Postgres DSN (#322)

* Allow specifying Postgres DSN

Author: mgdigital

bitmagnet.io/setup/configuration.md

@@ -10,6 +10,7 @@ nav_order: 2
 **bitmagnet** exposes quite a few configuration options. You shouldn't have to worry about most of them, but they are available for tinkering. If you're using the [example docker-compose file]({% link setup/installation.md %}#docker) then things _should_ "just work". I'll only cover only some of the more important options here:
 
 - `postgres.host`, `postgres.name` `postgres.user` `postgres.password` (default: `localhost`, `bitmagnet`, `postgres`, _empty_): Set these values to configure connection to your Postgres database.
+- `postgres.dsn`: Alternatively a Postgres Data Source Name (DSN) can be specified. If specified, all other `postgres.*` options are ignored.
 - `tmdb.api_key`: This is quite an important one, please [see below](#obtaining-a-tmdb-api-key) for more details.
 - `tmdb.enabled` (default: `true`): Specify `false` to disable the TMDB API integration.
 - `dht_crawler.save_files_threshold` (default: `100`): Some torrents contain many thousands of files, which impacts performance and uses a lot of database disk space. This parameter sets a maximum limit for the number of files saved by the crawler with each torrent.

internal/database/postgres/config.go

@@ -6,6 +6,7 @@ import (
 )
 
 type Config struct {
+	DSN               string
 	Host              string
 	User              string
 	Port              uint
@@ -27,7 +28,10 @@ func NewDefaultConfig() Config {
 	}
 }
 
-func (c *Config) DSN() string {
+func (c *Config) CreateDSN() string {
+	if c.DSN != "" {
+		return c.DSN
+	}
 	vals := dbValues(c)
 	p := make([]string, 0, len(vals))
 	for k, v := range vals {

internal/database/postgres/postgres.go

@@ -32,7 +32,7 @@ func New(p Params) (Result, error) {
 	waitGroup := &sync.WaitGroup{}
 	lazyPool := lazy.New(func() (*pgxpool.Pool, error) {
 		ctx, cancel := context.WithCancel(context.Background())
-		pl, plErr := pgxpool.New(ctx, p.Config.DSN())
+		pl, plErr := pgxpool.New(ctx, p.Config.CreateDSN())
 		if plErr != nil {
 			cancel()
 			return nil, plErr