Technical guide
Understand git merge --no-ff
Create a merge commit when a fast-forward would otherwise be possible, preserve ancestry, and understand the limits of merge-based rollback.
Explainer
Find the document root used by Nginx
Inspect the selected server and location instead of assuming a universal web-root directory across packages, containers, and source builds.
Technical guide
What __init__.py does in a Python package
Use __init__.py to define a regular package and a small public interface, while understanding import caching, namespace packages, and initialization side effects.
Technical guide
What does npm install --save do?
Understand npm’s default dependency saving, when --save still matters, and how development, exact-version, global, and no-save options differ.
Technical guide
Compare $host, $http_host, and $server_name in Nginx
Choose the parsed request hostname, received Host header, or selected server name deliberately for proxying, logging, and redirects.
Technical guide
Why npm install changes package-lock.json
Understand manifest reconciliation, npm lockfile versions, platform differences, and when npm ci is the appropriate reproducible-install command.
Explainer
Troubleshoot 502 Bad Gateway errors in Nginx
Find why Nginx cannot obtain a valid upstream response by checking listeners, proxy settings, socket permissions, and error logs.
Explainer
Fix an Nginx “Address already in use” error
Identify the process holding an Nginx listening port, resolve duplicate instances, and distinguish normal virtual hosts from socket conflicts.
Technical guide
Change a column’s data type in pandas
Convert pandas columns with astype, handle invalid values with to_numeric and to_datetime, and preserve missing values with nullable dtypes.
Explainer
Why client_max_body_size is not taking effect in Nginx
Trace an upload limit through Nginx configuration inheritance, reloads, upstream proxies, and application body parsers.
Explainer
Serve different directories under one Nginx subdomain
Map URL prefixes to separate directories with root and alias, handle trailing slashes, and verify single-page application routes.
Explainer
Convert between bytes and strings in Python
Decode bytes into text and encode strings into bytes with the right character encoding, including invalid-byte handling and Base64 output.