Function-Configuration Reference

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This document describes the various fields in the function configuration.

Basic structure

The basic structure resembles Kubernetes resource definitions, and includes the apiVersion, kind, metadata, spec, and status sections. Following is an example if a minimal definition:

apiVersion: ""
kind: NuclioFunction
  name: example
  image: example:latest


The metadata section includes the following attributes:

Path Type Description
name string The name of the function
namespace string A level of isolation provided by the platform (e.g., Kubernetes)
labels map A list of key-value tags that are used for looking up the function
annotations map A list of annotations based on the key-value tags


  name: example
  namespace: nuclio
    l1: lv1
    l2: lv2
    l3: 100
    a1: av1  


The spec section contains the requirements and attributes and has the following elements:

Path Type Description
description string A textual description of the function
handler string The entry point to the function, in the form of package:entrypoint. Varies slightly between runtimes, see the appropriate runtime documentation for specifics
runtime string The name of the language runtime. One of: golang, python:2.7, python:3.6, shell, java, nodejs, pypy
image string The container image holding the function
env map A name-value environment-variable tuple. It is also possible to point to secrets, as demonstrated in the following example
volumes map A map in an architecture similar to Kubernetes volumes, for Docker deployment
replicas int The number of desired instances; 0 for auto-scaling.
minReplicas int The minimum number of replicas
maxReplicas int The maximum number of replicas
targetCPU int Target CPU when auto scaling, as a percentage (default: 75%)
dataBindings See reference A map of data sources used by the function (“data bindings”)
triggers.(name).maxWorkers int The max number of concurrent requests this trigger can process
triggers.(name).kind string The kind of trigger. One of http, kafka, kinesis, eventhub, cron, nats, rabbitmq
triggers.(name).url string The trigger specific URL (not used by all triggers)
triggers.(name).annotations list of strings Annotations to be assigned to the trigger, if applicable
triggers.(name).workerAvailabilityTimeoutMilliseconds int The number of milliseconds to wait for a worker if one is not available. 0 = never wait
triggers.(name).attributes See reference The per-trigger attributes
build.path string A local directory or URL to a file/archive containing source and configuration
build.functionSourceCode string The source code of the function, encoded in Base64. Mutually exclusive with build.path
build.registry string The container image repository to which the built image will be pushed
build.noBaseImagePull string Do not pull any base images when building, use local images only
build.noCache string Do not use any caching when building container images
build.baseImage string The base image from which the processor image will be built
build.Commands list of string Commands run opaquely as part of container image build
build.onbuildImage string The “onbuild” image from which the processor image will be built; can use {{ .Label }} and {{ .Arch }} for formatting
runRegistry string The container image repository from which the platform will pull the image
runtimeAttributes See reference Runtime specific attributes, see runtime documentation for specifics
resources See reference Limit resources allocated to deployed function
readinessTimeoutSeconds int Number of seconds that the controller will wait for the function to become ready before declaring failure (default: 60)
avatar string Base64 representation of an icon to be shown in UI for the function
eventTimeout string Global event timeout, in the format supported for the Duration parameter of the time.ParseDuration Go function


  description: my Go function
  handler: main:Handler
  runtime: golang
  image: myfunctionimage:latest
  - name: SOME_ENV
    value: abc
        name: my-secret
        key: password
    - volume:
          path: "/var/run/docker.sock"
        mountPath: "/var/run/docker.sock"
  minReplicas: 2
  maxReplicas: 8
  targetCPU: 60
    registry: localhost:5000
    noBaseImagePull: true
    noCache: true
    - apk --update --no-cache add curl
    - pip install simplejson
      cpu: 1
      memory: 128M
      cpu: 2
      memory: 256M  

See also