Build caching for the deploy actions (sccache) — sub-plan 1: container digest-pin gate - #347
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aram356 wants to merge 8 commits into
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Build caching for the deploy actions (sccache) — sub-plan 1: container digest-pin gate#347aram356 wants to merge 8 commits into
aram356 wants to merge 8 commits into
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First increment of the build-caching feature (sub-plan 1, Task 1) per docs/specs/edgezero-deploy-build-caching.md (v6.14) and docs/superpowers/plans/2026-08-20-build-cache-container.md. The pinned build container's platform-id keys the whole feature on a sha256 manifest digest, so check-image-pin.sh fails closed on a tag, missing digest, or malformed JSON. Colocated unit test: 6 cases, all green; shellcheck clean.
aram356
marked this pull request as draft
August 27, 2026 04:46
…tion) The build-caching design spec was authored via the brainstorming flow, whose specs live under docs/superpowers/specs alongside their plans (the container sub-plan is already in docs/superpowers/plans). Relocate it there from docs/specs and update the two references (the plan's Spec: link and the validator's comment). Vitepress builds clean; the validator test stays green.
…nvention Siblings in docs/superpowers/specs are dated YYYY-MM-DD-<topic>-design.md; rename edgezero-deploy-build-caching.md to 2026-08-20-edgezero-deploy-build-caching-design.md (its authoring/plan date) and update the plan link + validator comment.
…ion gap)
The validator used jq -r, which coerces a numeric field to a string, so a
{"repository": 123, "tag": 1} would pass despite the contract requiring strings.
Assert the JSON type is string for repository, tag, and digest before the value
checks, and add a wrong-type test case. 7/7 green, shellcheck clean.
Harden the sccache design toward plan-ready. env: add PATH and RUSTUP_HOME and an absolute RUSTC_WRAPPER so rustc starts under env -i (rustup-image layout) (1). Narrow the sccache correctness claim (it hashes dep-info/args/deps/env/cwd) and make the undeclared-input proc-macro/build.rs risk an explicit cache opt-in (2). Bounded, collision-free generation: run_id-run_attempt-artifact, SCCACHE_CACHE_SIZE 2G, sccache --stop-server before save, aggregate bounded by GitHub's LRU (3). A complete FIXED mount table with a constant /work/app cwd so sccache's cwd hash is stable across host paths (4). Prove the writable /work/app is a faithful copy (content/modes/symlinks/ submodules, hardlinks broken) and state build/deploy use separate container instances (5). Warm test via sccache --show-stats ONLINE (dependency sources are not cached, so the network cannot be disabled for the fetch) (6). Public, anonymously-fetchable sources only; private auth is out of scope (7). RFC 8785 (JCS) canonical JSON and ustar-only archive with binary-size equality (8). Full 40-hex app-ref and length-framed hash encodings with golden vectors (9). Hardened validator smoke: --cap-drop=ALL, no-new-privileges, memory/pids/ timeout (10). Plan: fix the first-publish deadlock (authenticated smoke in the workflow; anonymous pull is the operator's post-make-public step) and drop the stale four-root-prune language (11). Design only.
The validator accepted any non-empty repository, so a pin naming a foreign repository could become platform-id. Require repository == the canonical ghcr.io/stackpop/edgezero-build-app-cli and add a foreign-repository reject case (8/8). A trusted digest is only trustworthy for the repository we publish.
…findings
Stable host cache path: actions/cache folds the on-disk path into the cache
version, so a per-run mktemp path forces permanent misses; use one fixed
${RUNNER_TEMP}/edgezero-sccache-v1, emptied before restore, mounted at
/work/sccache (1). Whole-repo /work/repo working copy with the compile cwd at the
relative working-directory, so a nested working-directory (apps/api under a parent
workspace) keeps its enclosing Cargo config and sibling path-deps; the flattened
/work/app is gone (2). Frozen source: git-ignored files excluded from the copy and
initialized submodules validated, and the SAME copy is reused across the separate
build/deploy container instances so build outputs reach deploy as derived state (3).
Storage restated as repository-global LRU that can evict unrelated caches and may be
billable, not family-local (4). Generation keyed on an app-cli-artifact unique across
every cache-writing invocation (fail-closed on a detectable collision), with concurrent
lineages forked, not merged (accepted) (5). PATH includes /usr/local/bin where Fastly
and sccache live; enumerated compile/validation/deploy env profiles listing EDGEZERO_*
by name, not the namespace (6). app-checkout-token assigned to the host-side app-repo-id
API check and barred from containers/copies/artifacts/caches (7). Exact byte contracts:
length-framed <len>:<bytes> hash encoding with normalized relative paths, normalized
ustar headers (zero mtime/uid/gid, fixed names), and abi as recomputed ELF metadata
(machine/interp=null-if-static/direct-DT_NEEDED; transitive resolved, dlopen out of
scope) (8). sccache undeclared-input risk stated as accepted (no proc-macro
input-declaration mechanism exists); fail-cold restore/audit/read failures; skip-save on
--stop-server failure (9). Plan: two-tier pin policy (major action tags per the repo's
own check-action-pins gate, image digests) resolving the apparent checkout@v7
inconsistency; validator canonical-repo requirement reflected; image.json rigor scoped
(the JCS/schema/dup-key provenance machinery is for produced artifacts, sub-plan 3) (10).
Design only.
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Summary
Starts the build-caching implementation for the deploy actions (design merged in #316). Tracks #346. This PR lands the feature in dependency order behind the pinned build container; the first increment is the container's fail-closed digest-pin validator.
Spec:
docs/superpowers/specs/2026-08-20-edgezero-deploy-build-caching-design.md(v6.14 — sccache pivot). Plan:docs/superpowers/plans/2026-08-20-build-cache-container.md(sub-plan 1 of 4).In this PR
.github/docker/build-app-cli/check-image-pin.sh— fail-closed validator that the build container'simage.jsonis pinned by asha256manifest digest (not a mutable tag), since the whole feature keysplatform-idon that digest. Rejects a tag, a short/missing digest, a missing repository, and malformed JSON (fail-closed)..github/actions/deploy-core/tests/check-image-pin.test.sh— 6 colocated unit cases, all green;shellcheck -S warningclean.Nothing here is wired into the runtime yet (no
image.json, Dockerfile, or workflow), so this is CI-neutral and self-contained.Next increments (same PR, dependency order)
wasm32-wasip1+ pinnedsccache+ Fastly CLI), the GHCR verify-by-digest → reviewableimage.jsonPR publish workflow, and wiring the digest pin into the contract suite.Notes
The design has been through extensive hardening review and continues to evolve; this PR intentionally starts from the most approach-stable, self-contained piece so review can proceed incrementally rather than against the whole feature at once.