Yes I am...
Typo in /etc/filebeat/filebeat.yml:
filebeat.inputs:
- type: zzzzzzlog
filebeat fails to start (good):
Mar 10 10:14:40 instance-39 filebeat[10626]: Exiting: Error while initializing input: Error creating input. No such input type ex
Mar 10 10:14:40 instance-39 systemd[1]: filebeat.service: Main process exited, code=exited, status=1/FAILURE
And, I am using selecting all selectors with logging.selectors: [ "*" ]
I changed the name of my logfile, to test, and it still does not appear 
logging.level: debug
logging.selectors: [ "*" ]
logging.to_files: true
logging.files:
  # Configure the path where the logs are written. The default is the logs directory
  # under the home path (the binary location).
  path: /var/log/filebeat
  # The name of the files where the logs are written to.
  name: mylogfile-beat
I still have no mylogfile-beat in /var/log/filebeat 
# ls -al /var/log/filebeat
total 28
drwx------  2 root root 4096 Mar  5 11:54 .
drwxr-xr-x 13 root root 4096 Mar 10 00:00 ..
-rw-------  1 root root  280 Mar  5 11:54 filebeat
-rw-------  1 root root  280 Mar  5 11:45 filebeat.1
-rw-------  1 root root  280 Mar  5 11:45 filebeat.2
-rw-------  1 root root  280 Mar  5 11:44 filebeat.3
-rw-------  1 root root  280 Mar  5 11:44 filebeat.4
Could it be an issue with rights to write in /var/log/filebeat? But I can't see why, I'm root, and filebeat is running as root...
I copy paste the entire filebeat.yml below in case I missed something:
######################## Filebeat Configuration ############################
# This file is a full configuration example documenting all non-deprecated
# options in comments. For a shorter configuration example, that contains only
# the most common options, please see filebeat.yml in the same directory.
#
# You can find the full configuration reference here:
# https://www.elastic.co/guide/en/beats/filebeat/index.html
#==========================  Modules configuration =============================
filebeat.modules:
#=========================== Filebeat inputs =============================
# List of inputs to fetch data.
filebeat.inputs:
# Each - is an input. Most options can be set at the input level, so
# you can use different inputs for various configurations.
# Below are the input specific configurations.
# Type of the files. Based on this the way the file is read is decided.
# The different types cannot be mixed in one input
#
# Possible options are:
# * log: Reads every line of the log file (default)
# * stdin: Reads the standard in
#------------------------------ Log input --------------------------------
- type: log
  # Change to true to enable this input configuration.
  enabled: true
  # Paths that should be crawled and fetched. Glob based paths.
  # To fetch all ".log" files from a specific level of subdirectories
  # /var/log/*/*.log can be used.
  # For each file found under this path, a harvester is started.
  # Make sure not file is defined twice as this can lead to unexpected behaviour.
  paths:
    - /home/axelle/cowrie/var/log/cowrie/cowrie.json*
    #- c:\programdata\elasticsearch\logs\*
  # Configure the file encoding for reading files with international characters
  # following the W3C recommendation for HTML5 (http://www.w3.org/TR/encoding).
  # Some sample encodings:
  #   plain, utf-8, utf-16be-bom, utf-16be, utf-16le, big5, gb18030, gbk,
  #    hz-gb-2312, euc-kr, euc-jp, iso-2022-jp, shift-jis, ...
  encoding: plain
#========================== Filebeat autodiscover ==============================
#========================= Filebeat global options ============================
# Enable filebeat config reloading
filebeat.config:
  #inputs:
    #enabled: false
    #path: inputs.d/*.yml
    #reload.enabled: true
    #reload.period: 10s
  modules:
    enabled: true
    path: modules.d/*.yml
    #reload.enabled: true
    #reload.period: 10s
#================================ General ======================================
#================================ Processors ===================================
#============================= Elastic Cloud ==================================
#================================ Outputs ======================================
# Configure what output to use when sending the data collected by the beat.
#-------------------------- Elasticsearch output -------------------------------
#----------------------------- Logstash output ---------------------------------
output.logstash:
  # Boolean flag to enable or disable the output module.
  enabled: true
  # The Logstash hosts
  hosts: ["localhost:5044"]
  # Number of workers per Logstash host.
  worker: 1
  # Set gzip compression level.
  #compression_level: 3
  # Configure escaping HTML symbols in strings.
  #escape_html: false
  # Optional index name. The default index name is set to filebeat
  # in all lowercase.
  #index: 'filebeat'
#== Templates
# Enable JSON template loading. If this is enabled, the fields.yml is ignored.
#setup.template.json.enabled: false
# Path to the JSON template file
#setup.template.json.path: "${path.config}/template.json"
# Name under which the template is stored in Elasticsearch
#setup.template.json.name: ""
# Overwrite existing template
#setup.template.overwrite: false
# Elasticsearch template settings
setup.template.settings:
  # A dictionary of settings to place into the settings.index dictionary
  # of the Elasticsearch template. For more details, please check
  # https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping.html
  #index:
    #number_of_shards: 1
    #codec: best_compression
    #number_of_routing_shards: 30
  # A dictionary of settings for the _source field. For more details, please check
  # https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-source-field.html
  #_source:
    #enabled: false
#============================== Kibana =====================================
# Starting with Beats version 6.0.0, the dashboards are loaded via the Kibana API.
# This requires a Kibana endpoint configuration.
setup.kibana:
  # Kibana Host
  # Scheme and port can be left out and will be set to the default (http and 5601)
  # In case you specify and additional path, the scheme is required: http://localhost:5601/path
  # IPv6 addresses should always be defined as: https://[2001:db8::1]:5601
  #host: "localhost:5601"
  # Optional protocol and basic auth credentials.
  #protocol: "https"
  #username: "elastic"
  #password: "changeme"
  # Optional HTTP path
  #path: ""
  # Use SSL settings for HTTPS. Default is true.
  #ssl.enabled: true
  # Configure SSL verification mode. If `none` is configured, all server hosts
  # and certificates will be accepted. In this mode, SSL based connections are
  # susceptible to man-in-the-middle attacks. Use only for testing. Default is
  # `full`.
  #ssl.verification_mode: full
  # List of supported/valid TLS versions. By default all TLS versions from 1.1
  # up to 1.3 are enabled.
  #ssl.supported_protocols: [TLSv1.1, TLSv1.2, TLSv1.3]
  # SSL configuration. The default is off.
  # List of root certificates for HTTPS server verifications
  #ssl.certificate_authorities: ["/etc/pki/root/ca.pem"]
  # Certificate for SSL client authentication
  #ssl.certificate: "/etc/pki/client/cert.pem"
  # Client certificate key
  #ssl.key: "/etc/pki/client/cert.key"
  # Optional passphrase for decrypting the certificate key.
  #ssl.key_passphrase: ''
  # Configure cipher suites to be used for SSL connections
  #ssl.cipher_suites: []
  # Configure curve types for ECDHE-based cipher suites
  #ssl.curve_types: []
#================================ Logging ======================================
# There are four options for the log output: file, stderr, syslog, eventlog
# The file output is the default.
# Sets log level. The default log level is info.
# Available log levels are: error, warning, info, debug
logging.level: debug
# Enable debug output for selected components. To enable all selectors use ["*"]
# Other available selectors are "beat", "publish", "service"
# Multiple selectors can be chained.
logging.selectors: [ "*" ]
# Send all logging output to stderr. The default is false.
#logging.to_stderr: false
# Send all logging output to syslog. The default is false.
#logging.to_syslog: false
# Send all logging output to Windows Event Logs. The default is false.
#logging.to_eventlog: false
# If enabled, Filebeat periodically logs its internal metrics that have changed
# in the last period. For each metric that changed, the delta from the value at
# the beginning of the period is logged. Also, the total values for
# all non-zero internal metrics are logged on shutdown. The default is true.
#logging.metrics.enabled: true
# The period after which to log the internal metrics. The default is 30s.
#logging.metrics.period: 30s
# Logging to rotating files. Set logging.to_files to false to disable logging to
# files.
logging.to_files: true
logging.files:
  # Configure the path where the logs are written. The default is the logs directory
  # under the home path (the binary location).
  path: /var/log/filebeat
  # The name of the files where the logs are written to.
  name: mylogfile-beat
  # Configure log file size limit. If limit is reached, log file will be
  # automatically rotated
  rotateeverybytes: 10485760 # = 10MB
  # Number of rotated log files to keep. Oldest files will be deleted first.
  keepfiles: 7
  # The permissions mask to apply when rotating log files. The default value is 0600.
  # Must be a valid Unix-style file permissions mask expressed in octal notation.
  permissions: 0600
  # Enable log file rotation on time intervals in addition to size-based rotation.
  # Intervals must be at least 1s. Values of 1m, 1h, 24h, 7*24h, 30*24h, and 365*24h
  # are boundary-aligned with minutes, hours, days, weeks, months, and years as
  # reported by the local system clock. All other intervals are calculated from the
  # Unix epoch. Defaults to disabled.
  #interval: 0
  # Rotate existing logs on startup rather than appending to the existing
  # file. Defaults to true.
  # rotateonstartup: true
# Set to true to log messages in JSON format.
#logging.json: false
#============================== X-Pack Monitoring ===============================
#================================ HTTP Endpoint ======================================
# Each beat can expose internal metrics through a HTTP endpoint. For security
# reasons the endpoint is disabled by default. This feature is currently experimental.
# Stats can be access through http://localhost:5066/stats . For pretty JSON output
# append ?pretty to the URL.
#============================= Process Security ================================
#================================= Migration ==================================
# This allows to enable 6.7 migration aliases
#migration.6_to_7.enabled: false
Thanks!