Pierre Souchay eddcf228ea Implementation of Weights Data structures (#4468)
* 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
2018-09-07 15:30:47 +01:00
..
2018-03-19 16:56:00 +00:00
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2018-07-06 10:55:25 +01:00

Consul API client

This package provides the api package which attempts to provide programmatic access to the full Consul API.

Currently, all of the Consul APIs included in version 0.6.0 are supported.

Documentation

The full documentation is available on Godoc

Usage

Below is an example of using the Consul client:

package main

import "github.com/hashicorp/consul/api"
import "fmt"

func main() {
	// Get a new client
	client, err := api.NewClient(api.DefaultConfig())
	if err != nil {
		panic(err)
	}

	// Get a handle to the KV API
	kv := client.KV()

	// PUT a new KV pair
	p := &api.KVPair{Key: "REDIS_MAXCLIENTS", Value: []byte("1000")}
	_, err = kv.Put(p, nil)
	if err != nil {
		panic(err)
	}

	// Lookup the pair
	pair, _, err := kv.Get("REDIS_MAXCLIENTS", nil)
	if err != nil {
		panic(err)
	}
	fmt.Printf("KV: %v %s\n", pair.Key, pair.Value)
}

To run this example, start a Consul server:

consul agent -dev

Copy the code above into a file such as main.go.

Install and run. You'll see a key (REDIS_MAXCLIENTS) and value (1000) printed.

$ go get
$ go run main.go
KV: REDIS_MAXCLIENTS 1000

After running the code, you can also view the values in the Consul UI on your local machine at http://localhost:8500/ui/dc1/kv