Programing date custom field into content type

Question

I'm building a module that creates a content type when it installs. I already have my content type, let's call it MyContentType and I have a field body that I created based on Drupal documentation (https://www.drupal.org/docs/8/api/entity-api/programming-custom-fields-into-your-content-type) and I could create the two additional fields but I can't find a way to add a field of type date, datetime or timestamp. I tried to replace 'type: text_default' to 'type: datetime' but when I did it all my fields disappeared! I know I should also have a file named field.field.node.mycontenttype.field_date.yml with the correct configuration but what is the way to tell drupal that the type is datetime ? And how can I set it to current time?

field.storage.node.field_date.yml

langcode: en
status: true
dependencies:
  module:
    - node
    - text
id: node.field_date
field_name: field_date
entity_type: node
type: datetime
settings: {  }
module: datetime
locked: false
cardinality: 1
translatable: true
indexes: {  }
persist_with_no_fields: false
custom_storage: false

field.field.node.mycontenttype.field_brand_information.yml

langcode: en
status: true
dependencies:
  config:
    - field.storage.node.field_date
    - node.type.mycontenttype
  module:
    - text
id: node.mycontenttype.field_date
field_name: field_date
entity_type: node
bundle: mycontenttype
label: 'Date'
description: 'Date'
required: false
translatable: false
default_value: {  }
default_value_callback: ''
settings:
  display_summary: false
field_type: datetime

And then I referenced it like:

core.entity_form_display.node.mycontenttype.default.yml

langcode: en
status: true
dependencies:
  config:
    - field.field.node.mycontenttype.field_date
    - node.type.mycontenttype
  module:
    - file
    - path
    - text
_core:
  default_config_hash: qZE-qJ04DTTNggVVQdVOPQmpE_I69GQ_LqB32kXivVg
id: node.mycontenttype.default
targetEntityType: node
bundle: mycontenttype
mode: default
content:
  created:
    type: datetime_timestamp
    weight: 2
    settings: {  }
    third_party_settings: {  }
    (...)

and

core.entity_view_display.node.mycontenttype.default.yml

langcode: en
status: true
dependencies:
  config:
    - field.field.node.mycontenttype.field_date
    - node.type.mycontenttype
  module:
    - file
    - text
    - user
_core:
  default_config_hash: Nfnv6VMugBKl6EOqi_U0I_LQ1ZQpbNDN3a9GXHWUBz4
id: node.mycontenttype.default
targetEntityType: node
bundle: mycontenttype
mode: default
content:
  field_date:
    weight: 101
    label: above
    settings: {  }
    third_party_settings: {  }
    type: datetime

Thank you.

Answer 1

Like 4k4 suggested, I used https://www.drupal.org/docs/8/api/entity-api/using-the-ui-to-export-the-code-for-your-custom-fields to create and export all my needed fields and it worked really well.

Note: With a lot of changes you may need to delete config for the already created settings. Remove it with: drush config-delete field.storage.node.field_name Found that here