emi
92e74c585a
Ports frontend/ (Jinja2/FastAPI, ~1180 LOC) to Go with html/template. No climate math, no DB, no auth -- every route fetches from the backend's /content/* API. Verified with a golden-HTML diff, not just unit tests: both the Python original and the Go rewrite were run against the same committed fixtures and every route compared byte-for-byte, confirmed programmatically. That process caught defects unit tests alone missed, since map[string]any has no compile-time field check: - Render-context keys were snake_case throughout while the templates read PascalCase fields. A missing map key doesn't error, it silently renders empty -- title, meta description, canonical URL, OpenGraph tags, and the homepage's entire ranked list were blank on every page despite every route returning 200. Fixed by renaming every key to match each template's own documented field contract, and passing API structs straight through wherever their fields already matched (removes a whole layer of future drift risk). - Three pages 500'd: ToolHref needed a composed href, not a bare "lat,lon" fragment; the records table needed the raw API struct. - JSON-LD was double-encoded: <script type="application/ld+json"> is JAVASCRIPT context to html/template's escaper regardless of the script's type attribute, so template.HTML gets re-escaped as a quoted JS string. Needed template.JS. The glossary term page's JSON-LD was never built at all -- added. - html/template silently strips literal HTML and JS comments from parsed output (verified in isolation) -- both need a FuncMap function returning template.HTML/template.JS to survive. Packaging: 187MB -> 22.6MB. Two defects caught before reaching a host: the Swarm stack's entrypoint override with no explicit command drops the image's CMD entirely (every deploy would have exited 127), and COPY --chown by name fails under the classic Docker builder on Alpine. Both fixed. go build/vet/test -race clean; docker build passes its embedded test step under both BuildKit and the classic builder; shellcheck 0 findings.
2.8 KiB
thermograph-frontend (Go)
The SSR frontend service, ported from the Python implementation one directory
up (app.py / content.py / api_client.py / format.py): server-rendered
content pages, the interactive tool's SPA shells, and every static asset. It
is I/O-bound glue over the backend's /content/* JSON API — no climate maths,
no database, no auth.
Layout
go.mod module thermograph/frontend (Go 1.26)
main.go config + mux + static + graceful shutdown
internal/config/ every env var the service reads (same names,
defaults and required/optional split as the
Python — see config.go's field docs)
internal/contentapi/ backend /content/* client: TTL cache, bounded
LRU, per-key single-flight, origin forwarding;
typed payloads in types.go
internal/render/ html/template engine over an embed.FS +
response ETag helpers (W/"sha1[:20]",
If-None-Match handling)
internal/render/templates/ the page templates (embedded; *.tmpl)
internal/contentdata/ glossary.yaml / pages.yaml loader (fail-loud
validation, file order preserved)
Dependencies: stdlib plus gopkg.in/yaml.v3 — the committed SSR copy in
frontend/content/*.yaml is shared with the rest of the repo and uses block/
folded scalars, so a YAML parser is genuinely required.
Run locally
cd frontend/server
go build -o thermograph-frontend .
cd .. # static/ and content/ resolve relative to the working dir
THERMOGRAPH_API_BASE_INTERNAL=http://127.0.0.1:8137 \
THERMOGRAPH_BASE=/thermograph \
./server/thermograph-frontend
THERMOGRAPH_API_BASE_INTERNAL is required — the boot fails loudly without it,
same as the Python raised at import. Other env vars (all optional):
THERMOGRAPH_BASE (default /thermograph; the image sets /),
THERMOGRAPH_API_VERSION (default v2 — bump only per the API-version pinning
contract in frontend/CLAUDE.md), THERMOGRAPH_API_BASE_PUBLIC,
THERMOGRAPH_SSR_CACHE_TTL (seconds, default 600),
THERMOGRAPH_GOOGLE_VERIFY / THERMOGRAPH_BING_VERIFY, and PORT
(default 8080).
The process expects static/ and content/ in its working directory
(frontend/ locally, /app in the image). Templates are embedded in the
binary; static assets and the YAML copy are read from disk.
Test / verify
cd frontend/server
go build ./... && go vet ./... && go test ./...
The deployed binary is /usr/local/bin/thermograph-frontend inside the
emi/thermograph/frontend image; the image name, frontend-* CI workflows and
deploy path are unchanged from the Python service.