Support blocking queries to /health

[chrisDeFouRire]

Here's a very modest proposal for enhancement, to make it possible to use blocking queries with consul.health.* endpoints... It's backwards compatible...

To use blocking queries, you must provide the ?index= param which you obtained in the response headers of the previous call. health HTTP responses do not include a ModifyIndex field like the kvones. Instead, you must use the X-Consul-Index HTTP header... But in consul.health, only the res.body is returned.

This modification adds an optional headers parameter to the callback so the caller can get the X-Consul-Index or other consul specific headers (do we have a leader ? time of last contact) as per the consul.io docs...

If the caller implements a classic 2 params callback, the headers are silently discarded.
If he implements the 3 params callback, he'll receive the headers.

What do you think ?

Example headers:

X-Consul-Index: 235237
X-Consul-Knownleader: true
X-Consul-Lastcontact: 0

[silas]

I was thinking about exposing res as the second parameter for all callbacks (including errors), that way you can easily get access to the raw response if you want it.

That seem like an acceptable solution to you?

[chrisDeFouRire]

Hi ! Do you mean having (err, res) as a callback for all calls ? or (err, data, res) ? The first option would break all existing code... the latter sounds good to me...

[silas]

Woops, I mean't the third parameter. So the callback signature would be function(err, data, res) where data is whatever currently exists (or undefined). But there would always be three values, regardless if data is defined or not.

[chrisDeFouRire]

it sounds like a good option...

[chrisDeFouRire]

as for testing, it would be cool if you could tell me about your test configuration: maybe I could build a Vagrant file for easy setup of the 3 nodes...

[silas]

So you should just need consul in your PATH and a couple of extra local IP's attached to your loopback address (see the development section if you haven't already seen it). Note that assumes a *nix environment. The loopback interface lo0 might be named something else, see ifconfig | grep -C 5 127.0.0.1.

Basically the helper.js script spawns a mini-cluster and waits for it to boot up.

I'm going to spend some time this weekend integrating your changes and writing some nock stubs for the current tests so it's easy to run the tests even without the above setup.

[silas]

Let me know if you run into issues, thanks for reporting!

[chrisDeFouRire]

Nice use of middlewares in rapi :-)
Thanks !