goschtalt

A customizable configuration library that supports multiple files and formats.

Goals & Themes

• Make support for multiple configuration files and sources easy to use and extend.
• Simplify tracing the origin of a configuration value.
• Favor user customization options over building everything in, keeping dependencies to a minimum.
• Embrace patterns that make using other powerful libraries (kong, fx, etc) simple.

API Stability

This package has not yet released to 1.x yet, so APIs are subject to change for a bit longer.

After v1 is released, SemVer will be followed.

Installation

go get github.com/goschtalt/goschtalt

Extensions

Instead of trying to build everything in, goschtalt tries to only build in what is absolutely necessary and favor extensions. This enables a diversity of ecosystem while not bloating your code with a bunch of dependencies.

The following are popular goschtalt extensions:

• Name nomenclature converter https://github.com/goschtalt/casemapper
• Environment variable decoder https://github.com/goschtalt/env-decoder
• JSON file type decoder https://github.com/goschtalt/json-decoder
• Properties file type Decoder https://github.com/goschtalt/properties-decoder
• YAML file type decoder https://github.com/goschtalt/yaml-decoder
• YAML file type encoder https://github.com/goschtalt/yaml-encoder

Examples

Coming soon.

Dependencies

There are only two production dependencies in the core goschtalt code beyond the go standard library. The rest are testing dependencies.

Production dependencies:

• github.com/mitchellh/hashstructure
• github.com/mitchellh/mapstructure

Compilation of a Configuration

This is more detailed overview of how the configuration is compiled.

stateDiagram-v2
    direction TB

    state Gather_Inputs {
        direction TB
        AddBuffer() --> New()
        AddFile() --> New()
        AddValue(AsDefault()) --> New()
    }

    state Sequence {
        direction TB
        Defaults:Defaults by order added.
        Records:Records sorted using record label.
        ex:Expand instructions by order added.

        Defaults --> Records
        Records --> ex
    }

    state Compile {
        calc:Calculate configuration<br/>tree at this point.
        eval:Apply all Expand()<br/>and ExpandEnv()<br/>to configuration<br/>tree in order.
        fetch:Call any user<br/>provided funcs with<br/>configuration tree.
        next:Next<br/>Configuration<br/>Tree Part
        merge:Merge the new<br/>configuration tree part<br/>with the current tree
        Empty:Empty<br/>Configuration<br/>Tree


        Empty --> calc
        calc --> eval:If a user func<br/>is provided
        calc --> next:If no user func<br/>is provided
        eval --> fetch
        fetch --> next
        next --> merge
        merge --> calc
    }

    state Expand {
        exp:Apply all Expand()<br/>and ExpandEnv()<br/>to configuration<br/>tree in order.
    }

    state Active {
        active:Active Configuration
        unmarshal:Unmarshal()
        active --> unmarshal
        unmarshal --> active
    }
    New() --> Sequence
    Sequence --> Compile
    Compile --> Expand
    Expand --> Active
    Active --> Sequence:With() or Compile() called<br/>resequences the lists and<br/>recalculates the <br/>configuration tree.

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