Guance Learn

Observability questions

Focused answers for definitions, architecture choices, troubleshooting, pricing, and evaluation.

Illustration of server operations and request logs
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.

  • Engineering
  • Explainer
3 min read
Log collectors routing application events to their destinations
Explainer

How do I add fields or routing tags to Fluentd events?

Use record_transformer to enrich Fluentd records, rewrite_tag_filter to route errors, and a tail input tag to identify file events.

  • Engineering
  • Explainer
3 min read
Illustration of server operations and request 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.

  • Engineering
  • Explainer
3 min read
Illustration of Git branches and shared commit history
Technical guide

Fix Git’s “Another Git process seems to be running” error

Check for an active Git operation before removing a stale lock. Locate the correct lock file, including in linked worktrees, and preserve staged changes.

  • Engineering
  • Technical guide
3 min read
Illustration of application infrastructure and operations
Technical guide

API gateway vs. reverse proxy: roles and tradeoffs

Compare API gateways and reverse proxies by routing, authentication, rate limits, and operations, and decide when an additional layer is useful.

  • Engineering
  • Technical guide
4 min read
Secure network connections and certificate management
Technical guide

Are HTTPS URLs encrypted?

HTTPS protects URL paths and query strings in transit. Learn what remains visible to networks, TLS proxies, servers, and logging systems.

  • Engineering
  • Technical guide
3 min read
Illustration of a Linux server and log data
Explainer

Set safe permissions for an Apache document root

Keep application code owned by the deployment account, give Apache read access, and grant write access only where the application needs it.

  • Engineering
  • Explainer
3 min read
Illustration of a Git commit history and an earlier revision
Technical guide

Create a Git branch from an earlier commit

Start a branch at an earlier commit or release tag, keep detached-HEAD work, and understand what happens when the branch later merges into main.

  • Engineering
  • Technical guide
3 min read
Log collection paths feeding a shared processing destination
Explainer

Can Filebeat load multiple configuration files?

Split Filebeat inputs and modules into separate YAML files, enable live reloading, and keep output settings in the main configuration.

  • Engineering
  • Explainer
2 min read
Illustration of Git branches and shared commit history
Technical guide

Can Git serve as a backup tool?

Use Git remotes, mirrors, and bundles to preserve committed history, while accounting for uncommitted files, LFS objects, repository metadata, and restore tests.

  • Engineering
  • Technical guide
3 min read
Illustration of log monitoring and analysis
Explainer

Can I remove the message field in Logstash?

Remove the original message after successful parsing, preserve failed events, and understand what field removal changes in Elasticsearch.

  • Engineering
  • Explainer
2 min read
Illustration of scheduled jobs, logs and Linux operations
Explainer

Show an rsync summary without a per-file listing

Use --stats without verbose output, read transfer statistics correctly, and keep detailed logs when needed.

  • Engineering
  • Explainer
3 min read