lnav (https://lnav.org/) config for ftl (https://github.com/tbd54566975/ftl)

_lnav.md

Log File Navigator (Optional)

lnav is a log file navigator that is capable of reading and analyzing log files in real time. It is a terminal application and is the a robust tool for navigating and analyzing log files.

It's similar to multitail but more powerful more discoverable UX.

Some notable features:

• Creates a unified view across multiple formats and types (e.g. JSON, syslog + ftl and temporal).
• Persistent log sessions (e.g. filters, queries, and views).
• Alternative querying via SQL (e.g. SELECT * FROM log WHERE level = 'error').
• Histogram view (e.g. log levels, time intervals) for a quick overview.
• Unique coloring based on value types (e.g. multiple payloads will be colored differently).

1. Install lnav definition

.lnav/install.sh

2. Getting logs from ftl

ftl dev . \
	--log-level=debug \
	--log-json 2>&1 |
	tee -a "logs/ftl-$(date +'%F').log.json"

ftl serve \
	--allow-origins "*" \
	--log-level=debug \
	--log-json 2>&1 |
	tee -a "logs/ftl-$(date +'%F').log.json"

3. Analyzing logs

lnav -r logs/*

ftl_json.sample.json

{
  "$schema": "https://lnav.org/schemas/format-v1.schema.json",
  "ftl_json": {
    "title": "FTL JSON log format",
    "description": "FTL JSON log format",
    "timestamp-field": "time",
    "json": true,
    "file-pattern": "ftl-.*\\.log\\.json",
    "level-field": "level",
    "level": {
      "debug": "debug",
      "info": "info",
      "warning": "warn",
      "error": "error",
      "fatal": "fatal"
    },
    "body-field": "message",
    "value": {
      "message": {
        "kind": "string",
        "identifier": false
      },
      "attributes": {
        "kind": "json",
        "identifier": true
      },
      "time": {
        "kind": "string",
        "identifier": false
      }
    },
    "highlights": {
      "fatal": {
        "color": "Red1",
        "pattern": "CRITICAL|FATAL|fatal"
      },
      "error": {
        "color": "OrangeRed1",
        "pattern": "ERROR"
      },
      "warning": {
        "color": "Orange1",
        "pattern": "WARN"
      },
      "info": {
        "color": "Blue1",
        "pattern": "INFO"
      },
      "debug": {
        "color": "Grey62",
        "pattern": "DEBUG"
      },
      "ipv4": {
        "color": "Yellow1",
        "pattern": "\\b(?:[0-9]{1,3}\\.){3}[0-9]{1,3}:[0-9]+\\b"
      }
    },
    "line-format": [
      {
        "field": "__timestamp__",
        "timestamp-format": "%Y-%m-%dT%H:%M:%S.%N%Z"
      },
      " ",
      {
        "field": "level",
        "text-transform": "uppercase",
        "auto-width": true,
        "min-width": 7,
        "align": "right",
        "prefix": "[",
        "suffix": "]"
      },
      " ",
      {
        "field": "message"
      }
    ]
  }
}

install.sh

#!/usr/bin/env bash

if ! command -v lnav &> /dev/null; then
  echo "error: lnav is not installed. Please install it first."
  exit 1
fi

version="$(lnav --version | cut -d'.' -f2)"
if [[ -z "$version" || "$version" -lt 12 ]]; then
  echo "error: lnav version 0.12 or higher is required"
  exit 1
fi

lnav_format="$(lnav -m format ftl_json source 2> /dev/null)"
if [ -n "$lnav_format" ]; then
  confirm="n"
  # prevent loss of customizations
  #  - https://github.com/tstack/lnav/issues/1240
  echo "warning: ftl_json format already exists '$lnav_format'"
  read -r -p "overwrite? [y/n] " confirm
  if [[ "$confirm" =~ [NnQq] ]]; then
    exit 0
  fi
fi

# always resolve to script directory to install the format
script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" &> /dev/null && pwd)"
find "$script_dir" -name '*.json' -print0 | xargs lnav -i

extracted from TBD54566975/ftl#1018