Function-Configuration Reference

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This document provides a reference of the Nuclio function configuration.

Basic configuration structure

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

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

Function Metadata (metadata)

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 (immutable, can't update after first deployment)
annotations map A list of annotations based on the key-value tags


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

Function Specification (spec)

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 — golang | python | shell | java | nodejs | pypy
image string The name of the function's container image — used for the image code-entry type; see Code-Entry Types
env map A name-value environment-variables tuple; it's also possible to reference secrets from the map elements, as demonstrated in the specification 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 string The name of the restart policy for the function-image container; applicable only to Docker platforms
platform.attributes.restartPolicy.maximumRetryCount int The maximum retries for restarting the function-image container; applicable only to Docker platforms
platform.attributes.processorMountMode string (DEPRECATED, use MountMode instead)
platform.attributes.mountMode string Function mount mode, which determines how Docker mounts the function configurations - bind | volume (default: bind); applicable only to Docker platforms
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 trigger type (kind) - cron | eventhub | http | kafka-cluster | kinesis | nats | rabbit-mq
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 (default: 10000, which is 10 seconds)
triggers.(name).attributes See reference The per-trigger attributes
build.path string The URL of a GitHub repository or an archive-file that contains the function code — for the github or archive code-entry type — or the URL of a function source-code file; see Code-Entry Types
build.functionSourceCode string Base-64 encoded function source code for the sourceCode code-entry type; see Code-Entry Types
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 name of a base container image from which to build the function's processor image
build.Commands list of string Commands run opaquely as part of container image build
build.onbuildImage string The name of an "onbuild" container image from which to build the function's processor image; the name can include {{ .Label }} and {{ .Arch }} for formatting
build.image string The name of the built container image (default: the function name)
build.codeEntryType string The function's code-entry type - archive | github | image | s3 | sourceCode; see Code-Entry Types
build.codeEntryAttributes See reference Code-entry attributes, which provide information for downloading the function when using the github, s3, or archive code-entry type
runRegistry string The container image repository from which the platform will pull the image
runtimeAttributes See reference Runtime specific attributes
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
securityContext.runAsUser int The user ID (UID) for runing the entry point of the container process
securityContext.runAsGroup int The group ID (GID) for running the entry point of the container process
securityContext.fsGroup int A supplemental group to add and use for running the entry point of the container process


  description: my Go function
  handler: main:Handler
  runtime: golang
  image: myfunctionimage:latest

      # Docker will retry starting the function's image container 3 times.
      # For more information, see
        name: on-failure
        maximumRetryCount: 3

      # Use `volume` to mount the processor into the function.
      # For more information, see
      mountMode: volume
  - 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
    runAsUser: 1000
    runAsGroup: 2000
    fsGroup: 3000

See also