Get Pod details about itself from a container (without using downwardAPI or env variables approach)

Question

Is it possible for an app running inside a pod to get details/metadata about its own pod. I know this can be easily achieved using downwardAPI or env variables.

Is there a third way?

I want to find out the service account and namespace of the pod without using either of these approaches. Is it possible?

Answer 1

Any particular reason to decouple container details ? Bear in mind that the downward api is intended to get details such as service account. Now, responding to your question i envision two possible ways to achieve your objective, kubectl and API Server. I elaborated on the kubectl approach:

Kubernetes client (kubectl)

• Get information about your Kubernetes secret object

kubectl get secret --namespace={namespace}

Following is a sample output:

NAME                  TYPE                                  DATA      AGE
admin.registrykey     kubernetes.io/dockercfg               1         1h
default-token-2mfqv   kubernetes.io/service-account-token   3         1h

• Get details of the service account token

kubectl get secret default-token-2mfqv --namespace={namespace} -o yaml

Following is a sample output, notice the annotations section:

apiVersion: v1
data:
 ca.crt: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSURVRENDQWppZ0F3SUJBZ0lKQUxSSHNCazBtblM4TUEwR0NTcUdTSWIzRFFFQkN3VUFNQjh4SFRBYkJnTlYKQkFNTUZERXlOeTR3TGpBdU1VQXhORGczTWprNU1EZ3lNQjRYRFRFM01ESXhOekF5TXpnd01sb1hEVEkzTURJeApOVEF5TXpnd01sb3dIekVkTUJzR0ExVUVBd3dVTVRJM0xqQXVNQzR4UURFME9EY3lPVGt3T0RJd2dnRWlNQTBHCkNTcUdTSWIzRFFFQkFRVUFBNElCRHdBd2dnRUtBb0lCQVFDMTUwZWxjRXZXUDBMVFZZK09jNTl4ZG9PUCtXb08Kd3BGNGRxaGpDSDdyZGtUcGVKSE1zeW0raU4wMWxBSjNsc2UvYjB0V2h5L1A5MVZpZmpjazFpaDBldDg0eUZLawpuQWFaNVF6clJxQjk2WGZ3VVVyUElZc0RjRlpzbnAwZUlZU0xJdEhSSHQ3dlY0R3hqbG1TLzlpMzBIcW5rTWJTCmtCbU0xWEp2ZXdjVkROdE55NUE3K1RhNmJWcmt5TlpPZFFjZTkzMk0yTGZ2bUFORzI2UTRtd0x1MlAxNnZGV3EKbkdDd055OVl3Y0k2YVhpQTFSVTNLdWR5d00zZzN2aU03UVMyMXRGbkh4RzJrcU5NNHVKdWZDYnNNZ1gwd1hNQgpuZWZzZ053K0p1b2VnZzFVcHd5RmQydjVyMEpQVkxBN0N1T1d6RzVtK0RrNWNlWExOaGVwMDhxUkFnTUJBQUdqCmdZNHdnWXN3SFFZRFZSME9CQllFRkxlV3ZDOThkZFJxQ2t0eGVla2t5bnY1aCtDSU1FOEdBMVVkSXdSSU1FYUEKRkxlV3ZDOThkZFJxQ2t0eGVla2t5bnY1aCtDSW9TT2tJVEFmTVIwd0d3WURWUVFEREJReE1qY3VNQzR3TGpGQQpNVFE0TnpJNU9UQTRNb0lKQUxSSHNCazBtblM4TUF3R0ExVWRFd1FGTUFNQkFmOHdDd1lEVlIwUEJBUURBZ0VHCk1BMEdDU3FHU0liM0RRRUJDd1VBQTRJQkFRQ2Z1ZTdQcVFFR2NMUitjQ2tJMXdISHR2ei9tZWJmNndqUHBqN0oKamV5TG5aeWVZMUVZeEJDWEJEYk9BaU5BRTh6aWQrcm1Fd0w5NndtOGFweUVnbEN6aDhmU1ZoZ1dtYmZKSUNQQQpTTGdFZ1ZjOFJDQk5OdjUwWTQ4L0NXWXFZL2pjZkxYQ1VOdVU5RXhQd1BKRE9jNHhFOFg1NHZDekxzZUF3ZnQ0CmlBS0R0QzZmS0FMNXZQL3RRbHBya2FuVC9zcEVackNZV2IyZXlkRjV4U1NMKzNUbVJTeXgvUkczd1FTWEtCT3cKVGdjaWxJdFQ1WlAwQ0V2WHI1OFBMRXZKMVE1TGZ2Q0w0bkliTEEzMmVucUQ4UlZkM01VbkgxSnFpLzU4VktLQgo4SFpBb1V2bkl2SG5SNGVVbnAwMXFWVFpsS21Xc0JtbjV3MkxaS1FWMEIvVzlnSFAKLS0tLS1FTkQgQ0VSVElGSUNBVEUtLS0tLQo=
 namespace: ZGVmYXVsdA==
 token: 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
kind: Secret
metadata:
 annotations:
   kubernetes.io/service-account.name: default
   kubernetes.io/service-account.uid: df441c69-f4ba-11e6-8157-525400225b53
 creationTimestamp: 2017-02-17T02:43:33Z
 name: default-token-2mfqv
 namespace: default
 resourceVersion: "37"
 selfLink: /api/v1/namespaces/default/secrets/default-token-2mfqv
 uid: df5f1109-f4ba-11e6-8157-525400225b53
type: kubernetes.io/service-account-token

Theres a complete document here