Another one about the v prefix for pre-release.

[kristof-mattei]

Based on an answer here: #517 (comment)

semver will match on the tag pattern, and it strips away the v prefix which the docs kind of mention (unless you prepend the v to the pattern as you did).

For the pre-release semver tags they are intentionally not supported for major/major.minor patterns: https://github.com/docker/metadata-action#typesemver

Pre-release (rc, beta, alpha) will only extend {{version}} (or {{raw}} if specified) as tag because they are updated frequently, and contain many breaking changes that are (by the author's design) not yet fit for public consumption.

Based on this statement, shouldn't v{{version}} still work for v0.1.0-beta.1? After all, we have more than {major} or {major}.{minor}?

The docs state:

v2.0.8-beta.67 | {{version}} |   | 2.0.8-beta.67

So in this case, why is the v swallowed when we use

type=semver,pattern=v{{version}}

for version v0.1.0-beta.1?

I seem to be missing a piece of the puzzle.

[crazy-max]

type=semver,pattern=v{{version}}

for version v0.1.0-beta.1?

I seem to be missing a piece of the puzzle.

I think semver module swallowed any v(s) on parsing:

metadata-action/src/meta.ts

Line 184 in a60f0f6

const sver = semver.parse(vraw, {

Have you tried with prefix attribute?

type=semver,pattern={{version}},prefix=v

[kristof-mattei]

Thank you @crazy-max.

I think I understand now, but to be sure:

Would it be correct to state that the pattern is merely for capturing something, and not for controlling how the tag is emitted?

On the output side of the equation: the current codebase does not emit v for pre-release versions. Adding prefix=v makes sure we always add one.

type=semver,pattern={{version}},prefix=v

Equally, the output side seems to be smart to not double-emit a v.