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If you need to get the current Account Number, or Account ID from within a Lambda execution, then you can access invoked_function_arn from the context and return the associated value as follows: aws_account_id = context.invoked_function_arn.split(":")[4]

AssumeRole – is useful for allowing existing IAM users to access AWS resources that they don’t already have access to. For example, the user might need access to resources in another AWS account. It is also useful as a means to temporarily gain privileged access—for example, to provide multi-factor authentication (MFA). You must call this API using existing IAM user credentials. AssumeRoleWithWebIdentity – returns a set of temporary security credentials for federated users who are authenticated through a public identity provider....

Optimistic locking is a strategy to ensure that the client-side item that you are updating (or deleting) is the same as the item in DynamoDB. Optimistic concurrency depends on checking a value upon save to ensure that it has not changed. If you use this strategy, then your database writes are protected from being overwritten by the writes of others — and vice-versa. By default, the DynamoDB write operations (PutItem, UpdateItem, DeleteItem) are unconditional: each of these operations will overwrite an existing item that has the specified primary key....

CodeDeploy provides two (2) deployment type options: Option 1 – In-place Deployment In-place deployment: The application on each instance in the deployment group is stopped, the latest application revision is installed, and the new version of the application is started and validated. You can use a load balancer so that each instance is deregistered during its deployment and then restored to service after the deployment is complete. Only deployments that use the EC2/On-Premises compute platform can use in-place deployments....

Amazon ECS supports the following task placement strategies: binpack – Place tasks based on the least available amount of CPU or memory. This minimizes the number of instances in use. random – Place tasks randomly. spread – Place tasks evenly based on the specified value. Accepted values are attribute key-value pairs, instanceId, or host.

– All at once – Deploy the new version to all instances simultaneously. All instances in your environment are out of service for a short time while the deployment occurs. – Rolling – Deploy the new version in batches. Each batch is taken out of service during the deployment phase, reducing your environment’s capacity by the number of instances in a batch. – Rolling with additional batch – Deploy the new version in batches, but first launch a new batch of instances to ensure full capacity during the deployment process....

If you need to sync the clock on Linux using the central NTP clock service, you can do the following: sudo service ntp stop sudo ntpd -gq sudo service ntp start The -gg flags do the following: Tell g flag tells the NTP Daemon to correct the time regardless of the offset The q flag tells it to exit immediately after setting the time

You can query the ip-ranges Amazon AWS URL, and parse the results through jq as follows: Generic S3 IP Ranges Query: curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | jq -r '.prefixes[] | select(.service=="S3")' Response: { "ip_prefix": "3.5.140.0/22", "region": "ap-northeast-2", "service": "S3", "network_border_group": "ap-northeast-2" } { "ip_prefix": "52.219.170.0/23", "region": "eu-central-1", "service": "S3", <truncated> Region Specific S3 IP Ranges Query: curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | jq -r '.prefixes[] | select(.region=="eu-west-1") | select(.service=="S3") | .ip_prefix' Response: 18.34.32.0/20 3....

The challenge Reverse Number is a number which is the same when reversed. For example, the first 20 Reverse Numbers are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101 Task You need to return the nth reverse number. (Assume that reverse numbers start from 0 as shown in the example.) Notes 1 < n <= 100000000000 The solution in Java Option 1:...

The challenge Write a function called sumIntervals/sum_intervals() that accepts an array of intervals, and returns the sum of all the interval lengths. Overlapping intervals should only be counted once. Intervals Intervals are represented by a pair of integers in the form of an array. The first value of the interval will always be less than the second value. Interval example: [1, 5] is an interval from 1 to 5. The length of this interval is 4....