configproperties

README

config-properties

Read Java .properties configuration through config — with no added dependency

Part of the phpboyscout Go toolkit — small, framework-free Go modules extracted from go-tool-base. Documented with the parent module at config.go.phpboyscout.uk

---

config reads and writes only YAML. Every other file format is a sibling module like this one — and this one adds nothing to your dependency graph, because a .properties file is read with the standard library.

import (
	"gitlab.com/phpboyscout/go/config"
	configproperties "gitlab.com/phpboyscout/go/config-properties"
)

store, err := config.NewStore(ctx,
	config.WithFiles(fsys, "/etc/app.yaml"),                               // YAML, the default
	config.WithBackend(configproperties.New(fsys, "/etc/app.properties")), // outranks it
)

Keys nest on dots

A properties key is dotted already, and each dot is a nesting separator:

server.host=localhost
server.port=8080

reads as server.host and server.port, so a properties layer merges into a nested YAML or JSON one by the same paths. In Java a dotted key is a single flat string; here it nests, which is what makes it a configuration layer rather than a map.

The format it honours

key=value, key:value and key value are all separators; leading whitespace and whitespace around the separator is ignored; # and ! begin a comment; a line ending in an odd number of backslashes continues onto the next; and the standard escapes are recognised in keys and values — \t \n \r \f \\, an escaped separator or space, and \uXXXX.

Read-only

Values are strings; the read path casts. The format is read-only.

What it costs

Only the config graph — a .properties file is parsed with the standard library, so there is no parser module. An allowlist test states it. No filesystem library: you supply the config.FS.

License

See LICENSE.

Documentation

Overview

Package configproperties reads Java `.properties` configuration through the config codec seam.

It is a sibling of the config core, not part of it, and adds no dependency at all — a properties file is read with the standard library.

config.NewStore(ctx,
	config.WithFiles(fsys, "/etc/app.yaml"),        // YAML, the default
	config.WithBackend(configproperties.New(fsys, "/etc/app.properties")),
)

Keys nest on dots

A properties key is dotted already, and each dot is a nesting separator, so `server.host=localhost` reads as server.host and merges into a nested YAML or JSON layer by the same path. In Java a dotted key is a single flat string; here it nests, which is what makes it a configuration layer rather than a map.

The format it honours

`key=value`, `key:value` and `key value` are all separators; leading whitespace and whitespace around the separator is ignored; `#` and `!` begin a comment; a line ending in an odd number of backslashes continues onto the next; and the standard escapes are recognised in keys and values — `\t \n \r \f \\`, an escaped separator or space, and `\uXXXX`. The format is read-only, and values are strings that the read path casts.

Index

• func New(filesystem config.FS, path string) config.Backend
• type Codec
  • func (Codec) Decode(path string, src []byte) ([]map[string]any, error)

Functions

func New

func New(filesystem config.FS, path string) config.Backend

New reads a Java properties document.

Types

type Codec

type Codec struct{}

Codec decodes key=value properties into layer values. New uses it, and it is exported so a backend adapter can reuse it as a value decoder — a key whose value is a properties document, decoded via that adapter's WithValueCodec option. It is a config.Codec.

func (Codec) Decode

func (Codec) Decode(path string, src []byte) ([]map[string]any, error)