Cloudwatch Custom Metric - Memory Utilization --from-cron not working - amazon-web-services

Question

I managed to follow all the steps listed here to setup the aws scripts to pick up the memory usage in the system and report it to cloudwatch. The problem i'm having is that it is not getting picked up in the Cloudwatch console.
When I do
$ ~/aws-scripts-mon/mon-put-instance-data.pl --mem-util --verbose
The metric gets successfully sent to Cloudwatch. I pick it up in the console
But when i try to do the same through a cron job, it doesnt get picked up in the Cloudwatch console.
To setup the cron , i did
$ sudo crontab -e
and added this line
*/5 * * * * ~/aws-scripts-mon/mon-put-instance-data.pl --mem-util --from-cron
saved and exited. When i check the /var/log/syslog, it says that the metric was successfully sent, but for some reason, i dont catch it in the cloudwatch console. What am i missing here ?
The syslog is below for reference (with ip masked)
Jan 18 22:55:01 ip-xxx-xx-xx-xx CRON[22536]: (root) CMD (~/aws-scripts-mon/mon-put-instance-data.pl --mem-util --from-cron)
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/pickup[22530]: 7FF494449A: uid=0 from=<root>
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/cleanup[22540]: 7FF494449A: message-id=<20170118225501.7FF494449A#ip-xxx-xx-xx-xx.localdomain>
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/qmgr[21671]: 7FF494449A: from=<root#ip-xxx-xx-xx-xx.localdomain>, size=673, nrcpt=1 (queue active)
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/local[22542]: warning: dict_nis_init: NIS domain name not set - NIS lookups disabled
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/local[22542]: 7FF494449A: to=<root#ip-xxx-xx-xx-xx.localdomain>, orig_to=<root>, relay=local, delay=0.03, delays=0.02/0/0/0, dsn=2.0.0, status=sent (delivered to mailbox)
Jan 18 22:55:01 ip-xxx-xx-xx-xx postfix/qmgr[21671]: 7FF494449A: removed
Note: The absolute path in the cron job did the trick. Documented the various hiccups here.

Answer 1

Cron doesn't use the login shell's environment variables, so ~ might not resolve to your current user's HOME directory as it would in your manual tests. Try replacing this with the absolute path (e.g., /home/sarul/aws-script-mon/mon-put-instance-data.pl and see if it runs the script correctly.
If you're using local AWS credentials in the user's environment or ~/.aws/config rather than an instance profile, you might need to add these credentials somewhere accessible by cron as well.
Also note that the postfix syslog entries indicate that a mail message of some sort is being queued - perhaps related to an error reported by the script invoked by cron.