Accessing nested JSON Value with variable key name in Logstash - json

Question

I've got a question regarding JSON in Logstash.
I have got a JSON Input that looks something like this:
{
"2": {
"name": "name2",
"state": "state2"
},
"1": {
"name": "name1",
"state": "state1"
},
"0": {
"name": "name0",
"state": "state0"
}
}
Now, let's say I want to add a field in the logstash config
json{
source => "message"
add_field => {
"NAME" => "%{ What to write here ?}"
"STATE" => "%{ What to write here ?}"
}
}
Is there a way to access the JSON Input such that I get a field Name with value name1, another field with name 2 and a third field with name 3. The first key in the JSON is changing, that means there can only be one or many more parts. So I don't want to hardcode it like
%{[0][name]}
Thanks for your help.

Answer 1

If you remove all new lines in your input you can simply use the json filter. You don't need any add_field action.
Working config without new lines:
filter {
json { source => message }
}
If you can't remove the new lines in your input you need to merge the lines with the multiline codec.
Working config with new lines:
input {
file {
path => ["/path/to/your/file"] # I suppose your input is a file.
start_position => "beginning"
sincedb_path => "/dev/null" # just for testing
codec => multiline {
pattern => "^}"
what => "previous"
negate => "true"
}
}
}
filter {
mutate { replace => { "message" => "%{message}}" } }
json { source => message }
}
I suppose that you use the file input. In case you don't, just change it.
Output (for both):
"2" => {
"name" => "name2",
"state" => "state2"
},
"1" => {
"name" => "name1",
"state" => "state1"
},
"0" => {
"name" => "name0",
"state" => "state0"
}