feat(transport): support http proxy

[mharrisb1]

Overview

Adds HTTP Proxy support using same approach as the httpfs extension:

https://duckdb.org/docs/stable/core_extensions/httpfs/https#http-proxy

Example Usage

To test, I used tinyproxy with the following config:

Port 5436
Listen 127.0.0.1
LogLevel Info
Allow 127.0.0.1
BasicAuth testuser testpass

And ran with:

tinyproxy -d -c tinyproxy.conf

Then you can either use global proxy configs:

./build/release/duckdb
DuckDB v1.4.0-dev4046 (Development Version) 555d9b7d14
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
D SET http_proxy = 'localhost:5436';
D SET http_proxy_username = 'testuser';
D SET http_proxy_password = 'testpass';
D CREATE SECRET (TYPE gsheet, PROVIDER key_file, FILEPATH 'service-account-credentials.json');
┌─────────┐
│ Success │
│ boolean │
├─────────┤
│ true    │
└─────────┘
D FROM read_gsheet('https://docs.google.com/spreadsheets/d/11QdEasMWbETbFVxry-SsD8jVcdYIT1zBQszcF84MdE8/edit');
┌─────────┬────────┬──────────┐
│  Name   │  Age   │ Location │
│ varchar │ double │ varchar  │
├─────────┼────────┼──────────┤
│ Alice   │   30.0 │ Toronto  │
│ Bob     │   25.0 │ New York │
│ Charlie │   45.0 │ Chicago  │
│ Drake   │   NULL │ NULL     │
│ NULL    │   NULL │ NULL     │
│ Archie  │   99.0 │ NULL     │
└─────────┴────────┴──────────┘
D

Or you can use secrets manager:

./build/release/duckdb
DuckDB v1.4.0-dev4046 (Development Version) 555d9b7d14
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
D CREATE SECRET (TYPE gsheet, PROVIDER key_file, FILEPATH 'service-account-credentials.json');
┌─────────┐
│ Success │
│ boolean │
├─────────┤
│ true    │
└─────────┘
D CREATE SECRET http_proxy (TYPE http, HTTP_PROXY 'localhost:5436', HTTP_PROXY_USERNAME 'testuser', HTTP_PROXY_PASSWORD 'testpass');
┌─────────┐
│ Success │
│ boolean │
├─────────┤
│ true    │
└─────────┘
D FROM read_gsheet('https://docs.google.com/spreadsheets/d/11QdEasMWbETbFVxry-SsD8jVcdYIT1zBQszcF84MdE8/edit');
┌─────────┬────────┬──────────┐
│  Name   │  Age   │ Location │
│ varchar │ double │ varchar  │
├─────────┼────────┼──────────┤
│ Alice   │   30.0 │ Toronto  │
│ Bob     │   25.0 │ New York │
│ Charlie │   45.0 │ Chicago  │
│ Drake   │   NULL │ NULL     │
│ NULL    │   NULL │ NULL     │
│ Archie  │   99.0 │ NULL     │
└─────────┴────────┴──────────┘
D