Extensions

Starting with titiler>=0.11, we added a new titiler package titiler.extensions which aim to ease the addition of optional endpoints to factories.

In titiler.core.factory.BaseTilerFactory class, we've added a new attribute: extensions: List[FactoryExtension] = field(default_factory=list). The list of extension will then be used in the post-init step such as:

def __post_init__(self):
    """Post Init: register route and configure specific options."""
    # Register endpoints
    self.register_routes()

    # Register Extensions
    for ext in self.extensions:
        ext.register(self)

    # Update endpoints dependencies
    for scopes, dependencies in self.route_dependencies:
        self.add_route_dependencies(scopes=scopes, dependencies=dependencies)

We defined extension using an Abstract Base Class to make sure they implement a register method:

@dataclass
class FactoryExtension(metaclass=abc.ABCMeta):
    """Factory Extension."""

    @abc.abstractmethod
    def register(self, factory: "BaseTilerFactory"):
        """Register extension to the factory."""
        ...

Available extensions

cogValidateExtension

• Goal: adds a /validate endpoint which return the content of rio-cogeo info method
• Additional requirements: titiler.extensions["cogeo"] (installs rio-cogeo)

cogViewerExtension

• Goal: adds a /viewer endpoint which return an HTML viewer for simple COGs

stacViewerExtension

• Goal: adds a /viewer endpoint which return an HTML viewer for STAC item

stacExtension

• Goal: adds a /stac endpoint which return an HTML viewer for STAC item
• Additional requirements: titiler.extensions["stac"] (installs rio-stac)

wmsExtension

• Goal: adds a /wms endpoint to support OGC WMS specification (GetCapabilities and GetMap)

How To

Use extensions

Extensions must be set at TilerFactory's creation using the extensions= options.

from fastapi import FastAPI
from titiler.core.factory import TilerFactory
from titiler.extensions import cogValidateExtension

# Create a FastAPI application
app = FastAPI(description="A lightweight Cloud Optimized GeoTIFF tile server")

# Create a set of endpoints using TiTiler TilerFactory
tiler = TilerFactory(
    router_prefix="/cog",
    extensions=[
        cogValidateExtension()  # the cogeoExtension will add a rio-cogeo /validate endpoint
    ]
)

# Register endpoints to the application
app.include_router(tiler.router, prefix="/cog")

See titiler.application for a full example.

Create your own

from dataclasses import dataclass, field
from typing import Tuple, List, Optional

import rasterio
from starlette.responses import Response
from fastapi import Depends, FastAPI, Query
from titiler.core.factory import BaseTilerFactory, FactoryExtension, TilerFactory
from titiler.core.dependencies import RescalingParams
from titiler.core.factory import TilerFactory
from titiler.core.resources.enums import ImageType


@dataclass
class thumbnailExtension(FactoryExtension):
    """Add endpoint to a TilerFactory."""

    # Set some options
    max_size: int = field(default=128)

    # Register method is mandatory and must take a BaseTilerFactory object as input
    def register(self, factory: BaseTilerFactory):
        """Register endpoint to the tiler factory."""

        # register an endpoint to the factory's router
        @factory.router.get(
            "/thumbnail",
            responses={
                200: {
                    "content": {
                        "image/png": {},
                        "image/jpeg": {},
                    },
                    "description": "Return an image.",
                }
            },
            response_class=Response,
        )
        def thumbnail(
            # we can reuse the factory dependency
            src_path: str = Depends(factory.path_dependency),
            layer_params=Depends(factory.layer_dependency),
            dataset_params=Depends(factory.dataset_dependency),
            post_process=Depends(factory.process_dependency),
            rescale: Optional[List[Tuple[float, ...]]] = Depends(RescalingParams),
            color_formula: Optional[str] = Query(
                None,
                title="Color Formula",
                description="rio-color formula (info: https://github.com/mapbox/rio-color)",
            ),
            colormap=Depends(factory.colormap_dependency),
            render_params=Depends(factory.render_dependency),
            reader_params=Depends(factory.reader_dependency),
            env=Depends(factory.environment_dependency),
        ):
            with rasterio.Env(**env):
                with factory.reader(src_path, **reader_params) as src:
                    image = src.preview(
                        max_size=self.max_size,
                        **layer_params,
                        **dataset_params,
                    )

            if post_process:
                image = post_process(image)

            if rescale:
                image.rescale(rescale)

            if color_formula:
                image.apply_color_formula(color_formula)

            format = ImageType.jpeg if image.mask.all() else ImageType.png

            content = image.render(
                img_format=format.driver,
                colormap=colormap,
                **format.profile,
                **render_params,
            )

            return Response(content, media_type=format.mediatype)

# Use it
app = FastAPI()
tiler = TilerFactory(
    extensions=[
        thumbnailExtension(max_size=64)
    ]
)
app.include_router(tiler.router)