为什么我们需要Logstash,Fluentd等日志摄取器？

[SERVICE]
    log_level info

[INPUT]
    Name forward
    Listen 0.0.0.0
    port 24224
    
[OUTPUT]
    Name es
    Match **
    Host 127.0.0.1
    Port 9243
    # When Logstash_Format is enabled, the Index name is composed using a prefix and the date
    Logstash_Format True
    # HTTP_User <user>
    # HTTP_Passwd <pw>
    # Alternative time key, useful if your log entries contain an @timestamp field that is used by Elasticsearch
    # Time_Key es_time
    # If your Elasticsearch is using TLS, configure this
    # tls On
    # tls.verify Off

version: "3.5"
services:
  elasticsearch:
    image: elasticsearch:7.6.2
    ports:
      - "9200:9200"
    environment:
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
      - discovery.type=single-node
  fluentbit:
    image: fluent/fluent-bit:1.5.3
    volumes:
      - type: bind
        source: ./fluent-bit.conf
        target: /fluent-bit/etc/fluent-bit.conf
    ports:
      - "24224:24224"
      - "24224:24224/udp"
    depends_on:
      - elasticsearch
  ubuntu:
    image: ubuntu
    command: [/bin/echo, "Dotnet Plus很干，值得关注！"]
    depends_on:
      - fluentbit
    logging:
      driver: fluentd
      options:
        tag: docker-ubuntu

curl localhost:9200/_cat/indices

 curl localhost:9200/logstash-2020.08.22/_search?pretty=true&q={'matchAll':{''}}

{
  "took" : 4,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "logstash-2020.08.22",
        "_type" : "_doc",
        "_id" : "z0WsFnQBU8QzIbCaBXGY",
        "_score" : 1.0,
        "_source" : {
          "@timestamp" : "2020-08-22T14:56:33.000Z",
          "log" : "Dotnet Plus很干，值得关注！",
          "container_id" : "e921435eb7b8dc61bbb8e938bf67cea2694e2afd699ca71c4ef5b6d7cca12e34",
          "container_name" : "/ef_ubuntu_1",
          "source" : "stdout"
        }
      }
    ]
  }
}