Merge pull request #66 from diogob/db-uri-from-file

Allow reading database connection string from file

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 0.9.0.0
 
+- Add @filename semantics to PGWS_DB_URI configiration variable to allow secret management to use a file instead of an environment variable.
 - Add PGWS_RETRIES to limit the amount of times the server tries to open a database connection upon startup (defaults to 5). This breaks backward compatibility if you rely on the behaviour of the server to try infitite times.
 
 ## 0.8.0.1

README.md

@@ -52,7 +52,9 @@ source sample-env && ~/.local/bin/postgres-websockets
 ```
 After running the above command, open your browser on http://localhost:3000 to see an example of usage.
 
-The sample config file provided in the [sample.conf](https://github.com/diogob/postgres-websockets/tree/master/sample.conf) file comes with a jwt secret just for testing and is used in the sample client.
+The sample config file provided in the [sample-env](https://github.com/diogob/postgres-websockets/tree/master/sample-env) file comes with a jwt secret just for testing and is used in the sample client.
+Note that the `sample-env` points to `./database-uri.txt` to load the URI from an external file. This is determined by the use of `@` as a prefix to the value of the variable `PGWS_DB_URI`. 
+This is entirely optional and the URI could be exported directly as `PGWS_DB_URI` without using the prefix `@`.
 You will find the complete sources for the example under the folder [client-example](https://github.com/diogob/postgres-websockets/tree/master/client-example).
 To run the server without giving access to any static files one can unser the variable `PGWS_ROOT_PATH`.
 

database-uri.txt

@@ -0,0 +1 @@
+postgres://localhost:5432/postgres

sample-env

@@ -1,5 +1,5 @@
 ## PostgreSQL URI where the server will connect to issue NOTIFY and LISTEN commands
-export PGWS_DB_URI="postgres://localhost:5432/postgres"
+export PGWS_DB_URI="@./database-uri.txt"
 
 ## Size of connection pool used to issue notify commands (LISTEN commands are always issued on the same connection that is not part of the pool).
 export PGWS_POOL_SIZE=10

src/PostgresWebsockets.hs

@@ -2,7 +2,7 @@
 Module      : PostgresWebsockets
 Description : PostgresWebsockets main library interface.
 
-These are all function necessary to start a fully functionaing service.
+These are all function necessary to configure and start the server.
 -}
 module PostgresWebsockets
   ( prettyVersion

src/PostgresWebsockets/Config.hs

@@ -43,7 +43,7 @@ prettyVersion = intercalate "." $ map show $ versionBranch version
 
 -- | Load all postgres-websockets config from Environment variables. This can be used to use just the middleware or to feed into warpSettings
 loadConfig :: IO AppConfig
-loadConfig = readOptions >>= loadSecretFile
+loadConfig = readOptions >>= loadSecretFile >>= loadDatabaseURIFile
 
 -- | Given a shutdown handler and an AppConfig builds a Warp Settings to start a stand-alone server
 warpSettings :: (IO () -> IO ()) -> AppConfig -> Settings
@@ -73,6 +73,14 @@ readOptions =
                 <*> var auto "PGWS_POOL_SIZE" (def 10 <> helpDef show <> help "How many connection to the database should be used by the connection pool")
                 <*> var auto "PGWS_RETRIES" (def 5 <> helpDef show <> help "How many times it should try to connect to the database on startup before exiting with an error")
 
+loadDatabaseURIFile :: AppConfig -> IO AppConfig
+loadDatabaseURIFile conf@AppConfig{..} =
+  case stripPrefix "@" configDatabase of
+    Nothing       -> pure conf
+    Just filename -> setDatabase . strip <$> readFile (toS filename)
+  where
+    setDatabase uri = conf {configDatabase = uri}
+
 loadSecretFile :: AppConfig -> IO AppConfig
 loadSecretFile conf = extractAndTransform secret
   where