cairnobs/web/README.md

web

SvelteKit frontend. Phase 0: one page, one query box, one table. No auth, no styling polish, no routing beyond /.

What it does

Textarea for a raw SQL string → POST {VITE_API_BASE_URL}/query on /api → renders {columns, rows} as an HTML table, or shows {error} from a rejected/failed query. That's the whole app — see src/routes/+page.svelte.

Why a static build, not a Node server

Scaffolded with @sveltejs/adapter-static: this page has no server-side data loading (all data comes from a client-side fetch triggered by the submit button), so there's nothing here that needs a running SvelteKit server. A prerendered static site is simpler to build, deploy, and reason about than running Node in production for a page that's this thin.

Because it's static, VITE_API_BASE_URL is baked in at build time, not read at container start. Set it before npm run build (or pass --build-arg VITE_API_BASE_URL=... to docker build) — changing it later means rebuilding, not just restarting the container.

Timestamps and the display timezone

Everything in Cairn OBS is UTC: ingest records Unix nanoseconds, ClickHouse stores UTC, and every API response is RFC3339 with a Z. The web UI renders those instants in whichever zone the reader picked (Settings → Display timezone), which changes presentation only -- never which rows a query returns, never their order, and never what earliest=/latest= mean. Two people in two zones looking at one log line see the same instant written two ways.

• src/lib/time.ts -- pure formatting. formatTimestamp is the one entry point; it detects timestamps by value, not by column name, since query output is arbitrary. Sub-second digits are copied verbatim from the source string rather than round-tripped through a JS Date, which is millisecond-precision and would silently drop the last six digits of a ClickHouse nanosecond timestamp.
• src/lib/timezone.svelte.ts -- where the choice is stored, which differs by deployment on purpose: per named user server-side when local login is on (PUT /auth/timezone, so it follows a person across browsers), per browser session on a public demo (a shared account's visitors shouldn't inherit each other's settings), per browser otherwise.
• Charts format their own axis and tooltip labels through the same helper. ECharts' type: 'time' axis otherwise renders in the browser's zone with no way to override it, which would put a chart's clock out of step with the table beside it.

The one place the UTC baseline is still visible to a user is query input: earliest=/latest= are parsed as UTC regardless of this setting. The Settings page says so explicitly rather than leaving it to be discovered.

Building & running

npm install
cp .env.example .env   # adjust VITE_API_BASE_URL if /api isn't on localhost:8080
npm run dev             # local dev server with hot reload
npm run check            # svelte-check, type errors
npm run build             # static output to build/
npm run preview            # serve the static build locally to sanity-check it

docker build -f Dockerfile -t cairnobs-web .   # context is web/, not the repo root
docker run -p 3000:3000 cairnobs-web

Tenant picker (Phase 4)

src/routes/select-tenant is the one route that isn't reachable by clicking around the app -- enterprise-auth's internal/loginhandler redirects a browser here after an SSO login resolves to more than one tenant_memberships row (see that package's doc comment), carrying a short-lived cairnobs_pending_login cookie instead of a real session. The page calls GET /auth/memberships to list the choices, and POST /auth/select-tenant on a click, both via fetch(..., {credentials: 'include'}) ($lib/api.ts's listMemberships/selectTenant) so that cookie -- and, on success, the real session cookie the POST response sets -- actually cross the origin boundary between this app and enterprise-auth. enterprise-auth's default POST_LOGIN_REDIRECT_URL (this app's own base URL) is also where CORS_ALLOWED_ORIGIN defaults to, and it has to be a literal origin, not * -- see api/httpserver.WithCredentialedCORS's doc comment for why a credentialed fetch and a wildcard CORS origin can never be combined; getAuthFeatures above deliberately doesn't send credentials for exactly this reason, and is why it could stay on the plain WithCORS every other endpoint in this repo uses.

Like every other route (export const prerender = true in this route's own +page.ts), no server-side data loading -- the membership list and the tenant choice both come from client-side fetch calls the same way the root query page's does.

Verified in a real browser in this environment: a throwaway Node server standing in for enterprise-auth (implementing the exact GET /auth/memberships/POST /auth/select-tenant wire contract, including the plain-text http.Error bodies the real handler sends, not JSON) on a different origin/port than this app's dev server, driven through the full flow -- cross-origin pending-login cookie set, the credentialed preflight + GET/POST round trip, a real click choosing a tenant, and the post-selection redirect landing back on / -- plus the missing/expired-cookie error path separately. No Docker or live Postgres/IdP needed for this, since the whole point was exercising this app's own fetch/CORS/cookie wiring against a contract-accurate fake, not enterprise-auth's internals (those are enterprise/internal/ loginhandler's own tests' job, already covered there).

Why nginx, not distroless

The repo convention prefers distroless/scratch base images. Serving a static SPA still needs some HTTP server, though, and nginx:alpine is the boring, standard choice for that job — writing a custom static-file binary just to stay distroless would be more engineering than a Phase 0 placeholder page justifies. nginx.conf here is minimal: serve build/, fall back to index.html for client-side routing (only one route exists today, but this is what you want the moment a second one is added).