Get EC2 Instance Metadata

Description

Retrieve EC2 instance metadata from the instance

Usage

is_ec2()

instance_document()

metadata

is_ecs()

ecs_metadata()

Format

An object of class list of length 25.

Details

is_ec2 returns a logical for whether the current R session appears to be running in an EC2 instance.

instance_document returns a list containing values from the Instance Identity Document, including the instance ID, AMI ID, region, availability zone, etc.

metadata is a list of functions to return various metadata values for the currently running EC2 instance. These are only meant to be called from an EC2 instance; no guarantees are made about behavior on other platforms. Two functions: versions() and meta_data_items() return the versions of the metadata, and the set of top-level metadata items, respectively.

The function item() retrieves a particular metadata item specified by its full path.

The remaining functions in the list are aliases for potentially commonly needed metadata items.

Value

is_ec2 returns a logical. Generally, all other functions will return a character string containing the requested information, otherwise a NULL if the response is empty. The iam_role() function returns a list. An error will occur if, for some reason, the request otherwise fails.

Author(s)

Thomas J. Leeper <thosjleeper@gmail.com>

References

Metadata Documentation

Examples

names(metadata)

## Not run: 
if (is_ec2()) {
  metadata$versions()
  metadata$items()

  # get instance id
  metadata$instance_id()
  # get ami id
  metadata$ami_id()
  
  # get IAM role (NULL if none specified)
  metadata$iam_info()
  metadata$iam_role("myrole")

  # get an arbitrary metadata item
  metadata$item("meta-data/placement/availability-zone")
  
  # get region from instance identity document
  instance_document()$region
}

# Can also get ECS container metadata
if (is_ecs()) {
  # Get ECS role credentials
  ecs_metadata()
}

## End(Not run)