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Keep secrets out of the Docker build context at every depth (closes #29 )

The canonical .dockerignore was three lines -- .git, node_modules, .DS_Store
-- while the canonical Dockerfile does `COPY . .`, so a developer's local
.env, *.pem or *.key was shipped into the build context and could land in an
image layer. Nothing surfaced it because .gitignore covers those patterns, so
the files are invisible to every git-based check.

The obvious repair, copying .gitignore's secret patterns across, is worse than
the gap it closes. .dockerignore does not use .gitignore semantics: Docker
matches with moby/patternmatcher, which is filepath.Match semantics plus a `**`
extension compiled to a regexp. `*` does not cross `/`, and a pattern without
a leading `**/` is anchored at the build-context root. A file listing .env,
*.pem and *.key therefore reads as solved, reviews as solved, and protects
only the repository root, while config/.env and certs/server.key still ship.
The three-line file at least invited scrutiny; the transplanted form
manufactures confidence and stops anyone looking.

So every depth-independent pattern here carries the `**/` prefix and only
genuinely root-anchored entries stay unprefixed. `**/node_modules` fixes a
defect the three-line file had today for any nested node_modules,
independently of the secret exposure.

Coverage is not limited to the three patterns the issue names, because the
enumeration found more shapes reaching the image. `**/*.env` covers the
prod.env / local.env convention, which the .env and .env.* spellings miss
entirely; `.envrc` is a secrets file by direnv convention; *.p12 and *.pfx are
bundles carrying private keys; and id_rsa, id_dsa, id_ecdsa and id_ed25519 are
the extensionless SSH keys that were covered before only when someone happened
to append a .key suffix.

Matching is case-sensitive, so `**/*.key` does not match certs/SERVER.KEY,
which is reachable on the case-insensitive filesystems most laptops use.
Doubling each pattern with an ALL-CAPS twin is not the fix: measured against
the planted set it still ships certs/Server.Key and certs/Ca.Pem while reading
as though case were handled, which is this issue's failure mode restated in a
new place. The matcher supports character ranges, so every secret name is
written that way -- `**/*.[kK][eE][yY]`, `**/*.[pP][eE][mM]`,
`**/.[eE][nN][vV][rR][cC]`, `**/[iI][dD]_[rR][sS][aA]` and the rest. The
extensionless SSH keys and .envrc are folded for the same reason the
extensions are: on the very filesystems that make SERVER.KEY reachable, direnv
reads .ENVRC and ssh reads ID_RSA, so exempting them would have contradicted
the rule that justifies the folding. Since `*` matches the empty string,
`**/*.[eE][nN][vV]` already covers a bare .ENV and no separate literal .env
entry is needed; the literal one is gone rather than left to imply that case
is unhandled there.

Deliberately not covered: bare `key` and `pem` filenames, which no tool
produces and which collide with legitimate paths (a `**/key` pattern would
delete an internal/key/ package directory from the context); `**/id_*`, which
would match ordinary source such as id_generator.go and ID_MAP.go; and *.crt
and *.cer, which are public certificates rather than secrets and are sometimes
a legitimate build input. Each of those is planted as a positive control and
verified present in the image after the change.

The one predictable false positive is a committed env template: `**/*.env`
excludes example.env. The remedy travels with the file rather than living in a
review thread -- the header comment and the policy both say to re-include it
with a negation, `!docs/example.env`, and never to delete the pattern, which
would reopen the exposure for everything else it covers.

The OS and editor patterns are included on their own merits rather than by
mirroring .gitignore. None of them is ever a build input, and editor state in
particular churns under a developer's hands, so each one is a source of
`COPY . .` invalidation carrying no information about the source tree. Now
that the checks are keyed on CHECK_EPOCH rather than on accidental context
churn, there is no reason left to keep churn in the context. Language build
artifacts are deliberately absent: they are per-repo, and the file's header
comment tells consuming repos to add their own host-built binaries, which is
the case that actually bites -- a host `make build` drops a multi-megabyte
artifact into the context where .gitignore hides it from every git-based
check. That comment gives the anchored form explicitly, `/myapp` rather than
`**/myapp`, because the prefixed spelling also matches cmd/myapp/ and deletes
the package directory. The header comment is the only part of this guidance a
consuming repo actually receives, since it is vendored with the file.

.gitignore is untouched. Its semantics are the inverse: an unanchored pattern
already matches at any depth, so `**/`-prefixing it produces a file that is
wrong in a way that looks careful. That asymmetry is why "derive one from the
other" was the wrong instruction, and it is now written down in
REPO_POLICIES.md in both directions, together with the case-sensitivity rule,
the negation remedy, and the requirement to verify by enumerating the image
rather than by reading the patterns. Every consuming repo inherits
.dockerignore by copy, so the trap has to live where the next person looks,
not only be fixed once here. Both repo checklists gain the same requirements.

Verified by planting 130 secret files -- twenty-six name shapes, including
every capitalisation of .env, .env.*, prod.env, .envrc, id_rsa, id_ed25519,
ca.pem, server.key, bundle.p12 and bundle.pfx, at five depths from the context
root to a/b/c -- alongside nine positive controls, then building a standalone
probe image doing `COPY . .` and listing what actually landed inside it. The
patterns as first written leaked 35 of the 130: every .ENVRC, .Envrc, ID_RSA,
Id_Rsa, ID_ED25519, .ENV.PRODUCTION and .Env.Local, at all five depths. A
lowercase-only control leaks 80, so the probe is not vacuous. After this
change: zero, with all nine controls still present, including
internal/ID_MAP.go and certs/CA.CRT.

Transferred-context size is recorded but load-bearing on nothing: an earlier
run reported 2.18kB transferred while 43 files, five of them secrets, were in
the image. BuildKit transfers only the delta from the previous build, so the
number describes the transfer and not the contents.

Planted files were removed and their absence confirmed against the filesystem
rather than against `git status`, which could not have seen them.

`make docker` re-run after the change: the check layer executed rather than
being served from cache, so the CHECK_EPOCH verification still holds under the
altered build context.

2026-08-09 16:42:00 +00:00

4.4 KiB

Raw Blame History

Workflow

branch (from main)
do the work in Next Step
move Next Step to the top of Completed Steps
move the top item of Future Steps into Next Step
commit (TODO.md changes in the same commit as the work)
merge to main if the branch is not protected, otherwise open a PR
push

Status

pre-1.0

Next Step

Finish the two draft prompt documents in the working tree and commit them: prompts/FIXUP_CLEAN.md (currently a near-empty stub) and prompts/FIXUP_REPORT.md (a rough draft). Write the missing content, run make fmt so they pass fmt-check, and commit.

Completed Steps

2026-08-09: Closed the secret exposure in the canonical .dockerignore: a developer's local .env, *.pem or *.key was reaching the Docker build context under COPY . ., invisible to every git-based check because .gitignore covers it. The patterns are written to .dockerignore's own moby/patternmatcher semantics — **/-prefixed so they hold at every depth, which also fixes nested node_modules — rather than transplanted from .gitignore, whose unprefixed form protects only the repository root while reading as solved. Coverage extends past the .env/.pem/.key trio to the prod.env convention, .envrc, PKCS#12 bundles and extensionless SSH keys, every one of them case-folded with character ranges because matching is case-sensitive and an ALL-CAPS twin per pattern still misses Server.Key. REPO_POLICIES.md and both repo checklists now state that asymmetry and require verification by enumerating the image rather than by reading the patterns. Verified with a probe image before, against three naive forms (unprefixed, lowercase-only, ALL-CAPS-doubled), and after.
2026-08-09: Made the pinned golangci-lint actually propagate: REPO_POLICIES.md now carries the canonical script/bootstrap snippet for Go repos, which installs when the installed version does not match the pin (the old if missing guard tested PATH presence only, so pins were inert on any provisioned machine and CI silently disagreed with local) and then re-resolves the binary through PATH and fails loudly, naming the shadowing path, when the install did not take effect — the failure mode the naive compare-then-install fix leaves behind while reporting success.
2026-08-09: Fixed the false green in the canonical CI gate: script/cibuild and script/docker now pass a per-invocation CHECK_EPOCH nonce, and the Dockerfile (plus the Go multistage template in REPO_POLICIES.md, in both its lint and builder stages) declares ARG CHECK_EPOCH with a guard that makes a bare docker build . fail closed. Corrected the org-canonical text that asserted a successful build implies all checks pass, across every document carrying it: REPO_POLICIES.md, both repo checklists (which still told agents to write the pre-fix script/cibuild and ended on an acceptance item the guard makes unsatisfiable), and the Go styleguide.
2026-08-07: Set the canonical .golangci.yml to the org-standard v2-schema config already deployed byte-identical across the org's Go repos (settings under linters.settings so thresholds like lll/funlen/cyclop/dupl actually apply under golangci-lint v2). Recorded the canonical golangci-lint version (v2.12.2, commit-pinned) in REPO_POLICIES.md.
2026-03-20: Strengthened constructor naming and Params struct rules in the Go styleguide.
2026-03-18: Documented fail-fast Dockerfile lint stage and conditional -v test rerun patterns in REPO_POLICIES.md.
2026-03-11: Added HTTP service hardening policy for 1.0 releases.
2026-03-10: Added policy: no build artifacts in repos.
2026-03-04: Added LLM prose tells reference and copyediting checklist, then several self-applied revision passes.
2026-02-28: Expanded the pre-1.0 schema migration rule; added clawpub reference.
2026-02-23: Added Go style rules (no type-only packages, Stringer for string-based types); template repos section in README.
2026-02-22: Initial policy corpus: REPO_POLICIES.md, code styleguides (general, Go, JS, Python), repo checklists, CI policy, hash pinning, Go HTTP server conventions, repo scaffolding.

Future Steps

Finish, format, and commit FIXUP_CLEAN.md and FIXUP_REPORT.md (the Next Step).
Commit this TODO.md at the repo root; it is the last missing policy file.
Decide the fate of untracked resume.sh: commit it or delete it.
Add more prompt templates for common development tasks (from README TODO).