Below is the syntax I have tried with 0 30 0 * * ? or0 30 1 * * ?, which should run at 12:30 or 1:30 midnight respectively.
Also I have tired running the flow with cron in nifi for every 20 minutes duration, it worked perfectly.
But we want it to be run, daily once at particular time as mentioned above example (0 30 0 * * ? or 0 30 1 * * ?).
But it is not working. can anyone please guide.
I believe NiFi uses the quartz scheduler to handle the cron scheduling. Syntax here, but according to the examples listed the following 3 expressions should do what you want (one of them is the one you used above):
0 30 1 ? * * 0 30 1 * * ? 0 30 1 * * ? *
Try the first expression (using '?' for the day of month field) and see if that works.
I set up a couple GenerateFlowFile processors to run using cron scheduling strategy and both the crons specified above. They appear to be working fine for me.
Perhaps the issue is more specific to your dataflow.
What version of NiFi are you running?
What processor are you using cron on as the scheduling strategy?
How heavily loaded is your flow at the time the cron should execute?