Chronograf 1.11.1 fails to build on `arm32v7`

[yosifkit]

Just a heads up that the arm32v7 builds of Chronograf 1.11.1 fail to build because the detached signature file is missing. The build fails at verifying the signature, but the real error is that it got a 404, so I'd also suggest adding a -f to the curl commands so that it would more clearly show a 404 failure instead of a signature failure. It'll then bail earlier when the download fails rather than trying to use the 404 page as a signature.

Recent build log (full):

+ gpg --batch --verify chronograf_1.11.1_armhf.deb.asc chronograf_1.11.1_armhf.deb
gpg: WARNING: unsafe permissions on homedir '/root/.gnupg'
gpg: no valid OpenPGP data found.
gpg: the signature could not be verified.

Test with curl:

root@d7cccd251d4f:/# curl -sSL0 https://dl.influxdata.com/chronograf/releases/chronograf_1.11.1_armhf.deb.asc
root@d7cccd251d4f:/# cat chronograf_1.11.1_armhf.deb.asc
<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Key>chronograf/releases/chronograf_1.11.1_armhf.deb.asc</Key><RequestId>0PJG3H1HERHYYFEG</RequestId><HostId>uNi3STgsecUhe2MXLAtryM9vPSaHOLzkrspWsinga8G3WwkyYuOxdpkCmJGAeX9eHLaDy32yZnRvWA2QwnZGn+l4GvzWjFvD</HostId></Error>
root@d7cccd251d4f:/# curl -fsSLO https://dl.influxdata.com/chronograf/releases/chronograf_1.11.1_armhf.deb.asc
curl: (22) The requested URL returned error: 404
root@d7cccd251d4f:/# echo $?
22

(copied over from docker-library/official-images#21267 (comment))