9eecfc8eef
All checks were successful
PR build (required check) / changes (pull_request) Successful in 6s
secrets-guard / encrypted (pull_request) Successful in 7s
PR build (required check) / build-backend (pull_request) Has been skipped
shell-lint / shellcheck (pull_request) Successful in 7s
PR build (required check) / validate-observability (pull_request) Has been skipped
PR build (required check) / build-frontend (pull_request) Successful in 1m0s
PR build (required check) / gate (pull_request) Successful in 2s
Ports frontend/ (Jinja2/FastAPI, ~1180 LOC) to Go with html/template. No climate math, no DB, no auth here -- every route fetches from the backend's /content/* API, so this is I/O-bound glue with no hard-porting wall; the risk was always in reproducing the rendering exactly, not the language. 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 (frontend/tests/fixtures/) and every one of the 11 routes compared byte-for-byte. The only surviving differences after that process are insignificant inter-tag whitespace and one attribute where Go's stricter escaper HTML-encodes an apostrophe Jinja left literal (functionally identical in every browser) -- confirmed programmatically by normalizing whitespace and unescaping before diffing, not by eyeballing. That process caught defects unit tests alone would have missed, because map[string]any has no compile-time field check: - Render-context keys were snake_case throughout (content.py's Jinja convention, ported verbatim) while the templates -- written independently -- read PascalCase fields. A missing map key doesn't error in html/template, it silently renders empty, so this was invisible in every status code and every "it built" signal: title, meta description, canonical URL, OpenGraph tags, the homepage's entire ranked list, and the brand-tag/nav-active state were all blank across every page. Fixed by renaming every key to match each template's own header comment (the authoritative per-page field contract) and, where an API struct's exported fields already matched what a template needed (contentapi.CityInfo, Crumb, HomeRanked, HubCountry, ...), passing the struct straight through instead of hand-rewrapping it in a map -- removes a whole layer of future drift risk, not just this instance of it. - Three pages 500'd outright: `.ToolHref` needed a fully-composed href string, not the bare "lat,lon" fragment the handlers were building; the all-time-records table needed the raw contentapi.AllTimeRecords struct, not a re-wrapped map. - JSON-LD was being double-encoded: `<script type="application/ld+json">` is JAVASCRIPT context to html/template's contextual escaper regardless of the script's `type` attribute, so a template.HTML-typed value placed there gets re-escaped as a quoted JS string instead of emitted raw -- the entire structured-data payload shipped as a JSON string containing JSON, which no crawler would parse as the intended object. Needed template.JS instead, the type that actually means "trusted JS source." The glossary term page's JSON-LD was simply never built at all (the Jinja original assembled it inline in the template rather than through content.py's context dict, and that got lost in translation) -- added. - html/template silently strips literal HTML comments AND JavaScript comments from the parsed output (verified in isolation, zero template actions involved) -- confirmed as real engine behavior, not a bug in either port, so both need a FuncMap function returning template.HTML / template.JS respectively to survive parsing rather than a literal `<!-- -->` or `//` in the template source. Packaging: multi-stage Go build, final image alpine (not distroless -- the Swarm stack's env-entrypoint.sh shim needs bash), 187MB -> 22.6MB. Two defects caught before they reached a host: - The Swarm stack overrides `entrypoint:` with no `command:`, which drops the image's own CMD entirely (Docker/Swarm semantics, not merged) -- env-entrypoint.sh then fell through to its hardcoded `exec uvicorn app:app` fallback, which doesn't exist in this image. Every deploy would have exited 127. Fixed with an explicit `command:` on the stack's frontend service, and corrected the shim's stale comment claiming CMD passes through automatically. - `COPY --chown=thermograph` resolves the group by NAME at copy time; Alpine's `adduser -S` with no `-G` doesn't create a same-named group, so the classic (non-BuildKit) Docker builder -- which this CI runner falls back to, since it installs plain `docker.io` with no buildx plugin -- failed outright. Fixed with an explicit group and numeric --chown. Verification: go build/vet/test -race clean across all packages; the Docker image builds and passes its embedded go test step under both BuildKit and the classic builder; shellcheck 0 findings on the one script touched; rebased onto current main (the ERA5 lake stack landed on both main and dev during this work -- confirmed additive, no overlap with frontend/daemon). |
||
|---|---|---|
| .. | ||
| internal | ||
| go.mod | ||
| go.sum | ||
| main.go | ||
| README.md | ||
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.