Add config option to disable HTTP printable char path check

[banks]

The documentation change pretty much sums up this PR:

Consul 1.0.3 fixed a potential security vulnerability where
malicious users could craft KV keys with unprintable chars that would confuse
operators using the CLI or UI into taking wrong actions. Users who had data
written in older versions of Consul that did not have this restriction will be
unable to delete those values by default in 1.0.3 or later. This setting
enables those users to temporarily disable the filter such that delete
operations can work on those keys again to get back to a healthy state. It is
strongly recommended that this filter is not disabled permanently as it
exposes the original security vulnerability.

[pearkes]

Nice, both the language in the docs and implementation look good to me.

I was going to suggest maybe logging at [WARN] on startup about the security risk but the configuration key is so clear that I think it is good as-is.

[slackpad]

An alternative way to remove bad keys like this is https://www.consul.io/api/txn.html, which doesn't carry the key name in the URL (it's in the JSON payload).

[banks]

Good point James! @pearkes we could consider removing this again and updating docs?

…

On Fri, Aug 10, 2018 at 4:59 PM James Phillips ***@***.***> wrote: An alternative way to remove bad keys like this is https://www.consul.io/api/txn.html, which doesn't carry the key name in the URL (it's in the JSON payload). — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#4442 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAHYU9AKGcFwYM6qC9ehSU5y4zs7E2w2ks5uPa3YgaJpZM4VgP2-> .

[pearkes]

Yeah that is a great point. In the scenario we've seen it was a time sensitive issue, so the idea that you could change the config and re-run some consul kv command to get out of a downtime scenario was helpful. My only concern with the transaction API is you'd have to educate someone about that live and it may require a bit more finagling...guess we could deprecate this option in 1.3 though and write a quick guide.

[slackpad]

Yeah the txn API would require a bit of JSON to use. You could change the consul kv delete CLI to always use the kv.Txn() API under the hood (it's fine even if it's just deleting a single key) so it always uses the form that doesn't depend on any URL weirdness. This isn't a huge deal in any case :-)