Juju 1.23-beta4 introduces ssh key bug when used w/ DHX

Update for perrito666:

This has been confirmed on AWS and HPCloud substrates (but i imagine it affects more)

Steps to reproduce:

Clone the juju-plugins repository according to the readme: https://github.com/juju/plugins/blob/master/README.md

Once you have confirmed the DHX plugin is present, create a debug-hooks-rc.yaml in your $JUJU_HOME directory, similar to the following:

import_ids: ['mbruzek','whitmo', 'lazypower']

Bootstrap and deploy services

juju bootstrap
juju deploy trusty/mariadb

Attempt to connect to a host once a service is registered:

juju dhx mariadb/0

The unit will attempt to register SSH Keys and panic - aborting the connection.

So, this is basically an API breakage caused by making import sanely when a key id corresponds to multiple keys.

cmd/juju/authorizedkeys_import.go

        results, err := client.ImportKeys(c.user, c.sshKeyIds...)
        if err != nil {
                return block.ProcessBlockedError(err, block.BlockChange)
        }
        for i, result := range results {
                if result.Error != nil {
                        fmt.Fprintf(context.Stderr, "cannot import key id %q: %v\n", c.sshKeyIds[i], result.Error)
                }
        }

This assumes that the returned results map 1:1 with the passed in sshKeyIds.

apiserver/keymanager/keymanager.go

func runSSHKeyImport(keyIds []string) []importedSSHKey {
        ...
        for _, keyId := range keyIds {
                output, err := RunSSHImportId(keyId)
                ...
                lines := strings.Split(output, "\n")
                hasKey := false
                for _, line := range lines {
                        ...
                        keyInfo = append(keyInfo, importedSSHKey{
                                key: line,
                                fingerprint: fingerprint,
                                err: errors.Annotatef(err, "invalid ssh key for %s", keyId),
                        })
                }
                ...
        }
        return keyInfo
}

This returns a longer keyInfo than given keyIds when ssh-import-id returns multiple lines of output.

The correct way to fix this depends on the branch. On trunk, we want a new api that returns a richer result struct.

On 1.23, we need to fix the current api by making the number of string-errors we return map to the key ids passed in.

For both, I think the runSSHKeyImport return should be changed to return []struct{keyId string, keyInfo []importedSSHKey}, and for the current api version we then mash all the errors into one.

I proposed http://reviews.vapour.ws/r/1580/ for 1.23 and will propose a more complete solution for master.