From 811411db6e67aac454cbdae8ff375ed467ef4eba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niklas=20Hamb=C3=BCchen?= <mail@nh2.me>
Date: Wed, 22 Apr 2020 02:14:03 +0200
Subject: [PATCH] journald service: Add helpful comments about the journal
getting full
---
nixos/modules/system/boot/systemd.nix | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/nixos/modules/system/boot/systemd.nix b/nixos/modules/system/boot/systemd.nix
index f955746f78a0..2167df60bc9a 100644
--- a/nixos/modules/system/boot/systemd.nix
+++ b/nixos/modules/system/boot/systemd.nix
@@ -593,6 +593,9 @@ in
each other's limit. The value may be specified in the following
units: s, min, h, ms, us. To turn off any kind of rate limiting,
set either value to 0.
+
+ See <option>services.journald.rateLimitBurst</option> for important
+ considerations when setting this value.
'';
};
@@ -604,6 +607,19 @@ in
interval) that is applied to all messages generated on the system.
This rate limiting is applied per-service, so that two services
which log do not interfere with each other's limit.
+
+ Note that the effective rate limit is multiplied by a factor derived
+ from the available free disk space for the journal as described on
+ <link xlink:href="https://www.freedesktop.org/software/systemd/man/journald.conf.html">
+ journald.conf(5)</link>.
+
+ Note that the total amount of logs stored is limited by journald settings
+ such as <literal>SystemMaxUse</literal>, which defaults to a 4 GB cap.
+
+ It is thus recommended to compute what period of time that you will be
+ able to store logs for when an application logs at full burst rate.
+ With default settings for log lines that are 100 Bytes long, this can
+ amount to just a few hours.
'';
};