Add support for API waiters

[stripecodahale]

e.g. https://github.com/boto/botocore/blob/develop/botocore/data/aws/ec2/2014-10-01.waiters.json

[lsegal]

There is experimental support for waiters in the waiters branch. Sample waiter code:

package main

import (
    "fmt"

    "github.com/awslabs/aws-sdk-go/aws"
    "github.com/awslabs/aws-sdk-go/service/ec2"
)

func main() {
    svc := ec2.New(nil)
    fmt.Println("Waiting on instance...")
    svc.WaitUntilInstanceRunning(&ec2.DescribeInstancesInput{
        InstanceIDs: []*string{aws.String("i-12345678f")},
    })
    fmt.Println("RUNNING!")
}

[jszwedko]

Awesome, that is looking good @lsegal.

One thing I like about some of the other AWS SDKs, e.g. Ruby, is that it provides a hook into the polling process.

[georgyo]

Has any progress been made on this, is there a plan to merge this, and what else needs to be done for it?

The last commits to the waiters branch were on Mar 28.

[jasdel]

Hi @georgyo I updated the waiters branch. Syncing it with the latest version of the SDK. We still are working on finishing up the Waiter support. Specifically we need to improve the JSON path searching waiters use to know what fields of a service response signify the status the waiter is waiting on.

[jszwedko]

👏 thank you @jasdel !

[jasdel]

Waiters have now been added to the SDK. Check them out in the latest release v0.10.3. Let us know if you have any questions or feedback.