Tag rules syntax

Tag rules follow the doublestar (aka globstar: **) matching pattern. Regex is unfortunately unsupported.

Patterns

doublestar supports the following special terms in the patterns:

Special Terms	Meaning	Example pattern	Example matches	Example doesn't match	Reason
*	matches any sequence of characters (excludes /)	env-*/app	env-prod/app env-dev/app	env-prod/sub/app	Only matches the single directory level
**	matches any sequence of characters (includes /)	**/redis	lib/redis proj/cache/redis	lib/redis-proxy	Matches any path ending in exactly /redis
?	matches any single character (excludes /)	qa-team?/*	qa-team0 qa-team9	qa-team10/app	Forces a single digit/letter suffix
[class]	matches any single character against a class of characters (See below) (excludes /)				see below
{alt1,alt2,...}	matches a sequence of characters if one of the comma-separated alternatives matches	release-{beta,rc}	release-beta release-rc	release-alpha	alpha is not an alternative

Any character with a special meaning can be escaped with a backslash (\).

Character classes support the following:

Class	Meaning	Example pattern	Example matches	Example doesn't match	Reason
[abc]	matches any single character within the set	service-[ab]	service-a service-b	service-c	c is not in Character class [ab]
[a-z] [0-9]	matches any single character in the range	build-[0-9]	build-1 build-7	build-a	a not in range
[^class]	matches any single character which does not match the class	release-[^9]*	release-1.0	release-9.0	9 is excluded from the class

Example for common tag pattern: Semantic Versioning (SemVer):

This is the most common versioning strategy (e.g., v1.0.1, 1.5.2).

This pattern uses alt-matches with an empty alt option, matching "nothing":

• The pattern {v,} matches v or an empty string ("nothing") which means it can match strings which start with v or not.

• The pattern [0-9]{,[0-9],[0-9][0-9]} matches a single digit (always) and one of 3 alt options: empty, single digit, or two digits; this gives us a matching pattern between 0 to 999

  • This limits us to to max version of v999.999.999 which should suffice for most usage. If not enough, just add another alt choice with more digits: [0-9]{,[0-9],[0-9][0-9],[0-9][0-9][0-9]}

Goal	Pattern	Matches	Does Not Match
Strict 3-part SemVer with optional v prefix	{v,}[0-9]{,[0-9],[0-9][0-9]}.[0-9]{,[0-9],[0-9][0-9]}.[0-9]{,[0-9],[0-9][0-9]}	v1.5.9 7.10.3 1.250.22	v1 v1.0 latest