FromAssigns] Arc.Authentication handlers, in order
policies [] [name: PolicyModule] for Arc.Policy
identity_details the single Arc.Identity.Provider found The identity provider to use. Without one, /.cratis/me is not served
trust_forwarded_identity_headers false Let Arc.Authentication.MicrosoftIdentityPlatform accept the x-ms-client-principal* headers. Unsigned, only behind an authenticating ingress; required for the two options below
forwarded_identity [enabled: false, audience: "", keys: []] Verify the signed x-cratis-forwarded-identity-signature envelope with 1 to 8 [key_id:, secret_base64:] keys. See Signed forwarded identity
on_behalf_of [enabled: false, issuer: "", audience: "", service: "", clock_skew: 30, signing_keys: []] Accept an RS256 assertion that an actor acts for the user, with [key_id:, public_key_pem:] keys. See Acting on behalf of a user
tenant_header "x-cratis-tenant-id" Header the :header tenancy resolver reads, and the fallback of the :subdomain one
tenancy [] (the header resolver) How the tenant is resolved: resolver: (:header, :query, :claim, :subdomain, :fixed, :development or a module), header:, query_parameter:, claim_type:, base_domain: and tenant_id:. See Tenancy
filters [] Arc.Filter modules: cross-cutting rules that run for every command and query
mongodb none The MongoDB options of cratis_arc_mongodb, see MongoDB
correlation_header "x-correlation-id" Header reused and echoed
max_body_bytes 1_000_000 Request body limit
introspection :authenticated Who may read the five discovery routes (commands, queries, identity schema, users, tenants): :authenticated, :anonymous or false to remove them. /.cratis/me is unaffected
expose_exceptions false Include exception messages and stack traces in results. Never enable in production

Proxy generation

Section titled “Proxy generation”

Set in mix.exs, under arc:. Without an output, nothing is generated.

Option Default Meaning
application required The Arc.Application module
output required The directory to generate into
remove_stale true Delete generated files for artifacts that no longer exist

Add compilers: Mix.compilers() ++ [:arc] to generate on compile.

Plug options

Section titled “Plug options”
Plug Option Meaning
Arc.Plug application The application module (required)
Arc.Plug.SinglePage root The directory of the built frontend (required)
Arc.Plug.SinglePage index Index document; default "index.html"
Arc.Plug.SinglePage api_prefixes Prefixes that are never the SPA; default ["/api/", "/.cratis/"]

Formatter

Section titled “Formatter”

Add import_deps: [:cratis_arc] to .formatter.exs so field, authorize and response stay free of parentheses.

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