Reading from disk, spending CPU cycles, allocating memory, and making queries on the network are all technically side effects--but they're not really cause for "sad panda".
Everything on a computer has some side effects, and the purpose of --dry-run is to stop execution without certain effects that we care about. It's impossible to eliminate side effects entirely, so this is not a goal.
I had http:// 192.168.100.123 :7654/lights_on.sh that idempotentially turns on lights in my room. Trying to query or even pre-fetching does it. I was aware it’s not wisest, wasn’t as stupid as to expose it, also it broke so it is no more, but there’s always the guy who does that.
The "n" key on your keyboard is connected to some dynamite attached under the desk, if you type "--dry-run" or even just "-n", it plays the song "Those Endearing Young Charms" and then explodes, killing everyone in the room.
At some point it doesn't matter if there's "the guy who does that", because the right choice is to let "the guy who does that" deal with the consequences of their own crazy setup.
HTTP GET is also idempotent in REST, and slightly easier than PUT (since you can just append any parameters onto the end of the URL with GET instead of inserting them into the HTTP headers with PUT)
I believe HTTP GET is "nullipotent", meaning that accessing a resource 0 times is supposed to be the same as accessing it once or more. So I don't think it's appropriate for actions like "lights on".
It's impossible to tell if someone is being sarcastic on the internet, because no matter how stupid your comment is at face value, there's always a percentage of people on the forum stupid enough to say it in earnest.
