ELASTICSEARCH - Include date automatically without a predefined date field - elasticsearch

Question

It is possible to include a "date and time" field in a document that receives elasticsearch without it being previously defined.
The date and time corresponds to the one received by the json to elasticsearch
This is the mapping:
{
"mappings": {
"properties": {
"entries":{"type": "nested"
}
}
}
}
Is it possible that it can be defined in the mapping field so that elasticsearch includes the current date automatically?

Answer 1

What you can do is to define an ingest pipeline to automatically add a date field when your document are indexed.
First, create a pipeline, like this (_ingest.timestamp is a built-in field that you can access):
PUT _ingest/pipeline/add-current-time
{
"description" : "automatically add the current time to the documents",
"processors" : [
{
"set" : {
"field": "#timestamp",
"value": "_ingest.timestamp"
}
}
]
}
Then when you index a new document, you need to reference the pipeline, like this:
PUT test-index/_doc/1?pipeline=add-current-time
{
"my_field": "test"
}
After indexing, the document would look like this:
GET test-index/_doc/1
=>
{
"#timestamp": "2020-08-12T15:48:00.000Z",
"my_field": "test"
}
UPDATE:
Since you're using index templates, it's even easier because you can define a default pipeline to be run for each indexed documents.
In your index templates, you need to add this to the index settings:
{
"order": 1,
"index_patterns": [
"attom"
],
"aliases": {},
"settings": {
"index": {
"number_of_shards": "5",
"number_of_replicas": "1",
"default_pipeline": "add-current-time" <--- add this
}
},
...
Then you can keep indexing documents without referencing the pipeline, it will be automatic.

Answer 2

"value": "{{{_ingest.timestamp}}}"
Source