* Implementation of Weights Data structures
Adding this datastructure will allow us to resolve the
issues #1088 and #4198
This new structure defaults to values:
```
{ Passing: 1, Warning: 0 }
```
Which means, use weight of 0 for a Service in Warning State
while use Weight 1 for a Healthy Service.
Thus it remains compatible with previous Consul versions.
* Implemented weights for DNS SRV Records
* DNS properly support agents with weight support while server does not (backwards compatibility)
* Use Warning value of Weights of 1 by default
When using DNS interface with only_passing = false, all nodes
with non-Critical healthcheck used to have a weight value of 1.
While having weight.Warning = 0 as default value, this is probably
a bad idea as it breaks ascending compatibility.
Thus, we put a default value of 1 to be consistent with existing behaviour.
* Added documentation for new weight field in service description
* Better documentation about weights as suggested by @banks
* Return weight = 1 for unknown Check states as suggested by @banks
* Fixed typo (of -> or) in error message as requested by @mkeeler
* Fixed unstable unit test TestRetryJoin
* Fixed unstable tests
* Fixed wrong Fatalf format in `testrpc/wait.go`
* Added notes regarding DNS SRV lookup limitations regarding number of instances
* Documentation fixes and clarification regarding SRV records with weights as requested by @banks
* Rephrase docs
There are also a lot of small bug fixes found when testing lots of things end-to-end for the first time and some cleanup now it's integrated with real CA code.
* Updates the API client to support the current `ScriptArgs` parameter
for checks.
* Updates docs for checks to explain the `ScriptArgs` parameter issue.
* Adds mappings for "args" and "script-args" to give th API parity
with config.
* Adds checks on return codes.
* Removes debug logging that shows empty when args are used.
Cancellation channels are often derived from a Context, which
returns a directional `<-chan struct{}` from Done(). In order to use
this with parts of of the consul API, one is required to create a new
channel and dispatch a separate goroutine to watch for context
cancellation and close the new channel.
Changing the signature for the methods that take cancellation channels
will allow easier integration with existing uses of Context. Since the
cancellation pattern only reads from these channels, there should be no
backwards incompatibility with existing codebases, and most of the
methods already accept only the correct type.
