After long live with XML format I’ve finally decided to improve the configuration
system to avoid various issues related to the configuration extending and readability.
In this post I try to describe the main features and principles of the configuration
language which I’ve called
RCL - rspamd configuration language.
RCL is heavily infused by
nginx configuration as the example of a convenient configuration
system. However, RCL is fully compatible with
JSON format and is able to parse json files.
For example, you can write the same configuration in the following ways:
- in nginx like:
- or in JSON:
Improvements to the json notation.
There are various things that makes json parsing more convenient for editing:
- Braces are not necessary to enclose the top object: it is automatically treated as object:
is the equivalent to:
- There is no requirement of quotes for strings and keys, moreover,
:sign may be replaced with
=sign or even skipped for objects:
is the equivalent to:
- No commas mess: you can safely place a comma or semicolon for the last element in array or object:
- Non-unique keys in an object are allowed and automatically converted to the arrays internally:
is converted to:
- Numbers can have suffixes to specify standard multipliers:
[kKmMgG]- standard 10 base multipliers (so
1kis translated to 1000)
[kKmMgG]b- 2 power multipliers (so
1kbis translated to 1024)
[s|min|d|w|y]- time multipliers, all time values are translated to float number of seconds, for example
10minis translated to 3600.0 and
10msis translated to 0.01
- Booleans can be specified as
- It is still possible to treat numbers and booleans as strings by enclosing them in double quotes.
RCL supports different style of comments:
- single line:
/* ... */
Multiline comments may be nested:
RCL supports external macroes both multiline and single line ones:
There are two internal macroes provided by RCL:
include- read a file
/path/to/fileor an url
http://example.com/fileand include it to the current place of RCL configuration;
includes- read a file or an url like the previous macro, but fetch and check the signature file (which is obtained by
Public key (or keys) used for the last command are specified by the concrete RCL user (by rspamd for example).
Each RCL object can be serialized to one of the three supported formats:
JSON- canonic json notation (with spaces indented structure);
Compacted JSON- compact json notation (without spaces or newlines);
Configuration- nginx like notation.
RCL has clear design that should be very convenient for reading and writing. At the same time it is compatible with JSON language and therefore can be used as a simple JSON parser. Macroes logic provides an ability to extend configuration language (for example by including some lua code) and comments allows to disable or enable the parts of a configuration quickly. Rspamd 0.6.0 will be the first version with RCL configuration. It will be possible to convert the existing XML configuration to RCL one by rspamd itself.