93% of all logs are not colored¹. It's sad. Maybe even illegal. It's time to logalize them. Logalize is a log colorizer like colorize and ccze. But it's faster and, much more importantly, it's extensible. No more hardcoded templates for logs and keywords. Logalize is fully customizable via logalize.yaml where you can define your log formats, keyword patterns and more.

Usage

cat /path/to/logs/file.log | logalize

Installation

Download DEB, RPM and Arch Linux packages or the binary for your architecture from releases.

Ubuntu/Debian:

sudo dpkg -i logalize_X.X.X_linux_amd64.deb

Fedora/Red Hat Enterprise Linux/CentOS:

sudo rpm -i logalize_X.X.X_linux_amd64.rpm

Arch Linux/Manjaro:

sudo pacman -U logalize_X.X.X_linux_amd64.pkg.tar.zst

or install from AUR:

# to install precompiled binary
yay -S logalize-bin

# to compile it on your machine
yay -S logalize

macOS:

brew install deponian/tap/logalize

Use go install if you already have $GOPATH/bin in your $PATH:

go install github.com/deponian/logalize@latest

How it works

Logalize reads one line from stdin at a time and then checks if it matches one of log formats (formats), general regular expressions (patterns) or plain English words and their inflected forms (words). See configuration below for more details.

Simplified version of the main loop:

1. Read a line from stdin
2. If the entire line matches one of the formats, print colored line and go to step 1, otherwise go to step 3
3. Find and color all patterns in the line and go to step 4
4. Find and color all words, print colored line and go to step 1

Configuration

Logalize looks for configuration files in these places:

• /etc/logalize/logalize.yaml
• ~/.config/logalize/logalize.yaml
• path from -c/--config flag
• .logalize.yaml in current directory

If more than one configuration file is found, they are merged. The lower the file in the list, the higher its priority.

A configuration file can contain five top-level keys: formats, patterns, words, themes and settings. In the first three you define what you want to catch and in themes you describe how you want to colorize it. settings is a way to set some options if you don't want to pass them as flags.

Log formats

Configuration example:

formats:
  kuvaq:
    - regexp: (\d{1,3}(\.\d{1,3}){3} )
      name: ip-address
    - regexp: (- )
      name: dash
    - regexp: ("[^"]+" )
      name: string
    - regexp: (\d\d\d)
      name: http-status-code
      alternatives:
        - regexp: (2\d\d)
          name: 2xx
        - regexp: (3\d\d)
          name: 3xx
        - regexp: (4\d\d)
          name: 4xx
        - regexp: (5\d\d)
          name: 5xx

formats describe complete log formats. A line must match a format completely to be colored. For example, the full regular expression for the "kuvaq" format above will look like this:
^(\d{1,3}(\.\d{1,3}){3} )(- )("[^"]+" )(\d\d\d)$

Only lines below will match this format:

• 127.0.0.1 - "menetekel" 200
• 7.7.7.7 - "m" 404

But not these:

• 127.0.0.1 - "menetekel" 503 lower ascension station
• Upper ascension station 127.0.0.1 - "menetekel" 403
• 127.0.0.1 - "menetekel" 404000

For an overview of regular expression syntax, see the regexp/syntax package.

Full log format example using all available fields:

formats:
  # name of a log format
  elysium:
    # regexp must begin with an opening parenthesis `(`
    # and it must end with a paired closing parenthesis `)`
    # regexp can't be empty `()`
    # that is, your regexp must be within one capture group
    # and contain a valid regular expression
    - regexp: (\d\d\d )
      # name of the capture group
      # it will be used to assign colors and style
      # later in "themes" section (see below)
      name: capture-group-name
      # alternatives are useful when you have general regular expression
      # but you want different colors for some specific subset of cases
      # within this regular expression
      # a common example is HTTP status code
      alternatives:
        # every regexp here has the same "name" field
        # but no "alternatives" field
        - regexp: (2\d\d )
          name: 2xx
        - regexp: (4\d\d )
          name: 4xx
    # each next regexp is added to the previous one
    # and together they form a complete regexp for the whole string
    - regexp: (--- )
      name: dashes
    - regexp: ([[:xdigit:]]{32})
      name: hash
    # full regexp for this whole example is:
    # ^(\d\d\d )(--- )([[:xdigit:]]{32})$

You can find built-in formats here. If you want to customize them or turn them off completely, overwrite the corresponding values in your logalize.yaml. See Customization section below for more details.

Patterns

Configuration example:

patterns:
  # simple patterns (one regexp)
  string:
    priority: 500
    regexp: ("[^"]+"|'[^']+')

  number:
    regexp: (\d+)

  # complex pattern (built from a list of regexps)
  ipv4-address-with-port:
    regexps:
      - regexp: (\d{1,3}(\.\d{1,3}){3})
        name: address
      - regexp: ((:\d{1,5})?)
        name: port

patterns are standard regular expressions. You can highlight any sequence of characters in a string that matches a regular expression. It may consist of several parts (see ipv4-address-with-port above). This is convenient if you want different parts of a pattern to have different colors or styles. Think of these complex patterns as little log formats that can be found in any part of a string.

Patterns have priority. Ones with higher priority will be painted earlier. Default priority is 0. The priorities of the built-in patterns are between -100 and 100.

Full pattern example using all available fields:

patterns:
  # simple pattern (when you use only "regexp" field)
  # name of a pattern
  http-status-code:
    # patterns with higher priority will be painted earlier
    # default priority is 0
    priority: 10
    # the same fields are used here as in log formats (see above)
    regexp: (\d\d\d)
    # patterns can have alternatives just like in log formats
    alternatives:
      - regexp: (2\d\d)
        name: 2xx
      - regexp: (3\d\d)
        name: 3xx
      - regexp: (4\d\d)
        name: 4xx
      - regexp: (5\d\d)
        name: 5xx

  # complex pattern (when you use "regexps" field)
  # the same fields are used here as in log formats (see above)
  # complex pattern are formed from all regexps in the "regexps" list
  # e.g. pattern below will be rendered as (\d{1,3}(\.\d{1,3}){3})((:\d{1,5})?)
  # the main difference from a simple pattern is that you can control
  # the style of the individual parts of the pattern
  ipv4-address-with-port:
    regexps:
      - regexp: (\d{1,3}(\.\d{1,3}){3})
        name: address
      - regexp: ((:\d{1,5})?)
        name: port

  # complex patterns are mainly used when you want to build a pattern
  # that builds on other patterns. for example, you want to make a highlighter
  # for the "logfmt" format. an example of "logfmt" log line:
  # ts=2024-02-16T23:00:02.953Z caller=db.go:16 level=info component=tsdb msg="Deleting..."
  # you can't use log formats (see above) because the structure of "logfmt" is variable.
  # in such a case, you can describe the base "logfmt" element (xxx=xxx) and look for other
  # existing patterns (date, time, IP address, etc.) on the right side of the equals sign
  # (see how to accomplish this below in the "themes" section)
  logfmt:
    regexps:
      - regexp: ( [^=]+)
        name: key
      - regexp: (=)
        name: equal-sign
      - regexp: ([^ ]+)
        name: value

You can find built-in patterns here. If you want to customize them or turn them off completely, overwrite the corresponding values in your logalize.yaml. See Customization section below for more details.

Words

Configuration example:

words:
  good:
    - "complete"
    - "enable"
    - "online"
    - "succeed"
    - "success"
    - "successful"
    - "successfully"
    - "true"
    - "valid"

  bad:
    - "block"
    - "critical"
    - "deny"
    - "disable"
    - "error"
    - "fail"
    - "false"
    - "fatal"
    - "invalid"

  your-word-group:
    - "lonzo"
    - "gizmo"
    - "lotek"
    - "toni"

words are just lists of words that will be colored according to your theme (see below). words could have been implemented using patterns, if it weren't for one feature.

Words from these lists are used not only literally, but also as lemmas. It means that by listing the word "complete", you will also highlight the words "completes", "completed" and "completing" in any line. Similarly, if you add the word "sing" to a list, the words "sang" and "sung" will also be highlighted. It works only for the English language.

There are two special word groups: good and bad. The negation of a word from good group will be colored using values from bad group and vice versa. For example, if good group has the word "complete" then "not completed", "wasn't completed", "cannot be completed" and other negative forms will be colored using values from bad word group.

You can find built-in words here. If you want to customize them or turn them off completely, overwrite the corresponding values in your logalize.yaml. See Customization section below for more details.

Themes

Configuration example:

themes:
  # name of a theme
  utopia:
    formats:
      kuvaq:
        ip-address:
          fg: "#f5ce42"
        dash:
          bg: "#807e7a"
          style: bold
        string:
          fg: "#9ddb56"
          bg: "#f5ce42"
        http-status-code:
          default:
            fg: "#ffffff"
          2xx:
            fg: "#00ff00"
            style: bold
          3xx:
            fg: "#00ffff"
            style: bold
          4xx:
            fg: "#ff0000"
            style: bold
          5xx:
            fg: "#ff00ff"
            style: bold

      elysium:
        capture-group-name:
          default:
            fg: "#ffffff"
          2xx:
            fg: "#00ff00"
            style: bold
          4xx:
            fg: "#ff0000"
            style: bold
        dashes:
          bg: "#807e7a"
          style: bold
        hash:
          fg: "#9ddb56"
          bg: "#f5ce42"

    patterns:
      string:
        fg: "#00ff00"

      number:
        bg: "#00ffff"
        style: bold

      http-status-code:
        default:
          fg: "#ffffff"
        2xx:
          fg: "#00ff00"
        3xx:
          fg: "#00ffff"
        4xx:
          fg: "#ff0000"
        5xx:
          fg: "#ff00ff"

      ipv4-address-with-port:
        address:
          fg: "#ffc777"
        port:
          fg: "#ff966c"

      logfmt:
        key:
          fg: "#ff0000"
        equal-sign:
          fg: "#00ff00"
        value:
          style: patterns-and-words

    words:
      good:
        fg: "#52fa8a"
        style: bold

      bad:
        fg: "#f06c62"
        style: bold

      your-word-group:
        bg: "#0b78f1"

  # another theme
  menetekel:
    formats:
      # . . .
    patterns:
      # . . .
    words:
      # . . .

themes is the place where you apply colors and style to log formats, patterns and word groups you defined earlier (or to the built-in ones). Every capture group can be colorized using fg, bg and style fields.

fg and bg are foreground and background colors correspondingly. They can be a hex value like #ff0000 or a number between 0 and 255 for ANSI colors.

style field can be set to one of 7 regular styles: bold, faint, italic, underline, overline, crossout and reverse. There are also three special styles:

• patterns - use highlighting from patterns section (see above)
• words - use highlighting from words section (see above)
• patterns-and-words - use highlighting from patterns and words sections

You can get a list of all available themes with -T/--list-themes flag and set it with -t/--theme flag or theme key in settings section (see below).

Settings

Configuration example:

settings:
  theme: "utopia"

  no-builtin-logformats: false
  no-builtin-patterns: false
  no-builtin-words: false
  no-builtins: true

  only-logformats: false
  only-patterns: false
  only-words: false

Here you can set some options that are equivalent to command line flags. theme is the same as --theme flag and so on. Only the flags from the example above are supported.

Customization

I want to change one of the colors in one of the built-in themes

1. Suppose you don't like the color of the "uuid" pattern in the "tokyonight-dark" theme
2. Just override it in your logalize.yaml like this:

# . . .
themes:
  tokyonight-dark:
    patterns:
      uuid:
        fg: "#ff0000"
        bg: "#00ff00"
        style: bold
# . . .

I want to define and use my own theme

1. Use one of the existing themes as an example. Pick one here
2. Copy it to your logalize.yaml, rename and change the way you like it:

# . . .
themes:
  your-theme-name:
    formats:
      # . . .
    patterns:
      # . . .
    words:
      # . . .
# . . .

3. Test it using logs from testlogs directory:

cat testlogs/* | logalize --theme your-theme-name

4. Set the theme in your logalize.yaml in settings section when it's ready:

# . . .
settings:
  theme: your-theme-name
  # . . .
# . . .

5. If it's a well known theme and you think others might benefit from it, feel free to open a PR asking to add that theme as one of the built-in themes

I want to disable all builtins and use only data from my own logalize.yaml

1. Define any log formats, patterns, word groups and themes in your logalize.yaml
2. Disable builtins in settings section:

# . . .
settings:
  # . . .
  no-builtins: true
  # . . .
# . . .

3. ... or use -N/--no-builtins flag:

cat logs | logalize -N

Acknowledgements

Thanks to my brother @emptysad for coming up with the name Logalize and for the logo idea.

Thanks to @ekivoka for the help with choosing the design and testing the logo.

Thanks to the authors of these awesome libraries:

• spf13/cobra
• aaaton/golem
• knadh/koanf
• muesli/termenv
• goccy/go-yaml

Footnotes

1. I made that up ↩