Reasons why AWS Greengrass Nucleus downloads 40MB of data on reboot
Howdy. I have a fleet of Raspberry Pi devices using a collection of Greengrass Components and a few Components we've built ourselves. The devices use 4G data, and so we try to limit the amount of data it downloads/uploads to minimise costs.
We noticed a few weeks ago that each time the devices reboot they download between 39.7MB to 40.1MB of data from "Amazon CloudFront" in the AWS region we are using for Greengrass. Through process of elimination we've narrowed the troublesome component down to Nucleus. If we remove all components from the device entirely the pis do not download any data on reboot. If we add Nucleus and no other components (Greengrass or our own), then the pis will download ~40MB on reboot.
I was wondering if anyone has ideas on how to figure out what the data is (the data is a split up into thousands of packets and encrypted, so wireshark is not super useful), and if there's a way to stop it?
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Greengrass Nucleus is like any other Greengrass component and the current running Nucleus would download another version only if it differs from the one currently running. This normally happen as you specify the Nucleus component explicitly or implicitly in a deployment, but once updated, it should not be necessary to download it again, even across reboots.
Could you share the content of the greengrass.service file used to start Greengrass, if you use systemd to manage the Greengrass daemon, or any other relevant detail about how Greengrass is started. It would also be useful to inspect the greengrass.log for clues about this behaviour.
Hi, is Nucleus reboot due to a deployment? If you make a new deployment but not pin the Nucleus version, it's possible that Nucleus upgrades to latest version which causing Nucleus to reboot. In this case, it's expected for Nucleus to download the latest version from CloudFront link (as we first install Nucleus) which is ~37MBs.
Reference here
We are having the same issue. We have Pi's in the Field using a Mobile carrier/dongle. Data charges are exceedingly high and it is not due to our messaging. I tested removing Log Manager and this had little affect bringing it down. Question I have is how does one profile this? What tool does one use to see exactly what Greengrass is doing here? My Nucleus version is 2.12.4. I do a standard Greengrass installation on the Pi -- nothing unusual. Tried wireshark but its not much help. Any help getting to the bottom of this is appreciated.
Thanks Massimiliano, this got me to the answer. The image we are using was using a systemctl command to install Nucleus on initial boot. This command was never disabled, resulting in it re-downloading Nucleus (along with a few other things) every time the device rebooted.