Recommended Labels [page]deterministic
You can visualize and manage Kubernetes objects with more tools than kubectl and the dashboard. A common set of labels allows tools to work interoperably, describing objects in a common manner that all tools can understand.
In addition to supporting tooling, the recommended labels describe applications in a way that can be queried.
The metadata is organized around the concept of an _application_. Kubernetes is not a platform as a service (PaaS) and doesn't have or enforce a formal notion of an application. Instead, applications are informal and described with metadata. The definition of what an application contains is loose.
> Note: These are recommended labels. They make it easier to manage applications but aren't required for any core tooling.
Shared labels and annotations share a common prefix: `app.kubernetes.io`. Labels without a prefix are private to users. The shared prefix ensures that shared labels do not interfere with custom user labels.
## Labels
In order to take full advantage of using these labels, they should be applied on every resource object.
| Key | Description | Example | Type | | ----------------------------------- | --------------------- | -------- | ---- | | `app.kubernetes.io/name` | The name of the application | `mysql` | string | | `app.kubernetes.io/instance` | A unique name identifying the instance of an application | `mysql-abcxyz` | string | | `app.kubernetes.io/version` | The current version of the application (e.g., a [SemVer 1.0](https://semver.org/spec/v1.0.0.html), revision hash, etc.) | `5.7.21` | string | | `app.kubernetes.io/component` | The component within the architecture | `database` | string | | `app.kubernetes.io/part-of` | The name of a higher level application this one is part of | `wordpress` | string | | `app.kubernetes.io/managed-by` | The tool being used to manage the operation of an application | `Helm` | string |
To illustrate these labels in action, consider the following [StatefulSet](#gloss:statefulset) object:
```yaml # This is an excerpt apiVersion: apps/v1 kind: StatefulSet metadata: labels: app.kubernetes.io/name: mysql app.kubernetes.io/instance: mysql-abcxyz app.kubernetes.io/version: "5.7.21" app.kubernetes.io/component: database app.kubernetes.io/part-of: wordpress app.kubernetes.io/managed-by: Helm ```
## Applications And Instances Of Applications
An application can be installed one or more times into a Kubernetes cluster and, in some cases, the same namespace. For example, WordPress can be installed more than once where different websites are different installations of WordPress.
The name of an application and the instance name are recorded separately. For example, WordPress has a `app.kubernetes.io/name` of `wordpress` while it has an instance name, represented as `app.kubernetes.io/instance` with a value of `wordpress-abcxyz`. This enables the application and instance of the application to be identifiable. Every instance of an application must have a unique name.
## Examples
To illustrate different ways to use these labels the following examples have varying complexity.
### A Simple Stateless Service
Consider the case for a simple stateless service deployed using `Deployment` and `Service` objects. The following two snippets represent how the labels could be used in their simplest form.
The `Deployment` is used to oversee the pods running the application itself. ```yaml apiVersion: apps/v1 kind: Deployment metadata: labels: app.kubernetes.io/name: myservice app.kubernetes.io/instance: myservice-abcxyz ... ```
The `Service` is used to expose the application. ```yaml apiVersion: v1 kind: Service metadata: labels: app.kubernetes.io/name: myservice app.kubernetes.io/instance: myservice-abcxyz ... ```
### Web Application With A Database
Consider a slightly more complicated application: a web application (W …(trimmed)