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.