Env overrides for config

config.ts

import _ from 'lodash';

const ENV_PREFIX = `APP_CONFIG`;
function setEnvOverrides(cfg: Config) {
    const foundVars = Object.keys(process.env).filter(name => name.startsWith(ENV_PREFIX));

    for (const v of foundVars) {
        const actualName = v.substr(ENV_PREFIX.length);
        // console.log(`Processing ENV var ${actualName}`);

        const pieces = actualName.split('_');
        const oldVal: any = _.get(cfg, pieces, void 0);
        const envVal = process.env[v].trim();
        if (typeof oldVal == 'number') {
            _.set(cfg, pieces, Number(envVal));
        } else if (typeof oldVal == 'boolean') {
            try {
                _.set(config, pieces, Boolean(JSON.parse(envVal.toLowerCase())));
            } catch (err) {
                console.warn(`Igoring ENV var ${actualName}; did not parse to boolean`);
            }
        } else {
            // Anything else we'll just treat as a string
            _.set(cfg, pieces, envVal);
        }
    }
    return cfg;
}