alertmanager2es index template mappings

alerts.json

{
    "template": "alerts-*",
    "settings": {
        "number_of_shards": 1,
        "number_of_replicas": 1,
        "index.refresh_interval": "10s",
        "index.query.default_field": "groupLabels.alertname"
    },
    "index_patterns": ["alerts-*"],
    "mappings": {
        "_doc": {
            "dynamic": true,
            "date_detection": true,
            "properties": {
                "@timestamp": { "type": "date", "doc_values": true }
            },
            "dynamic_templates": [{
                "string_fields": {
                    "match": "*",
                    "match_mapping_type": "string",
                    "mapping": {
                        "type": "keyword",
                        "index": "true",
                        "ignore_above": 1024,
                        "doc_values": true
                    }
                }
            }]
        }
    }
}