Use default format for nginx (Common Log format)

[javiercr]

This PR fixes the date parsing for nginx's access log.

According to nginx documentation the default format for its access log is:

log_format combined '$remote_addr - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent"';

Where $time_local is the local time in the Common Log Format. According to Wikipedia this mean the format is %d/%b/%Y:%H:%M:%S %z.

[awood45]

Thank you for the contribution Javier.

I'm going to give this a test soon, since the current code setup works. One thing that could help, is there an example of a format that your change will correctly pick up, that does not currently work?

[javiercr]

Hi Alex, are you sure the current code setup is picking up the right datetime from the nginx logs? Are you sure the CloudWatch Logs Agent is not falling back to the current datetime for each log event?

Because according to the nginx docs, to me it seems it is not possible that the agent is parsing correctly the default datetime format used by nginx.