Ravi Sir's Cards › AWS
Run only once
What is a VPC: your own private network inside one AWS Region, example ThreeTierVpc 10.0.0.0/16.
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What this card says
Why do we need it?
Two cron runs can overlap.
What is it?
Lock or skip.
flock -n /tmp/job.lock job.sh
How to do it
Wait max 30 s.
flock -w 30 /tmp/job.lock job.sh
Example
Lock frees on exit.