Allow server details to be set through configuration in addition to environment variables

[kriswest]

Is your feature request related to a problem? Please describe.

The key server settings below are not configurable via the git proxy config file, they a can be set via environment variables and defaults for them are set in source code, rather than in the same place as all other config settings:

git-proxy/src/config/env.ts

Lines 19 to 27 in ffd6937

	const {
	GIT_PROXY_SERVER_PORT = 8000,
	GIT_PROXY_HTTPS_SERVER_PORT = 8443,
	GIT_PROXY_UI_HOST = 'http://localhost',
	GIT_PROXY_UI_PORT = 8080,
	GIT_PROXY_HTTPS_UI_PORT = 8444,
	GIT_PROXY_COOKIE_SECRET,
	GIT_PROXY_MONGO_CONNECTION_STRING = 'mongodb://localhost:27017/git-proxy',
	} = process.env;

These are likely the oldest settings for git proxy and the difference in how they are configured is a legacy/tech debt. The difference in how they are set is confusing and creates complexity for those running Git Proxy installations for no real benefit.

Describe the solution you'd like

These settings should be added to the config schema and read from the default and user config files for consistency with the rest of the configuration.

GIT_PROXY_COOKIE_SECRET is the one variable that is currently settable from both config file and environment variable and can be used as an example:

see:

git-proxy/src/config/index.ts

Lines 187 to 190 in ffd6937

	cookieSecret:
	serverConfig.GIT_PROXY_COOKIE_SECRET ||
	userSettings.cookieSecret ||
	defaultConfig.cookieSecret,

and:

git-proxy/src/config/index.ts

Lines 301 to 309 in ffd6937

	export const getCookieSecret = (): string => {
	const config = loadFullConfiguration();
	if (!config.cookieSecret) {
	throw new Error('cookieSecret is not set!');
	}
	return config.cookieSecret;
	};

Usage of the config settings will need to shift to using get* functions rather than direct import of the variables from env.ts. I.e. replace:

git-proxy/src/service/index.ts

Line 36 in ffd6937

const { GIT_PROXY_UI_PORT: uiPort, GIT_PROXY_HTTPS_UI_PORT: uiHttpsPort } = serverConfig;

git-proxy/src/proxy/index.ts

Lines 35 to 36 in ffd6937

	const { GIT_PROXY_SERVER_PORT: proxyHttpPort, GIT_PROXY_HTTPS_SERVER_PORT: proxyHttpsPort } =
	serverConfig;

git-proxy/src/service/urls.ts

Line 22 in ffd6937

const { GIT_PROXY_SERVER_PORT: PROXY_HTTP_PORT, GIT_PROXY_UI_PORT: UI_PORT } = serverConfig;

We could deprecate the environment variables or maintain support for them with primacy over the config file (as is the case for GIT_PROXY_COOKIE_SECRET.

Describe alternatives you've considered

Continue on with most config going through the config file, but key server settings only being settable via environment variables.

Additional context

Identified as necessary when reviewing #1542, which sought to export the server config and would have locked in this pattern by enabling external use.