Rollover_alias errors on logstash daily indices from client application (fluentd)

Elastic Stack Elasticsearch
3

I was able to make it work with a date in the index name, but by making the following modifications to my fluentd Kubernetes yaml file:

- name: FLUENT_ELASTICSEARCH_LOGSTASH_FORMAT
  value: "false"
- name: FLUENT_ELASTICSEARCH_LOGSTASH_INDEX_NAME
  value: "logstash-fluentd-kubernetes"
- name: FLUENT_ELASTICSEARCH_ENABLE_ILM
  value: "true"
- name: FLUENT_ELASTICSEARCH_TEMPLATE_FILE
  value: /host/index_template.json
- name: FLUENT_ELASTICSEARCH_TEMPLATE_NAME
  value: "logstash-fluentd-kubernetes"
- name: FLUENT_ELASTICSEARCH_INCLUDE_TIMESTAMP
  value: "true"
- name: FLUENT_ELASTICSEARCH_APPLICATION_NAME
  value: "logging"

volumes:
- name: es-template
  configMap:
    name: es-template

volumeMounts:
- name: es-template
  mountPath: /host
  readOnly: true

---
apiVersion: v1
data:
  index_template.json: |-
    {
        "index_patterns": [
            "logstash-fluentd-kubernetes-*"
        ]
    }
kind: ConfigMap
metadata:
  name: es-template
  namespace: kube-system

The index now look like this when I force a rollover:

logstash-fluentd-kubernetes-logging-2021.04.06-000002
logstash-fluentd-kubernetes-logging-2021.04.06-000001

... and it keeps writing to the same date it initially created the index with (not creating a new one everyday).

The index template name is: "logstash-fluentd-kubernetes" and its pattern: "logstash-fluentd-kubernetes-*"