Example Heka configuration to get some metadata items from the `ec2metadata` tool

ec2metadata.toml

[ec2_metadata]
type = "ProcessInput"
ticker_interval = 10
decoder = "ec2_metadata_decoder"

        [ec2_metadata.command.0]
        bin = "/usr/bin/ec2metadata"
        args = ["--ami-id", "--instance-id", "--instance-type", "--local-ipv4"]

[ec2_metadata_decoder]
type = "PayloadRegexDecoder"
log_errors = true
match_regex = '^(?P<AmiID>\S+)\n(?P<InstanceID>\S+)\n(?P<InstanceType>\S+)\n(?P<InstanceIPV4>\S+)'

        [ec2_metadata_decoder.message_fields]
        Type = "ec2metadata"
        ami_id = "%AmiID%"
        instance_id = "%InstanceID%"
        instance_type = "%InstanceType%"
        instance_ipv4|ipv4 = "%InstanceIPV4%"

[ec2_metadata_encoder]
type = "ESJsonEncoder"
index = "%{Type}"
type_name = "%{Hostname}"
es_index_from_timestamp = true
fields = ["DynamicFields", "Uuid", "Logger", "Hostname"]
dynamic_fields = ["ami_id", "instance_id", "instance_type", "instance_ipv4"]

        [ec2_metadata_encoder.field_mappings]
        Timestamp = "@timestamp"

[ESLogstashV0Encoder]

[out:stdout]
type = "LogOutput"
message_matcher = "TRUE"
encoder = "ec2_metadata_encoder"
payload_only = false

The ec2metadata tool can be found here