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rename pod injection to pod preset
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Signed-off-by: Jess Frazelle <[email protected]>
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@jessfraz
jessfraz committed Feb 24, 2017
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94 changes: 47 additions & 47 deletions .../design-proposals/pod-injection-policy.md → contributors/design-proposals/pod-preset.md
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# Pod Injection Policy
# Pod Preset

* [Abstract](#abstract)
* [Motivation](#motivation)
Expand All @@ -8,15 +8,15 @@
* [Prior Art](#prior-art)
* [Objectives](#objectives)
* [Proposed Changes](#proposed-changes)
* [PodInjectionPolicy API object](#podinjectionpolicy-api-object)
* [PodPreset API object](#podpreset-api-object)
* [Validations](#validations)
* [AdmissionControl Plug-in: PodInjectionPolicy](#admissioncontrol-plug-in-podinjectionpolicy)
* [AdmissionControl Plug-in: PodPreset](#admissioncontrol-plug-in-podpreset)
* [Behavior](#behavior)
* [Examples](#examples)
* [Simple Pod Spec Example](#simple-pod-spec-example)
* [Pod Spec with `ConfigMap` Example](#pod-spec-with-`configmap`-example)
* [ReplicaSet with Pod Spec Example](#replicaset-with-pod-spec-example)
* [Multiple PodInjectionPolicy Example](#multiple-podinjectionpolicy-example)
* [Multiple PodPreset Example](#multiple-podpreset-example)
* [Conflict Example](#conflict-example)


Expand Down Expand Up @@ -67,7 +67,7 @@ information into every pod spec where it is needed.
1. Database Administrator provisions a MySQL service for their cluster.
2. Database Administrator creates secrets for the cluster containing the
database name, username, and password.
3. Database Administrator creates a `PodInjectionPolicy` defining the database
3. Database Administrator creates a `PodPreset` defining the database
port as an enviornment variable, as well as the secrets. See
[Examples](#examples) below for various examples.
4. Developer of an application can now label their pod with the specified
Expand All @@ -81,7 +81,7 @@ information required to access non-Kubernetes-Services, such as accessing an
instances of Cloud Spanner. Accessing external services such as Cloud Spanner
may require the Pods to have specific credential and endpoint data.

Using a Pod Injection Policy allows pod template authors to not have to explicitly
Using a Pod Preset allows pod template authors to not have to explicitly
set information for every pod. This way authors of pod templates consuming a
specific service do not need to know all the details about that service.

Expand Down Expand Up @@ -111,24 +111,24 @@ with the credential and endpoint data required to do so).

## Proposed Changes

### PodInjectionPolicy API object
### PodPreset API object

This resource is alpha. The policy itself is immutable. The API group will be
added to `apps` and the version is `v1alpha1`.
added to new group `settings` and the version is `v1alpha1`.

```go
// PodInjectionPolicy is a policy resource that defines additional runtime
// PodPreset is a policy resource that defines additional runtime
// requirements for a Pod.
type PodInjectionPolicy struct {
type PodPreset struct {
unversioned.TypeMeta
ObjectMeta

// +optional
Spec PodInjectionPolicySpec
Spec PodPresetSpec
}

// PodInjectionPolicySpec is a description of a pod injection policy.
type PodInjectionPolicySpec struct {
// PodPresetSpec is a description of a pod preset.
type PodPresetSpec struct {
// Selector is a label query over a set of resources, in this case pods.
// Required.
Selector unversioned.LabelSelector
Expand All @@ -151,7 +151,7 @@ type PodInjectionPolicySpec struct {

#### Validations

In order for the Pod Injection Policy to be valid it must fulfill the
In order for the Pod Preset to be valid it must fulfill the
following constraints:

- The `Selector` field must be defined. This is how we know which pods
Expand All @@ -173,7 +173,7 @@ injection. These are as follows:

- Merging lists with no conflicts: if a pod already has a `Volume`,
`VolumeMount` or `EnvVar` defined **exactly** as defined in the
PodInjectionPolicy. No error will occur since they are the exact same. The
PodPreset. No error will occur since they are the exact same. The
motivation behind this is if services have no quite converted to using pod
injection policies yet and have duplicated information and an error should
obviously not be thrown if the items that need to be injected already exist
Expand All @@ -188,14 +188,14 @@ injection. These are as follows:
> **Note:** In the case of a conflict nothing will be injected. The entire
> policy is ignored and an event is thrown on the pod detailing the conflict.
### AdmissionControl Plug-in: PodInjectionPolicy
### AdmissionControl Plug-in: PodPreset

The **PodInjectionPolicy** plug-in introspects all incoming pod creation
The **PodPreset** plug-in introspects all incoming pod creation
requests and injects the pod based off a `Selector` with the desired
attributes.

For the initial alpha, the order of precedence for applying multiple
`PodInjectionPolicy` specs is from oldest to newest. All Pod Injection
`PodPreset` specs is from oldest to newest. All Pod Injection
Policies in a namespace should be order agnostic; the order of application is
unspecified. Users should ensure that policies do not overlap.
However we can use merge keys to detect some of the conflicts that may occur.
Expand All @@ -219,8 +219,8 @@ all containers in the pod with the specified matching `Selector`. The
changes to `Volumes` apply to the pod spec for all pods matching `Selector`.

The resultant modified pod spec will be annotated to show that it was modified by
the `PodInjectionPolicy`. This will be of the form
`podinjectionpolicy.admission.kubernetes.io/<pip name>": "<resource version>"`.
the `PodPreset`. This will be of the form
`podpreset.admission.kubernetes.io/<pip name>": "<resource version>"`.

*Why modify all containers in a pod?*

Expand All @@ -235,7 +235,7 @@ In the future, even if container labels were added, we would need to be careful
about not making breaking changes to the current behavior.

Other solutions include basing the container to inject based off
matching its name to another field in the `PodInjectionPolicy` spec, but
matching its name to another field in the `PodPreset` spec, but
this would not scale well and would cause annoyance with configuration
management.

Expand Down Expand Up @@ -267,11 +267,11 @@ spec:
- containerPort: 80
```
**Example Pod Injection Policy:**
**Example Pod Preset:**
```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: allow-database
namespace: myns
Expand Down Expand Up @@ -301,7 +301,7 @@ metadata:
app: website
role: frontend
annotations:
podinjectionpolicy.admission.kubernetes.io/allow-database: "resource version"
podpreset.admission.kubernetes.io/allow-database: "resource version"
spec:
containers:
- name: website
Expand Down Expand Up @@ -360,11 +360,11 @@ data:
REPLACE_ME: "a value"
```

**Example Pod Injection Policy:**
**Example Pod Preset:**

```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: allow-database
namespace: myns
Expand Down Expand Up @@ -406,7 +406,7 @@ metadata:
app: website
role: frontend
annotations:
podinjectionpolicy.admission.kubernetes.io/allow-database: "resource version"
podpreset.admission.kubernetes.io/allow-database: "resource version"
spec:
containers:
- name: website
Expand Down Expand Up @@ -444,7 +444,7 @@ Injection Policy.
**User submitted ReplicaSet:**

```yaml
apiVersion: podinjection/v1alpha1
apiVersion: settings/v1alpha1
kind: ReplicaSet
metadata:
name: frontend
Expand Down Expand Up @@ -475,11 +475,11 @@ spec:
- containerPort: 80
```

**Example Pod Injection Policy:**
**Example Pod Preset:**

```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: allow-database
namespace: myns
Expand Down Expand Up @@ -507,7 +507,7 @@ kind: Pod
app: guestbook
tier: frontend
annotations:
podinjectionpolicy.admission.kubernetes.io/allow-database: "resource version"
podpreset.admission.kubernetes.io/allow-database: "resource version"
spec:
containers:
- name: php-redis
Expand All @@ -531,7 +531,7 @@ kind: Pod
emptyDir: {}
```

### Multiple PodInjectionPolicy Example
### Multiple PodPreset Example

This is an example to show how a Pod spec is modified by multiple Pod
Injection Policies.
Expand All @@ -554,11 +554,11 @@ spec:
- containerPort: 80
```

**Example Pod Injection Policy:**
**Example Pod Preset:**

```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: allow-database
namespace: myns
Expand All @@ -577,11 +577,11 @@ spec:
emptyDir: {}
```

**Another Pod Injection Policy:**
**Another Pod Preset:**

```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: proxy
namespace: myns
Expand All @@ -608,8 +608,8 @@ metadata:
app: website
role: frontend
annotations:
podinjectionpolicy.admission.kubernetes.io/allow-database: "resource version"
podinjectionpolicy.admission.kubernetes.io/proxy: "resource version"
podpreset.admission.kubernetes.io/allow-database: "resource version"
podpreset.admission.kubernetes.io/proxy: "resource version"
spec:
containers:
- name: website
Expand Down Expand Up @@ -660,11 +660,11 @@ spec:
- containerPort: 80
```

**Example Pod Injection Policy:**
**Example Pod Preset:**

```yaml
kind: PodInjectionPolicy
apiVersion: podinjection/v1alpha1
kind: PodPreset
apiVersion: settings/v1alpha1
metadata:
name: allow-database
namespace: myns
Expand Down Expand Up @@ -714,5 +714,5 @@ $ kubectl describe ...
....
Events:
FirstSeen LastSeen Count From SubobjectPath Reason Message
Tue, 07 Feb 2017 16:56:12 -0700 Tue, 07 Feb 2017 16:56:12 -0700 1 {podinjectionpolicy.admission.kubernetes.io/allow-database } conflict Conflict on pod injection policy. Duplicate mountPath /cache.
Tue, 07 Feb 2017 16:56:12 -0700 Tue, 07 Feb 2017 16:56:12 -0700 1 {podpreset.admission.kubernetes.io/allow-database } conflict Conflict on pod preset. Duplicate mountPath /cache.
```

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