This guide describes how to collect application and container logs in Kubernetes using the Logging operator, and how to send them to Kafka.

The following figure gives you an overview about how the system works. The Logging operator collects the logs from the application, selects which logs to forward to the output, and sends the selected log messages to the output. For more details about the Logging operator, see the Logging operator overview.

Deploy Kafka 🔗︎

In this demo we are using our Koperator to create an Apache Kafka cluster in Kubernetes. For details on installing it, see the Koperator installation guide.

Deploy the Logging operator and a demo Application 🔗︎

Install the Logging operator and a demo application to provide sample log messages.

Deploy the Logging operator with Helm 🔗︎

To install the Logging operator using Helm, complete these steps.

Note: For the Helm-based installation you need Helm v3.2.1 or later.

  1. Add the chart repository of the Logging operator using the following commands:

    helm repo add banzaicloud-stable https://kubernetes-charts.banzaicloud.com
helm repo update

  2. Install the Logging operator into the logging namespace:

    helm upgrade --install --wait --create-namespace --namespace logging logging-operator banzaicloud-stable/logging-operator

  3. Install the demo application and its logging definition.

    helm upgrade --install --wait --create-namespace --namespace logging logging-demo banzaicloud-stable/logging-demo \
  --set "kafka.enabled=True"

  4. Validate your deployment.

  5. Create the logging resource.

    kubectl -n logging apply -f - <<"EOF"
apiVersion: logging.banzaicloud.io/v1beta1
kind: Logging
metadata:
  name: default-logging-simple
spec:
  fluentd: {}
  fluentbit: {}
  controlNamespace: logging
EOF

    Note: You can use the ClusterOutput and ClusterFlow resources only in the controlNamespace.

  6. Create a Kafka output definition.

    kubectl -n logging apply -f - <<"EOF"
apiVersion: logging.banzaicloud.io/v1beta1
kind: Output
metadata:
 name: kafka-output
spec:
 kafka:
   brokers: kafka-headless.kafka.svc.cluster.local:29092
   default_topic: topic
   format:
     type: json
   buffer:
     tags: topic
     timekey: 1m
     timekey_wait: 30s
     timekey_use_utc: true
EOF

    Note: In production environment, use a longer timekey interval to avoid generating too many objects.

  7. Create a flow resource.

    kubectl -n logging apply -f - <<"EOF"
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
  name: kafka-flow
spec:
  filters:
    - tag_normaliser: {}
    - parser:
        remove_key_name_field: true
        reserve_data: true
        parse:
          type: nginx
  match:
    - select:
        labels:
          app.kubernetes.io/name: log-generator
  localOutputRefs:
    - kafka-output
EOF

  8. Install the demo application.

    kubectl -n logging apply -f - <<"EOF"
apiVersion: apps/v1
kind: Deployment
metadata:
 name: log-generator
spec:
 selector:
   matchLabels:
     app.kubernetes.io/name: log-generator
 replicas: 1
 template:
   metadata:
     labels:
       app.kubernetes.io/name: log-generator
   spec:
     containers:
     - name: nginx
       image: banzaicloud/log-generator:0.3.2
EOF

  9. Validate your deployment.

Validate the deployment 🔗︎

Run the following command to consume some log messages from Kafka:

kubectl -n kafka run kafka-consumer -it --image=banzaicloud/kafka:2.13-2.4.0 --rm=true --restart=Never -- /opt/kafka/bin/kafka-console-consumer.sh --bootstrap-server kafka-headless:29092 --topic topic --from-beginning

Expected output:

{"stream":"stdout","logtag":"F","kubernetes":{"pod_name":"logging-demo-log-generator-5f9f9cdb9f-z76wr","namespace_name":"logging","pod_id":"a7174256-31bf-4ace-897b-77899873d9ad","labels":{"app.kubernetes.io/instance":"logging-demo","app.kubernetes.io/name":"log-generator","pod-template-hash":"5f9f9cdb9f"},"host":"ip-192-168-3-189.eu-west-2.compute.internal","container_name":"log-generator","docker_id":"7349e6bb2926b8c93cb054a60f171a3f2dd1f6751c07dd389da7f28daf4d70c5","container_hash":"ghcr.io/banzaicloud/log-generator@sha256:814a69be8ab8a67aa6b009d83f6fa6c4776beefbe629a869ff16690fde8ac362","container_image":"ghcr.io/banzaicloud/log-generator:0.3.3"},"remote":"79.104.42.168","host":"-","user":"-","method":"PUT","path":"/products","code":"302","size":"18136","referer":"-","agent":"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.166 Safari/537.36 OPR/20.0.1396.73172","http_x_forwarded_for":"-"}
{"stream":"stdout","logtag":"F","kubernetes":{"pod_name":"logging-demo-log-generator-5f9f9cdb9f-mpp98","namespace_name":"logging","pod_id":"e2822c26-961c-4be8-99a2-b17517494ca1","labels":{"app.kubernetes.io/instance":"logging-demo","app.kubernetes.io/name":"log-generator","pod-template-hash":"5f9f9cdb9f"},"host":"ip-192-168-2-102.eu-west-2.compute.internal","container_name":"log-generator","docker_id":"26ffbec769e52e468216fe43a331f4ce5374075f9b2717d9b9ae0a7f0747b3e2","container_hash":"ghcr.io/banzaicloud/log-generator@sha256:814a69be8ab8a67aa6b009d83f6fa6c4776beefbe629a869ff16690fde8ac362","container_image":"ghcr.io/banzaicloud/log-generator:0.3.3"},"remote":"26.220.126.5","host":"-","user":"-","method":"POST","path":"/","code":"200","size":"14370","referer":"-","agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0","http_x_forwarded_for":"-"}

If you don’t get the expected result you can find help in the troubleshooting section.

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