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haraka-config

Haraka config file loader, parser, and watcher.

Config Files

Config file type/formats

Haraka's config loader can load several types of configuration files.

  • value - load a flat file containing a single value (default)
  • ini - load an ini file
  • json - load a json file
  • hjson - load a hjson file
  • yaml - load a yaml file
  • list - load a flat file containing a list of values
  • data - load a flat file containing a list, keeping comments and whitespace.
  • binary - load a binary file into a Buffer

See the File Formats section below for a more detailed explanation of each of the formats.

Usage

// From within a plugin:
const cfg = this.config.get(name, [type], [callback], [options])

This will load the file config/rambling.paths in the Haraka directory.

name is not a full path, but a filename in the config/ directory. For example:

const cfg = this.config.get('rambling.paths', 'list')

type can be any of the types listed above.

If the file name has an .ini, .json or .yaml suffix, the type parameter can be omitted.

callback is an optional callback function that will be called when an update is detected on the file after the configuration cache has been updated by re-reading the file. Use this to refresh configuration variables within your plugin. Example:

exports.register = function () {
  this.loginfo('register called')
  this.load_my_plugin_ini()
}

exports.load_my_plugin_ini = function () {
  this.cfg = this.config.get('my_plugin.ini', () => {
    // This closure is run a few seconds after my_plugin.ini changes
    // Re-run the outer function again
    this.load_my_plugin_ini()
  })
  this.loginfo(`cfg=${JSON.stringify(this.cfg)}`)
}

exports.hook_connect = function (next, connection) {
  // this.cfg here will be kept updated
}

The options object can accepts the following keys:

  • no_watch (default: false) - prevents Haraka from watching for updates.
  • no_cache (default: false) - prevents Haraka from caching the file. The file will be re-read on every call to config.get. This is not recommended as config files are read syncronously and will slow down Haraka.
  • booleans (default: none) - for .ini files, this allows specifying boolean type keys. Default true or false can be specified.

Default Config and Overrides

The config loader supports dual config files - a file containing defaults, and another user installed file containing overrides. The default configs reside:

  • Haraka: within the config directory in the Haraka install (where npm i installed Haraka)
  • NPM plugins - inside the module/config directory

Config files with overrides are always installed in the Haraka config directory, which you specified when you ran haraka -i.

Overrides work in the following manner:

  • For json, ini and yaml config, values are overridden on a deep key by key basis.
  • For every other config format, an override file replaces the entire config.
  • If smtp.json or smtp.yaml exist, their contents will be loaded before all other config files. You can make use of JSON Overrides here for a single file config.

Examples

  1. a plugin installed as a module (or a core Haraka plugin) loads a list config from their own config/plugin_name file. That list can be completely overridden by a file called config/plugin_name in the Haraka local install directory.

  2. a plugin using default config from config/plugin_name.ini can be overridden on a key-by-key basis. A default plugin_name.ini might contain:

toplevel1=foo
toplevel2=bar

[subsection]
sub1=something

And the local plugin_name.ini might contain:

toplevel2=blee

[subsection]
sub2=otherthing

This would be the equivalent of loading config containing:

toplevel1=foo
toplevel2=blee

[subsection]
sub1=something
sub2=otherthing

This allows plugins to ship a default config and users can override values on a key-by-key basis.

File Formats

Ini Files

INI files are key=value pairs, with optional [sections]. A typical example:

first_name=Matt
last_name=Sergeant

[job]
title=Senior Principal Software Engineer
role=Architect

[projects]
haraka
qpsmtpd
spamassassin

That produces the following Javascript object:

{
    main: {
        first_name: 'Matt',
        last_name: 'Sergeant'
    },
    job: {
        title: 'Senior Principal Software Engineer',
        role: 'Architect'
    },
    projects: {
        haraka: undefined,
        qpsmtpd: undefined,
        spamassassin: undefined,
    }
}

Items before any [section] marker are in the implicit [main] section.

Some values on the right hand side of the equals are converted:

  • integers are converted to integers
  • floats are converted to floats.

The key=value pairs support continuation lines using the backslash "" character.

The options object allows you to specify which keys are boolean:

{
  booleans: ['reject', 'some_true_value']
}

On the options declarations, key names are formatted as section.key. If the key name does not specify a section, it is presumed to be [main].

Declaring booleans ensures that values are converted as boolean when parsed, and supports the following options for boolean values:

true, yes, ok, enabled, on, 1

Anything else is treated as false.

To default a boolean as true (when the key is undefined or the config file is missing), prefix the key with +:

{
  booleans: ['+reject']
}

For completeness the inverse is also allowed:

{
  booleans: ['-reject']
}

Lists are supported using this syntax:

hosts[] = first_host
hosts[] = second_host
hosts[] = third_host

which produces this javascript array:

['first_host', 'second_host', 'third_host']

Flat Files

Flat files are simply either lists of values separated by \n or a single value in a file on its own. Qmail or qpsmtpd users will be familiar with this format. Lines starting with '#' and blank lines will be ignored unless the type is specified as 'data', however even then line endings will be stripped.

JSON Files

These are as you would expect, and returns an object as given in the file.

If a requested .json or .hjson file does not exist then the same file will be checked for with a .yaml extension and that will be loaded instead. This is done because YAML files are far easier for a human to write.

JSON Overrides

You can use JSON, HJSON or YAML files to override any other file by prefixing the outer variable name with a ! e.g.

{
  "!smtpgreeting": ['this is line one', 'this is line two'],
  "!smtp.ini": {
    main: {
      nodes: 0,
    },
    headers: {
      max_lines: 1000,
      max_received: 100,
    },
  },
  "!custom-plugin.yaml": {
    secret: 'example',
  },
}

If the config/smtpgreeting wasn't loaded before, then this value would replace it. Since smtp.json is always loaded first, it can be used to override existing config files.

NOTE: You must ensure that the data type (e.g. Object, Array or String) for the replaced value is correct. This cannot be done automatically.

Hjson Files

Hjson is a syntax extension to JSON. It is intended to be used like a user interface for humans, to read and edit before passing the JSON data to the machine. That means you can use it to parse JSON files but it is not intended as a replacement.

You can check Hjson's homepage to get familiar with it and you can try out its syntax.

Main features:

  • Comments
  • Optional quotes
  • Optional commas
  • Heredoc

Example syntax

{
  # specify rate in requests/second (because comments are helpful!)
  rate: 1000

  // prefer c-style comments?
  /* feeling old fashioned? */

  # did you notice that rate does not need quotes?
  hey: look ma, no quotes for strings either!

  # best of all
  notice: []
  anything: ?

  # yes, commas are optional!
}

NOTE: Hjson can be also replaced by a YAML configuration file. You can find more on this issue under JSON section.

YAML Files

As per JSON files above but in YAML format.

Reloading/Caching

Haraka automatically reloads configuration files, but this only works if whatever is looking at that config re-calls config.get() to retrieve the new config. Providing a callback in the config.get() call is the most efficient method to do this.

Configuration files are watched for changes using filesystem events which are inexpensive. Due to caching, calling config.get() is normally a lightweight process.

On Linux/Windows, newly created files that Haraka has tried to read in the past will be noticed immediately and loaded. For other operating systems, it may take up to 60 seconds to load, due to differences between in the kernel APIs for watching files/directories.

Haraka reads a number of configuration files at startup. Any files read in a plugins register() function are read before Haraka drops privileges. Be sure that Haraka's user/group has permission to read these files else Haraka will be unable to update them after changes.