Resource Attach displays cryptic HTML error when no revision is specified on CLI

From @lazypower on July 26, 2016 20:47

I'm not entirely certian why this is the case, but the charm command seems to misbehave when the revision is not specified during charm attach. It gives a bad gateway error, which seems like it should instead tell me that it wants the revision (As you cannot publish any revision of a charm requiring resources, without the resource.

I propose a change, that the charm command itself run a split on the entity we are attempting to attach resources, and if the last characters post split('-') are non numeric, that the charm not reach out over the wire, at all, and complain to the user they need to specify a revision.

The following output was captured during discovery of the behavior:

charles@Tennoki ~/projects/work/builds/certificate-authority/utils $ charm attach cs:~lazypower/certificate-authority cfssl=./cfssl
ERROR can't upload resource: cannot post resource: cannot unmarshal error response "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n<html><head>\n<title>502 Bad Gateway</title>\n</head><body>\n<h1>Bad Gateway</h1>\n<p>The proxy server received an invalid\r\nresponse from an upstream server.<br />\r\n</p>\n<hr>\n<address>Apache/2.4.7 (Ubuntu) Server at api.jujucharms.com Port 443</address>\n</body></html>\n": invalid character '<' looking for beginning of value
charles@Tennoki ~/projects/work/builds/certificate-authority/utils $ charm attach cs:~lazypower/certificate-authority cfssl=./cfssl
ERROR can't upload resource: cannot post resource: cannot unmarshal error response "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n<html><head>\n<title>502 Bad Gateway</title>\n</head><body>\n<h1>Bad Gateway</h1>\n<p>The proxy server received an invalid\r\nresponse from an upstream server.<br />\r\n</p>\n<hr>\n<address>Apache/2.4.7 (Ubuntu) Server at api.jujucharms.com Port 443</address>\n</body></html>\n": invalid character '<' looking for beginning of value
charles@Tennoki ~/projects/work/builds/certificate-authority/utils $ charm attach cs:~lazypower/certificate-authority-0 cfssl=./cfssl
uploaded revision 0 of cfssl%                                                                                                                                                                               charles@Tennoki ~/projects/work/builds/certificate-authority/utils $ charm attach cs:~lazypower/certificate-authority-0 cfssljson=./cfssljson
uploaded revision 0 of cfssljson%

Copied from original issue: CanonicalLtd/charmstore-client#222

juju / charmstore-client

Resource Attach displays cryptic HTML error when no revision is specified on CLI #202