Ambassador

Note: Ambassador uses CustomResourceDefinitions with apiVersion = apiextensions.k8s.io/v1beta1 which was removed in Kubernetes version 1.22+. Please ensure your Kubernetes version is compatible with the version of Ambassador you're using

kusk-gen ambassador --help
Generates Ambassador Mappings for your service

Usage:
  kusk-gen ambassador [flags]

Flags:
  -i, --in string                         file path to api spec file to generate mappings from. e.g. --in apispec.yaml
      --namespace string                  namespace for generated resources (default "default")
      --service.name string               target Service name
      --service.namespace string          namespace containing the target Service (default "default")
      --service.port int32                target Service port (default 80)
      --path.base string                  a base path for Service endpoints (default "/")
      --path.split                        force Kusk to generate a separate Mapping for each operation
      --path.trim_prefix string           a prefix to trim from the URL before forwarding to the upstream Service
      --timeouts.idle_timeout uint32      idle connection timeout (seconds)
      --timeouts.request_timeout uint32   total request timeout (seconds)
  -h, --help                              help for ambassador

The Ambassador generator generates Mapping resources for mapping resource to services. All options that can be set via flags can also be set using our x-kusk OpenAPI extension in your specification.

CLI flags apply only at the global level i.e. applies to all paths and methods.

To override settings on the path or HTTP method level, you are required to use the x-kusk extension at that path in your API specification.

Full Options Reference

Name	CLI Option	OpenAPI Spec x-kusk label	Descriptions	Overwritable at path / method
OpenAPI or Swagger File	--in	N/A	Location of the OpenAPI or Swagger specification	❌
Namespace	--namespace	namespace	the namespace in which to create the generated resources (Required)	❌
Service Name	--service.name	service.name	the name of the service running in Kubernetes (Required)	❌
Service Namespace	--service.namespace	service.namespace	The namespace where the service named above resides (default value: default)	❌
Service Port	--service.port	service.port	Port the service is listening on (default value: 80)	❌
Path Base	--path.base	path.base	Prefix for your resource routes	❌
Path Trim Prefix	--path.trim_prefix	path.trim_prefix	Trim the specified prefix from URl before passing request onto service	❌
Path split	--path.split	path.split	Boolean; whether or not to force generator to generate a mapping for each path	❌
Host	--host	host	The value to set the host field to in the Mapping resource	✅
Rate limit (RPS)	--rate_limits.rps	rate_limits.rps	Request per second rate limit	✅
Rate limit (burst)	--rate_limits.burst	rate_limits.burst	Rate limit burst	✅
Rate limit group	N/A	rate_limits.group	Rate limit endpoint group
Request Timeout	--timeouts.request_timeout	timeouts.request_timeout	Total request timeout (seconds)	✅
Idle Timeout	--timeouts.idle_timeout	timeouts.idle_timeout	Idle connection timeout (seconds)	✅
CORS Origins	N/A	cors.origins	Array of origins	✅
CORS Methods	N/A	cors.methods	Array of methods	✅
CORS Headers	N/A	cors.headers	Array of headers	✅
CORS ExposeHeaders	N/A	cors.expose_headers	Array of headers to expose	✅
CORS Credentials	N/A	cors.credentials	Boolean: enable credentials (default value: false)	✅
CORS Max Age	N/A	cors.max_age	Integer:how long the response to the preflight request can be cached for without sending another preflight request	✅
## Basic Usage

CLI Flags

kusk-gen ambassador -i examples/booksapp/booksapp.yaml \
--namespace my-namespace \
--service.name booksapp \
--service.port 7000 \
--service.namespace my-service-namespace

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
paths:
  /:
    get: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp
  namespace: my-namespace
spec:
  prefix: "/"
  service: booksapp.my-service-namespace:7000
  rewrite: ""

Split Path

By setting split path to true, kusk-gen will generate a mapping per route specified in the provided OpenAPI specification

CLI Flags

kusk-gen ambassador -i examples/booksapp/booksapp.yaml \
--namespace my-namespace \
--service.name booksapp \
--service.port 7000 \
--service.namespace my-service-namespace \
--path.split true

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  path:
    split: true
paths:
  /:
    get: {}

  /books:
    post: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp-get
  namespace: my-namespace
spec:
  prefix: "/"
  method: GET
  service: booksapp.my-service-namespace:7000
  rewrite: ""
---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp-postbooks
  namespace: my-namespace
spec:
  prefix: "/books"
  method: POST
  service: booksapp.my-service-namespace:7000
  rewrite: ""

Base Path and Trim Prefix

Setting the Base path option allows your service to be identified with the base path acting as a prefix.

Setting the trim prefix options will instruct ambassador to trim the prefix before sending the request onto the service.

CLI Flags

kusk-gen ambassador -i examples/booksapp/booksapp.yaml \
--namespace my-namespace \
--service.name booksapp \
--service.port 7000 \
--service.namespace my-service-namespace \
--path.base /my-app \
--path.trim_prefix /my-app

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  path:
    base: /my-app
    trim_prefix: /my-app
paths:
  /:
    get: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp
  namespace: my-namespace
spec:
  prefix: "/my-app"
  service: booksapp.my-service-namespace:7000
  regex_rewrite:
    pattern: '/my-app(.*)'
    substitution: '\1'

Setting timeouts

kusk-gen allows for setting both idle and request timeouts via flags or the x-kusk OpenAPI extension

CLI Flags

kusk-gen ambassador -i examples/booksapp/booksapp.yaml \
--namespace my-namespace \
--service.name booksapp \
--service.port 7000 \
--service.namespace my-service-namespace \
--timeouts.idle_timeout 120 \
--timeouts.request_timeout 120

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  timeouts:
    request_timeout: 120
    idle_timeout: 120
paths:
  /:
    get: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp
  namespace: my-namespace
spec:
  prefix: "/"
  service: booksapp.my-service-namespace:7000
  rewrite: ""
  timeout_ms: 120000
  idle_timeout_ms: 120000

Setting the Host header

kusk-gen allows for setting both idle and request timeouts via flags or the x-kusk OpenAPI extension

CLI Flags

kusk-gen ambassador -i examples/booksapp/booksapp.yaml \
--namespace my-namespace \
--service.name booksapp \
--service.port 7000 \
--service.namespace my-service-namespace \
--host "somehost.io"

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  host: somehost.io
paths:
  /:
    get: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: booksapp
  namespace: my-namespace
spec:
  prefix: "/"
  host: somehost.io
  service: booksapp.my-service-namespace:7000
  rewrite: ""
  timeout_ms: 120000
  idle_timeout_ms: 120000

CORS

Via the x-kusk extension, you can set cors policies on your resources

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  cors:
    origins:
      - http://foo.example
      - http://bar.example
    methods:
      - POST
      - GET
      - OPTIONS
    headers:
      - Content-Type
    credentials: true
    expose_headers:
      - X-Custom-Header
    max_age: 86400
paths:
  /:
    get: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: webapp
  namespace: booksapp
spec:
  prefix: "/"
  service: webapp.booksapp:7000
  rewrite: ""
  cors:
    origins: http://foo.example,http://bar.example
    methods: POST,GET,OPTIONS
    headers: Content-Type
    exposed_headers: X-Custom-Header
    credentials: true
    max_age: "86400"

Basic Path settings override

For this example, let's assume that one of the paths in the API specification should have different CORS headers than the rest.

OpenAPI Specification

openapi: 3.0.1
x-kusk:
  namespace: booksapp
  service:
    name: webapp
    namespace: booksapp
    port: 7000
  cors:
    methods:
      - POST
      - GET
      - OPTIONS
    headers:
      - Content-Type
    credentials: true
    expose_headers:
      - X-Custom-Header
    max_age: 86400
paths:
  /:
    get: {}
  /books:
    x-kusk:
      cors:
        methods:
          - POST
        headers:
          - Other-Content-Type
        credentials: true
        expose_headers:
          - X-Other-Custom-Header
        max_age: 120
    post: {}
...

Sample Output

---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: webapp-get
  namespace: booksapp
spec:
  prefix: "/"
  method: GET
  service: webapp.booksapp:7000
  rewrite: ""
  cors:
    origins:
    methods: POST,GET,OPTIONS
    headers: Content-Type
    exposed_headers: X-Custom-Header
    credentials: true
    max_age: "86400"
---
apiVersion: getambassador.io/v2
kind: Mapping
metadata:
  name: webapp-postbooks
  namespace: booksapp
spec:
  prefix: "/books"
  method: POST
  service: webapp.booksapp:7000
  rewrite: ""
  cors:
    origins:
    methods: POST
    headers: Other-Content-Type
    exposed_headers: X-Other-Custom-Header
    credentials: true
    max_age: "120"