Change:
} func ReadUrl(url string, client *http.Client, header *http.Header) (body []byte, err error) { <ins> retryInterval := time.Second wait.PollImmediate(retryInterval, readURLTimeout, func() (bool, error) { body, err = readUrl(url, client, header) if err != nil { glog.V(4).Infof("Error reading %q: %v", url, err) return false, nil } return true, nil }) return body, err } func readUrl(url string, client *http.Client, header *http.Header) (body []byte, err error) { </ins> req, err := http.NewRequest("GET", url, nil) if err != nil { return nil, err

Discussion:
http://pr-
Something holding the port already?
The previous masterless case just barely passed with a 12.5 second timeout (25 tries at 0.5 second interval) I think we just need to increase the timeout.
I randomly sampled 5 green builds and they all have this test (starting kubelet in masterful/less mode) finished in 3s or less. Judging for the successful masterless mode startup before the failure, kubelet spent the most time trying to register credential providers (a 10s gap in the log). The same roughly applies to the failed "masterful mode", based on where the log message stopped. From , the registering process basically tries to access the metadata url to see if the credential provider is enabled. I think this may just be the slow response from the metadata server.
I am wondering even if this issue might be related to a slow response from the metadata server, why it does not show "Registering credential provider: .dockercfg" always in failed logs?
If there is a possibility that ReadUrl in may take longer than expected, would it be preferred to use a Timeout (0) with the http client to not get stuck longer than expected?
I am unsure why it didn't show that, but even in the passing round we see a 10 second gap, which almost maxed out the timeout. I think adding a timeout is reasonable, but I am not sure what value is reasonable given that the previous request took 10s. do you have any idea?
Even I am not sure exactly what should be a reasonable value. My guess would be that if in normal cases, average response time is x seconds (perhaps a guestimate could be computed based on "normal" successful tests), then x could be a starting point, or otherwise another option is choosing something randomly (like 5s). And I think that if at some point, the server is responding in 10s, and even though the test passes, its not normal and something is going wrong.
uses a 10 second timeout, but the request will be retried. Given that we don't retry this request, a short timeout is worrisome. Maybe we should add both retry and timeout in this case.
SGTM.
I reopen this one since pr was reverted.

Noticed a similar hang in: The logs are a bit different from those observed in
if kubelet couldn't start up properly, the test itself should've timed out and logged "Timed out waiting for kubelet to answer at http://127.0.0.1:/healthz; tried 25 waiting 0.5 between each". I am not sure if this failure is related.
failure is not relevant to this issue. The most recent report of such flake was over a week ago. I think the cause is the slow metadata url response in GCE, and that should've been fixed by the recent rollout. I am going to close this issue. Feel free to reopen if there is another occurrence.