feat: Add MMDB Key-Value Store

[jshlbrd]

Description

• Adds an MMDB KV store

Motivation and Context

MMDB is an alternative to the IP database (IPDB) component. Unlike that feature, this one does not interpret data from the database before returning it to the caller, which makes it more modular at the expense of potentially requiring more user configuration -- any file in MMDB format is supported.

How Has This Been Tested?

Tested locally via integration test. Tests can be recreated using these examples:

local sub = import '../../build/config/substation.libsonnet';

local kv = sub.interfaces.processor.kv_store(
	settings={key: 'addr', set_key: 'mmdb'},
	options={type: 'get', 'kv_options': sub.interfaces.kv_store.mmdb(
		settings={file: '/path/to/file.mmdb'}
	)}
);

kv

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"os"

	"github.com/brexhq/substation/config"
	"github.com/brexhq/substation/process"
)

func main() {
	cfg, err := os.ReadFile("./config.json")
	if err != nil {
		panic(err)
	}

	conf := config.Config{}
	if err := json.Unmarshal(cfg, &conf); err != nil {
		panic(err)
	}

	processor, err := process.NewApplier(conf)
	if err != nil {
		panic(err)
	}

	fmt.Println("> printing processor settings ...")
	fmt.Println(processor)

	b := []byte(`{"addr":"8.8.8.8"}`)
	fmt.Println("> printing raw data ...")
	fmt.Println(string(b))

	b, err = process.ApplyBytes(context.TODO(), b, processor)
	if err != nil {
		panic(err)
	}

	fmt.Println("> printing processed data ...")
	fmt.Println(string(b))
}

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.