refactor aws-ec2 main

main.go

package main

import (
        "flag"
        "fmt"
        "github.com/aws/aws-sdk-go/aws"
        "github.com/aws/aws-sdk-go/aws/session"
        "github.com/aws/aws-sdk-go/service/ec2"
)

type Params struct {
        region, name, env string
}

type instanceOutput struct {
        name, env, id, private_ip, state, launched, instance_type string
}

var regionPtr string
var envPtr string

func init() {
        flag.StringVar(&regionPtr, "region", "us-west-1", "which region")
        flag.StringVar(&envPtr, "environment", "", "which environment")
        flag.StringVar(&namePtr, "name", "", "which instance name")
        flag.Parse()
}

func makeParams(r, n, e string) *Params {
        if envPtr == "" && namePtr == "" {
                return nil
        } else {
                params := &Params{
                        region: r,
                        name:   n,
                        env:    e,
                }
                return params
        }
}

func getInstances(p, *Params) instanceOutput {
        svc := ec2.New(session.New(), &aws.Config{
                Region: &regionPtr,
        })
        params := &ec2.DescribeInstancesInput{
                Filters: []*ec2.Filter{
                        &ec2.Filter{
                                Name: aws.String("tag-value"),
                                Values: []*string{
                                        aws.String(p.region),
                                        aws.String(p.name),
                                        aws.String(p.env),
                                },
                        },
                },
        }
        resp, err := svc.DescribeInstances(&p)
        CheckErr(err)
}

func main() {
        params := makeParams(regionPtr, namePtr, envPtr)
        getInstances(params)
}