How to get different application logs to Elasticsearch using fluentd in kubernetes

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

kind: ConfigMapapiVersion: v1metadata:  name: fluentd-es-config-debug  namespace: kube-system  labels:    addonmanager.kubernetes.io/mode: Reconciledata:  system.conf: |-    <system>      root_dir /tmp/fluentd-buffers/    </system>  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 & 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 & the    # fluent-plugin-kubernetes_metadata_filter plugins.    # See https://github.com/uken/fluent-plugin-elasticsearch &    # 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 & add labels to the log record if properly configured. This enables users    # to filter & 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    #    ->    #    /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 & container name    # which are added to the log message as a kubernetes field object & 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    <source>      @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    </source>    # Detect exceptions in the log output and forward them as one log entry.    <match raw.kubernetes.**>      @id raw.kubernetes      @type detect_exceptions      remove_tag_prefix raw      message log      stream stream      multiline_flush_interval 5      max_bytes 500000      max_lines 1000    </match>  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    <source>      @id minion      @type tail      format /^(?<time>[^ ]* [^ ,]*)[^\[]*\[[^\]]*\]\[(?<severity>[^ \]]*) *\] (?<message>.*)$/      time_format %Y-%m-%d %H:%M:%S      path /var/log/salt/minion      pos_file /var/log/salt.pos      tag salt    </source>    # Example:    # Dec 21 23:17:22 gke-foo-1-1-4b5cbd14-node-4eoj startupscript: Finished running startup script /var/run/google.startup.script    <source>      @id startupscript.log      @type tail      format syslog      path /var/log/startupscript.log      pos_file /var/log/es-startupscript.log.pos      tag startupscript    </source>    # Examples:    # time="2016-02-04T06:51:03.053580605Z" level=info msg="GET /containers/json"    # time="2016-02-04T07:53:57.505612354Z" level=error msg="HTTP Error" err="No such image: -f" statusCode=404    # TODO(random-liu): Remove this after cri container runtime rolls out.    <source>      @id docker.log      @type tail      format /^time="(?<time>[^)]*)" level=(?<severity>[^ ]*) msg="(?<message>[^"]*)"( err="(?<error>[^"]*)")?( statusCode=($<status_code>\d+))?/      path /var/log/docker.log      pos_file /var/log/es-docker.log.pos      tag docker    </source>    # Example:    # 2016/02/04 06:52:38 filePurge: successfully removed file /var/etcd/data/member/wal/00000000000006d0-00000000010a23d1.wal    <source>      @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    </source>    # 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]    <source>      @id kubelet.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      time_format %m%d %H:%M:%S.%N      path /var/log/kubelet.log      pos_file /var/log/es-kubelet.log.pos      tag kubelet    </source>    # 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    <source>      @id kube-proxy.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      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    </source>    # 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]    <source>      @id kube-apiserver.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      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    </source>    # Example:    # I0204 06:55:31.872680       5 servicecontroller.go:277] LB already exists and doesn't need update for service kube-system/kube-ui    <source>      @id kube-controller-manager.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      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    </source>    # 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]    <source>      @id kube-scheduler.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      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    </source>    # Example:    # I1104 10:36:20.242766       5 rescheduler.go:73] Running Rescheduler    <source>      @id rescheduler.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      time_format %m%d %H:%M:%S.%N      path /var/log/rescheduler.log      pos_file /var/log/es-rescheduler.log.pos      tag rescheduler    </source>    # Example:    # I0603 15:31:05.793605       6 cluster_manager.go:230] Reading config from path /etc/gce.conf    <source>      @id glbc.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      time_format %m%d %H:%M:%S.%N      path /var/log/glbc.log      pos_file /var/log/es-glbc.log.pos      tag glbc    </source>    # Example:    # I0603 15:31:05.793605       6 cluster_manager.go:230] Reading config from path /etc/gce.conf    <source>      @id cluster-autoscaler.log      @type tail      format multiline      multiline_flush_interval 5s      format_firstline /^\w\d{4}/      format1 /^(?<severity>\w)(?<time>\d{4} [^\s]*)\s+(?<pid>\d+)\s+(?<source>[^ \]]+)\] (?<message>.*)/      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    </source>    # Logs from systemd-journal for interesting services.    # TODO(random-liu): Remove this after cri container runtime rolls out.    <source>      @id journald-docker      @type systemd      filters [{ "_SYSTEMD_UNIT": "docker.service" }]      <storage>        @type local        persistent true      </storage>      read_from_head true      tag docker    </source>    <source>      @id journald-container-runtime      @type systemd      filters [{ "_SYSTEMD_UNIT": "{{ container_runtime }}.service" }]      <storage>        @type local        persistent true      </storage>      read_from_head true      tag container-runtime    </source>    <source>      @id journald-kubelet      @type systemd      filters [{ "_SYSTEMD_UNIT": "kubelet.service" }]      <storage>        @type local        persistent true      </storage>      read_from_head true      tag kubelet    </source>    <source>      @id journald-node-problem-detector      @type systemd      filters [{ "_SYSTEMD_UNIT": "node-problem-detector.service" }]      <storage>        @type local        persistent true      </storage>      read_from_head true      tag node-problem-detector    </source>  forward.input.conf: |-    # Takes the messages sent over TCP    <source>      @type forward    </source>  monitoring.conf: |-    # Prometheus Exporter Plugin    # input plugin that exports metrics    <source>      @type prometheus    </source>    <source>      @type monitor_agent    </source>    # input plugin that collects metrics from MonitorAgent    <source>      @type prometheus_monitor      <labels>        host ${hostname}      </labels>    </source>    # input plugin that collects metrics for output plugin    <source>      @type prometheus_output_monitor      <labels>        host ${hostname}      </labels>    </source>    # input plugin that collects metrics for in_tail plugin    <source>      @type prometheus_tail_monitor      <labels>        host ${hostname}      </labels>    </source>  output.conf: |-    # Enriches records with Kubernetes metadata    <filter kubernetes.**>      @type kubernetes_metadata    </filter>    <match **>      @id elasticsearch      @type elasticsearch      @log_level info      include_tag_key true      host elasticsearch-logging      port 9200      logstash_format true      <buffer>        @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      </buffer>    </match>

And read the comments, they might help you achieve what you want, assuming that you have read through the doc for fluentd https://docs.fluentd.org/v1.0/articles/quickstart.

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: https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/fluentd-elasticsearch/fluentd-es-configmap.yaml ).