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This page describes how to create a local, user-defined binary cache for E4S-based builds. The workflow lets you define a package set in a Spack environment, build it, and publish signed binaries to your own mirror location for reuse by your team or site.

Prerequisites

  1. Install Spack and initialize your shell. 
    git clone https://github.com/spack/spack.git
. spack/share/spack/setup-env.sh
spack -V
  2. Discover compilers on your system. 
    spack compiler find
spack compilers
  3. Decide where your cache will live (filesystem path or object storage URL). Examples:
    • Local/shared filesystem: file:///sw/spack/mirror/e4s-local
    • S3-style endpoint: s3://my-e4s-cache
  4. Create or obtain a GPG key used to sign your binaries. 
    spack gpg create "E4S Local Cache" "cache@example.org"
spack gpg list

Step 1 — Define the E4S package set in spack.yaml

Create a dedicated environment and list the products you want to provide from your local cache.

mkdir e4s-local-cache-env && cd e4s-local-cache-env
spack env activate -d .

cat > spack.yaml <<'YAML'
spack:
  specs:
  - hypre +mpi
  - petsc +mpi
  - kokkos +openmp
  concretizer:
    unify: true
  view: false
YAML

Replace specs/variants/compilers with the exact E4S product selection needed at your site.

Step 2 — Concretize and build

Concretize your environment and build all packages.

spack concretize -f
spack install

Validate what is now installed:

spack find -vl

Step 3 — Configure your local binary mirror

Add your destination mirror and initialize indices.

export LOCAL_E4S_MIRROR="file:///sw/spack/mirror/e4s-local"   # change to your location
spack mirror add --scope=user e4s-local "${LOCAL_E4S_MIRROR}"
spack mirror list

Step 4 — Push built binaries to your mirror

Publish binaries from your environment to your configured mirror.

# Push all concretized specs from the active environment
spack buildcache push --update-index e4s-local $(spack find --format '/{hash}')

If you want to push a subset, provide selected hashes or specs instead of all installed hashes.

Step 5 — Consume your local cache from another environment

On another system or user environment, configure your mirror and trust signing keys:

spack mirror add --scope=user e4s-local "${LOCAL_E4S_MIRROR}"
spack buildcache keys --install --trust

Then install with cache preference:

spack install -b auto hypre +mpi
spack install -b only petsc +mpi
  • -b auto prefers binaries and falls back to source.
  • -b only requires binaries and fails if unavailable.

Step 6 — Keep the cache updated for new E4S versions

For each new E4S-aligned stack update:

  1. Update spack.yaml specs/versions/variants.
  2. Re-run spack concretize -f and spack install.
  3. Re-run spack buildcache push --update-index ....

This incremental workflow lets you maintain a local cache-backed container or software stack tuned to your site needs.

Common pitfalls

  • Missing binaries for a spec: ABI tuple (OS/arch/compiler/SDK) differs from the build system.
  • Signature verification errors: consumer does not trust the producer GPG key.
  • Unexpected source builds: use -b only to enforce binary-only installs for validation.

Summary

  • Define your E4S package set in a Spack environment.
  • Build once, then publish with spack buildcache push.
  • Reuse those binaries from your own mirror with -b auto or -b only policies.