Summary

uriFromLifecycleVersion in pkg/client/create_builder.go builds the download URL for the lifecycle binary based on the builder image's OS and architecture. The current implementation has several gaps and inaccuracies compared to what the lifecycle project actually publishes at https://github.com/buildpacks/lifecycle/releases.

This issue tracks making the method accurate and complete for all supported OS/arch combinations.

Current behavior

func (c *Client) uriFromLifecycleVersion(version semver.Version, os string, architecture string) string {
    arch := "x86-64"

    if os == "windows" {
        return fmt.Sprintf("...+windows.%s.tgz", version, version, arch)
    }

    if builder.SupportedLinuxArchitecture(architecture) { // only arm64, ppc64le, s390x
        arch = architecture
    } else {
        c.logger.Warnf("failed to find a lifecycle binary for requested architecture %s, defaulting to %s", ...)
    }

    return fmt.Sprintf("...+linux.%s.tgz", version, version, arch)
}

Problems:

1. Linux — amd64 input emits a spurious warning even though amd64 and x86-64 name the same architecture and the correct binary is downloaded. (Being fixed by fix: treat amd64 as equivalent to x86-64 for lifecycle binary selection #2544, but the root of the problem is that the arch mapping is missing.)
2. FreeBSD — entirely unhandled. The function always falls through to the linux URL template, producing a wrong URL for FreeBSD builder images.
3. Windows — deprecated but silently broken. Windows container support was deprecated at lifecycle v0.20.5 (see announcement). No Windows lifecycle binary exists beyond that version, but the function still attempts to build a URL for any version, and the arch variable used in the Windows path is always the default x86-64 (the architecture parameter is ignored entirely for Windows).

Lifecycle release artifacts (as of latest)

Example URLs:

https://github.com/buildpacks/lifecycle/releases/download/v0.21.5/lifecycle-v0.21.5+freebsd.amd64.tgz
https://github.com/buildpacks/lifecycle/releases/download/v0.21.5/lifecycle-v0.21.5+linux.x86-64.tgz
https://github.com/buildpacks/lifecycle/releases/download/v0.20.5/lifecycle-v0.20.5+windows.x86-64.tgz

Expected behavior per OS

Linux

FreeBSD

Windows

Windows container support ended at lifecycle v0.20.5. The function should:

• Cap the requested version at v0.20.5 if a higher version is requested.
• Apply the same amd64 → x86-64 alias as Linux.
• Always log a deprecation warning pointing to the announcement.

Suggested implementation approach

• Introduce a lastWindowsLifecycleVersion constant ("0.20.5").
• Replace SupportedLinuxArchitecture with explicit per-OS arch maps (or a helper per OS).
• Handle the freebsd OS branch alongside linux and windows in uriFromLifecycleVersion.
• Add/update unit tests in pkg/client/create_builder_test.go following the pattern of the existing arm64 test at line 616.

Related

• Spurious "failed to find a lifecycle binary for requested architecture" warning when using amd64 #2528 — spurious amd64 warning on AMD64 systems
• Validation of lifecycle image os/arch should be more flexible #2163 — FIXME note about unknown arch being an error case
• PR fix: treat amd64 as equivalent to x86-64 for lifecycle binary selection #2544 — partial fix for the amd64/Linux case