v3.15.14 tarball layout change (diff/ → helm-diff-<os>-<arch>/) breaks `helm plugin update diff` for existing installs

[goldserg]

What happened

v3.15.14 (via #1072, "fix: make release tarballs installable offline by helm 4") renamed the top-level directory inside release archives from diff/ to helm-diff-<os>-<arch>/. This breaks helm plugin update diff on any machine where the plugin was installed with a pre-3.15.14 release.

Reason: for existing installs the update hook runs the already-installed copy of install-binary.sh (platformHooks.update → ${HELM_PLUGIN_DIR}/install-binary.sh -u), which is the old pre-3.15.14 script. The old script's installFile() hardcodes HELM_TMP_BIN="$HELM_TMP/diff/bin/diff", while in update mode it always downloads releases/latest — which is now the v3.15.14 archive with the new layout:

Downloading https://github.com/databus23/helm-diff/releases/latest/download/helm-diff-linux-amd64.tgz
Preparing to install into /root/.local/share/helm/plugins/helm-diff
Failed to install helm-diff
	For support, go to https://github.com/databus23/helm-diff.

STDERR:
  cp: cannot stat '/tmp/helm-diff-6OmpsW/diff/bin/diff': No such file or directory
  Error: Failed to update plugin diff, got error (plugin update hook for "diff" exited with error)

This hits CI pipelines that reuse containers with a cached plugin — in our case helmfile init --force → helm plugin update diff → helmfile panics with helmexec.ExitError.

A fresh install works fine, because the v3.15.14 install-binary.sh handles both layouts (explicit fallback to $HELM_TMP/diff/bin/$bin).

Verified by diffing the archives:

# v3.15.13
diff/plugin.yaml
diff/install-binary.sh
diff/bin/diff

# v3.15.14
helm-diff-linux-amd64/plugin.yaml
helm-diff-linux-amd64/install-binary.sh
helm-diff-linux-amd64/bin/diff

Affected

Every install of helm-diff < 3.15.14 on helm plugin update diff. Until the affected machine reinstalls the plugin, every update attempt fails.

Possible directions

• Revert the layout rename so old update hooks keep working (helm 4 offline-install compat would then need another approach).
• Or, minimally, document that pre-3.15.14 installs need a one-time helm plugin uninstall diff + reinstall, since the layout rename cannot be picked up by the already-installed update hook.

[yxxhero]

@goldserg thanks for you issue. I will try solve this.

[yxxhero]

Thanks for the detailed report — the root-cause analysis is exactly right: helm plugin update runs the already installed copy of install-binary.sh, which hardcodes $HELM_TMP/diff/bin/diff, and 3.15.14's archive layout change broke it for every pre-3.15.14 install.

Fix is up in #1077. Rather than reverting the helm 4 offline-install support from #1071 (or requiring a one-time reinstall), the next release will:

• wrap all release archives in diff/ again — the layout every released install/update hook expects — so helm plugin update diff starts working again on existing installs, including installs on 3.15.14 (its hook falls back to diff/bin/diff);
• additionally publish each platform under a versioned name, diff-<version>-<os>-<arch>.tgz (byte-identical content, own .prov). Helm 4 derives the directory it expects inside a locally installed tarball from the tarball file name (stripping a -<version> component), so diff-3.15.15-linux-amd64.tgz → diff/ keeps the Offline install not working in helm 4 unless you --verify=false #1071 offline/verified-install flow working; the historical helm-diff-<os>-<arch>.tgz name can never satisfy that flow because it has no version component to strip.

If you're blocked before the next release lands, the one-time workaround is as you described: helm plugin uninstall diff && helm plugin install https://github.com/databus23/helm-diff.