This PR standardizes the log message key from msg to message across all non-legacy logging formats in Tyk to improve consistency for log processing and analysis.

This is achieved by introducing a new FieldMap utility that wraps logrus.FieldMap to handle the remapping of log field keys. This utility is integrated into the standard JSONFormatter and TextFormatter. A new defaultFieldMap function establishes the default mapping of msg to message, which is now applied to all standard formatters. The legacy log formatter remains unchanged to ensure backward compatibility.

Files Changed Analysis

• log/field_map.go & log/field_map_test.go (New): These files introduce the FieldMap struct, which provides a Resolve method to look up and replace log field keys. This is the core logic for the remapping. Comprehensive unit tests are included.
• log/json_formatter.go (Modified): The custom JSONFormatter is updated to include and use the new FieldMap. It now resolves standard log keys (msg, level, time, error) to their mapped values before serializing the log entry.
• log/log.go (Modified): The functions that create log formatters (newFormatterText, newFormatterJson, newFormatterLogrusJson) are updated to use a new defaultFieldMap function, applying the msg to message mapping. The legacy formatter is explicitly configured with an empty map to be excluded from this change.

Architecture & Impact Assessment

• What this PR accomplishes: It standardizes the primary log message key to message for all text and JSON log outputs. This change simplifies log parsing and querying for downstream observability platforms.
• Key technical changes introduced: A FieldMap utility has been introduced to handle the remapping of log field keys. This map is now integrated into the gateway's log formatters to apply the new standard key.
• Affected system components: The change affects the global logging subsystem of the Tyk Gateway. All logs generated by the gateway (except those using the legacy format) will now use "message" instead of "msg" as the key for the log entry's main text. This could be a breaking change for any external log monitoring or aggregation systems that have parsing rules specifically targeting the msg field.

Log Formatting Flow

graph TD
    A[Log Event Triggered] --> B[logrus.Entry Created];
    B --> C{Formatter Selected};
    C --> D[JSONFormatter / TextFormatter];
    
    subgraph "Format() Method"
        F["defaultFieldMap: msg -> message"] --> G["FieldMap.Resolve(key)"];
        G --> H["Remap 'msg' key to 'message'"];
    end

    D --> F;
    H --> I[Formatted Log String/JSON];
    I --> J[Log Output];

Scope Discovery & Context Expansion

The changes are localized within the log package but have a global impact on the application's logging output. The central log.NewFormatter function, used throughout the gateway to initialize logging, now configures this new field mapping by default. Consequently, any component using the standard logger will automatically adopt the new log format. While this PR doesn't modify other modules directly, its effect is system-wide. This could impact users' custom scripts, dashboards, and alerting rules that rely on the previous log structure.

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Last updated: 2026-06-10T13:18:48.473Z | Triggered by: pr_updated | Commit: 6c38135

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✅ Security Check Passed

No security issues found – changes LGTM.

✅ Performance Check Passed

No performance issues found – changes LGTM.

✅ Security Check Passed

No security issues found – changes LGTM.

✅ Performance Check Passed

No performance issues found – changes LGTM.

Quality Issues (1)

	// The format to use is the same than for time.Format or time.Parse from the standard

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Last updated: 2026-06-10T13:18:03.277Z | Triggered by: pr_updated | Commit: 6c38135

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/visor ask Wrong assumption regarding FieldMap; logrus.FieldMap uses fieldKey type as a key, and it makes imposiible getting the value from map; I can't initiate logrus.fieldKey; I have to remap all the keys

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Last updated: 2026-05-19T07:52:35.295Z | Triggered by: shults | Commit: a1c3b37

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/visor ask look at my prev question. wtyd?

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Last updated: 2026-05-19T11:48:41.016Z | Triggered by: shults | Commit: a1c3b37

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🚨 Jira Linter Failed

Commit: 6c38135
Failed at: 2026-06-10 13:17:08 UTC

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🎯 Recommended Merge Targets

Based on JIRA ticket TT-15935: Feature Request - Standardize Log Message Key Across All Tyk Components

Fix Version: Tyk 5.14.0

⚠️ Warning: Expected release branches not found in repository

Required:

• master - No matching release branches found. Fix will be included in future releases.

📋 Workflow

1. Merge this PR to master first

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
95.0% Coverage on New Code
0.0% Duplication on New Code

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