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Eric Paris
2016-03-04 12:49:17 -05:00
parent a20258efae
commit f334fc4179
134 changed files with 136 additions and 23433 deletions
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35
docs/user-guide/downward-api/README.md
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@@ -32,40 +32,7 @@ Documentation for other releases can be found at
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# Downward API example
Following this example, you will create a pod with a container that consumes the pod's name and
namespace using the [downward API](../downward-api.md).
## Step Zero: Prerequisites
This example assumes you have a Kubernetes cluster installed and running, and that you have
installed the `kubectl` command line tool somewhere in your path. Please see the [getting
started](../../../docs/getting-started-guides/) for installation instructions for your platform.
## Step One: Create the pod
Containers consume the downward API using environment variables. The downward API allows
containers to be injected with the name and namespace of the pod the container is in.
Use the [`examples/downward-api/dapi-pod.yaml`](dapi-pod.yaml) file to create a Pod with a container that consumes the
downward API.
```console
$ kubectl create -f docs/user-guide/downward-api/dapi-pod.yaml
```
### Examine the logs
This pod runs the `env` command in a container that consumes the downward API. You can grep
through the pod logs to see that the pod was injected with the correct values:
```console
$ kubectl logs dapi-test-pod | grep POD_
2015-04-30T20:22:18.568024817Z MY_POD_NAME=dapi-test-pod
2015-04-30T20:22:18.568087688Z MY_POD_NAMESPACE=default
2015-04-30T20:22:18.568092435Z MY_POD_IP=10.0.1.6
```
This file has moved to: http://kubernetes.github.io/docs/user-guide/downward-api/README/
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docs/user-guide/downward-api/volume/README.md
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# Downward API volume plugin
Following this example, you will create a pod with a downward API volume.
A downward API volume is a k8s volume plugin with the ability to save some pod information in a plain text file. The pod information can be for example some [metadata](../../../../docs/devel/api-conventions.md#metadata).
Supported metadata fields:
1. `metadata.annotations`
2. `metadata.namespace`
3. `metadata.name`
4. `metadata.labels`
### Step Zero: Prerequisites
This example assumes you have a Kubernetes cluster installed and running, and the ```kubectl``` command line tool somewhere in your path. Please see the [gettingstarted](../../../../docs/getting-started-guides/) for installation instructions for your platform.
### Step One: Create the pod
Use the `docs/user-guide/downward-api/dapi-volume.yaml` file to create a Pod with a  downward API volume which stores pod labels and pod annotations to `/etc/labels` and  `/etc/annotations` respectively.
```shell
$ kubectl create -f docs/user-guide/downward-api/volume/dapi-volume.yaml
```
### Step Two: Examine pod/container output
The pod displays (every 5 seconds) the content of the dump files which can be executed via the usual `kubectl log` command
```shell
$ kubectl logs kubernetes-downwardapi-volume-example
cluster="test-cluster1"
rack="rack-22"
zone="us-est-coast"
build="two"
builder="john-doe"
kubernetes.io/config.seen="2015-08-24T13:47:23.432459138Z"
kubernetes.io/config.source="api"
```
### Internals
In pod's `/etc` directory one may find the file created by the plugin (system files elided):
```shell
$ kubectl exec kubernetes-downwardapi-volume-example -i -t -- sh
/ # ls -laR /etc
/etc:
total 32
drwxrwxrwt 3 0 0 180 Aug 24 13:03 .
drwxr-xr-x 1 0 0 4096 Aug 24 13:05 ..
drwx------ 2 0 0 80 Aug 24 13:03 ..2015_08_24_13_03_44259413923
lrwxrwxrwx 1 0 0 30 Aug 24 13:03 ..downwardapi -> ..2015_08_24_13_03_44259413923
lrwxrwxrwx 1 0 0 25 Aug 24 13:03 annotations -> ..downwardapi/annotations
lrwxrwxrwx 1 0 0 20 Aug 24 13:03 labels -> ..downwardapi/labels
/etc/..2015_08_24_13_03_44259413923:
total 8
drwx------ 2 0 0 80 Aug 24 13:03 .
drwxrwxrwt 3 0 0 180 Aug 24 13:03 ..
-rw-r--r-- 1 0 0 115 Aug 24 13:03 annotations
-rw-r--r-- 1 0 0 53 Aug 24 13:03 labels
/ #
```
The file `labels` is stored in a temporary directory (`..2015_08_24_13_03_44259413923` in the example above) which is symlinked to by `..downwardapi`. Symlinks for annotations and labels in `/etc` point to files containing the actual metadata through the `..downwardapi` indirection.  This structure allows for dynamic atomic refresh of the metadata: updates are written to a new temporary directory, and the `..downwardapi` symlink is updated atomically using `rename(2)`.
This file has moved to: http://kubernetes.github.io/docs/user-guide/downward-api/volume/README/
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