Technical guide
Recover a deleted Git branch
Find a surviving branch tip in local refs, the reflog, or remaining objects, then recreate the branch. Recovery depends on object availability, not a fixed deadline.
Technical guide
Can one DNS name have multiple CNAME records?
A DNS name can have only one CNAME target. Use address records or a provider-supported routing feature when you need multiple destinations.
Explainer
Remove selected fields or keep an allowlist in Logstash
Choose mutate for named fields, prune for a top-level allowlist, and conditional removal for events that need different retention rules.
Explainer
Can you use environment variables in a Fluentd configuration?
Reference environment variables in Fluentd, require missing values explicitly, and supply settings through a shell, systemd, or Kubernetes.
Explainer
What is the maximum message size in centralized rsyslog?
Separate syslog protocol limits from rsyslog input limits, raise maxMessageSize, and verify that every hop preserves long messages.
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
Map new Elasticsearch string fields as keyword by default
Use an index template and a dynamic template to map new string fields as keyword, with clear boundaries for legacy versions and existing data.
Technical guide
Check whether a string starts with a digit
Use a start-anchored regular expression and choose ASCII or Unicode digit semantics explicitly for JavaScript, Python, and Java.
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.
Technical guide
Commit only part of a file in Git
Use git add --patch to stage selected changes, inspect the complete staged snapshot, and commit it without accidentally including the rest of the file.
Technical guide
Compare two Git branches
Choose endpoint diffs, merge-base diffs, or commit ranges to compare Git branches, then generate and check a patch when you need to transfer file changes.
Explainer
How to apply conditional logic in Fluentd
Filter records, route them by field values, or assign a derived field with Fluentd plugins and explicit handling for unmatched events.