检查 EC2 实例是否完成初始化。 使用 AWS Java SDK v2

Question

I am programatically spinning up an EC2 instance from the AWS Java SDK v2. I then associate an elastic IP address to this instance. This takes a couple minutes. AWS then initializes the instance. In the AWS console it looks like this... I cannot ssh into this instance until the initialization completes. Is there a way to programatically check that the instance has completed initialization? I have seen the method describeInstances(), but to the best of my knowledge, the most relevant information this method's response contains is the instance's state. The state is "running" and is not therefore probably not the variable that indicates initializing status. Maybe there is a different variable or a different method that is helpful for monitoring this initialization process? Cheers.

Answer 1

Not really.

Amazon EC2 is responsible for creating the virtual machine, attaching a disk with the operating system and then booting the instance. Everything after that is up to the operating system and startup scripts. The Amazon EC2 service can't 'see' what is happening on the instance.

If you particularly need to know this information, you could use a script on the instance to 'publish' this fact somewhere. For example, it could add a Tag to the instance saying State: Ready . Or, if you need to programmatically respond somehow, the script could trigger an AWS Lambda function or put a message into an Amazon SQS queue.

Answer 2

I check EC2 instance status after starting an instance with this Java code and the AWS SDK. An EC2 cd5.large instance takes about 90 seconds to stop and start back to the "running" state and then takes about another 3.5 minutes to complete initializing. This code is after the part which you probably have that spins the instance up to "running"...

boolean isInstanceInitialized = false;
while (!isInstanceInitialized) {
  final DescribeInstanceStatusResult result = ec2
          .describeInstanceStatus(
                  new DescribeInstanceStatusRequest()
                          .withInstanceIds(instanceId));
  final List<InstanceStatus> instanceStatuses = result.getInstanceStatuses();
  boolean isInstanceStatusOK;
  boolean isSystemStatusOK;

  for (final InstanceStatus instanceStatus : instanceStatuses) {
    LOGGER.info("  InstanceStatus.instanceStatus: " + instanceStatus.getInstanceStatus().getStatus());
    LOGGER.info("  SystemStatus:                  " + instanceStatus.getSystemStatus().getStatus());
    isInstanceStatusOK = ("ok".equals(instanceStatus.getInstanceStatus().getStatus()));
    isSystemStatusOK = ("ok".equals(instanceStatus.getSystemStatus().getStatus()));
    isInstanceInitialized = isInstanceStatusOK && isSystemStatusOK;
  }


  if (isInstanceInitialized) {
    break;
  } else {
    try {
      // sleep 10 seconds between polling the instance state
      Thread.sleep(10_000);
    } catch (InterruptedException ex) {
      // ignore
    }
  }
}

Answer 3

You can potentially use the waiter feature in AWS SDK for Java. EC2 supports waiters for a number of operations , one of which is waitUntilInstanceExists .