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https://github.com/hahow/common-chart
A Helm helper chart for building Helm charts
https://github.com/hahow/common-chart
helm helm-chart
Last synced: 15 days ago
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A Helm helper chart for building Helm charts
- Host: GitHub
- URL: https://github.com/hahow/common-chart
- Owner: hahow
- Created: 2020-04-15T06:45:54.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2023-09-22T08:12:09.000Z (over 1 year ago)
- Last Synced: 2024-11-17T14:34:34.790Z (3 months ago)
- Topics: helm, helm-chart
- Language: Mustache
- Size: 122 KB
- Stars: 23
- Watchers: 18
- Forks: 3
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
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README
# Common: The Helm Helper Chart
This chart was originally forked from [`incubator/common`](https://github.com/helm/charts/tree/master/incubator/common), which is designed to make it easier for you to build and maintain Helm charts.
It provides utilities that reflect best practices of Kubernetes chart development, making it faster for you to write charts.
## Contents
- [Getting Started](#getting-started)
- [Adding Repository](#adding-repository)
- [Adding Dependency](#adding-dependency)
- [Using Starter](#using-starter)
- [Resource Kinds](#resource-kinds)
- [`common.configMap`](#commonconfigmap)
- [`common.cronJob`](#commoncronjob)
- [`common.deployment`](#commondeployment)
- [`common.hpa`](#commonhpa)
- [`common.ingress`](#commoningress)
- [`common.pdb`](#commonpdb)
- [`common.secret`](#commonsecret)
- [`common.service`](#commonservice)
- [`common.serviceAccount`](#commonserviceaccount)
- [`common.serviceMonitor`](#commonservicemonitor)
- [`common.serviceMonitor.secret`](#commonservicemonitorsecret)
- [Partial Objects](#partial-objects)
- [`common.chart`](#commonchart)
- [`common.container`](#commoncontainer)
- [`common.fullname`](#commonfullname)
- [`common.labels`](#commonlabels)
- [`common.metadata`](#commonmetadata)
- [`common.name`](#commonname)
- [`common.pod.template`](#commonpodtemplate)
- [`common.selectorLabels`](#commonselectorlabels)
- [`common.serviceAccountName`](#commonserviceaccountname)
## Getting Started
### Adding Repository
The following command allows you to download and install all the charts from our repository:
```shell
$ helm repo add hahow https://hahow-helm-charts.storage.googleapis.com/
```
### Adding Dependency
To use the library chart, `common` should be listed in `dependencies` field in your `Chart.yaml`:
```yaml
dependencies:
- name: common
version: 0.4.1
repository: https://hahow-helm-charts.storage.googleapis.com/
```
Once you have defined dependencies, you should run the following command to download this chart into your `charts/` directory:
```shell
$ helm dep build
```
### Using Starter
The best way to get started is to use the [`create` script](create.sh) to generate a new chart.
You can fetch that script, and then execute it locally:
```shell
$ curl -fsSL -o create.sh https://raw.githubusercontent.com/hahow/common-chart/master/create.sh
$ chmod 700 create.sh
$ ./create.sh mychart
```
or simply
```shell
$ curl https://raw.githubusercontent.com/hahow/common-chart/master/create.sh | bash -s -- mychart
```
Now, there is a chart in `./mychart`. You can edit it and create your own templates.
## Resource Kinds
Kubernetes defines a variety of resource kinds, from `Secret` to `StatefulSet`. We define some of the most common kinds in a way that lets you easily work with them.
The resource kind templates are designed to make it much faster for you to define _basic_ versions of these resources. They allow you to extend and modify just what you need, without having to copy around lots of boilerplate.
To make use of these templates you must define a template that will extend the base template (though it can be empty). The name of this template is then passed to the base template, for example:
```yaml
{{- include "common.service" (list . .Values.service "mychart.service") }}
{{- define "mychart.service" -}}
## Define overrides for your Service resource here, e.g.
# metadata:
# labels:
# custom: label
# spec:
# ports:
# - port: 8080
# targetPort: http
# protocol: TCP
# name: http
{{- end }}
```
Note that the [`common.service`](#commonservice) template defines three parameters:
- The root context (usually `.`)
- A dictionary of values which are used in the template
- A optional template name containing the service definition overrides
A limitation of the Go template library is that a template can only take a single argument. The `list` function is used to workaround this by constructing a list or array of arguments that is passed to the template.
The [`common.service`](#commonservice) template is responsible for rendering the templates with the root context and merging any overrides. As you can see, this makes it very easy to create a basic `Service` resource without having to copy around the standard metadata and labels.
Each implemented base resource is described in greater detail below.
### `common.configMap`
The `common.configMap` template accepts a list of two values:
- `$top`, the top context
- [optional] the template name of the overrides
It creates an empty `ConfigMap` resource that you can override with your configuration.
Example use:
```yaml
{{- include "common.configMap" (list . "mychart.configMap") }}
{{- define "mychart.configMap" -}}
data:
zeus: cat
athena: cat
julius: cat
one: |-
{{ .Files.Get "file1.txt" }}
{{- end }}
```
Output:
```yaml
apiVersion: v1
data:
athena: cat
julius: cat
one: This is a file.
zeus: cat
kind: ConfigMap
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
```
### `common.cronJob`
The `common.cronJob` template accepts a list of five values:
- `$top`, the top context
- `$cronJob`, a dictionary of values used in the cronjob template
- `$pod`, a dictionary of values used in the pod template
- `$serviceAccount`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It defines a basic `CronJob` with the following defaults:
- Labels of `JobTemplate` are defined with [`common.selectorLabels`](#commonselectorlabels) as this is also used as the selector.
- Restart policy of pod is set to `OnFailure`
In addition, it uses the following configuration from the `$cronJob`:
| Value | Description |
| ------------------------------------- | ------------------------------------------------------- |
| `$cronJob.schedule` | Schedule for the cronjob |
| `$cronJob.concurrencyPolicy` | [optional] `Allow\|Forbid\|Replace` concurrent jobs |
| `$cronJob.failedJobsHistoryLimit` | [optional] Specify the number of failed jobs to keep |
| `$cronJob.successfulJobsHistoryLimit` | [optional] Specify the number of completed jobs to keep |
| `$cronJob.suspend` | [optional] Specify cronjob is suspend, default false |
| `$cronJob.activeDeadlineSeconds` | [optional] Specify cronjob activeDeadlineSeconds |
Underneath the hood, it invokes [`common.pod.template`](#commonpodtemplate) template with `$pod` to populate the `PodTemplate`.
Example use:
```yaml
{
{
- include "common.cronJob" (list . .Values.cronJob .Values .Values.serviceAccount),
},
}
## The following is the same as above:
# {{- include "common.cronJob" (list . .Values.cronJob .Values .Values.serviceAccount "mychart.cronJob") }}
# {{- define "mychart.cronJob" -}}
# {{- end }}
```
### `common.deployment`
The `common.deployment` template accepts a list of five values:
- `$top`, the top context
- `$deployment`, a dictionary of values used in the deployment template
- `$autoscaling`, a dictionary of values used in the hpa template
- `$serviceAccount`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It defines a basic `Deployment` with the following settings:
| Value | Description |
| -------------------------------- | -------------------------------------------------------------------------- |
| `$deployment.replicaCount` | Number of replica. If autoscaling enabled, this field will be ignored |
| `$deployment.imagePullSecrets` | [optional] Name of Secret resource containing private registry credentials |
| `$deployment.podSecurityContext` | [optional] Security options for pod |
| `$deployment.nodeSelector` | [optional] Node labels for pod assignment |
| `$deployment.affinity` | [optional] Expressions for affinity |
| `$deployment.tolerations` | [optional] Toleration labels for pod assignment |
| `$autoscaling.enabled` | [optional] Set this to `true` to enable autoscaling |
Underneath the hood, it invokes [`common.pod.template`](#commonpodtemplate) template with `$deployment` to populate the `PodTemplate`.
Example use:
```yaml
{
{
- include "common.deployment" (list . .Values .Values.autoscaling .Values.serviceAccount),
},
}
## The following is the same as above:
# {{- include "common.deployment" (list . .Values .Values.autoscaling .Values.serviceAccount "mychart.deployment") }}
# {{- define "mychart.deployment" -}}
# {{- end }}
```
### `common.hpa`
The `common.hpa` template accepts a list of three values:
- `$top`, the top context
- `$autoscaling`, a dictionary of values used in the hpa template
- [optional] the template name of the overrides
It creates a basic `HorizontalPodAutoscaler` resource with the following defaults:
- The name of scaled target is set with [`common.fullname`](#commonfullname)
An example values file that can be used to configure the `HorizontalPodAutoscaler` resource is:
```yaml
autoscaling:
enabled: true
minReplicas: 3
maxReplicas: 5
cpuUtilizationPercentage: 50
memoryUtilizationPercentage: 90
```
Example use:
```yaml
{ { - include "common.hpa" (list . .Values.autoscaling) } }
## The following is the same as above:
# {{- include "common.hpa" (list . .Values.autoscaling "mychart.hpa") }}
# {{- define "mychart.hpa" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
spec:
maxReplicas: 5
metrics:
- resource:
name: cpu
target:
averageUtilization: 50
type: Utilization
type: Resource
- resource:
name: memory
target:
averageUtilization: 90
type: Utilization
type: Resource
minReplicas: 3
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: release-name-mychart
```
### `common.ingress`
The `common.ingress` template accepts a list of four values:
- `$top`, the top context
- `$ingress`, a dictionary of values used in the ingress template
- `$service`, a dictionary of values used in the service template
- [optional] the template name of the overrides
It is designed to give you a well-defined `Ingress` resource, that can be configured using `$ingress`. An example values file that can be used to configure the `Ingress` resource is:
```yaml
ingress:
enabled: true
annotations:
kubernetes.io/ingress.class: nginx
kubernetes.io/tls-acme: "true"
hosts:
- host: chart-example.local
paths:
- path: /path/to/somewhere
pathType: ImplementationSpecific
tls:
- secretName: chart-example-tls
hosts:
- chart-example.local
service:
type: ClusterIP
port: 80
```
Example use:
```yaml
{ { - include "common.ingress" (list . .Values.ingress .Values.service) } }
## The following is the same as above:
# {{- include "common.ingress" (list . .Values.ingress .Values.service "mychart.ingress") }}
# {{- define "mychart.ingress" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
annotations:
kubernetes.io/ingress.class: nginx
kubernetes.io/tls-acme: "true"
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
spec:
rules:
- host: "chart-example.local"
http:
paths:
- backend:
service:
name: release-name-mychart
port:
number: 80
path: /path/to/somewhere
pathType: ImplementationSpecific
tls:
- hosts:
- "chart-example.local"
secretName: chart-example-tls
```
### `common.pdb`
The `common.pdb` template accepts a list of five values:
- `$top`, the top context
- `$pdb`, a dictionary of values used in the hpa template
- `$deployment`, a dictionary of values used in the deployment template
- `$autoscaling`, a dictionary of values used in the hpa template
- [optional] the template name of the overrides
It creates a basic `PodDisruptionBudget` resource with the following defaults:
- Selector is set with [`common.selectorLabels`](#commonselectorlabels) to match the default used in the `Pod` resource
An example values file that can be used to configure the `PodDisruptionBudget` resource is:
```yaml
podDisruptionBudget:
## You can specify only one of maxUnavailable and minAvailable in a single PodDisruptionBudget
minAvailable: 2
# maxUnavailable: 1
```
Example use:
```yaml
{
{
- include "common.pdb" (list . .Values.podDisruptionBudget .Values .Values.autoscaling),
},
}
## The following is the same as above:
# {{- include "common.pdb" (list . .Values.podDisruptionBudget .Values .Values.autoscaling "mychart.pdb") }}
# {{- define "mychart.pdb" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
spec:
minAvailable: 2
selector:
matchLabels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
```
### `common.secret`
The `common.secret` template accepts a list of two values:
- `$top`, the top context
- [optional] the template name of the overrides
It creates an empty `Secret` resource that you can override with your secrets.
Example use:
```yaml
{{- include "common.secret" (list . "mychart.secret") }}
{{- define "mychart.secret" -}}
data:
zeus: {{ print "cat" | b64enc }}
athena: {{ print "cat" | b64enc }}
julius: {{ print "cat" | b64enc }}
one: |-
{{ .Files.Get "file1.txt" | b64enc }}
{{- end }}
```
Output:
```yaml
apiVersion: v1
data:
athena: Y2F0
julius: Y2F0
one: VGhpcyBpcyBhIGZpbGUuCg==
zeus: Y2F0
kind: Secret
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
type: Opaque
```
### `common.service`
The `common.service` template accepts a list of three values:
- `$top`, the top context
- `$service`, a dictionary of values used in the service template
- [optional] the template name of the overrides
It creates a basic `Service` resource with the following defaults:
- Service type (ClusterIP, NodePort, LoadBalancer) made configurable by `$service.type`
- Named port `http` configured on port `$service.port`
- Selector set with [`common.selectorLabels`](#commonselectorlabels) to match the default used in the `Deployment` resource
Example template:
```yaml
{{- include "common.service" (list . .Values.service "mychart.mail.service") }}
{{- define "mychart.mail.service" -}}
{{- $top := first . }}
metadata:
name: {{ include "common.fullname" $top }}-mail # overrides the default name to add a suffix
labels: # appended to the labels section
protocol: mail
spec:
ports: # composes the `ports` section of the service definition.
- name: smtp
port: 25
targetPort: 25
- name: imaps
port: 993
targetPort: 993
selector: # this is appended to the default selector
protocol: mail
{{- end }}
---
{{ include "common.service" (list . .Values.service "mychart.web.service") }}
{{- define "mychart.web.service" -}}
{{- $top := first . }}
metadata:
name: {{ include "common.fullname" $top }}-www # overrides the default name to add a suffix
labels: # appended to the labels section
protocol: www
spec:
ports: # composes the `ports` section of the service definition.
- name: www
port: 80
targetPort: 8080
{{- end }}
```
The above template defines _two_ services: a web service and a mail service.
The most important part of a service definition is the `ports` object, which defines the ports that this service will listen on. Most of the time, `selector` is computed for you. But you can replace it or add to it.
The output of the example above is:
```yaml
apiVersion: v1
kind: Service
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
protocol: www
name: release-name-mychart-www
spec:
ports:
- name: www
port: 80
targetPort: 8080
selector:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
type: ClusterIP
---
apiVersion: v1
kind: Service
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
protocol: mail
name: release-name-mychart-mail
spec:
ports:
- name: smtp
port: 25
targetPort: 25
- name: imaps
port: 993
targetPort: 993
selector:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
protocol: mail
type: ClusterIP
```
### `common.serviceAccount`
The `common.serviceAccount` template accepts a list of three values:
- `$top`, the top context
- `$serviceAccount`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It creates a basic `ServiceAccount` resource with the following defaults:
- The name is set with [`common.serviceAccountName`](#commonserviceaccountname)
- Lays out the annotations using `$serviceAccount.annotations`
An example values file that can be used to configure the `ServiceAccount` resource is:
```yaml
serviceAccount:
create: true
annotations: {}
name:
```
Example use:
```yaml
{ { - include "common.serviceAccount" (list . .Values.serviceAccount) } }
## The following is the same as above:
# {{- include "common.serviceAccount" (list . .Values.serviceAccount "mychart.serviceAccount") }}
# {{- define "mychart.serviceAccount" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
```
### `common.serviceMonitor`
The `common.serviceMonitor` template accepts a list of three values:
- `$top`, the top context
- `$serviceMonitor`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It creates a basic `ServiceMonitor` resource with the following defaults:
- Namespace selector is set to the release namespace
- Selector is set with [`common.selectorLabels`](#commonselectorlabels) to match the default used in the `Service` resource
An example values file that can be used to configure the `ServiceMonitor` resource is:
```yaml
serviceMonitor:
enabled: true
namespace: monitoring
port: 80
path: /path/to/metrics
interval: 30s
scrapeTimeout: 30s
basicAuth:
enabled: true
username: administrator
password: password
```
Example use:
```yaml
{ { - include "common.serviceMonitor" (list . .Values.serviceMonitor) } }
## The following is the same as above:
# {{- include "common.serviceMonitor" (list . .Values.serviceMonitor "mychart.serviceMonitor") }}
# {{- define "mychart.serviceMonitor" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
namespace: monitoring
spec:
endpoints:
- basicAuth:
password:
key: password
name: release-name-mychart
username:
key: username
name: release-name-mychart
interval: 30s
path: /path/to/metrics
port: 80
scrapeTimeout: 30s
namespaceSelector:
matchNames:
- default
selector:
matchLabels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
```
### `common.serviceMonitor.secret`
The `common.serviceMonitor.secret` template accepts a list of three values:
- `$top`, the top context
- `$serviceMonitor`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It creates a `Secret` resource contains the BasicAuth information for the `ServiceMonitor`.
An example `values.yaml` for your `ServiceMonitor` could look like:
```yaml
serviceMonitor:
basicAuth:
enabled: true
username: administrator
password: password
```
Example use:
```yaml
{ { - include "common.serviceMonitor.secret" (list . .Values.serviceMonitor) } }
## The following is the same as above:
# {{- include "common.serviceMonitor.secret" (list . .Values.serviceMonitor "mychart.serviceMonitor.secret") }}
# {{- define "mychart.serviceMonitor.secret" -}}
# {{- end }}
```
Output:
```yaml
apiVersion: v1
data:
password: cGFzc3dvcmQ=
username: YWRtaW5pc3RyYXRvcg==
kind: Secret
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
namespace: monitoring
type: Opaque
```
## Partial Objects
When writing Kubernetes resources, you may find the following helpers useful to construct parts of the spec.
### `common.chart`
The `common.chart` helper prints the chart name and version, escaped to be legal in a Kubernetes label field.
Example template:
```yaml
helm.sh/chart: { { include "common.chart" . } }
```
For the chart `foo` with version `1.2.3-beta.55+1234`, this will render:
```yaml
helm.sh/chart: foo-1.2.3-beta.55_1234
```
(Note that `+` is an illegal character in label values)
### `common.container`
The `common.container` template accepts a list of three values:
- `$top`, the top context
- `$container`, a dictionary of values used in the container template
- [optional] the template name of the overrides
It creates a basic `Container` spec to be used within a `Deployment` or `CronJob`. It holds the following defaults:
- The name is set to the chart name
- Uses `$container.image` to describe the image to run, with the following spec:
```yaml
image:
repository: nginx
tag: stable
pullPolicy: IfNotPresent
```
- Lays out the security options using `$container.securityContext`
- Lays out the compute resources using `$container.resources`
Example use:
```yaml
{{- include "common.deployment" (list . .Values .Values.autoscaling "mychart.deployment") }}
{{- define "mychart.deployment" -}}
## Define overrides for your Deployment resource here, e.g.
{{- $top := first . }}
{{- $deployment := index . 1 }}
spec:
template:
spec:
containers:
- {{- include "common.container" (list $top $deployment "mychart.deployment.container") | nindent 8 }}
{{- end }}
{{- define "mychart.deployment.container" -}}
## Define overrides for your Container here, e.g.
ports:
- name: http
containerPort: 80
protocol: TCP
livenessProbe:
httpGet:
path: /
port: http
readinessProbe:
httpGet:
path: /
port: http
{{- end }}
```
The above example creates a `Deployment` resource which makes use of the `common.container` template to populate the `PodSpec`'s container list. The usage of this template is similar to the other resources, you must define and reference a template that contains overrides for the container object.
The most important part of a container definition is the image you want to run. As mentioned above, this is derived from `$container.image` by default. It is a best practice to define the image, tag and pull policy in your charts' values as this makes it easy for an operator to change the image registry, or use a specific tag or version. Another example of configuration that should be exposed to chart operators is the container's required compute resources, as this is also very specific to an operators environment. An example `values.yaml` for your chart could look like:
```yaml
replicaCount: 1
image:
repository: nginx
tag: stable
pullPolicy: IfNotPresent
securityContext:
capabilities:
drop:
- ALL
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
resources:
limits:
cpu: 100m
memory: 128Mi
requests:
cpu: 100m
memory: 128Mi
```
The output of running the above values through the earlier template is:
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
spec:
replicas: 1
selector:
matchLabels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
template:
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
spec:
containers:
- image: nginx:stable
imagePullPolicy: IfNotPresent
livenessProbe:
httpGet:
path: /
port: http
name: mychart
ports:
- containerPort: 80
name: http
protocol: TCP
readinessProbe:
httpGet:
path: /
port: http
resources:
limits:
cpu: 100m
memory: 128Mi
requests:
cpu: 100m
memory: 128Mi
securityContext:
capabilities:
drop:
- ALL
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
serviceAccountName: release-name-mychart
```
### `common.fullname`
The `common.fullname` template generates a name suitable for the `name:` field in Kubernetes metadata. It is used like this:
```yaml
name: { { include "common.fullname" . } }
```
This prints the value of `{{ .Release.Name }}-{{ .Chart.Name }}` by default, but can be overridden with `.Values. fullnameOverride`:
```yaml
fullnameOverride: some-name
```
Example output:
```yaml
---
# with the values above
name: some-name
---
# the default, for release "release-name" and chart "mychart"
name: release-name-mychart
```
Output of this function is truncated at 63 characters, which is the maximum length of name.
### `common.labels`
`common.selectorLabels` prints the standard set of labels.
Example usage:
```
{{ include "common.labels" . }}
```
Example output:
```yaml
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
```
### `common.metadata`
The `common.metadata` helper generates value for the `metadata:` section of a Kubernetes resource.
This takes a list of two values:
- `$top`, the top context
- [optional] the template name of the overrides
It generates standard labels and a name field.
Example template:
```yaml
metadata: { { - include "common.metadata" (list .) | nindent 2 } }
## The following is the same as above:
# metadata:
# {{- include "common.metadata" (list . "mychart.metadata") | nindent 2 }}
# {{- define "mychart.metadata" -}}
# {{- end }}
```
Example output:
```yaml
metadata:
labels:
app.kubernetes.io/instance: release-name
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: mychart
app.kubernetes.io/version: 1.16.0
helm.sh/chart: mychart-0.1.0
name: release-name-mychart
```
Most of the common templates that define a resource type (e.g. `common.configMap` or `common.cronJob`) use this to generate the metadata, which means they inherit the same `labels` and `name` fields.
### `common.name`
The `common.name` template generates a name suitable for the `app.kubernetes.io/name` label. It is used like this:
```yaml
app.kubernetes.io/name: { { include "common.name" . } }
```
This prints the value of `{{ .Chart.Name }}` by default, but can be overridden with `.Values.nameOverride`:
```yaml
nameOverride: some-name
```
Example output:
```yaml
---
# with the values above
app.kubernetes.io/name: some-name
---
# the default, for chart "mychart"
app.kubernetes.io/name: mychart
```
Output of this function is truncated at 63 characters, which is the maximum length of name.
### `common.pod.template`
The `common.pod.template` template accepts a list of four values:
- `$top`, the top context
- `$pod`, a dictionary of values used in the container template
- `$serviceAccount`, a dictionary of values used in the service account template
- [optional] the template name of the overrides
It creates a basic `PodTemplate` spec to be used within a `Deployment` or `CronJob`. It holds the following defaults:
- Labels are defined with [`common.selectorLabels`](#commonselectorlabels) as this is also used as the selector.
- Service account name is set with [`common.serviceAccountName`](#commonserviceaccountname)
It also uses the following configuration from the `$pod`:
| Value | Description |
| ------------------------- | -------------------------------------------------------- |
| `$pod.imagePullSecrets` | Names of secrets containing private registry credentials |
| `$pod.podAnnotations` | Pod annotations |
| `$pod.podSecurityContext` | Security options |
| `$pod.nodeSelector ` | Node labels for pod assignment |
| `$pod.affinity ` | Expressions for affinity |
| `$pod.tolerations ` | Toleration labels for pod assignment |
| `$pod.podLabels` | Pod extra labels |
| `$pod.priorityClassName` | Pod priorityClassName |
Underneath the hood, it invokes [`common.container`](#commoncontainer) template with `$pod` to populate the `PodSpec`'s container list.
### `common.selectorLabels`
`common.selectorLabels` prints the standard set of selector labels.
Example usage:
```
{{ include "common.selectorLabels" . }}
```
Example output:
```yaml
app.kubernetes.io/instance: release-name
app.kubernetes.io/name: mychart
```
### `common.serviceAccountName`
The `common.serviceAccountName` template accepts a list of two values:
- `$top`, the top context
- `$serviceAccount`, a dictionary of values used in the service account template
It generates a name suitable for the `serviceAccountName` field of a `Pod` resource.
Example usage:
```
serviceAccountName: {{ include "common.serviceAccountName" . .Values.serviceAccount }}
```
The following values can influence the output:
```yaml
serviceAccount:
create: true
# The name of the service account to use.
# If not set and create is true, a name is generated using the fullname template
name: some-name
```
Example output:
```yaml
---
# with the values above
serviceAccountName: some-name
---
# if serviceAccount.name is not set, the value will be the same as "common.fullname"
serviceAccountName: release-name-mychart
---
# if serviceAccount.create is false, the value will be "default"
serviceAccountName: default
```