Remove Jinja dependency for landing page generation

optimade/server/routers/landing.py

@@ -1,39 +1,88 @@
-""" OPTIMADE landing page, rendered as a Jinja2 template. """
+""" OPTIMADE landing page router. """
 
 from pathlib import Path
+from functools import lru_cache
 
 from fastapi import Request
-from fastapi.templating import Jinja2Templates
+from fastapi.responses import HTMLResponse
 from starlette.routing import Router, Route
 from optimade import __api_version__
 
 from optimade.server.routers import ENTRY_COLLECTIONS
 from optimade.server.routers.utils import meta_values, get_base_url
 from optimade.server.config import CONFIG
 
-template_dir = Path(__file__).parent.joinpath("static").resolve()
-TEMPLATES = Jinja2Templates(directory=[template_dir])
 
+@lru_cache()
+def render_landing_page(url: str) -> HTMLResponse:
+    """Render and cache the landing page.
 
-async def landing(request: Request):
-    """Show a human-readable landing page when the base URL is accessed."""
+    This function uses the template file `./static/landing_page.html`, adapted
+    from the original Jinja template. Instead of Jinja, some basic string
+    replacement is used to fill out the fields from the server configuration.
 
-    meta = meta_values(request.url, 1, 1, more_data_available=False)
+    !! warning
+    The removal of Jinja means that the fields are no longer validated as
+    web safe before inclusion in the template.
+
+    """
+    meta = meta_values(url, 1, 1, more_data_available=False)
     major_version = __api_version__.split(".")[0]
-    versioned_url = f"{get_base_url(request.url)}/v{major_version}/"
+    versioned_url = f"{get_base_url(url)}/v{major_version}/"
+
+    template_dir = Path(__file__).parent.joinpath("static").resolve()
 
-    context = {
-        "request": request,
-        "request_url": request.url,
+    with open(template_dir / "landing_page.html", "r") as f:
+        html = "\n".join(f.readlines())
+
+    # Build a dictionary that maps the old Jinja keys to the new simplified replacements
+    replacements: dict[str, str] = {
         "api_version": __api_version__,
-        "implementation": meta.implementation,
-        "versioned_url": versioned_url,
-        "provider": meta.provider,
-        "index_base_url": CONFIG.index_base_url,
-        "endpoints": list(ENTRY_COLLECTIONS.keys()) + ["info"],
     }
 
-    return TEMPLATES.TemplateResponse("landing_page.html", context)
+    if meta.provider:
+        replacements.update(
+            {
+                "provider.name": meta.provider.name,
+                "provider.prefix": meta.provider.prefix,
+                "provider.description": meta.provider.description,
+                "provider.homepage": str(meta.provider.homepage) or "",
+            }
+        )
+
+    if meta.implementation:
+        replacements.update(
+            {
+                "implementation.name": meta.implementation.name or "",
+                "implementation.version": meta.implementation.version or "",
+                "implementation.source_url": str(meta.implementation.source_url or ""),
+            }
+        )
+
+    for replacement in replacements:
+        html = html.replace(f"{{{{ {replacement} }}}}", replacements[replacement])
+
+    # Build the list of endpoints. The template already opens and closes the `<ul>` tag.
+    endpoints_list = [
+        f'<li><a href="{versioned_url}{endp}">{versioned_url}{endp}'
+        for endp in list(ENTRY_COLLECTIONS.keys()) + ["info"]
+    ]
+    html = html.replace("{% ENDPOINTS %}", "\n".join(endpoints_list))
+
+    # If the index base URL has been configured, also list it
+    index_base_url_html = ""
+    if CONFIG.index_base_url:
+        index_base_url_html = f"""<h3>Index base URL:</h3>
+<p><a href={CONFIG.index_base_url}>{CONFIG.index_base_url}</a></p>
+"""
+    html = html.replace("{% INDEX_BASE_URL %}", index_base_url_html)
+
+    return HTMLResponse(html)
+
+
+async def landing(request: Request):
+    """Show a human-readable landing page when the base URL is accessed."""
+    return render_landing_page(str(request.url))
 
 
 router = Router(routes=[Route("/", endpoint=landing)])

optimade/server/routers/static/landing_page.html

@@ -1,13 +1,11 @@
 <!DOCTYPE html>
 <html lang="en">
     <head>
-        {% block head %}
-        <title>{{ optimade_title }}</title>
+        <title>{{ provider.name }}</title>
         <meta charset="UTF-8">
         <meta name="viewport" content="width=device-width, initial-scale=1">
         <meta name="keywords" content="optimade,materials,crystals,database">
         <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
-        {% endblock %}
 
     <style>
         html { margin: 2em; }
@@ -31,14 +29,9 @@ <h4>{{ implementation.name }}</h4>
         <p><a href={{ implementation.source_url }}>{{ implementation.source_url }}</a></p>
         <h3>Available endpoints:</h3>
         <ul>
-        {% for endpoint in endpoints %}
-        {{ '<li><a href="{}{}">{}{}</a></li>'.format(versioned_url, endpoint, versioned_url, endpoint) | safe }}
-        {% endfor %}
+        {% ENDPOINTS %}
         </ul>
-        {% if index_base_url != None %}
-            <h3>Index base URL:</h3>
-            <p><a href={{ index_base_url }}>{{ index_base_url }}</a></p>
-        {% endif %}
+        {% INDEX_BASE_URL %}
     </body>
     <footer>
         <div class="footer_text">

requirements.txt

@@ -1,7 +1,6 @@
 elasticsearch-dsl==6.4.0
 email_validator==1.1.3
 fastapi==0.65.2
-Jinja2==3.0.3
 lark-parser==0.12.0
 mongomock==4.0.0
 pydantic==1.9.0