diff --git a/CHANGELOG.md b/CHANGELOG.md --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,5 +1,9 @@ Changelog for tmp-postgres +1.15.0.0 + #137 Remove SocketClass and listen unconditionally on 127.0.0.1, ::1 and a UNIX socket. + #138 Fix bug where optionsToDefaultConfig would make createdb plan even if one is not needed. + 1.14.1.0 #122 Fix bug that would prevent temporary directory removal diff --git a/src/Database/Postgres/Temp.hs b/src/Database/Postgres/Temp.hs --- a/src/Database/Postgres/Temp.hs +++ b/src/Database/Postgres/Temp.hs @@ -1,7 +1,8 @@ {-| This module provides functions for creating a temporary @postgres@ instance. By default it will create a temporary data directory and -a temporary directory for a UNIX domain socket for @postgres@ to listen on. +a temporary directory for a UNIX domain socket for @postgres@ to listen on in addition to +listening on 127.0.0.1 and ::1. Here is an example using the expection safe 'with' function: diff --git a/src/Database/Postgres/Temp/Config.hs b/src/Database/Postgres/Temp/Config.hs --- a/src/Database/Postgres/Temp/Config.hs +++ b/src/Database/Postgres/Temp/Config.hs @@ -16,7 +16,7 @@ , prettyPrintConfig -- *** 'Config' Lenses , planL - , socketClassL + , socketDirectoryL , dataDirectoryL , portL , connectionTimeoutL @@ -54,8 +54,6 @@ , keyBasedL -- ** 'DirectoryType' , DirectoryType (..) - -- ** 'SocketClass' - , SocketClass (..) -- ** 'Logger' , Logger -- * Internal events passed to the 'logger' . diff --git a/src/Database/Postgres/Temp/Internal.hs b/src/Database/Postgres/Temp/Internal.hs --- a/src/Database/Postgres/Temp/Internal.hs +++ b/src/Database/Postgres/Temp/Internal.hs @@ -221,7 +221,11 @@ } --- @since 1.14.0.0 +{-| +A config that logs as little as possible. + +@since 1.14.0.0 +-} silentPostgresConfig :: [String] silentPostgresConfig = [ "shared_buffers = 12MB" @@ -275,21 +279,13 @@ generated '<>' extra @ -Based on the value of 'socketClass' a \"postgresql.conf\" is created with: - - @ - listen_addresses = \'IP_ADDRESS\' - @ - - if it is 'IpSocket'. If is 'UnixSocket' then the lines: +Based on the value of 'socketDirectory' a \"postgresql.conf\" is created with: @ - listen_addresses = '' + listen_addresses = '127.0.0.1, ::1' unix_socket_directories = \'SOCKET_DIRECTORY\' @ -are added. - Additionally the @generated@ `Config` also does the following: * Sets a `connectionTimeout` of one minute. @@ -311,7 +307,7 @@ or just use 'withConfig'. If you are calling 'startConfig' you probably want 'withConfig' anyway. -@since 1.12.0.0 +@since 1.15.0.0 -} startConfig :: Config -- ^ @extra@ configuration that is 'mappend'ed last to the generated `Config`. @@ -376,7 +372,7 @@ Exception safe database create with options. See 'startConfig' for more details. Calls 'stop' even in the face of exceptions. -@since 1.12.0.0 +@since 1.15.0.0 -} withConfig :: Config -- ^ @extra@. 'Config' combined with the generated 'Config'. See @@ -393,7 +389,7 @@ 'with' = 'withConfig' 'defaultConfig' @ -@since 1.12.0.0 +@since 1.15.0.0 -} with :: (DB -> IO a) -- ^ @action@ continuation. @@ -411,7 +407,7 @@ -- want to create a database owned by a specific user you will also login -- with among other use cases. -- --- @since 1.13.1.0 +-- @since 1.15.0.0 optionsToDefaultConfig :: Client.Options -> Config optionsToDefaultConfig opts@Client.Options {..} = let generated = optionsToConfig opts diff --git a/src/Database/Postgres/Temp/Internal/Config.hs b/src/Database/Postgres/Temp/Internal/Config.hs --- a/src/Database/Postgres/Temp/Internal/Config.hs +++ b/src/Database/Postgres/Temp/Internal/Config.hs @@ -26,7 +26,6 @@ import Data.Maybe import Data.Monoid import Data.Monoid.Generic -import Data.Typeable import qualified Database.PostgreSQL.Simple.Options as Client import GHC.Generics (Generic) import Network.Socket.Free (getFreePort) @@ -341,100 +340,6 @@ CPermanent _ -> pure () CTemporary filePath -> rmDirIgnoreErrors filePath --- | A type for configuring the listening address of the @postgres@ process. --- @postgres@ can listen on several types of sockets simulatanously but we --- don't support that behavior. One can either listen on a IP based socket --- or a UNIX domain socket. --- --- @since 1.12.0.0 -data CompleteSocketClass - = CIpSocket String - -- ^ IP socket type. The 'String' is either an IP address or - -- a host that will resolve to an IP address. - | CUnixSocket CompleteDirectoryType - -- ^ UNIX domain socket - deriving (Show, Eq, Ord, Generic, Typeable) - -instance Pretty CompleteSocketClass where - pretty = \case - CIpSocket x -> text "CIpSocket:" <+> pretty x - CUnixSocket x -> text "CUnixSocket:" <+> pretty x - --- | Create the extra config lines for listening based on the 'CompleteSocketClass'. -socketClassToConfig :: CompleteSocketClass -> [String] -socketClassToConfig = \case - CIpSocket ip -> ["listen_addresses = '" <> ip <> "'"] - CUnixSocket dir -> - [ "listen_addresses = ''" - , "unix_socket_directories = '" <> toFilePath dir <> "'" - ] - --- | Many processes require a \"host\" flag. We can generate one from the --- 'CompleteSocketClass'. -socketClassToHostFlag :: CompleteSocketClass -> [(String, Maybe String)] -socketClassToHostFlag x = [("-h", Just (socketClassToHost x))] - --- | Get the IP address, host name or UNIX domain socket directory --- as a 'String'. -socketClassToHost :: CompleteSocketClass -> String -socketClassToHost = \case - CIpSocket ip -> ip - CUnixSocket dir -> toFilePath dir - --- | 'SocketClass' is used to specify how @postgres@ should listen for connections --- The two main options are a `IpSocket` which takes a hostname or IP address. --- if not is given the default it "127.0.0.1". Alternatively one can --- specify 'UnixSocket' for a UNIX domain socket. If a directory is --- specified the socket will live in that folder. Otherwise a --- temporary folder will get created for the socket. --- --- @since 1.12.0.0 -data SocketClass - = IpSocket (Last String) - -- ^ The monoid for combining IP address configuration. - | UnixSocket DirectoryType - -- ^ The monoid for combining UNIX socket configuration. - deriving stock (Show, Eq, Ord, Generic, Typeable) - -instance Pretty SocketClass where - pretty = \case - IpSocket x -> "CIpSocket:" <+> pretty (getLast x) - UnixSocket x -> "CUnixSocket" <+> pretty x - --- | Last 'IpSocket' wins. 'UnixSocket' 'DirectoryType' as --- 'mappend'ed together. -instance Semigroup SocketClass where - x <> y = case (x, y) of - (IpSocket a, IpSocket b) -> IpSocket $ a <> b - (a@(IpSocket _), UnixSocket _) -> a - (UnixSocket _, a@(IpSocket _)) -> a - (UnixSocket a, UnixSocket b) -> UnixSocket $ a <> b - --- | Treats 'UnixSocket' 'mempty' as 'mempty'. -instance Monoid SocketClass where - mempty = UnixSocket mempty - --- | Turn a 'SocketClass' to a 'CompleteSocketClass'. If the 'IpSocket' is --- 'Nothing' default to \"127.0.0.1\". If the is a 'UnixSocket' --- optionally create a temporary directory if configured to do so. -setupSocketClass - :: String - -- ^ Temporary directory. - -> SocketClass - -- ^ The type of socket. - -> IO CompleteSocketClass -setupSocketClass tempDir theClass = case theClass of - IpSocket mIp -> pure $ CIpSocket $ fromMaybe "127.0.0.1" $ - getLast mIp - UnixSocket mFilePath -> - CUnixSocket <$> setupDirectoryType tempDir "tmp-postgres-socket" mFilePath - --- | Cleanup the UNIX socket temporary directory if one was created. -cleanupSocketConfig :: CompleteSocketClass -> IO () -cleanupSocketConfig = \case - CIpSocket {} -> pure () - CUnixSocket dir -> cleanupDirectoryType dir - -- | @postgres@ process config and corresponding client connection -- 'Client.Options'. -- @@ -542,13 +447,13 @@ -- | The high level options for overriding default behavior. -- --- @since 1.12.0.0 +-- @since 1.15.0.0 data Config = Config { plan :: Plan -- ^ Extend or replace any of the configuration used to create a final -- 'CompletePlan'. - , socketClass :: SocketClass - -- ^ Override the default 'CompleteSocketClass' by setting this. + , socketDirectory :: DirectoryType + -- ^ Override the default temporary UNIX socket directory by setting this. , dataDirectory :: DirectoryType -- ^ Override the default temporary data directory by passing in -- 'Permanent' @DIRECTORY@. @@ -569,9 +474,9 @@ <> softline <> pretty plan <> hardline - <> text "socketClass:" + <> text "socketDirectory:" <> softline - <> pretty socketClass + <> pretty socketDirectory <> hardline <> text "dataDirectory:" <> softline @@ -583,6 +488,12 @@ <> softline <> pretty (getLast temporaryDirectory) +socketDirectoryToConfig :: FilePath -> [String] +socketDirectoryToConfig dir = + [ "listen_addresses = '127.0.0.1, ::1'" + , "unix_socket_directories = '" <> dir <> "'" + ] + -- | Create a 'Plan' that sets the command line options of all processes -- (@initdb@, @postgres@ and @createdb@). This the @generated@ plan -- that is combined with the @extra@ plan from @@ -594,13 +505,13 @@ -- ^ Make @createdb@ options -> Int -- ^ port - -> CompleteSocketClass - -- ^ Whether to listen on a IP address or UNIX domain socket -> FilePath + -- ^ Socket directory + -> FilePath -- ^ The @postgres@ data directory -> Plan -toPlan makeInitDb makeCreateDb port socketClass dataDirectoryString = mempty - { postgresConfigFile = socketClassToConfig socketClass +toPlan makeInitDb makeCreateDb port socketDirectory dataDirectoryString = mempty + { postgresConfigFile = socketDirectoryToConfig socketDirectory , dataDirectoryString = pure dataDirectoryString , connectionTimeout = pure (60 * 1000000) -- 1 minute , logger = pure print @@ -614,7 +525,7 @@ } } , connectionOptions = mempty - { Client.host = pure $ socketClassToHost socketClass + { Client.host = pure socketDirectory , Client.port = pure port , Client.dbname = pure "postgres" } @@ -623,8 +534,9 @@ then pure $ standardProcessConfig { commandLine = mempty { keyBased = Map.fromList $ - socketClassToHostFlag socketClass <> - [("-p ", Just $ show port)] + [ ("-h", Just socketDirectory) + , ("-p ", Just $ show port) + ] } } else Nothing @@ -650,15 +562,15 @@ envs <- lift getEnvironment thePort <- lift $ maybe getFreePort pure $ join $ getLast port let resourcesTemporaryDir = fromMaybe "/tmp" $ getLast temporaryDirectory - resourcesSocket <- ContT $ bracketOnError - (setupSocketClass resourcesTemporaryDir socketClass) cleanupSocketConfig + resourcesSocketDirectory <- ContT $ bracketOnError + (setupDirectoryType resourcesTemporaryDir "tmp-postgres-socket" socketDirectory) cleanupDirectoryType resourcesDataDir <- ContT $ bracketOnError (setupDirectoryType resourcesTemporaryDir "tmp-postgres-data" dataDirectory) cleanupDirectoryType let hostAndDir = toPlan (hasInitDb plan) (hasCreateDb plan) thePort - resourcesSocket + (toFilePath resourcesSocketDirectory) (toFilePath resourcesDataDir) finalPlan = hostAndDir <> plan resourcesPlan <- lift $ @@ -669,7 +581,7 @@ -- | Free the temporary resources created by 'setupConfig'. cleanupConfig :: Resources -> IO () cleanupConfig Resources {..} = do - cleanupSocketConfig resourcesSocket + cleanupDirectoryType resourcesSocketDirectory cleanupDirectoryType resourcesDataDir -- | Display a 'Config'. @@ -686,9 +598,8 @@ data Resources = Resources { resourcesPlan :: CompletePlan -- ^ Final 'CompletePlan'. See 'startPlan' for information on 'CompletePlan's. - , resourcesSocket :: CompleteSocketClass - -- ^ The 'CompleteSocketClass'. Used to track if a temporary directory was made - -- as the socket location. + , resourcesSocketDirectory :: CompleteDirectoryType + -- ^ The used to potentially cleanup the temporary unix socket directory. , resourcesDataDir :: CompleteDirectoryType -- ^ The data directory. Used to track if a temporary directory was used. , resourcesTemporaryDir :: FilePath @@ -703,7 +614,7 @@ <> indent 2 (pretty resourcesPlan) <> hardline <> text "resourcesSocket:" - <+> pretty resourcesSocket + <+> pretty resourcesSocketDirectory <> hardline <> text "resourcesDataDir:" <+> pretty resourcesDataDir @@ -728,14 +639,14 @@ = ( mempty { plan = optionsToPlan opts , port = maybe (Last Nothing) (pure . pure) $ getLast port - , socketClass = maybe mempty hostToSocketClass $ getLast host + , socketDirectory = maybe mempty hostToSocketClass $ getLast host } ) -- Convert the 'Client.Options' to a 'Plan' that can -- be connected to with the 'Client.Options'. optionsToPlan :: Client.Options -> Plan optionsToPlan opts@Client.Options {..} - = maybe mempty dbnameToPlan (getLast dbname) + = maybe mempty (dbnameToPlan (getLast user) (getLast password)) (getLast dbname) <> maybe mempty userToPlan (getLast user) <> maybe mempty passwordToPlan (getLast password) <> clientOptionsToPlan opts @@ -752,12 +663,7 @@ -- Create a 'Plan' given a user. userToPlan :: String -> Plan userToPlan user = mempty - { createDbConfig = pure $ mempty - { commandLine = mempty - { keyBased = Map.singleton "--username=" $ Just user - } - } - , initDbConfig = pure $ mempty + { initDbConfig = pure $ mempty { commandLine = mempty { keyBased = Map.singleton "--username=" $ Just user } @@ -768,14 +674,18 @@ -- as the database name. -- It does nothing if the db names are "template1" or -- "postgres" -dbnameToPlan :: String -> Plan -dbnameToPlan dbName +dbnameToPlan :: Maybe String -> Maybe String -> String -> Plan +dbnameToPlan muser mpassword dbName | dbName == "template1" || dbName == "postgres" = mempty | otherwise = mempty { createDbConfig = pure $ mempty { commandLine = mempty { indexBased = Map.singleton 0 dbName + , keyBased = maybe mempty (Map.singleton "--username=" . Just) muser } + , environmentVariables = mempty + { specific = maybe mempty (Map.singleton "PGPASSWORD") mpassword + } } } @@ -787,19 +697,14 @@ { specific = Map.singleton "PGPASSWORD" password } } - , createDbConfig = pure mempty - { environmentVariables = mempty - { specific = Map.singleton "PGPASSWORD" password - } - } } -- Parse a host string as either an UNIX domain socket directory -- or a domain or IP. -hostToSocketClass :: String -> SocketClass +hostToSocketClass :: String -> DirectoryType hostToSocketClass hostOrSocketPath = case hostOrSocketPath of - '/' : _ -> UnixSocket $ Permanent hostOrSocketPath - _ -> IpSocket $ pure hostOrSocketPath + '/' : _ -> Permanent hostOrSocketPath + _ -> Temporary ------------------------------------------------------------------------------- -- Lenses @@ -1007,14 +912,14 @@ (f resourcesPlan) {-# INLINE resourcesPlanL #-} --- | Lens for 'resourcesSocket'. +-- | Lens for 'resourcesSocketDirectory'. -- --- @since 1.12.0.0 -resourcesSocketL :: Lens' Resources CompleteSocketClass -resourcesSocketL f (resources@Resources {..}) - = fmap (\x -> resources { resourcesSocket = x }) - (f resourcesSocket) -{-# INLINE resourcesSocketL #-} +-- @since 1.15.0.0 +resourcesSocketDirectoryL :: Lens' Resources CompleteDirectoryType +resourcesSocketDirectoryL f (resources@Resources {..}) + = fmap (\x -> resources { resourcesSocketDirectory = x }) + (f resourcesSocketDirectory) +{-# INLINE resourcesSocketDirectoryL #-} -- | Lens for 'dataDirectory'. -- @@ -1043,16 +948,16 @@ (f port) {-# INLINE portL #-} --- | Lens for 'socketClass'. +-- | Lens for 'socketDirectory'. -- -- @since 1.12.0.0 -socketClassL :: Lens' Config SocketClass -socketClassL f (config@Config{..}) - = fmap (\ x -> config { socketClass = x } ) - (f socketClass) -{-# INLINE socketClassL #-} +socketDirectoryL :: Lens' Config DirectoryType +socketDirectoryL f (config@Config{..}) + = fmap (\ x -> config { socketDirectory = x } ) + (f socketDirectory) +{-# INLINE socketDirectoryL #-} --- | Lens for 'socketClass'. +-- | Lens for 'socketDirectory'. -- -- @since 1.12.0.0 temporaryDirectoryL :: Lens' Config (Last FilePath) diff --git a/test/Main.hs b/test/Main.hs --- a/test/Main.hs +++ b/test/Main.hs @@ -14,7 +14,7 @@ import Database.Postgres.Temp.Internal.Config import Database.Postgres.Temp.Internal.Core import GHC.Generics (Generic) -import qualified Network.Socket as N +-- import qualified Network.Socket as N import Network.Socket.Free import System.Directory import System.Environment @@ -27,7 +27,9 @@ import Test.Hspec withConn :: DB -> (PG.Connection -> IO a) -> IO a -withConn db = bracket (PG.connectPostgreSQL $ toConnectionString db ) PG.close +withConn db f = do + let connStr = toConnectionString db + bracket (PG.connectPostgreSQL connStr) PG.close f withConfig' :: Config -> (DB -> IO a) -> IO a withConfig' config = either throwIO pure <=< withConfig config @@ -147,15 +149,15 @@ optionsToDefaultConfigFilledOutConfigAssert :: Int -> ConfigAndAssertion optionsToDefaultConfigFilledOutConfigAssert expectedPort = let - expectedDbName = "fancy" + expectedDbName = "foobar" expectedUser = "some_user" expectedPassword = "password" expectedHost = "localhost" cConfig = optionsToDefaultConfig mempty - { Client.dbname = pure expectedDbName + { Client.port = pure expectedPort + , Client.dbname = pure expectedDbName , Client.user = pure expectedUser - , Client.port = pure expectedPort , Client.password = pure expectedPassword , Client.host = pure expectedHost } @@ -164,9 +166,9 @@ let Client.Options {..} = toConnectionOptions db port `shouldBe` pure expectedPort user `shouldBe` pure expectedUser - host `shouldBe` pure expectedHost - password `shouldBe` pure expectedPassword dbname `shouldBe` pure expectedDbName + password `shouldBe` pure expectedPassword + host `shouldBe` pure expectedHost in ConfigAndAssertion {..} @@ -189,7 +191,13 @@ defaultIpConfig = let cConfig = mempty - { socketClass = IpSocket $ Last Nothing + { plan = mempty + { postgresPlan = mempty + { connectionOptions = mempty + { Client.host = pure "127.0.0.1" + } + } + } } cAssert db = do @@ -198,25 +206,12 @@ in ConfigAndAssertion {..} --- TODO add check of actual host -specificHostIpConfigAssert :: ConfigAndAssertion -specificHostIpConfigAssert = - let - cConfig = mempty - { socketClass = IpSocket $ pure "localhost" - } - cAssert db = do - let Client.Options {..} = toConnectionOptions db - host `shouldBe` pure "localhost" - - in ConfigAndAssertion {..} - specificUnixSocket :: FilePath -> ConfigAndAssertion specificUnixSocket filePath = let cConfig = mempty - { socketClass = UnixSocket $ Permanent filePath + { socketDirectory = Permanent filePath } cAssert db = do let @@ -264,7 +259,7 @@ happyPaths = describe "succeeds with" $ do it "mempty and extra postgresql.conf" $ testWithTemporaryDirectory - (silentConfigAssert <> memptyConfigAndAssertion <> extraConfigAssert) + (defaultConfigAssert <> memptyConfigAndAssertion <> extraConfigAssert) testSuccessfulConfig it "optionsToDefaultConfig mempty is the same as mempty Config" $ @@ -305,11 +300,6 @@ (silentConfigAssert <> defaultIpConfig) testSuccessfulConfig - it "specific ip option works" $ - testWithTemporaryDirectory - (defaultConfigAssert <> specificHostIpConfigAssert) - testSuccessfulConfig - it "specific unix socket works" $ withTempDirectory "/tmp" "tmp-postgres-spec-socket" $ \socketFilePath -> testWithTemporaryDirectory @@ -377,6 +367,7 @@ } timeout 100000 (withConfig (silentConfig <> invalidConfig) (const $ pure ())) `shouldReturn` Nothing +{- it "throws StartPostgresFailed if the port is taken" $ bracket openFreePort (N.close . snd) $ \(thePort, _) -> do let invalidConfig = optionsToDefaultConfig mempty @@ -385,21 +376,33 @@ } withConfig invalidConfig (const $ pure ()) `shouldReturn` Left (StartPostgresFailed $ ExitFailure 1) - +-} it "throws StartPostgresFailed if the host does not exist" $ do let invalidConfig = optionsToDefaultConfig mempty { Client.host = pure "focalhost" } - withConfig invalidConfig (const $ pure ()) - `shouldReturn` Left (StartPostgresFailed $ ExitFailure 1) + invalidConfig' = invalidConfig + { plan = (plan invalidConfig) + { connectionTimeout = pure 100000 + } + } + withConfig invalidConfig' (const $ pure ()) + `shouldReturn` Left ConnectionTimedOut + it "throws StartPostgresFailed if the host does not resolve to ip that is local" $ do let invalidConfig = optionsToDefaultConfig mempty { Client.host = pure "yahoo.com" } - withConfig invalidConfig (const $ pure ()) - `shouldReturn` Left (StartPostgresFailed $ ExitFailure 1) + invalidConfig' = invalidConfig + { plan = (plan invalidConfig) + { connectionTimeout = pure 100000 + } + } + withConfig invalidConfig' (const $ pure ()) + `shouldReturn` Left ConnectionTimedOut + it "throws StartPostgresFailed if the host path does not exist" $ do let invalidConfig = optionsToDefaultConfig mempty { Client.host = pure "/focalhost" @@ -583,7 +586,7 @@ , "postgresConfig:" , "postgresConfigFile:" , "postgresPlan:" - , "socketClass:" + , "socketDirectory:" , "specific:" , "stdErr:" , "stdIn:" @@ -613,7 +616,7 @@ , "fsync=on" , "synchronous_commit=on" ] - backupResources = silentConfig <> justBackupResources + backupResources = justBackupResources it "can support backup and restore" $ withConfig' backupResources $ \db@DB {..} -> do let dataDir = toFilePath (resourcesDataDir dbResources) @@ -631,10 +634,20 @@ let Just port = getLast $ Client.port $ postgresProcessClientOptions dbPostgresProcess Just host = getLast $ Client.host $ postgresProcessClientOptions dbPostgresProcess - backupCommand = "pg_basebackup -D " ++ baseBackupFile ++ " --format=tar -p" - ++ show port ++ " -h" ++ host + backupCommandFlags = + [ "-D" ++ baseBackupFile + , "--format=tar" + , "-p" ++ show port + , "-h" ++ host + ] - system backupCommand `shouldReturn` ExitSuccess + (exitCode, stdouts, errs) <- readProcessWithExitCode "pg_basebackup" backupCommandFlags [] + case exitCode of + ExitSuccess -> pure () + ExitFailure _ -> do + putStrLn stdouts + putStrLn errs + fail $ "pg_basebackup failed with flags " ++ unwords backupCommandFlags bracket (PG.connectPostgreSQL $ toConnectionString db ) PG.close $ \conn -> do _ <- PG.execute_ conn "CREATE TABLE foo(id int PRIMARY KEY);" diff --git a/tmp-postgres.cabal b/tmp-postgres.cabal --- a/tmp-postgres.cabal +++ b/tmp-postgres.cabal @@ -1,5 +1,5 @@ name: tmp-postgres -version: 1.14.1.0 +version: 1.15.0.0 synopsis: Start and stop a temporary postgres description: Start and stop a temporary postgres. See README.md homepage: https://github.com/jfischoff/tmp-postgres#readme