From 9317dcfff033fe04ad407c6939949eabc4ecfc85 Mon Sep 17 00:00:00 2001 From: Luc Perkins Date: Wed, 18 Jul 2018 17:39:42 -0700 Subject: [PATCH] Add new field selectors doc (#9174) * Add new field selectors doc * Address wording issues and remove warning * add note on = and == Signed-off-by: lucperkins --- .../working-with-objects/field-selectors.md | 58 +++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 content/en/docs/concepts/overview/working-with-objects/field-selectors.md diff --git a/content/en/docs/concepts/overview/working-with-objects/field-selectors.md b/content/en/docs/concepts/overview/working-with-objects/field-selectors.md new file mode 100644 index 00000000000..243eecce24d --- /dev/null +++ b/content/en/docs/concepts/overview/working-with-objects/field-selectors.md @@ -0,0 +1,58 @@ +--- +title: Field Selectors +weight: 60 +--- + +_Field selectors_ let you [select Kubernetes resources](/docs/concepts/overview/working-with-objects/kubernetes-objects) based on the value of one or more resource fields. Here are some example field selector queries: + +* `metadata.name=my-service` +* `metadata.namespace!=default` +* `status.phase=Pending` + +This `kubectl` command selects all Pods for which the value of the [`status.phase`](/docs/concepts/workloads/pods/pod-lifecycle/#pod-phase) field is `Running`: + +```shell +$ kubectl get pods --field-selector status.phase=Running +``` + +{{< note >}} +Field selectors are essentially resource *filters*. By default, no selectors/filters are applied, meaning that all resources of the specified type are selected. This makes the following `kubectl` queries equivalent: + +```shell +$ kubectl get pods +$ kubectl get pods --field-selector "" +``` +{{< /note >}} + +## Supported fields + +Supported field selectors vary by Kubernetes resource type. All resource types support the `metadata.name` and `metadata.namespace` fields. Using unsupported field selectors produces an error. For example: + +```shell +$ kubectl get ingress --field-selector foo.bar=baz +Error from server (BadRequest): Unable to find "ingresses" that match label selector "", field selector "foo.bar=baz": "foo.bar" is not a known field selector: only "metadata.name", "metadata.namespace" +``` + +## Supported operators + +You can use the `=`, `==`, and `!=` operators with field selectors (`=` and `==` mean the same thing). This `kubectl` command, for example, selects all Kubernetes Services that aren't in the `default` namespace: + +```shell +$ kubectl get services --field-selector metadata.namespace!=default +``` + +## Chained selectors + +As with [label](/docs/concepts/overview/working-with-objects/labels) and other selectors, field selectors can be chained together as a comma-separated list. This `kubectl` command selects all Pods for which the `status.phase` does not equal `Running` and the `spec.restartPolicy` field equals `Always`: + +```shell +$ kubectl get pods --field-selector=status.phase!=Running,spec.restartPolicy=Always +``` + +## Multiple resource types + +You use field selectors across multiple resource types. This `kubectl` command selects all Statefulsets and Services that are not in the `default` namespace: + +```shell +$ kubectl get statefulsets,services --field-selector metadata.namespace!=default +```