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prefect-worker

Overview

Workers are lightweight polling services that retrieve scheduled runs from a work pool and execute them.

Workers each have a type corresponding to the execution environment to which they will submit flow runs. Workers are only able to join work pools that match their type. As a result, when deployments are assigned to a work pool, you know in which execution environment scheduled flow runs for that deployment will run.

Installing the Chart

Prerequisites

  1. Add the Prefect Helm repository to your Helm client:

    helm repo add prefect https://prefecthq.github.io/prefect-helm
helm repo update

  2. Create a new namespace in your Kubernetes cluster to deploy the Prefect worker in:

    kubectl create namespace prefect

Configuring a Worker for Prefect Cloud

  1. Create a Kubernetes secret for a Prefect Cloud API key

    First create a file named api-key.yaml with the following contents:

    apiVersion: v1
kind: Secret
metadata:
  name: prefect-api-key
  namespace: prefect
type: Opaque
data:
  key:  <base64-encoded-api-key>

    Replace <base64-encoded-api-key> with your Prefect Cloud API key encoded in base64. The helm chart looks for a secret of this name and schema, this can be overridden in the values.yaml.

    You can use the following command to generate the base64-encoded value:

    echo -n "your-prefect-cloud-api-key" | base64

    Then apply the api-key.yaml file to create the Kubernetes secret:

    kubectl apply -f api-key.yaml

    Alternatively, you can create the Kubernetes secret via the cli with the following command. In this case, Kubernetes will take care of base64 encoding the value on your behalf:

    kubectl create secret generic prefect-api-key --from-literal=key=pnu_xxxx

  2. Configure the Prefect worker values

    Create a values.yaml file to customize the Prefect worker configuration. Add the following contents to the file:

    worker:
  cloudApiConfig:
    accountId: <target account ID>
    workspaceId: <target workspace ID>
  config:
    workPool: <target work pool name>

    These settings will ensure that the worker connects to the proper account, workspace, and work pool. View your Account ID and Workspace ID in your browser URL when logged into Prefect Cloud. For example: https://app.prefect.cloud/account/abc-my-account-id-is-here/workspaces/123-my-workspace-id-is-here

Configuring a Worker for Self Hosted Cloud (not to be confused with Prefect Server)

  1. Create a Kubernetes secret for a Prefect Self Hosted Cloud API key

    First create a file named api-key.yaml with the following contents:

    apiVersion: v1
kind: Secret
metadata:
  name: prefect-api-key
  namespace: prefect
type: Opaque
data:
  key:  <base64-encoded-api-key>

    Replace <base64-encoded-api-key> with your Prefect Self Hosted Cloud API key encoded in base64. The helm chart looks for a secret of this name and schema, this can be overridden in the values.yaml.

    You can use the following command to generate the base64-encoded value:

    echo -n "your-prefect-self-hosted-cloud-api-key" | base64

    Then apply the api-key.yaml file to create the Kubernetes secret:

    kubectl apply -f api-key.yaml

    Alternatively, you can create the Kubernetes secret via the cli with the following command. In this case, Kubernetes will take care of base64 encoding the value on your behalf:

    kubectl create secret generic prefect-api-key --from-literal=key=pnu_xxxx

  2. Configure the Prefect worker values

    Create a values.yaml file to customize the Prefect worker configuration. Add the following contents to the file:

    worker:
  apiConfig: selfHosted
  config:
    workPool: <target work pool name>
  selfHostedCloudApiConfig:
    # If the prefect server is located external to this cluster, set a fully qualified domain name as the apiUrl
    # If the prefect server pod is deployed to this cluster, use the cluster DNS endpoint: http://<prefect-server-service-name>.<namespace>.svc.cluster.local:<prefect-server-port>/api
    apiUrl: "https://<DNS of Self Hosted Cloud API>"
    accountId: <target account ID>
    workspaceId: <target workspace ID>
    uiUrl: "https://<DNS of Self Hosted Cloud UI>"

    These settings will ensure that the worker connects to the proper account, workspace, and work pool. View your Account ID and Workspace ID in your browser URL when logged into Prefect Cloud. For example: https://self-hosted-prefect.company/account/abc-my-account-id-is-here/workspaces/123-my-workspace-id-is-here

Configuring a Worker for Prefect Server

  1. Configure the Prefect worker values

    Create a values.yaml file to customize the Prefect worker configuration. Add the following contents to the file:

    worker:
  apiConfig: server
  config:
    workPool: <target work pool name>
  serverApiConfig:
    apiUrl: <dns or ip address of the prefect-server pod here>

    These settings will ensure the worker connects with the local deployment of Prefect Server. If the Prefect Server pod is deployed in the same cluster, you can use the local Kubernetes DNS address to connect to it: prefect-server.<namespace>.svc.cluster.local

Installing & Verifying Deployment of the Prefect Worker

  1. Install the Prefect worker using Helm

    helm install prefect-worker prefect/prefect-worker --namespace=prefect -f values.yaml

  2. Verify the deployment

    Check the status of your Prefect worker deployment:

    kubectl get pods -n prefect

NAME                              READY   STATUS    RESTARTS       AGE
prefect-worker-658f89bc49-jglvt   1/1     Running   0              25m

    You should see the Prefect worker pod running

FAQ

Deploying multiple workers to a single namespace

If you want to run more than one worker in a single Kubernetes namespace, you will need to specify the fullnameOverride parameter at install time of one of the workers.

fullnameOverride: prefect-worker-2

If you want the workers to share a service account, add the following to your values.yaml:

fullnameOverride: prefect-worker-2
serviceAccount:
  create: false
  name: "prefect-worker"

Configuring a Base Job Template on the Worker

If you want to define the base job template of the worker and pass it as a value in this chart, you will need to do the following. Note if the workPool already exists, the base job template passed will be ignored.

  1. Define the base job template in a local file. To get a formatted template, run the following command & store locally in base-job-template.json
# you may need to install `prefect-kubernetes` first
pip install prefect-kubernetes

prefect work-pool get-default-base-job-template --type kubernetes > base-job-template.json

  1. Modify the base job template as needed

  2. Install the chart as you usually would, making sure to use the --set-file command to pass in the base-job-template.json file as a paramater:

helm install prefect-worker prefect/prefect-worker -f values.yaml --set-file worker.config.baseJobTemplate.configuration=base-job-template.json

Updating the Base Job Template

If a base job template is set through Helm (via either .Values.worker.config.baseJobTemplate.configuration or .Values.worker.config.baseJobTemplate.existingConfigMapName), we'll run an optional initContainer that will sync the template configuration to the work pool named in .Values.worker.config.workPool.

Any time the base job template is updated, the subsequent initContainer run will run prefect work-pool update <work-pool-name> --base-job-template <template-json> and sync this template to the API.

Please note that configuring the template via baseJobTemplate.existingConfigMapName will require a manual restart of the prefect-worker Deployment in order to kick off the initContainer - alternatively, you can use a tool like reloader to automatically restart an associated Deployment. However, configuring the template via baseJobTemplate.configuration value will automatically roll the Deployment on any update.

Maintainers

Name Email Url
jamiezieziula [email protected]
jimid27 [email protected]
parkedwards [email protected]
mitchnielsen [email protected]

Requirements

Repository Name Version
https://charts.bitnami.com/bitnami common 2.20.5

Values

Key Type Default Description
commonAnnotations object {} annotations to add to all deployed objects
commonLabels object {} labels to add to all deployed objects
fullnameOverride string "prefect-worker" fully override common.names.fullname
nameOverride string "" partially overrides common.names.name
namespaceOverride string "" fully override common.names.namespace
role.create bool true specifies whether a Role should be created
role.extraPermissions list [] array with extra permissions to add to the worker role
rolebinding.create bool true specifies whether a RoleBinding should be created
serviceAccount.annotations object {} additional service account annotations (evaluated as a template)
serviceAccount.create bool true specifies whether a ServiceAccount should be created
serviceAccount.name string "" the name of the ServiceAccount to use. if not set and create is true, a name is generated using the common.names.fullname template
worker.affinity object {} affinity for worker pods assignment
worker.apiConfig string "cloud" one of 'cloud', 'selfHosted', or 'server'
worker.autoscaling.enabled bool false enable autoscaling for the worker
worker.autoscaling.maxReplicas int 1 maximum number of replicas to scale up to
worker.autoscaling.minReplicas int 1 minimum number of replicas to scale down to
worker.autoscaling.targetCPUUtilizationPercentage int 80 target CPU utilization percentage for scaling the worker
worker.autoscaling.targetMemoryUtilizationPercentage int 80 target memory utilization percentage for scaling the worker
worker.cloudApiConfig.accountId string "" prefect account ID
worker.cloudApiConfig.apiKeySecret.key string "key" prefect API secret key
worker.cloudApiConfig.apiKeySecret.name string "prefect-api-key" prefect API secret name
worker.cloudApiConfig.cloudUrl string "https://api.prefect.cloud/api" prefect cloud API url; the full URL is constructed as https://cloudUrl/accounts/accountId/workspaces/workspaceId
worker.cloudApiConfig.workspaceId string "" prefect workspace ID
worker.clusterUid string "" unique cluster identifier, if none is provided this value will be infered at time of helm install
worker.config.baseJobTemplate.configuration string nil JSON formatted base job template. If data is provided here, the chart will generate a configmap and mount it to the worker pod
worker.config.baseJobTemplate.existingConfigMapName string "" the name of an existing ConfigMap containing a base job template. NOTE - the key must be 'baseJobTemplate.json'
worker.config.http2 bool true connect using HTTP/2 if the server supports it (experimental)
worker.config.installPolicy string "prompt" install policy to use workers from Prefect integration packages.
worker.config.limit string nil maximum number of flow runs to start simultaneously (default: unlimited)
worker.config.name string nil the name to give to the started worker. If not provided, a unique name will be generated.
worker.config.prefetchSeconds int 10 when querying for runs, how many seconds in the future can they be scheduled
worker.config.queryInterval int 5 how often the worker will query for runs
worker.config.type string "kubernetes" specify the worker type
worker.config.workPool string "" the work pool that your started worker will poll.
worker.config.workQueues list [] one or more work queue names for the worker to pull from. if not provided, the worker will pull from all work queues in the work pool
worker.containerSecurityContext.allowPrivilegeEscalation bool false set worker containers' security context allowPrivilegeEscalation
worker.containerSecurityContext.capabilities object {} set worker container's security context capabilities
worker.containerSecurityContext.readOnlyRootFilesystem bool true set worker containers' security context readOnlyRootFilesystem
worker.containerSecurityContext.runAsNonRoot bool true set worker containers' security context runAsNonRoot
worker.containerSecurityContext.runAsUser int 1001 set worker containers' security context runAsUser
worker.extraArgs list [] array with extra Arguments for the worker container to start with
worker.extraContainers list [] additional sidecar containers
worker.extraEnvVars list [] array with extra environment variables to add to worker nodes
worker.extraEnvVarsCM string "" name of existing ConfigMap containing extra env vars to add to worker nodes
worker.extraEnvVarsSecret string "" name of existing Secret containing extra env vars to add to worker nodes
worker.extraVolumeMounts list [] array with extra volumeMounts for the worker pod
worker.extraVolumes list [] array with extra volumes for the worker pod
worker.image.debug bool false enable worker image debug mode
worker.image.prefectTag string "3-python3.11-kubernetes" prefect image tag (immutable tags are recommended)
worker.image.pullPolicy string "IfNotPresent" worker image pull policy
worker.image.pullSecrets list [] worker image pull secrets
worker.image.repository string "prefecthq/prefect" worker image repository
worker.initContainer.containerSecurityContext object {"allowPrivilegeEscalation":false,"capabilities":{},"readOnlyRootFilesystem":true,"runAsNonRoot":true,"runAsUser":1001} security context for the sync-base-job-template initContainer
worker.initContainer.containerSecurityContext.allowPrivilegeEscalation bool false set init containers' security context allowPrivilegeEscalation
worker.initContainer.containerSecurityContext.capabilities object {} set init container's security context capabilities
worker.initContainer.containerSecurityContext.readOnlyRootFilesystem bool true set init containers' security context readOnlyRootFilesystem
worker.initContainer.containerSecurityContext.runAsNonRoot bool true set init containers' security context runAsNonRoot
worker.initContainer.containerSecurityContext.runAsUser int 1001 set init containers' security context runAsUser
worker.initContainer.resources object {} the resource specifications for the sync-base-job-template initContainer Defaults to the resources defined for the worker container
worker.livenessProbe.config.failureThreshold int 3 The number of consecutive failures allowed before considering the probe as failed.
worker.livenessProbe.config.initialDelaySeconds int 10 The number of seconds to wait before starting the first probe.
worker.livenessProbe.config.periodSeconds int 10 The number of seconds to wait between consecutive probes.
worker.livenessProbe.config.successThreshold int 1 The minimum consecutive successes required to consider the probe successful.
worker.livenessProbe.config.timeoutSeconds int 5 The number of seconds to wait for a probe response before considering it as failed.
worker.livenessProbe.enabled bool false
worker.nodeSelector object {} node labels for worker pods assignment
worker.podAnnotations object {} extra annotations for worker pod
worker.podLabels object {} extra labels for worker pod
worker.podSecurityContext.fsGroup int 1001 set worker pod's security context fsGroup
worker.podSecurityContext.runAsNonRoot bool true set worker pod's security context runAsNonRoot
worker.podSecurityContext.runAsUser int 1001 set worker pod's security context runAsUser
worker.priorityClassName string "" priority class name to use for the worker pods; if the priority class is empty or doesn't exist, the worker pods are scheduled without a priority class
worker.replicaCount int 1 number of worker replicas to deploy
worker.resources.limits object {"cpu":"1000m","memory":"1Gi"} the requested limits for the worker container
worker.resources.requests object {"cpu":"100m","memory":"256Mi"} the requested resources for the worker container
worker.revisionHistoryLimit int 10 the number of old ReplicaSets to retain to allow rollback
worker.selfHostedCloudApiConfig.accountId string "" prefect account ID
worker.selfHostedCloudApiConfig.apiKeySecret.key string "key" prefect API secret key
worker.selfHostedCloudApiConfig.apiKeySecret.name string "prefect-api-key" prefect API secret name
worker.selfHostedCloudApiConfig.apiUrl string "" prefect API url (PREFECT_API_URL)
worker.selfHostedCloudApiConfig.uiUrl string "" self hosted UI url
worker.selfHostedCloudApiConfig.workspaceId string "" prefect workspace ID
worker.serverApiConfig.apiUrl string "" prefect API url (PREFECT_API_URL)
worker.serverApiConfig.uiUrl string "http://localhost:4200" prefect UI url
worker.tolerations list [] tolerations for worker pods assignment

Autogenerated from chart metadata using helm-docs v1.13.1