Loading data with signed URLs

ref: developmentseed/titiler?331

Goal: allow users to pass signed url or url containing query parameters (delimited with &)

requirements: titiler.core

What / Why / How

Passing a signed URL or a complex URL for a dataset is not supported by default in TiTiler because the parameters (delimited with &) from the signed url conflict with the query parameters from the application itself. In order to allow signed url in the application there are two solutions:

1. URL Encoding

1.1 Full URL

The easiest way (from the application's point of view) to allow complex URLs is to allow an encoded url as an input parameter.

import base64
url = "http://my.dataset.com/cog.tif?p=aaa&c&1234&t=4321"

# base64.b64encode(url.encode())
>>> "aHR0cDovL215LmRhdGFzZXQuY29tL2NvZy50aWY/cD1hYWEmYyYxMjM0JnQ9NDMyMQ=="

When base64 encoded, the url is just a regular string and thus will be valid in the application.

"""Minimal COG tiler with Signed URL support."""

import base64
from titiler.core.factory import TilerFactory
from titiler.core.errors import DEFAULT_STATUS_CODES, add_exception_handlers

from fastapi import FastAPI


# Custom Path dependency which can `decode` a base64 url
def DatasetPathParams(
    url: str = Query(..., description="Dataset URL"),
    base64_encoded: bool = Query(None)
) -> str:
    """Create dataset path from args"""
    if base64_encoded:
        url = base64.b64decode(url).decode()
    return url

app = FastAPI(title="My simple app")

cog = TilerFactory(path_dependency=DatasetPathParams)
app.include_router(cog.router, tags=["Cloud Optimized GeoTIFF"])

add_exception_handlers(app, DEFAULT_STATUS_CODES)


@app.get("/healthz", description="Health Check", tags=["Health Check"])
def ping():
    """Health check."""
    return {"ping": "pong!"}

import base64
from my_provider import signed_url

my_url = "https://dataset.com/...."

# Get signed URL
my_signed_url = signed_url(my_url)

# Encode the signed url using base64
url = base64.b64encode(my_signed_url.encode())

info = request.get(f"{titiler_endpoint}/info", params={"url": url, signed_url: True})

1.2 Encode only the url params

"""Minimal COG tiler with Signed URL support."""

import base64
from titiler.core.factory import TilerFactory
from titiler.core.errors import DEFAULT_STATUS_CODES, add_exception_handlers

from fastapi import FastAPI


# Another solution is to pass only the query parameters encoded in base64
def DatasetPathParams(
    url: str = Query(..., description="Dataset URL"),
    url_params: str = Query(
        None, description="Base64 encoded Query parameters to add to the dataset URL."
    ),
) -> str:
    """DatasetPath Params."""
    if url_params:
        url += f"?{b64decode(url_params).decode()}"
    return url


app = FastAPI(title="My simple app")

cog = TilerFactory(path_dependency=DatasetPathParams)
app.include_router(cog.router, tags=["Cloud Optimized GeoTIFF"])

add_exception_handlers(app, DEFAULT_STATUS_CODES)


@app.get("/healthz", description="Health Check", tags=["Health Check"])
def ping():
    """Health check."""
    return {"ping": "pong!"}

import base64
from urllib.parse import urlparse
from my_provider import signed_url

my_url = "https://dataset.com/...."

# Get signed URL
my_signed_url = signed_url(my_url)

# Extract the url parameters
signed_params = urlparse(my_signed_url).query

# Encode the parameters using base64
encoded_params = base64.b64encode(signed_params.encode())

info = request.get(f"{titiler_endpoint}/info", params={"url": url, url_params: encoded_params})

2. Signing URL in the application

Another solution is to sign the URL directly in TiTiler.

"""Minimal COG tiler with Signed URL support."""

import my_provider  # e.g AWS, Google, ...

from titiler.core.factory import TilerFactory
from titiler.core.errors import DEFAULT_STATUS_CODES, add_exception_handlers

from fastapi import FastAPI


# Custom Path dependency which will sign url
# !!! You may want to add caching here to avoid to many call to the signing provider !!!
def DatasetPathParams(
    url: str = Query(..., description="Dataset URL"),
) -> str:
    """Create dataset path from args"""
    # Use your provider library to sign the URL
    return my_provider.sign(url)


app = FastAPI(title="My simple app")

cog = TilerFactory(path_dependency=DatasetPathParams)
app.include_router(cog.router, tags=["Cloud Optimized GeoTIFF"])

add_exception_handlers(app, DEFAULT_STATUS_CODES)


@app.get("/healthz", description="Health Check", tags=["Health Check"])
def ping():
    """Health check."""
    return {"ping": "pong!"}

import base64
from my_provider import signed_url

my_url = "https://dataset.com/...."

info = request.get(f"{titiler_endpoint}/info", params={"url": my_url})