streamlit

name	streamlit
description	Build a CEDA Streamlit app the house way — src/ layout with a frontend/ page tree, st.navigation multipage wiring, npuls logo/branding, and uv+Docker packaging. Use when creating a new Streamlit app, adding a page, or structuring the frontend of a CEDA tool.

streamlit

CEDA Streamlit apps follow a shared shape. Start from streamlit-template-app for a new app; match the target repo's existing structure when extending one.

When this applies

This is a knowledge skill — it loads (explicitly via /streamlit, or automatically) when you create a new Streamlit app, add a page, or structure the frontend of a CEDA tool. It is reference/convention.

Project layout

src/
├── main.py                 # entrypoint: page config, navigation, logo
├── frontend/               # pages grouped by subdirectory
│   ├── Overview/Home.py    # (or Home/Home.py)
│   ├── Files/...
│   └── Modules/...
├── backend/                # non-UI logic (file handling, processing)
├── config/                 # config.yaml + helpers
└── assets/                 # npuls_logo.png etc.

Two multipage patterns (match the repo)

1. Auto-discovery (streamlit-template-app): config/screen_scanner.py provides get_screens() + group_pages_by_subdirectory(); main.py calls st.navigation(grouped_pages). Add a page = drop a .py in a frontend/ subdir; no wiring needed.
2. Explicit (1cijferho): main.py declares each page with st.Page("frontend/<Group>/<Page>.py", icon="…", title="…") and passes the list to st.navigation([...]). Add a page = add a .py and a st.Page line.

main.py essentials

st.set_page_config(page_title="CEDA …", page_icon=":material/edit:")
pg = st.navigation(pages)          # grouped dict or explicit list
st.logo("src/assets/npuls_logo.png")
pg.run()

Global CSS is applied once in main.py and shared across pages. For NPULS house style, see the npuls-huisstijl skill.

Auth (optional, SRAM)

Apps gate access with OIDC via SRAM when OIDC_PROVIDER is set — wrap the app in require_authentication(). See /sram-oidc. Auth is disabled cleanly when the env vars are absent, so local dev needs no login.

Packaging & run

• Deps via uv (pyproject.toml + uv.lock); run uv run streamlit run src/main.py.
• Container + local dev: see /docker. Deploy on SDP: see /sdp-onboard, /surf-sdp-helm-flux (Streamlit URL pattern https://<app>.<env>.sdp.surf.nl, health probe /healthz, ingress port 8501).

Important

• Match the repo's multipage pattern (auto-discovery vs explicit st.Page); don't mix them.
• Streamlit UI can't be meaningfully unit-tested headless — run the app and click through the golden path before calling a UI change done; say so if you can't.
• Auth is opt-in: no OIDC_PROVIDER → app runs open (fine for local dev). See /sram-oidc. Packaging/deploy: /docker, /sdp-onboard.
• Applies to cedanl repos.