support large/slow downloads

[aojea]

current download code was using http.client timeout, that will
interrupt reading of the response body, breaking slow downloads
or very large files.

This patch modified the http client to detect idle downloads, and
fail after 30 seconds of innactivity. It still keeps a global
timeout of 5 minutes.

[aojea]

/assign @hakman @justinsb

[hakman]

5 minutes is a little much. Usually when nodes are IPv4 only, it takes 1-2 seconds to download such files. Let's see how this goes.
/test pull-kops-e2e-ipv6-conformance

[aojea]

5 minutes is a little much. Usually when nodes are IPv4 only, it takes 1-2 seconds to download such files. Let's see how this goes.
/test pull-kops-e2e-ipv6-conformance

I made it configurable, just choose a random value, the point is that now we can differentiate between idle and slow connections

[hakman]

Cool. Thanks. 😄

[hakman]

Mostly ok, doing a few more runs.
/test pull-kops-e2e-ipv6-conformance

[hakman]

/test pull-kops-e2e-ipv6-conformance

[hakman]

/test pull-kops-e2e-ipv6-conformance

[hakman]

Just perfect, thanks @aojea!
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hakman

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [hakman]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment