Nixos-21.05 channel not updating

Although has indicated that the current
git hash for nixos-21.05 is 6bfe71f2a4e, a nix-channel update
still returns 110a2c9ebbf.

My nix-channel --list response is:


Following that url in a web browser brings a redirect to:

Which seems to point to the older information.

However going to '` and following
the nixos-21.05 link brings me to:

which has the newer info.

Is there some setup problem?


This smells like a bug…

I posted this message here because I was uncertain what github project was responsible for the the code that set up these links, or how the whole process works.
I finally submitted a bug to nixos-org-configurations. However nixos-homepage also sets up some links.

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The problem seems to be related to Fastly caching of web pages. There was a change by @zimbatm to reduce the TTL to 5 minutes, But I have not seen a significant improvement after several days.

Would this be better dealt with by a change in nix-channel.

It seems that currently nix-channel take urls like

and parses the redirection response to get the git hash. Would it
be cleaner to do something like using the format:


for formal Nix channels, and then get a Prometheus API call. I currently
do a:

to get channel hashes. This would also allow a new option:

nix-channel --list-active

to list all the currently active official Nix channels.