<p>I am using <a href="https://github.com/fluent/fluentd-kubernetes-daemonset" rel="noreferrer">fluentd daemonset</a> to get kubernetes logs to Elasticsearch/Kibana which is working fine. Now the problem is that there are 3 4 application running in kubernetes which have different log pattern, these are running in pods and pods are writing to stdout. How should I capture these logs from different apps using fluentd and forward to ES?</p>

<p>I want to tag different application logs with the name of application. If possible please provide a fluentd config block to achieve the same.</p>

<p>Any help would be appreciable.</p>

<p>Sure! check this ConfigMap, which I believe you have as well somewhere in your cluster:</p>

<pre><code>kind: ConfigMap
apiVersion: v1
metadata:
  name: fluentd-es-config-debug
  namespace: kube-system
  labels:
    addonmanager.kubernetes.io/mode: Reconcile
data:
  system.conf: |-
    &lt;system&gt;
      root_dir /tmp/fluentd-buffers/
    &lt;/system&gt;

  containers.input.conf: |-
    # This configuration file for Fluentd / td-agent is used
    # to watch changes to Docker log files. The kubelet creates symlinks that
    # capture the pod name, namespace, container name &amp; Docker container ID
    # to the docker logs for pods in the /var/log/containers directory on the host.
    # If running this fluentd configuration in a Docker container, the /var/log
    # directory should be mounted in the container.
    #
    # These logs are then submitted to Elasticsearch which assumes the
    # installation of the fluent-plugin-elasticsearch &amp; the
    # fluent-plugin-kubernetes_metadata_filter plugins.
    # See https://github.com/uken/fluent-plugin-elasticsearch &amp;
    # https://github.com/fabric8io/fluent-plugin-kubernetes_metadata_filter for
    # more information about the plugins.
    #
    # Example
    # =======
    # A line in the Docker log file might look like this JSON:
    #
    # {"log":"2014/09/25 21:15:03 Got request with path wombat\n",
    #  "stream":"stderr",
    #   "time":"2014-09-25T21:15:03.499185026Z"}
    #
    # The time_format specification below makes sure we properly
    # parse the time format produced by Docker. This will be
    # submitted to Elasticsearch and should appear like:
    # $ curl 'http://elasticsearch-logging:9200/_search?pretty'
    # ...
    # {
    #      "_index" : "logstash-2014.09.25",
    #      "_type" : "fluentd",
    #      "_id" : "VBrbor2QTuGpsQyTCdfzqA",
    #      "_score" : 1.0,
    #      "_source":{"log":"2014/09/25 22:45:50 Got request with path wombat\n",
    #                 "stream":"stderr","tag":"docker.container.all",
    #                 "@timestamp":"2014-09-25T22:45:50+00:00"}
    #    },
    # ...
    #
    # The Kubernetes fluentd plugin is used to write the Kubernetes metadata to the log
    # record &amp; add labels to the log record if properly configured. This enables users
    # to filter &amp; search logs on any metadata.
    # For example a Docker container's logs might be in the directory:
    #
    #  /var/lib/docker/containers/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b
    #
    # and in the file:
    #
    #  997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b-json.log
    #
    # where 997599971ee6... is the Docker ID of the running container.
    # The Kubernetes kubelet makes a symbolic link to this file on the host machine
    # in the /var/log/containers directory which includes the pod name and the Kubernetes
    # container name:
    #
    #    synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log
    #    -&gt;
    #    /var/lib/docker/containers/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b-json.log
    #
    # The /var/log directory on the host is mapped to the /var/log directory in the container
    # running this instance of Fluentd and we end up collecting the file:
    #
    #   /var/log/containers/synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log
    #
    # This results in the tag:
    #
    #  var.log.containers.synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log
    #
    # The Kubernetes fluentd plugin is used to extract the namespace, pod name &amp; container name
    # which are added to the log message as a kubernetes field object &amp; the Docker container ID
    # is also added under the docker field object.
    # The final tag is:
    #
    #   kubernetes.var.log.containers.synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log
    #
    # And the final log record look like:
    #
    # {
    #   "log":"2014/09/25 21:15:03 Got request with path wombat\n",
    #   "stream":"stderr",
    #   "time":"2014-09-25T21:15:03.499185026Z",
    #   "kubernetes": {
    #     "namespace": "default",
    #     "pod_name": "synthetic-logger-0.25lps-pod",
    #     "container_name": "synth-lgr"
    #   },
    #   "docker": {
    #     "container_id": "997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b"
    #   }
    # }
    #
    # This makes it easier for users to search for logs by pod name or by
    # the name of the Kubernetes container regardless of how many times the
    # Kubernetes pod has been restarted (resulting in a several Docker container IDs).

    # Json Log Example:
    # {"log":"[info:2016-02-16T16:04:05.930-08:00] Some log text here\n","stream":"stdout","time":"2016-02-17T00:04:05.931087621Z"}
    # CRI Log Example:
    # 2016-02-17T00:04:05.931087621Z stdout F [info:2016-02-16T16:04:05.930-08:00] Some log text here
    &lt;source&gt;
      @id fluentd-containers.log
      @type tail
      path /var/log/containers/*.log
      pos_file /var/log/es-containers.log.pos
      time_format %Y-%m-%dT%H:%M:%S.%NZ
      tag raw.kubernetes.*
      format json
      read_from_head true
    &lt;/source&gt;

    # Detect exceptions in the log output and forward them as one log entry.
    &lt;match raw.kubernetes.**&gt;
      @id raw.kubernetes
      @type detect_exceptions
      remove_tag_prefix raw
      message log
      stream stream
      multiline_flush_interval 5
      max_bytes 500000
      max_lines 1000
    &lt;/match&gt;

  system.input.conf: |-
    # Example:
    # 2015-12-21 23:17:22,066 [salt.state       ][INFO    ] Completed state [net.ipv4.ip_forward] at time 23:17:22.066081
    &lt;source&gt;
      @id minion
      @type tail
      format /^(?&lt;time&gt;[^ ]* [^ ,]*)[^\[]*\[[^\]]*\]\[(?&lt;severity&gt;[^ \]]*) *\] (?&lt;message&gt;.*)$/
      time_format %Y-%m-%d %H:%M:%S
      path /var/log/salt/minion
      pos_file /var/log/salt.pos
      tag salt
    &lt;/source&gt;

    # Example:
    # Dec 21 23:17:22 gke-foo-1-1-4b5cbd14-node-4eoj startupscript: Finished running startup script /var/run/google.startup.script
    &lt;source&gt;
      @id startupscript.log
      @type tail
      format syslog
      path /var/log/startupscript.log
      pos_file /var/log/es-startupscript.log.pos
      tag startupscript
    &lt;/source&gt;

    # Examples:
    # time="2016-02-04T06:51:03.053580605Z" level=info msg="GET /containers/json"
    # time="2016-02-04T07:53:57.505612354Z" level=error msg="HTTP Error" err="No such image: -f" statusCode=404
    # TODO(random-liu): Remove this after cri container runtime rolls out.
    &lt;source&gt;
      @id docker.log
      @type tail
      format /^time="(?&lt;time&gt;[^)]*)" level=(?&lt;severity&gt;[^ ]*) msg="(?&lt;message&gt;[^"]*)"( err="(?&lt;error&gt;[^"]*)")?( statusCode=($&lt;status_code&gt;\d+))?/
      path /var/log/docker.log
      pos_file /var/log/es-docker.log.pos
      tag docker
    &lt;/source&gt;

    # Example:
    # 2016/02/04 06:52:38 filePurge: successfully removed file /var/etcd/data/member/wal/00000000000006d0-00000000010a23d1.wal
    &lt;source&gt;
      @id etcd.log
      @type tail
      # Not parsing this, because it doesn't have anything particularly useful to
      # parse out of it (like severities).
      format none
      path /var/log/etcd.log
      pos_file /var/log/es-etcd.log.pos
      tag etcd
    &lt;/source&gt;

    # Multi-line parsing is required for all the kube logs because very large log
    # statements, such as those that include entire object bodies, get split into
    # multiple lines by glog.

    # Example:
    # I0204 07:32:30.020537    3368 server.go:1048] POST /stats/container/: (13.972191ms) 200 [[Go-http-client/1.1] 10.244.1.3:40537]
    &lt;source&gt;
      @id kubelet.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/kubelet.log
      pos_file /var/log/es-kubelet.log.pos
      tag kubelet
    &lt;/source&gt;

    # Example:
    # I1118 21:26:53.975789       6 proxier.go:1096] Port "nodePort for kube-system/default-http-backend:http" (:31429/tcp) was open before and is still needed
    &lt;source&gt;
      @id kube-proxy.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/kube-proxy.log
      pos_file /var/log/es-kube-proxy.log.pos
      tag kube-proxy
    &lt;/source&gt;

    # Example:
    # I0204 07:00:19.604280       5 handlers.go:131] GET /api/v1/nodes: (1.624207ms) 200 [[kube-controller-manager/v1.1.3 (linux/amd64) kubernetes/6a81b50] 127.0.0.1:38266]
    &lt;source&gt;
      @id kube-apiserver.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/kube-apiserver.log
      pos_file /var/log/es-kube-apiserver.log.pos
      tag kube-apiserver
    &lt;/source&gt;

    # Example:
    # I0204 06:55:31.872680       5 servicecontroller.go:277] LB already exists and doesn't need update for service kube-system/kube-ui
    &lt;source&gt;
      @id kube-controller-manager.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/kube-controller-manager.log
      pos_file /var/log/es-kube-controller-manager.log.pos
      tag kube-controller-manager
    &lt;/source&gt;

    # Example:
    # W0204 06:49:18.239674       7 reflector.go:245] pkg/scheduler/factory/factory.go:193: watch of *api.Service ended with: 401: The event in requested index is outdated and cleared (the requested history has been cleared [2578313/2577886]) [2579312]
    &lt;source&gt;
      @id kube-scheduler.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/kube-scheduler.log
      pos_file /var/log/es-kube-scheduler.log.pos
      tag kube-scheduler
    &lt;/source&gt;

    # Example:
    # I1104 10:36:20.242766       5 rescheduler.go:73] Running Rescheduler
    &lt;source&gt;
      @id rescheduler.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/rescheduler.log
      pos_file /var/log/es-rescheduler.log.pos
      tag rescheduler
    &lt;/source&gt;

    # Example:
    # I0603 15:31:05.793605       6 cluster_manager.go:230] Reading config from path /etc/gce.conf
    &lt;source&gt;
      @id glbc.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/glbc.log
      pos_file /var/log/es-glbc.log.pos
      tag glbc
    &lt;/source&gt;

    # Example:
    # I0603 15:31:05.793605       6 cluster_manager.go:230] Reading config from path /etc/gce.conf
    &lt;source&gt;
      @id cluster-autoscaler.log
      @type tail
      format multiline
      multiline_flush_interval 5s
      format_firstline /^\w\d{4}/
      format1 /^(?&lt;severity&gt;\w)(?&lt;time&gt;\d{4} [^\s]*)\s+(?&lt;pid&gt;\d+)\s+(?&lt;source&gt;[^ \]]+)\] (?&lt;message&gt;.*)/
      time_format %m%d %H:%M:%S.%N
      path /var/log/cluster-autoscaler.log
      pos_file /var/log/es-cluster-autoscaler.log.pos
      tag cluster-autoscaler
    &lt;/source&gt;

    # Logs from systemd-journal for interesting services.
    # TODO(random-liu): Remove this after cri container runtime rolls out.
    &lt;source&gt;
      @id journald-docker
      @type systemd
      filters [{ "_SYSTEMD_UNIT": "docker.service" }]
      &lt;storage&gt;
        @type local
        persistent true
      &lt;/storage&gt;
      read_from_head true
      tag docker
    &lt;/source&gt;

    &lt;source&gt;
      @id journald-container-runtime
      @type systemd
      filters [{ "_SYSTEMD_UNIT": "{{ container_runtime }}.service" }]
      &lt;storage&gt;
        @type local
        persistent true
      &lt;/storage&gt;
      read_from_head true
      tag container-runtime
    &lt;/source&gt;

    &lt;source&gt;
      @id journald-kubelet
      @type systemd
      filters [{ "_SYSTEMD_UNIT": "kubelet.service" }]
      &lt;storage&gt;
        @type local
        persistent true
      &lt;/storage&gt;
      read_from_head true
      tag kubelet
    &lt;/source&gt;

    &lt;source&gt;
      @id journald-node-problem-detector
      @type systemd
      filters [{ "_SYSTEMD_UNIT": "node-problem-detector.service" }]
      &lt;storage&gt;
        @type local
        persistent true
      &lt;/storage&gt;
      read_from_head true
      tag node-problem-detector
    &lt;/source&gt;

  forward.input.conf: |-
    # Takes the messages sent over TCP
    &lt;source&gt;
      @type forward
    &lt;/source&gt;

  monitoring.conf: |-
    # Prometheus Exporter Plugin
    # input plugin that exports metrics
    &lt;source&gt;
      @type prometheus
    &lt;/source&gt;

    &lt;source&gt;
      @type monitor_agent
    &lt;/source&gt;

    # input plugin that collects metrics from MonitorAgent
    &lt;source&gt;
      @type prometheus_monitor
      &lt;labels&gt;
        host ${hostname}
      &lt;/labels&gt;
    &lt;/source&gt;

    # input plugin that collects metrics for output plugin
    &lt;source&gt;
      @type prometheus_output_monitor
      &lt;labels&gt;
        host ${hostname}
      &lt;/labels&gt;
    &lt;/source&gt;

    # input plugin that collects metrics for in_tail plugin
    &lt;source&gt;
      @type prometheus_tail_monitor
      &lt;labels&gt;
        host ${hostname}
      &lt;/labels&gt;
    &lt;/source&gt;

  output.conf: |-
    # Enriches records with Kubernetes metadata
    &lt;filter kubernetes.**&gt;
      @type kubernetes_metadata
    &lt;/filter&gt;

    &lt;match **&gt;
      @id elasticsearch
      @type elasticsearch
      @log_level info
      include_tag_key true
      host elasticsearch-logging
      port 9200
      logstash_format true
      &lt;buffer&gt;
        @type file
        path /var/log/fluentd-buffers/kubernetes.system.buffer
        flush_mode interval
        retry_type exponential_backoff
        flush_thread_count 2
        flush_interval 5s
        retry_forever
        retry_max_interval 30
        chunk_limit_size 2M
        queue_limit_length 8
        overflow_action block
      &lt;/buffer&gt;
    &lt;/match&gt;
</code></pre>

<p>And read the comments, they might help you achieve what you want, assuming that you have read through the doc for fluentd <a href="https://docs.fluentd.org/v1.0/articles/quickstart" rel="nofollow noreferrer">https://docs.fluentd.org/v1.0/articles/quickstart</a>.</p>

<p>Also bear in mind that logs parsing changes based on the scenario you need to apply it to, so the above is the best example that I can come up with (referenced from: <a href="https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/fluentd-elasticsearch/fluentd-es-configmap.yaml" rel="nofollow noreferrer">https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/fluentd-elasticsearch/fluentd-es-configmap.yaml</a> ).</p>
