using C# to get an ec2-instance tag

问题

I'm not a developer so maybe the answer is out there for a different solution but I can't really translate it from python or something else.

I'm trying to use the AWS .NET SDK to find an instance and then get the instance's tags. I've gotten as far as being able to determine if an instance is up and running or not. I also see how I can create and delete tags (not in code example below). But I don't see an easy way to actually check if a tag exists and get the value of the tag if it does exist.

Sorry if I'm missing the obvious but this is all new to me. Here's an example of the code I'm using to check if an instance is running.

            instanceID = "i-myInstanceID";
            do {
                var myrequest = new DescribeInstanceStatusRequest();
                DescribeInstanceStatusResponse myresponse = ec2.DescribeInstanceStatus(myrequest);
                int isCount = myresponse.DescribeInstanceStatusResult.InstanceStatuses.Count;
                for (int isc=0; isc < isCount; isc++) {
                    InstanceStatus instanceStatus = myresponse.DescribeInstanceStatusResult.InstanceStatuses[isc];
                    if (instanceStatus.InstanceId.Contains(instanceID)) {
                        Console.WriteLine("It looks like instance "+instanceID+" is running.");
                        idIdx = isc;
                        foundID = true;
                        break;
                    }
                }
                if ((foundID==false) && (secondCounter==1)) {
                    Console.Write("Looking for instance "+instanceID);
                } else {
                    Console.Write(".");
                }
                Thread.Sleep(1000);
                secondCounter++;
                if (secondCounter > 5) {
                    break;
                }
            } while (foundID == false) ;

回答1:

First send a DescribeInstancesRequest to get the list of Instances:

    public DescribeInstancesResult GetInstances(Ec2Key ec2Key)
    {
        _logger.Debug("GetInstances Start.");

        AmazonEC2 ec2 = CreateAmazonEc2Client(ec2Key);

        var ec2Request = new DescribeInstancesRequest();

        DescribeInstancesResponse describeInstancesResponse = ec2.DescribeInstances(ec2Request);

        DescribeInstancesResult result = describeInstancesResponse.DescribeInstancesResult;

        _logger.Debug("GetInstances End.");

        return result;
    }

Then loop through the instances until you find the one you want, and then use the Tag.GetTagValueByKey method:

        // This just calls the above code
        DescribeInstancesResult ec2Instances = _ec2ResourceAccess.GetInstances(ec2Key);

        var returnInstances = new List<Ec2UtilityInstance>();
        foreach (var reservation in ec2Instances.Reservation)
        {
            foreach (var runningInstance in reservation.RunningInstance)
            {
                var returnInstance = new Ec2UtilityInstance();

                returnInstance.InstanceId = runningInstance.InstanceId;
                returnInstance.InstanceName = runningInstance.Tag.GetTagValueByKey("Name");
                returnInstance.Status = (Ec2UtilityInstanceStatus)Enum.Parse(typeof(Ec2UtilityInstanceStatus), runningInstance.InstanceState.Name, true);
                returnInstance.DefaultIp = runningInstance.Tag.GetTagValueByKey("DefaultIp");
                returnInstance.InstanceType = runningInstance.InstanceType;
                returnInstance.ImageId = runningInstance.ImageId;

                returnInstances.Add(returnInstance);   
            }
        }

Here is the link for full source that this was taken from:

https://github.com/escherrer/EC2Utilities

Common\Manager

and

Common\ResourceAccess

来源：https://stackoverflow.com/questions/24663104/using-c-sharp-to-get-an-ec2-instance-tag