[lxc-devel] [lxd/master] Update documentation for snapshots.pattern

[lepokle on Github]

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From e100640fa601184f9d9f807e6f664bc066fa16fe Mon Sep 17 00:00:00 2001
From: lepokle <lepokle at users.noreply.github.com>
Date: Tue, 19 Mar 2019 20:43:51 +0100
Subject: [PATCH] Update documentation for snapshots.pattern

The current documentation for usage of "creation_date" is unclear for users not familiar with pongo2. In addition the documentation about date formatting with pongo2 out there is minimal.
The explanation of the suffix is just wrong and should be corrected.
---
 doc/containers.md | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/doc/containers.md b/doc/containers.md
index a0f9dabb90..2e853f59d3 100644
--- a/doc/containers.md
+++ b/doc/containers.md
@@ -591,5 +591,11 @@ cron expression: `<minute> <hour> <day-of-month> <month> <day-of-week>`. If this
 empty (default), no snapshots will be created. `snapshots.schedule.stopped`
 controls whether or not stopped container are to be automatically snapshotted.
 It defaults to `false`. `snapshots.pattern` takes a pongo2 template string,
-and the pongo2 context contains the `creation_date` variable. In order to avoid
-name colisions, snapshots will be suffixed with `-0`, `-1`, and so on.
+and the pongo2 context contains the `creation_date` variable. Be aware that you
+should format the date (e.g. use `{{ creation_date|date:"2006-01-02_15-04-05" }}`) 
+in your template string to avoid forbidden characters in your snapshot name.
+Another way to avoid name collisions is to use the placeholder `%d`. If a snapshot
+with the same name (excluding the placeholder) already exists, all existing snapshot
+names will be taken into account to find the highest number at the placeholders
+position. This numnber will be incremented by one for the new name. The starting
+number if no snapshot exists will be `0`.