hiera - data retrieved once or everytime a lookup is required

[Andrew Hibbert]

Hi,

I'm looking into hiera particularly the http backend (https://github.com/crayfishx/hiera-http).

I'm wandering when using hiera if a single lookup is done at the start of the puppet run or if everytime a value needs to be looked up the file is accesed or in this case the http api queried?

Thanks

[Ellison Marks]

In general, every time a hiera* function is called, the backend's lookup function will be called. Any caching decisions are performed by the backend code. In the case of this http-backend, I see a few parameters relating to caching, specifically cache_timeout and cache_clean interval, so I'm guessing it performs some caching.

[Craig Dunn]

Hiera will pass the query to the backend on every lookup. In the
particular case of hiera-http (since 1.3) you can enabling caching to
reduce the number of HTTP API queries using the cache_timeout and
cache_clean_interval flags.

Regards
Craig