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instances.go
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/
instances.go
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/*
Copyright 2017 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package aws
import (
"fmt"
"net/url"
"strings"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/ec2"
)
// awsInstanceID represents the ID of the instance in the AWS API, e.g. i-12345678
// The "traditional" format is "i-12345678"
// A new longer format is also being introduced: "i-12345678abcdef01"
// We should not assume anything about the length or format, though it seems
// reasonable to assume that instances will continue to start with "i-".
type awsInstanceID string
func (i awsInstanceID) awsString() *string {
return aws.String(string(i))
}
// kubernetesInstanceID represents the id for an instance in the kubernetes API;
// the following form
// * aws:///<zone>/<awsInstanceId>
// * aws:////<awsInstanceId>
// * <awsInstanceId>
type kubernetesInstanceID string
// mapToAWSInstanceID extracts the awsInstanceID from the kubernetesInstanceID
func (name kubernetesInstanceID) mapToAWSInstanceID() (awsInstanceID, error) {
s := string(name)
if !strings.HasPrefix(s, "aws://") {
// Assume a bare aws volume id (vol-1234...)
// Build a URL with an empty host (AZ)
s = "aws://" + "/" + "/" + s
}
url, err := url.Parse(s)
if err != nil {
return "", fmt.Errorf("Invalid instance name (%s): %v", name, err)
}
if url.Scheme != "aws" {
return "", fmt.Errorf("Invalid scheme for AWS instance (%s)", name)
}
awsID := ""
tokens := strings.Split(strings.Trim(url.Path, "/"), "/")
if len(tokens) == 1 {
// instanceId
awsID = tokens[0]
} else if len(tokens) == 2 {
// az/instanceId
awsID = tokens[1]
}
// We sanity check the resulting volume; the two known formats are
// i-12345678 and i-12345678abcdef01
// TODO: Regex match?
if awsID == "" || strings.Contains(awsID, "/") || !strings.HasPrefix(awsID, "i-") {
return "", fmt.Errorf("Invalid format for AWS instance (%s)", name)
}
return awsInstanceID(awsID), nil
}
// Gets the full information about this instance from the EC2 API
func describeInstance(ec2Client EC2, instanceID awsInstanceID) (*ec2.Instance, error) {
request := &ec2.DescribeInstancesInput{
InstanceIds: []*string{instanceID.awsString()},
}
instances, err := ec2Client.DescribeInstances(request)
if err != nil {
return nil, err
}
if len(instances) == 0 {
return nil, fmt.Errorf("no instances found for instance: %s", instanceID)
}
if len(instances) > 1 {
return nil, fmt.Errorf("multiple instances found for instance: %s", instanceID)
}
return instances[0], nil
}