Extended resources cannot be overcommitted, so make sure that request and limit are equal
 if both are present in a container spec.

 - The default Bootstrap Token created with `kubeadm init` v1.8 expires
 and is deleted after 24 hours by default to limit the exposure of the
 valuable credential. You can create a new Bootstrap Token with
 `kubeadm token create` or make the default token permanently valid by specifying

        .addHeader("icy-url:http://www.A2Rradio.com")
        .addHeader("Server: Icecast 2.3.3-kh8")
        .addHeader("Cache-Control: no-cache")
        .addHeader("Pragma: no-cache")
        .addHeader("Expires: Mon, 26 Jul 1997 05:00:00 GMT")
        .addHeader("icy-metaint:16000")
        .body("mp3 data")
        .build(),
    )
    val response = getResponse(newRequest("/"))

* Native support for token based bootstrap flow.  This includes signing a well known ConfigMap in the `kube-public` namespace and cleaning out expired tokens. ([#36101](https://github.com/kubernetes/kubernetes/pull/36101), [@jbeda](https://github.com/jbeda))

### ConfigMap

		"Content-Encoding",
		"Content-Length",
		"Content-Type",
		"Content-Disposition",
		"Last-Modified",
		"Content-Language",
		"Cache-Control",
		"Retry-After",
		"X-Amz-Bucket-Region",
		"Expires",
		"X-Amz*",
		"X-Amz*",
		"*",
	}
	expectedMap.Set("Vary", "Origin")

	req, _ := http.NewRequest(http.MethodOptions, s.endPoint, nil)
	req.Header.Set("Origin", "http://foobar.com")

- Allow ImageReview backend to return annotations to be added to the created pod. ([#64597](https://github.com/kubernetes/kubernetes/pull/64597), [@wteiken](https://github.com/wteiken))

- Fixed an issue blocking azure auth to prompt to device code authentication flow when refresh token expires. ([#102063](https://github.com/kubernetes/kubernetes/pull/102063), [@tdihp](https://github.com/tdihp))

- Kube-apiserver now deletes expired kube-apiserver Lease objects:
  - The feature is under feature gate `APIServerIdentity`.

- Azure auth module for kubectl now requests login after refresh token expires. ([#86481](https://github.com/kubernetes/kubernetes/pull/86481), [@tdihp](https://github.com/tdihp)) [SIG API Machinery and Auth]

Certificate management has become more robust in 1.15, with kubeadm now seamlessly rotating all your certificates (on upgrades) before they expire. Check the [kubeadm documentation](https://github.com/kubernetes/website/blob/dev-1.15/content/en/docs/reference/setup-tools/kubeadm/kubeadm-alpha.md) for information on how to manage your certificates.