From 2e538be5d7474a0624cd11b3b33be7c6107ce33c Mon Sep 17 00:00:00 2001 From: Ganesh Vernekar Date: Thu, 12 Jan 2023 13:33:45 +0530 Subject: [PATCH] docs: Update federation docs for native histograms Signed-off-by: Ganesh Vernekar --- docs/federation.md | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/docs/federation.md b/docs/federation.md index 0a241144a..3344a0ed0 100644 --- a/docs/federation.md +++ b/docs/federation.md @@ -8,8 +8,15 @@ sort_rank: 6 Federation allows a Prometheus server to scrape selected time series from another Prometheus server. -_Note about native histograms (experimental feature): Federation does not -support native histograms yet._ +_Note about native histograms (experimental feature): To scrape native histograms +via federation, the scraping Prometheus server needs to run with native histograms +enabled (via the command line flag `--enable-feature=native-histograms`), implying +that the protobuf format is used for scraping. Should the federated metrics contain +a mix of different sample types (float64, counter histogram, gauge histogram) for +the same metric name, the federation payload will contain multiple metric families +with the same name (but different types). Technically, this violates the rules of +the protobuf exposition format, but Prometheus is nevertheless able to ingest all +metrics correctly._ ## Use cases