Configuration Reference

Complete reference for all options in config/logfilter.json.

Overview

All configuration is done through a single JSON file at config/logfilter.json. The file is auto-generated with defaults on first launch. Changes are hot-reloaded automatically — no restart required.

JSON Validation

If your rules aren't taking effect, check for JSON syntax errors. A misplaced comma or missing bracket will cause the file to fail silently, falling back to defaults.

---

configVersion

Internal version number for future config format compatibility.

Type: Integer Default: 1

"configVersion": 1

Do not change this value unless instructed by a future update.

---

enabled

Master toggle for all log filtering.

Type: Boolean Default: true

"enabled": true

Set to false to disable all filtering without removing the mod or deleting your rules. Individual rules retain their own enabled state.

---

rules

An array of filter rules. Rules are evaluated in order — the first matching rule determines the outcome for that log message.

Type: Array of rule objects Default: Five example rules (all disabled)

Each rule has the following fields:

Field	Type	Required	Description
name	String	No	A descriptive label for the rule (for your reference only)
enabled	Boolean	No	Whether this rule is active. Default: true
type	String	Yes	The matching strategy. See Rule Types
pattern	String	Yes	The pattern to match against. Interpretation depends on type
action	String	Yes	What to do when the rule matches. See Actions
level	String	No	Restrict this rule to a specific log level. See Level Restriction

---

Rule Types

The type field determines how the pattern is matched against each log message.

Type	Matches Against	Pattern Format	Match Behavior
MESSAGE_REGEX	The formatted log message text	Java regex	Partial match (find())
LOGGER_NAME	The logger's name (e.g., net.minecraft.server.level.ServerLevel)	Exact string	Exact match or hierarchy prefix
LOGGER_REGEX	The logger's name	Java regex	Partial match (find())
LEVEL	The log level	Level name	Exact match

MESSAGE_REGEX

Matches against the formatted log message content using a Java regular expression. The pattern uses find(), meaning it matches if the pattern appears anywhere in the message — it does not need to match the entire message.

{
  "name": "Suppress advancement loading",
  "enabled": true,
  "type": "MESSAGE_REGEX",
  "pattern": "Loaded \\d+ advancements",
  "action": "DENY"
}

note

Backslashes must be doubled in JSON. The regex \d+ is written as \\d+ in the config file.

---

LOGGER_NAME

Matches against the logger's name using exact string comparison or hierarchy prefix matching. A pattern of net.minecraft.server.level will match:

• net.minecraft.server.level (exact match)
• net.minecraft.server.level.ServerLevel (child logger)
• net.minecraft.server.level.DistanceManager (child logger)

But will not match:

• net.minecraft.server (parent logger)
• net.minecraft.server.leveldata (different hierarchy — no . separator)

{
  "name": "Suppress server level loggers",
  "enabled": true,
  "type": "LOGGER_NAME",
  "pattern": "net.minecraft.server.level",
  "action": "DENY"
}

---

LOGGER_REGEX

Matches against the logger's name using a Java regular expression. Like MESSAGE_REGEX, the pattern uses find() for partial matching.

{
  "name": "Suppress all Forge loggers",
  "enabled": true,
  "type": "LOGGER_REGEX",
  "pattern": "^net\\.minecraftforge\\.",
  "action": "DENY"
}

---

LEVEL

Matches log messages by their log level. The pattern field should contain the level name.

Valid level values: TRACE, DEBUG, INFO, WARN, ERROR, FATAL

{
  "name": "Always allow error messages",
  "enabled": true,
  "type": "LEVEL",
  "pattern": "ERROR",
  "action": "ALLOW"
}

---

Actions

The action field determines what happens when a rule matches.

Action	Effect	Log4j2 Result
DENY	The message is suppressed and will not appear in the console or log file	DENY
ALLOW	The message is explicitly permitted, bypassing any later DENY rules	ACCEPT
NEUTRAL	No decision — continue evaluating subsequent rules	NEUTRAL

tip

Use ALLOW rules early in your rule list to protect important messages from being caught by broader DENY rules later. For example, always allow ERROR messages before denying an entire logger hierarchy.

---

Level Restriction

Any rule can optionally include a level field to restrict it to messages of a specific log level. The rule will only match if both the pattern and the level match.

{
  "name": "Suppress DEBUG from server level",
  "enabled": true,
  "type": "LOGGER_NAME",
  "pattern": "net.minecraft.server.level",
  "action": "DENY",
  "level": "DEBUG"
}

This rule suppresses DEBUG messages from net.minecraft.server.level and its child loggers, but allows INFO, WARN, and ERROR messages through.

Valid level values: TRACE, DEBUG, INFO, WARN, ERROR, FATAL

If the level field is omitted or set to null, the rule matches messages at any level.

---

Rule Evaluation Order

Rules are evaluated in the order they appear in the rules array. The first rule that matches a log message determines the outcome.

1. If the master enabled flag is false, all messages pass through unfiltered
2. LogFilter's own messages (logger name LogFilter) are never filtered
3. For each enabled rule, in order:
   • If the rule has a level restriction and the message level doesn't match, skip the rule
   • If the pattern matches (based on type), return the rule's action
4. If no rules match, the message passes through unchanged (NEUTRAL)

warning

Rule order matters. Place ALLOW rules before DENY rules when you need to protect specific messages from broader filters.

---

Complete Default Config

{
  "configVersion": 1,
  "enabled": true,
  "rules": [
    {
      "name": "Suppress OpenAL info spam",
      "enabled": false,
      "type": "LOGGER_NAME",
      "pattern": "org.lwjgl.openal",
      "action": "DENY"
    },
    {
      "name": "Suppress advancement loading",
      "enabled": false,
      "type": "MESSAGE_REGEX",
      "pattern": "Loaded \\d+ advancements",
      "action": "DENY"
    },
    {
      "name": "Suppress DEBUG from server level",
      "enabled": false,
      "type": "LOGGER_NAME",
      "pattern": "net.minecraft.server.level",
      "action": "DENY",
      "level": "DEBUG"
    },
    {
      "name": "Suppress recipe loading messages",
      "enabled": false,
      "type": "MESSAGE_REGEX",
      "pattern": "Loaded \\d+ recipes",
      "action": "DENY"
    },
    {
      "name": "Always allow error messages",
      "enabled": false,
      "type": "LEVEL",
      "pattern": "ERROR",
      "action": "ALLOW"
    }
  ]
}

---

Next Steps

• Examples — Real-world log filtering scenarios
• Troubleshooting — Common issues and solutions
• Getting Started — Installation and first-time setup