For the cluster-wide logging solution on Kubernetes, see post at Kubernetes Logging

1. What is the ELK/EFK Stack?

ELK is the arconym for three open source projects: Elasticsearch, Logstash, and Kibana.

  • Elasticsearch is a search and analytics engine.

  • Logstash is a server-side data processing pipeline that ingests data from multiple sources simultaneously, tranforms it, and then sends it to a "stash" like Elasticsearch.

  • Kibana lets users visualize data with charts and graphs in Elasticsearch.

EFK is the arconym for Elasticsearch, Fluent Bit (or Fluentd, Filebeat etc.), Kibana.

Fluentd & LogStash

Fluentd & Fluent Bit

2. What is the Fluentd?

Before Fluentd After Fluentd

Fluentd is an open source data collector, which lets you unify the data collection and consumption for a better use and understanding of data.

3. What is Fluent Bit?

Fluent Bit is an open source and multi-platform log processor tool which aims to be a fast and lightweight generic Swiss knife for logs processing and distribution.

Fluent Bit is a CNCF sub-project under the umbrella of Fluentd, it’s licensed under the terms of the Apache License v2.0. The project was originally created by Treasure Data and is currently a vendor neutral and community driven project.

Logging and data processing in general can be complex, and at scale a bit more, that’s why it was born.

Fluentd has become more than a simple tool, it has grown into a fullscale ecosystem that contains SDKs for different languages and sub-projects like Fluent Bit.

Both projects share a lot of similarities, Fluent Bit is fully designed and built on top of the best ideas of Fluentd architecture and general design. Choosing which one to use depends on the end-user needs.

The following table describes a comparison in different areas of the projects:

Fluentd Fluent Bit

Scope

Containers / Servers

Embedded Linux / Containers / Servers

Language

C & Ruby

C

Memory

~40MB

~650KB

Performance

High Performance

High Performance

Dependencies

Built as a Ruby Gem, it requires a certain number of gems.

Zero dependencies, unless some special plugin requires them.

Plugins

More than 1000 plugins available

Around 70 plugins available

License

Apache License v2.0

Apache License v2.0

Both Fluentd and Fluent Bit can work as Aggregators or Forwarders, they both can complement each other or use them as standalone solutions.

Fluent Bit collects and process logs from different input sources and allows to parse and filter these records before they hit the Storage interface. Once data is processed and it’s in a safe state (either in memory or the file system), the records are routed through the proper output destinations.

Fluent Bit Data Pipeline

4. Collect Docker logs with EFK Stack

Starting from Docker v1.8, it provides a Fluentd Logging Driver which implements the Forward protocol. Fluent Bit have native support for this protocol, so it can be used as a lightweight log collector.

ref: https://fluentbit.io/articles/docker-logging-elasticsearch/

Talk is cheap, show me the code @ https://github.com/ousiax/efk-docker/tree/oss-7.10.2

$ tree
.
├── conf
│   ├── fluent-bit.conf
│   └── parsers.conf
├── docker-compose.yml
├── LICENSE
└── README.md

1 directory, 5 files
docker-compose.yml
version: "2.4"
services:
    elasticsearch:
        image: docker.elastic.co/elasticsearch/elasticsearch-oss:7.10.2
        restart: on-failure
        mem_limit: 2g
        environment:
          - discovery.type=single-node
        ports:
          - 9200
        volumes:
          - /var/lib/elasticsearch:/usr/share/elasticsearch/data
        networks:
          - local
        depends_on:
          - fluent-bit
        logging:
          driver: fluentd
          options:
            tag: efk.es
    kibana:
        image: docker.elastic.co/kibana/kibana-oss:7.10.2
        restart: on-failure
        mem_limit: 256m
        environment:
          - ELASTICSEARCH_HOSTS=http://elasticsearch:9200
        ports:
          - 5601:5601
        networks:
          - local
        depends_on:
          - fluent-bit
          - elasticsearch
        logging:
          driver: fluentd
          options:
            tag: efk.kibana
    fluent-bit:
        image: fluent/fluent-bit:1.8
        command:
          - /fluent-bit/bin/fluent-bit
          - --config=/etc/fluent-bit/fluent-bit.conf
        environment:
          - FLB_ES_HOST=elasticsearch
          - FLB_ES_PORT=9200
        ports:
          #- 2020:2020
          - 24224:24224
        volumes:
          - ./conf/:/etc/fluent-bit/:ro
        networks:
          - local
        logging:
          driver: fluentd
          options:
            tag: efk.fluent-bit
networks:
  local:
    driver: bridge
conf/fluent-bit.conf
[SERVICE]
    flush     5
    daemon    off
    http_server on
    log_level info
    parsers_file parsers.conf

[INPUT]
    Name   forward
    Listen 0.0.0.0
    Port   24224

[FILTER]
    name parser
    match efk.*
    key_name log
    parser json
    reserve_data true

[OUTPUT]
    name            es
    match           *
    host            ${FLB_ES_HOST}
    port            ${FLB_ES_PORT}
    replace_dots    on
    retry_limit     false
    logstash_format on
    logstash_prefix fluent-bit
conf/parsers.conf
[PARSER]
    name   json
    format json
    time_key time
    time_format %d/%b/%Y:%H:%M:%S %z

[PARSER]
    name        docker
    format      json
    time_key    time
    time_format %Y-%m-%dT%H:%M:%S.%L
    time_keep   On

By default, Elasticsearch runs inside the container as user elasticsearch using uid:gid 1000:0.

If you are bind-mouting a local directory or file, ensure it is readable by this user, while the data and log dirs additionally require write access. A good strategy is to grant group access to gid 1000 or 0 for the local directory. As an example, to prepare a local directory for storing data through a bind-mout:

mkdir esdatadir
chmod g+rwx esdatadir
chgrp 1000 esdatadir

For more information, see Configuration files must be readable by the elasticsearch user

Now let’s create host path for ES data directory and start our EFK services.

  • Create ES data directory.

    $ sudo mkdir /var/lib/elasticsearch
$ sudo chown 1000 /var/lib/elasticsearch
$ sudo ls -ldn /var/lib/elasticsearch
drwxr-xr-x 2 1000 0 4096 Jan 11 17:53 /var/lib/elasticsearch

  • Use docker-compose to start services

    • Fluent Bit Test

      $ docker-compose up fluent-bit
Creating network "efk-docker_local" with driver "bridge"
Creating efk-docker_fluent-bit_1 ... done
Attaching to efk-docker_fluent-bit_1
fluent-bit_1     | Fluent Bit v1.8.11
fluent-bit_1     | * Copyright (C) 2019-2021 The Fluent Bit Authors
fluent-bit_1     | * Copyright (C) 2015-2018 Treasure Data
fluent-bit_1     | * Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
fluent-bit_1     | * https://fluentbit.io
fluent-bit_1     |
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [engine] started (pid=1)
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [storage] version=1.1.5, initializing...
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [storage] in-memory
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [storage] normal synchronization mode, checksum disabled, max_chunks_up=128
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [cmetrics] version=0.2.2
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [input:forward:forward.0] listening on 0.0.0.0:24224
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [http_server] listen iface=0.0.0.0 tcp_port=2020
fluent-bit_1     | [2022/01/11 09:36:39] [ info] [sp] stream processor started
^CGracefully stopping... (press Ctrl+C again to force)
Stopping efk-docker_fluent-bit_1 ... done

      With regex parser, you can also take any unstructured fluent-bit_1 log entry and give them a structure that makes easier it processing and further filtering.

      conf/parsers.conf
      [PARSER]
    name   json
    format json
    time_key time
    time_format %d/%b/%Y:%H:%M:%S %z

[PARSER]
    name        docker
    format      json
    time_key    time
    time_format %Y-%m-%dT%H:%M:%S.%L
    time_keep   On

[PARSER]
    name   fluentbit
    format regex
    regex ^\[(?<time>[^\]]+)\] \[ (?<level>\w+)\] \[(?<compoment>\w+)\] (?<message>.*)$
    time_key time
    time_format %Y/%m/%d %H:%M:%S
      conf/fluent-bit.conf
      [SERVICE]
    flush     5
    daemon    off
    http_server on
    log_level info
    parsers_file parsers.conf

[INPUT]
    Name   forward
    Listen 0.0.0.0
    Port   24224

[FILTER]
    name parser
    match efk.*
    key_name log
    parser json
    reserve_data true

[FILTER]
    name parser
    match efk.fluent-bit
    key_name log
    parser fluentbit
    reserve_data true

[OUTPUT]
    name            es
    match           *
    host            ${FLB_ES_HOST}
    port            ${FLB_ES_PORT}
    replace_dots    on
    retry_limit     false
    logstash_format on
    logstash_prefix fluent-bit

      The following is a structured sample log output:

      [
    1642068626.000000000,
    {
        "level"=>"info",
        "compoment"=>"storage",
        "message"=>"normal synchronization mode, checksum disabled, max_chunks_up=128",
        "container_id"=>"1a8f252975be8d83b534e76c81a2a47466314f52a5344b892d14c14f1d4be58b",
        "container_name"=>"/efk-docker_fluent-bit_1",
        "source"=>"stderr"
    }
]

    • ElasticSearch Test

      $ docker-compose up elasticsearch
Creating network "efk-docker_local" with driver "bridge"
Creating efk-docker_fluent-bit_1 ... done
Creating efk-docker_elasticsearch_1 ... done
Attaching to efk-docker_elasticsearch_1
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:23,016Z", "level": "INFO", "component": "o.e.n.Node", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "version[7.10.2], pid[9], build[oss/docker/747e1cc71def077253878a59143c1f785afa92b9/2021-01-13T00:42:12.435326Z], OS[Linux/5.10.0-9-amd64/amd64], JVM[AdoptOpenJDK/OpenJDK 64-Bit Server VM/15.0.1/15.0.1+9]" }
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:23,019Z", "level": "INFO", "component": "o.e.n.Node", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "JVM home [/usr/share/elasticsearch/jdk], using bundled JDK [true]" }
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:23,020Z", "level": "INFO", "component": "o.e.n.Node", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "JVM arguments [-Xshare:auto, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -XX:+ShowCodeDetailsInExceptionMessages, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dio.netty.allocator.numDirectArenas=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.locale.providers=SPI,COMPAT, -Xms1g, -Xmx1g, -XX:+UseG1GC, -XX:G1ReservePercent=25, -XX:InitiatingHeapOccupancyPercent=30, -Djava.io.tmpdir=/tmp/elasticsearch-16115776092982339533, -XX:+HeapDumpOnOutOfMemoryError, -XX:HeapDumpPath=data, -XX:ErrorFile=logs/hs_err_pid%p.log, -Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m, -Des.cgroups.hierarchy.override=/, -XX:MaxDirectMemorySize=536870912, -Des.path.home=/usr/share/elasticsearch, -Des.path.conf=/usr/share/elasticsearch/config, -Des.distribution.flavor=oss, -Des.distribution.type=docker, -Des.bundled_jdk=true]" }
...
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:24,020Z", "level": "INFO", "component": "o.e.e.NodeEnvironment", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "using [1] data paths, mounts [[/usr/share/elasticsearch/data (/dev/sda1)]], net usable_space [47.2gb], net total_space [97.9gb], types [ext4]" }
...
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:28,189Z", "level": "INFO", "component": "o.e.t.TransportService", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "publish_address {192.168.112.3:9300}, bound_addresses {0.0.0.0:9300}" }
...
elasticsearch_1  | {"type": "server", "timestamp": "2022-01-11T09:56:28,724Z", "level": "INFO", "component": "o.e.h.AbstractHttpServerTransport", "cluster.name": "docker-cluster", "node.name": "453b5fbbea27", "message": "publish_address {192.168.112.3:9200}, bound_addresses {0.0.0.0:9200}", "cluster.uuid": "Ylk56XOzTIehhBYYTVod2A", "node.id": "GJJwqaYqQWmv_wLXTquCqA"  }
...
^CGracefully stopping... (press Ctrl+C again to force)
Stopping efk-docker_elasticsearch_1 ... done

  • Startup all three services

    $ docker-compose up
Creating network "efk-docker_local" with driver "bridge"
Creating efk-docker_fluent-bit_1 ... done
Creating efk-docker_elasticsearch_1 ... done
Creating efk-docker_kibana_1        ... done
Attaching to efk-docker_fluent-bit_1, efk-docker_elasticsearch_1, efk-docker_kibana_1
...

  • Please go to http://localhost:5601 with your browser and follow the Kibana documentation to define your index pattern with fluent-bit-*,

    Create Index Pattern

  • Fllow the Kibana documentation to explore your logging data for the Discover page.

    Discover Logging Data

5. References