<parse> directive for input plugins (e.g. in_tail, in_syslog, in_tcp and in_udp) cannot parse the user's custom data format (for example, a context-dependent grammar that can't be parsed with a regular expression). To address such cases, Fluentd has a pluggable system that enables the user to create their own parser formats.<parse> directive, call the customin_tail and parser_nginx:td-agent is launched by systemd, the default user of the td-agent process is the td-agent user. You must ensure that this user has read permission to the tailed /path/to/file. For instance, on Ubuntu, the default Nginx access file /var/log/nginx/access.log is mode 0640 and owned by www-data:adm. In this case, several options are available to allow read access:td-agent user to the adm group, e.g. through usermod -aG, orgrok patterns, grok-parser plugin is useful. Use > 1.0.0 versions for fluentd v0.14/v1.0.multi-format-parser is useful.<parse> directive: