From 067ddc66b45cd60b8924d9190312b99a29545cdc Mon Sep 17 00:00:00 2001
From: bcumming <bcumming@cscs.ch>
Date: Tue, 9 Jun 2026 13:06:19 +0200
Subject: [PATCH] Do not rebuild build cache index every time we push

* rebuilding the index is expensive: scaling linearly with the number of
  packages in the build cache
* it is not required for concretizer:reuse:false, which is the default
  mode of operation for stackinator
---
 stackinator/templates/Makefile              | 2 +-
 stackinator/templates/Makefile.compilers    | 2 +-
 stackinator/templates/Makefile.environments | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/stackinator/templates/Makefile b/stackinator/templates/Makefile
index 10a0ea58..628ac854 100644
--- a/stackinator/templates/Makefile
+++ b/stackinator/templates/Makefile
@@ -84,7 +84,7 @@ cache-force: mirror-setup
 	$(warning likely have to start a fresh build (but that's okay, because build caches FTW))
 	$(warning ================================================================================)
 	$(SANDBOX) $(MAKE) -C generate-config
-	$(SANDBOX) $(SPACK) --color=never -C $(STORE)/config buildcache create --rebuild-index --only=package alpscache \
+	$(SANDBOX) $(SPACK) --color=never -C $(STORE)/config buildcache create --only=package alpscache \
 	$$($(SANDBOX) $(SPACK_HELPER) -C $(STORE)/config find --format '{name};{/hash};version={version}' \
 	| grep -v -E '^({% for p in exclude_from_cache %}{{ pipejoiner() }}{{ p }}{% endfor %});'\
 	| grep -v -E 'version=git\.'\
diff --git a/stackinator/templates/Makefile.compilers b/stackinator/templates/Makefile.compilers
index 8418fbf0..ef41d8be 100644
--- a/stackinator/templates/Makefile.compilers
+++ b/stackinator/templates/Makefile.compilers
@@ -19,7 +19,7 @@ all:{% for compiler in compilers %} {{ compiler }}/generated/build_cache{% endfo
 {% for compiler, config in compilers.items() %}
 {{ compiler }}/generated/build_cache: {{ compiler }}/generated/env
 {% if push_to_cache %}
-	$(SPACK) -e ./{{ compiler }} buildcache create --rebuild-index --only=package alpscache \
+	$(SPACK) -e ./{{ compiler }} buildcache create --only=package alpscache \
 	$$($(SPACK_HELPER) -e ./{{ compiler }} find --format '{name};{/hash}' \
 	| grep -v -E '^({% for p in config.exclude_from_cache %}{{ pipejoiner() }}{{ p }}{% endfor %});'\
 	| cut -d ';' -f2)
diff --git a/stackinator/templates/Makefile.environments b/stackinator/templates/Makefile.environments
index 5a530232..b7bfa27f 100644
--- a/stackinator/templates/Makefile.environments
+++ b/stackinator/templates/Makefile.environments
@@ -18,7 +18,7 @@ all:{% for env in environments %} {{ env }}/generated/build_cache{% endfor %}
 {% for env, config in environments.items() %}
 {{ env }}/generated/build_cache: {{ env }}/generated/view_config
 {% if push_to_cache %}
-	$(SPACK) --color=never -e ./{{ env }} buildcache create --rebuild-index --only=package alpscache \
+	$(SPACK) --color=never -e ./{{ env }} buildcache create --only=package alpscache \
 	$$($(SPACK_HELPER) -e ./{{ env }} find --format '{name};{/hash};version={version}' \
 	| grep -v -E '^({% for p in config.exclude_from_cache %}{{ pipejoiner() }}{{ p }}{% endfor %});'\
 	| grep -v -E 'version=git\.'\