Helm Library

Helm library chart

Including the library chart

In your microservice Helm chart:

• Update Chart.yaml to apiVersion: v2.
• Add the library chart under dependencies and choose the version you want (example below). Version number can include ~ or ^ to pick up latest PATCH and MINOR versions respectively.
• Issue the following commands to add the repo that contains the library chart, update the repo, then update dependencies in your Helm chart:

helm repo add https://helm.lynxmagnus.com
helm repo update
helm dependency update <helm_chart_location>

An example Chart.yaml:

apiVersion: v2
description: A Helm chart
name: microservice
version: 1.0.0
dependencies:
- name: helm-library
  version: 1.0.0
  repository: https://helm.lynxmagnus.com

Cluster IP service template

• Template file: _cluster-ip-service.yaml
• Template name: helm-library.cluster-ip-service

A K8s Service object of type ClusterIP.

A basic usage of this object template would involve the creation of templates/cluster-ip-service.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.cluster-ip-service" (list . "microservice.service") -}}
{{- define "microservice.service" -}}
# Microservice specific configuration in here
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

container:
  port: <integer>

Container template

• Template file: _container.yaml
• Template name: helm-library.container

A template for the container definition to be used within a K8s Deployment object.

A basic usage of this object template would involve the creation of templates/_container.yaml in the parent Helm chart (e.g. microservice). Note the _ in the name. This template is part of the Deployment object definition and will be used in conjunction the _deployment.yaml template (see below). As a minimum templates/_container.yaml would define environment variables and may also include liveness/readiness probes when applicable e.g.:

{{- define "microservice.container" -}}
env: <list>
livenessProbe: <map>
readinessProbe: <map>
{{- end -}}

The liveness and readiness probes could take advantage of the helper templates for http GET probe and exec probe defined within the library chart and described below.

Required values

The following values need to be set in the parent chart's values.yaml:

container:
  requestMemory: <string>
  requestCpu: <string>
  limitMemory: <string>

Optional values

The following values can optionally be set in the parent chart's values.yaml to enable a command with arguments to run within the container:

container:
  command: <list of strings>
  args: <list of strings>
  resourceTier: <char> # S, M, L, XL - used in place of requestMemory, requestCpu, limitMemory

Deployment template

• Template file: _deployment.yaml
• Template name: helm-library.deployment

A K8s Deployment object.

A basic usage of this object template would involve the creation of templates/deployment.yaml in the parent Helm chart (e.g. microservice) that includes the template defined in _container.yaml template:

{{- include "helm-library.deployment" (list . "microservice.deployment") -}}
{{- define "microservice.deployment" -}}
{{- end -}}

Optional values

The following value can optionally be set in the parent chart's values.yaml to enable the configuration of imagePullSecrets in the K8s object:

deployment:
  imagePullSecret: <string>

StatefulSet template

• Template file: _statefulset.yaml
• Template name: helm-library.statefulset

A K8s StatefulSet object.

A basic usage of this object template would involve the creation of templates/statefulset.yaml in the parent Helm chart (e.g. microservice) that includes the template defined in _container.yaml template:

{{- include "helm-library.statefulset" (list . "microservice.deployment") -}}
{{- define "microservice.deployment" -}}
{{- end -}}

Ingress template

• Template file: _ingress.yaml
• Template name: helm-library.ingress

A K8s Ingress object that can be configured for Nginx or AWS ALB (Amazon Load Balancer).

A basic Nginx Ingress object would involve the creation of templates/ingress.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.ingress" (list . "microservice.ingress") -}}
{{- define "microservice.ingress" -}}
{{- end -}}

Required values

Optional values

The following values can optionally be set in the parent chart's values.yaml to set the value of host:

ingress:
  host: <string>

Postgres service template

• Template file: _postgres-service.yaml
• Template name: helm-library.postgres-service

A K8s Service object of type ExternalName configured to refer to a Postgres database hosted on a server outside of the K8s cluster such as AWS RDS.

A basic usage of this object template would involve the creation of templates/postgres-service.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.postgres-service" (list . "microservice.postgres-service") -}}
{{- define "microservice.postgres-service" -}}
# Microservice specific configuration in here
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

postgres:
  host: <string>
  externalName: <string>
  port: <integer>

Secret template

• Template file: _secret.yaml
• Template name: helm-library.secret

A K8s Secret object to host sensitive data such as a password or token.

A basic usage of this object template would involve the creation of templates/secret.yaml in the parent Helm chart (e.g. microservice), which should include the data map containing the sensitive data :

{{- include "helm-library.secret" (list . "microservice.secret") -}}
{{- define "microservice.secret" -}}
stringData:
  <key1>: <value1>
  ...
{{- end -}}

Service template

• Template file: _service.yaml
• Template name: helm-library.service

A generic K8s Service object requiring a service type to be set.

A basic usage of this object template would involve the creation of templates/secret.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.service" (list . "microservice.service") -}}
{{- define "microservice.service" -}}
# Microservice specific configuration in here
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

service:
  type: <string>

Cron Job template

• Template file: _cron-job.yaml
• Template name: helm-library.cron-job

A k8s CronJob.

A basic usage of this object template would involve the creation of templates/cron-job.yaml in the parent Helm chart (e.g. microservice) that includes the template defined in _container.yaml template:

{{- include "helm-library.cron-job" (list . "microservice.cron-job") -}}
{{- define "microservice.cron-job" -}}
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

cronJob:
  schedule: <string>
  concurrencyPolicy: <string>

Horizontal Pod Autoscaler template

• Template file: _horizontal-pod-autoscaler.yaml
• Template name: helm-library.horizontal-pod-autoscaler

A k8s HorizontalPodAutoscaler.

A basic usage of this object template would involve the creation of templates/horizontal-pod-autoscaler.yaml in the parent Helm chart (e.g. microservice).

{{- include "helm-library.horizontal-pod-autoscaler" (list . "microservice.horizontal-pod-autoscaler") -}}
{{- define "microservice.horizontal-pod-autoscaler" -}}
spec:
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50
  - type: Resource
    resource:
      name: memory
      target:
        type: AverageValue
        averageValue: 100Mi
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

deployment:
  minReplicas: <int>
  maxReplicas: <int>

Helper templates

In addition to the K8s object templates described above, a number of helper templates are defined in _helpers.tpl that are both used within the library chart and available to use within a consuming parent chart.

Default check required message

• Template name: helm-library.default-check-required-msg
• Usage: {{- include "helm-library.default-check-required-msg" . }}

A template defining the default message to print when checking for a required value within the library. This is not designed to be used outside of the library.

Labels

• Template name: helm-library.labels
• Usage: {{- include "helm-library.labels" . }}

Common labels to apply to metadata of all K8s objects on the K8s platform..

Selector labels

• Template name: helm-library.selector-labels
• Usage: {{- include "helm-library.selector-labels" . }}

Common selector labels that can be applied where necessary to K8s objects on the K8s platform.

Http GET probe

• Template name: helm-library.http-get-probe
• Usage: {{- include "helm-library.http-get-probe" (list . <map_of_probe_values>) }}

Template for configuration of an http GET probe, which can be used for readinessProbe and/or livenessProbe in a container definition within a Deployment (see container template). The following values need to be passed to the probe in the <map_of_probe_values>:

path: <string>
port: <integer>
initialDelaySeconds: <integer>
periodSeconds: <integer>
failureThreshold: <integer>

Exec probe

• Template name: helm-library.exec-probe
• Usage: {{- include "helm-library.exec-probe" (list . <map_of_probe_values>) }}

Template for configuration of an "exec" probe that runs a local script, which can be used for readinessProbe and/or livenessProbe in a container definition within a Deployment (see container template). The following values need to be passed to the probe in the <map_of_probe_values>:

script: <string>
initialDelaySeconds: <integer>
periodSeconds: <integer>
failureThreshold: <integer>

Azure Identity template

• Template file: _azure-identity.yaml
• Template name: helm-library.azure-identity

A K8s AzureIdentity object. Must be used in conjunction with the AzureIdentityBinding described below. The name of the template is set automatically based on the name of the Helm chart (as defined by name: in the values.yaml) to <name>-identity.

A basic usage of this object template would involve the creation of templates/azure-identity.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.azure-identity" (list . "microservice.azure-identity") -}}
{{- define "microservice.azure-identity" -}}
{{- end -}}

Required values

The following values need to be set in the parent chart's values.yaml:

azureIdentity:
  resourceID:
  clientID:

Azure Identity Binding template

• Template file: _azure-identity-binding.yaml
• Template name: helm-library.azure-identity-binding

A K8s AzureIdentityBinding object. Must be used in conjunction with the AzureIdentity described above. The name of the template is set automatically based on the name of the Helm chart (as defined by name: in the values.yaml) to <name>-identity-binding.

A basic usage of this object template would involve the creation of templates/azure-identity-binding.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.azure-identity-binding" (list . "microservice.azure-identity-binding") -}}
{{- define "microservice.azure-identity-binding" -}}
{{- end -}}

Infiscal secret

• Template file: _infiscal-secret.yaml
• Template name: helm-library.infiscal-secret

A K8s InfiscalSecret object.

A basic usage of this object template would involve the creation of templates/azure-identity-binding.yaml in the parent Helm chart (e.g. microservice) containing:

{{- include "helm-library.infiscal-secret" (list . "microservice.infiscal-secret") -}}
{{- define "microservice.infiscal-secret" -}}
{{- end -}}