Store NGINX access logs in Elasticsearch with Logging operator

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

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 Elasticsearch

First, deploy Elasticsearch in your Kubernetes cluster. The following procedure is based on the Elastic Cloud on Kubernetes quickstart, but there are some minor configuration changes, and we install everything into the logging namespace.

1. Install the Elasticsearch operator.

   kubectl apply -f https://download.elastic.co/downloads/eck/1.3.0/all-in-one.yaml
   

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2. Create the logging Namespace.

   kubectl create ns logging
   

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3. Install the Elasticsearch cluster into the logging namespace.

   cat <<EOF | kubectl apply -n logging -f -
   apiVersion: elasticsearch.k8s.elastic.co/v1
   kind: Elasticsearch
   metadata:
     name: quickstart
   spec:
     version: 7.10.0
     nodeSets:
     - name: default
       count: 1
       config:
         node.master: true
         node.data: true
         node.ingest: true
         node.store.allow_mmap: false
   EOF
   

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4. Install Kibana into the logging namespace.

   cat <<EOF | kubectl apply -n logging -f -
   apiVersion: kibana.k8s.elastic.co/v1
   kind: Kibana
   metadata:
     name: quickstart
   spec:
     version: 7.10.0
     count: 1
     elasticsearchRef:
       name: quickstart
   EOF
   

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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 the following steps.

Note: You need Helm v3.8 or later to be able to install the chart from an OCI registry.

1. Install the Logging operator into the logging namespace:

   helm upgrade --install --wait --create-namespace --namespace logging logging-operator oci://ghcr.io/kube-logging/helm-charts/logging-operator
   

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   Expected output:

   Release "logging-operator" does not exist. Installing it now.
   Pulled: ghcr.io/kube-logging/helm-charts/logging-operator:4.3.0
   Digest: sha256:c2ece861f66a3a2cb9788e7ca39a267898bb5629dc98429daa8f88d7acf76840
   NAME: logging-operator
   LAST DEPLOYED: Wed Aug  9 11:02:12 2023
   NAMESPACE: logging
   STATUS: deployed
   REVISION: 1
   TEST SUITE: None
   

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   Note:

   • Helm has a known issue in version 3.13.0 that requires users to log in to the registry, even though the repo is public.

     Upgrade to 3.13.1 or higher to avoid having to log in, see: https://github.com/kube-logging/logging-operator/issues/1522

   • If you’re installing the Helm chart from Terraform, reference the repository as repository = "oci://ghcr.io/kube-logging/helm-charts/" (without the logging-operator suffix). Otherwise, you’ll get a 403 Forbidden error.

2. Validate your deployment.

Configure the Logging operator

1. 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
   

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

2. Create an Elasticsearch output definition.

   kubectl -n logging apply -f - <<"EOF"
   apiVersion: logging.banzaicloud.io/v1beta1
   kind: Output
   metadata:
     name: es-output
   spec:
     elasticsearch:
       host: quickstart-es-http.logging.svc.cluster.local
       port: 9200
       scheme: https
       ssl_verify: false
       ssl_version: TLSv1_2
       user: elastic
       password:
         valueFrom:
           secretKeyRef:
             name: quickstart-es-elastic-user
             key: elastic
       buffer:
         timekey: 1m
         timekey_wait: 30s
         timekey_use_utc: true
   EOF
   

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

3. Create a flow resource. (Mind the label selector in the match that selects a set of pods that we will install in the next step)

   kubectl -n logging apply -f - <<"EOF"
   apiVersion: logging.banzaicloud.io/v1beta1
   kind: Flow
   metadata:
     name: es-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:
       - es-output
   EOF
   

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4. Install the demo application.

   helm upgrade --install --wait --create-namespace --namespace logging log-generator oci://ghcr.io/kube-logging/helm-charts/log-generator
   

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5. Validate your deployment.

Validate the deployment

To validate that the deployment was successful, complete the following steps.

1. Check fluentd logs:

   kubectl logs -f -n logging default-logging-simple-fluentd-0 -c fluentd
   

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   Fluentd logs were written to the container filesystem up until Logging operator version 4.3, which has been changed to stdout with 4.4. See FluentOutLogrotate why this was changed and how you can re-enable it if needed.

2. Use the following command to retrieve the password of the elastic user:

   kubectl -n logging get secret quickstart-es-elastic-user -o=jsonpath='{.data.elastic}' | base64 --decode; echo
   

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3. Enable port forwarding to the Kibana Dashboard Service.

   kubectl -n logging port-forward svc/quickstart-kb-http 5601
   

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4. Open the Kibana dashboard in your browser at https://localhost:5601 and login as elastic using the retrieved password.

5. By default, the Logging operator sends the incoming log messages into an index called fluentd. Create an Index Pattern that includes this index (for example, fluentd*), then select Menu > Kibana > Discover. You should see the dashboard and some sample log messages from the demo application.

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