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Guidelines: set matchLabels as being mandatory (#7692)

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* Guidelines: set matchLabels as being mandatory.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* fixup! Guidelines: set matchLabels as being mandatory.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* fixup! fixup! Guidelines: set matchLabels as being mandatory.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* Update guidelines: mention DaemonSets as well.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* Review guidelines: be more precise + specify upgrade

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* Review guidelines: fix typos, add persistence paragraph and do not repeat component part.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* Review guidelines: add PVC paragraph.

Signed-off-by: Cédric de Saint Martin <cdesaintmartin@wiremind.fr>

* Fix spelling/typos

Signed-off-by: Reinhard Nägele <unguiculus@gmail.com>

* Fix incorrect typo fix

Signed-off-by: Reinhard Nägele <unguiculus@gmail.com>
This commit is contained in:
Cédric de Saint Martin
2018-10-24 11:30:53 -07:00
committed by k8s-ci-robot
parent dd44567cec
commit 234f0ebf45
1 changed files with 56 additions and 3 deletions
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REVIEW_GUIDELINES.md
+56 -3
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@@ -33,7 +33,8 @@ Stable charts should not depend on charts in incubator.
## Names and Labels
Resources and labels should follow some conventions. The standard resource metadata should be this:
### Metadata
Resources and labels should follow some conventions. The standard resource metadata (`metadata.labels` and `spec.template.metadata.labels`) should be this:
```yaml
name: {{ template "myapp.fullname" . }}
@@ -44,8 +45,41 @@ labels:
heritage: {{ .Release.Service }}
```
If a chart has multiple components, a `component` label should be added (e. g. `component: server`). The resource name should get the component as suffix (e. g. `name: {{ template "myapp.fullname" . }}-server`).
Note that templates have to be namespaced. With Helm 2.7+, `helm create` does this out-of-the-box. The `app` label should use the `name` template, not `fullname` as is still the case with older charts.
### Deployments, StatefulSets, DaemonSets Selectors
`spec.selector.matchLabels` must be specified should follow some conventions. The standard selector should be this:
```yaml
selector:
matchLabels:
app: {{ template "myapp.name" . }}
release: {{ .Release.Name }}
```
If a chart has multiple components, a `component` label should be added to the selector (see above).
`spec.selector.matchLabels` defined in `Deployments`/`StatefulSets`/`DaemonSets` `>=v1/beta2` **must not** contain `chart` label or any label containing a version of the chart, because the selector is immutable.
The chart label string contains the version, so if it is specified, whenever the the Chart.yaml version changes, Helm's attempt to change this immutable field would cause the upgrade to fail.
#### Fixing Selectors
##### For Deployments, StatefulSets, DaemonSets apps/v1beta1 or extensions/v1beta1
- If it does not specify `spec.selector.matchLabels`, set it
- Remove `chart` label in `spec.selector.matchLabels` if it exists
- Bump patch version of the Chart
##### For Deployments, StatefulSets, DaemonSets >=apps/v1beta2
- Remove `chart` label in `spec.selector.matchLabels` if it exists
- Bump major version of the Chart as it is a breaking change
### Service Selectors
Label selectors for services must have both `app` and `release` labels.
```yaml
@@ -54,7 +88,26 @@ selector:
release: {{ .Release.Name }}
```
If a chart has multiple components, a `component` label should be added (e. g. `component: server`). The resource name should get the component as suffix (e. g. `name: {{ template "myapp.fullname" . }}-server`). The `component` label must be added to label selectors as well.
If a chart has multiple components, a `component` label should be added to the selector (see above).
### Persistence Labels
### StatefulSet
In case of a `Statefulset`, `spec.volumeClaimTemplates.metadata.labels` must have both `app` and `release` labels, and **must not** contain `chart` label or any label containing a version of the chart, because `spec.volumeClaimTemplates` is immutable.
```yaml
labels:
app: {{ template "myapp.name" . }}
release: {{ .Release.Name }}
```
If a chart has multiple components, a `component` label should be added to the selector (see above).
### PersistentVolumeClaim
In case of a `PersistentVolumeClaim`, unless special needs, `matchLabels` should not be specified
because it would prevent automatic `PersistentVolume` provisioning.
## Formatting
@@ -269,7 +322,7 @@ spec:
We officially support compatibility with the current and the previous minor version of Kubernetes. Generated resources should use the latest possible API versions compatible with these versions. For extended backwards compatibility conditional logic based on capabilities may be used (see [built-in objects](https://github.com/helm/helm/blob/master/docs/chart_template_guide/builtin_objects.md)).
## Kubernetes Native Workloads.
## Kubernetes Native Workloads
While reviewing Charts that contain workloads such as [Deployments](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/), [StatefulSets](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/), [DaemonSets](https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/) and [Jobs](https://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/) the below points should be considered. These are to be seen as best practices rather than strict enforcement.