Not able to index documents using app search(7.6.1)

Elastic Search
13 
- name: Install elasticsearch
  hosts: kombare_es
  roles:
    - role: elastic.elasticsearch
  vars:
    es_enable_xpack: true
    es_version: 7.6.1
    es_heap_size: 4g
    es_enable_http_ssl: true
    es_api_basic_auth_username: elastic
    es_api_basic_auth_password: changme
    es_ssl_keystore: "files/certs/my-keystore.p12"
    es_ssl_truststore: "files/certs/ca-public-private.p12"
    es_validate_certs: no
    es_config:
      # network.host: 0.0.0.0
      # network.publish_host: 0.0.0.0
      network.host: 127.0.0.1
      network.publish_host: 127.0.0.1
     # http.port: 8001
      node.name: e1
#      cluster.initial_master_nodes:
#        - kombare-es.com
      discovery.type: single-node
      http.cors.enabled: true
      http.cors.allow-origin: "*" # todo make it specific
      xpack:
        security:
          authc:
            realms:
              native:
                native1:
                  order: 0

  become: yes

  tasks:
    - name: add nginx server config
      import_tasks: _elasticsearch_nginx.yml
      tags: nginx

I am using official ansible playbook: https://github.com/elastic/ansible-elasticsearch

is the issue related to nginx? is this topic related Issue with app search (download) release -- not quite a connection issue ?

Following this article I moved the app search to the same server - to communicate with elasticsearch directly without nginx reverse proxy- and changed app-search.yml to

allow_es_settings_modification: true
elasticsearch.username: "{{ elasticsearch_username }}"
elasticsearch.password: "{{ elasticsearch_password }}"
elasticsearch.ssl.enabled: true
elasticsearch.ssl.verify: false
app_search.external_url: https://localhost:9200
app_search.auth.source: elasticsearch-native

then I was this error:

unable to find valid certification path to requested target

even when

elasticsearch.ssl.verify: false

@orhantoy