<p>I have a problem with connecting my FluentD installation in Amazon EKS cluster which is going to send data direct to an ElasticSearch stack in Azure. I would like to configure it like you do with Filebeat with a certificate (ca.pem, cert.pem and cert.key) instead of user/password authentication.</p>

<p>I have managed to get the FluentD pods up and running and the RBAC is working as it should and as the documentation for certificate authorization is non existing as it seems, I have tried to do some trial and error but to no vail.</p>

<p>My config for the certificate is as follows:</p>

<pre><code>apiVersion: v1
kind: ServiceAccount
metadata:
  name: fluentd
  namespace: elasticsearch-azure
---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: fluentd-role
  namespace: elastisearch-azure
rules:
  - apiGroups: [""]
    resources:
      - namespaces
      - pods
      - pods/logs
    verbs: ["get", "list", "watch"]
---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: fluentd-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: fluentd-role
subjects:
  - kind: ServiceAccount
    name: fluentd
    namespace: elasticsearch-azure
---

apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: fluentd
  namespace: elasticsearch-azure
  labels:
    k8s-app: fluentd-logging
    version: v1
spec:
  template:
    metadata:
      labels:
        k8s-app: fluentd-logging
        version: v1
    spec:
      serviceAccountName: fluentd
      tolerations:
      - key: node-role.kubernetes.io/master
        effect: NoSchedule
      containers:
      - name: fluentd
        image: fluent/fluentd-kubernetes-daemonset:v1-debian-elasticsearch
        envFrom:
        - secretRef:
            name: fluent-tls
        env:
          - name:  FLUENT_ELASTICSEARCH_HOST
            value: "{{server_namne}}"
          - name:  FLUENT_ELASTICSEARCH_PORT
            value: "{port}"
          - name: FLUENT_ELASTICSEARCH_SCHEME
            value: "https"
          # Option to configure elasticsearch plugin with self signed certs
          # ================================================================
          - name: FLUENT_ELASTICSEARCH_SSL_VERIFY
            value: "true"
          # Option to configure elasticsearch plugin with tls
          # ================================================================
          - name: FLUENT_ELASTICSEARCH_SSL_VERSION
            value: "TLSv1_2"
        resources:
          limits:
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 200Mi
        volumeMounts:
        - name: varlog
          mountPath: /var/log
        - name: varlibdockercontainers
          mountPath: /var/lib/docker/containers
          readOnly: true
        - name: ssl
          mountPath: /fluent-tls/ssl
          readOnly: true
      terminationGracePeriodSeconds: 30
      volumes:
      - name: varlog
        hostPath:
          path: /var/log
      - name: varlibdockercontainers
        hostPath:
          path: /var/lib/docker/containers
      # certificates folder for filebeat
      - name: ssl
        secret:
          secretName: fluent-tls
</code></pre>

<p>I have create the secret with the following command:</p>

<pre><code>kubectl create secret generic fluent-tls \
--from-file=ca_file=./chain.pem \
--from-file=cert_pem=./cert.pem \
--from-file=cert_key=./cert.key
</code></pre>

<p>The error I get when running the pods is as follows:</p>

<pre><code> &lt;match **&gt;
    @type elasticsearch
    @id out_es
    @log_level "info"
    include_tag_key true
    host "super-sercret-host.com"
    port even-more-secret-portnumber
    path ""
    scheme https
    ssl_verify false
    ssl_version TLSv1_2
    reload_connections false
    reconnect_on_error true
    reload_on_failure true
    log_es_400_reason false
    logstash_prefix "logstash"
    logstash_format true
    index_name "logstash"
    type_name "fluentd"
    &lt;buffer&gt;
      flush_thread_count 8
      flush_interval 5s
      chunk_limit_size 2M
      queue_limit_length 32
      retry_max_interval 30
      retry_forever true
    &lt;/buffer&gt;
  &lt;/match&gt;
&lt;/ROOT&gt;
2019-12-16 14:51:30 +0000 [info]: starting fluentd-1.7.4 pid=6 ruby="2.6.5"
2019-12-16 14:51:30 +0000 [info]: spawn command to main:  cmdline=["/usr/local/bin/ruby", "-Eascii-8bit:ascii-8bit", "/fluentd/vendor/bundle/ruby/2.6.0/bin/fluentd", "-c", "/fluentd/etc/fluent.conf", "-p", "/fluentd/plugins", "--gemfile", "/fluentd/Gemfile", "--under-supervisor"]
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-concat' version '2.4.0'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-detect-exceptions' version '0.0.13'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-elasticsearch' version '3.7.1'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-grok-parser' version '2.6.1'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-json-in-json-2' version '1.0.2'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-kubernetes_metadata_filter' version '2.3.0'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-multi-format-parser' version '1.0.0'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-prometheus' version '1.6.1'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-record-modifier' version '2.0.1'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-rewrite-tag-filter' version '2.2.0'
2019-12-16 14:51:31 +0000 [info]: gem 'fluent-plugin-systemd' version '1.0.2'
2019-12-16 14:51:31 +0000 [info]: gem 'fluentd' version '1.7.4'
2019-12-16 14:51:31 +0000 [info]: adding match pattern="fluent.**" type="null"
2019-12-16 14:51:31 +0000 [info]: adding filter pattern="kubernetes.**" type="kubernetes_metadata"
2019-12-16 14:51:31 +0000 [info]: adding match pattern="**" type="elasticsearch"
2019-12-16 14:51:34 +0000 [warn]: #0 [out_es] Could not communicate to Elasticsearch, resetting connection and trying again. SSL_connect returned=1 errno=0 state=error: sslv3 alert handshake failure (OpenSSL::SSL::SSLError)
2019-12-16 14:51:34 +0000 [warn]: #0 [out_es] Remaining retry: 14. Retry to communicate after 2 second(s).
2019-12-16 14:51:38 +0000 [warn]: #0 [out_es] Could not communicate to Elasticsearch, resetting connection and trying again. SSL_connect returned=1 errno=0 state=error: sslv3 alert handshake failure (OpenSSL::SSL::SSLError)
2019-12-16 14:51:38 +0000 [warn]: #0 [out_es] Remaining retry: 13. Retry to communicate after 4 second(s).
</code></pre>

<p>I know that if I only could get the configuration attributes: ca_file, client_pem and client_key parameters into the  tag it would probably work, but I have not managed that so far. Any help is appreciated.</p>

Mikael Nyborg
<p>THANK YOU! Thank you so much; your config example helped to solve my SSL auth problem between FLuentD and ES, and now maybe I can help you.</p>

<p>I am using the Open Distro for Elasticsearch with Bitnami's FluentD, and I was getting a similar error. My resolution was to use parts of your config, but I had to change the <em>host</em> to <em>hosts</em>, like this;</p>

<pre><code>hosts               https://admin:admin@odfe-node1:9200
</code></pre>

<p>It seems that you must specify the username, protocol and port on a single line, the same way that you must specify multiple hosts in a cluster. It worked for me. Look at the <a href="https://docs.fluentd.org/output/elasticsearch" rel="nofollow noreferrer">FluentD docs</a> for further reference. </p>
