| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Database.Postgres.Temp
Contents
Description
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 in addition to
listening on 127.0.0.1 and ::1.
Here is an example using the expection safe with function:
with$ \db ->bracket(connectPostgreSQL(toConnectionStringdb))close$ \conn ->execute_conn "CREATE TABLE foo (id int)"
To extend or override the defaults use withConfig (or startConfig).
tmp-postgres ultimately calls (optionally) initdb, postgres and
(optionally) createdb.
All of the command line, environment variables and configuration files that are generated by default for the respective executables can be extended.
In general tmp-postgres is useful if you want a clean temporary
postgres and do not want to worry about clashing with an existing
postgres instance (or needing to ensure postgres is already running).
Here are some different use cases for tmp-postgres and their respective
configurations:
- The default
withandstartfunctions can be used to make a sandboxed temporary database for testing. - By disabling
initdbone could run a temporary isolated postgres on a base backup to test a migration. - By using the
stopPostgresandwithRestartfunctions one can test backup strategies.
WARNING!!
Ubuntu's PostgreSQL installation does not put initdb on the PATH. We need to add it manually.
The necessary binaries are in the /usr/lib/postgresql/VERSION/bin/ directory, and should be added to the PATH
echo "export PATH=$PATH:/usr/lib/postgresql/VERSION/bin/" >> /home/ubuntu/.bashrc
Synopsis
- with :: (DB -> IO a) -> IO (Either StartError a)
- withConfig :: Config -> (DB -> IO a) -> IO (Either StartError a)
- withRestart :: DB -> (DB -> IO a) -> IO (Either StartError a)
- withDbCache :: (CacheResources -> IO a) -> IO a
- withDbCacheConfig :: CacheConfig -> (CacheResources -> IO a) -> IO a
- withSnapshot :: DirectoryType -> DB -> (Snapshot -> IO a) -> IO (Either StartError a)
- start :: IO (Either StartError DB)
- startConfig :: Config -> IO (Either StartError DB)
- stop :: DB -> IO ()
- restart :: DB -> IO (Either StartError DB)
- stopPostgres :: DB -> IO ExitCode
- stopPostgresGracefully :: DB -> IO ExitCode
- setupInitDbCache :: CacheConfig -> IO CacheResources
- cleanupInitDbCache :: CacheResources -> IO ()
- takeSnapshot :: DirectoryType -> DB -> IO (Either StartError Snapshot)
- cleanupSnapshot :: Snapshot -> IO ()
- data DB
- toConnectionString :: DB -> ByteString
- toConnectionOptions :: DB -> Options
- toDataDirectory :: DB -> FilePath
- toTemporaryDirectory :: DB -> FilePath
- makeDataDirPermanent :: DB -> DB
- reloadConfig :: DB -> IO ()
- prettyPrintDB :: DB -> String
- data Snapshot
- data CacheResources
- data StartError
- = StartPostgresFailed ExitCode
- | InitDbFailed { }
- | CreateDbFailed { }
- | CompletePlanFailed String [String]
- | CompleteProcessConfigFailed String [String]
- | ConnectionTimedOut
- | DeleteDbError SqlError
- | EmptyDataDirectory
- | CopyCachedInitDbFailed String ExitCode
- | FailedToFindDataDirectory String
- | SnapshotCopyFailed String ExitCode
- defaultConfig :: Config
- defaultPostgresConf :: [String] -> Config
- standardProcessConfig :: ProcessConfig
- silentConfig :: Config
- silentProcessConfig :: ProcessConfig
- defaultCacheConfig :: CacheConfig
- snapshotConfig :: Snapshot -> Config
- optionsToDefaultConfig :: Options -> Config
- data CacheConfig = CacheConfig {}
- module Database.Postgres.Temp.Config
Exception safe interface
Arguments
| :: (DB -> IO a) |
|
| -> IO (Either StartError a) |
Arguments
| :: Config |
|
| -> (DB -> IO a) |
|
| -> IO (Either StartError a) |
Exception safe database create with options. See startConfig for more
details. Calls stop even in the face of exceptions.
Since: 1.15.0.0
withRestart :: DB -> (DB -> IO a) -> IO (Either StartError a) Source #
Exception safe version of restart.
Since: 1.12.0.0
withDbCache :: (CacheResources -> IO a) -> IO a Source #
Equivalent to withDbCacheConfig with the CacheConfig
defaultCacheConfig makes.
Since: 1.20.0.0
Arguments
| :: CacheConfig | Configuration |
| -> (CacheResources -> IO a) | action for which caching is enabled |
| -> IO a |
Enable initdb data directory caching. This can lead to a 4x speedup.
Exception safe version of setupInitDbCache. Equivalent to
withDbCacheConfig= bracket (setupInitDbCacheconfig)cleanupInitDbCache
Since: 1.20.0.0
withSnapshot :: DirectoryType -> DB -> (Snapshot -> IO a) -> IO (Either StartError a) Source #
Exception safe method for taking a file system level copy of the database cluster.
Snapshots are useful if you would like to start every test from a migrated database and the migration process is more time consuming then copying the additional data.
Since: 1.20.0.0
Separate start and stop interface.
start :: IO (Either StartError DB) Source #
Default start behavior. Equivalent to calling startConfig with the
defaultConfig.
Since: 1.12.0.0
Arguments
| :: Config |
|
| -> IO (Either StartError DB) |
Create zero or more temporary resources and use them to make a Config.
The passed in config is inspected and a generated config is created. The final config is built by
generated <> extra
Based on the value of socketDirectory a "postgresql.conf" is created with:
listen_addresses = '127.0.0.1, ::1' unix_socket_directories = 'SOCKET_DIRECTORY'
Additionally the generated Config also does the following:
- Sets a
connectionTimeoutof one minute. - Logs internal
Events. - Sets the processes to use the standard input and output handles.
- Sets the
dataDirectoryStringto file path generated fromdataDirectory.
All of these values can be overrided by the extra config.
The returned DB requires cleanup. startConfig should be
used with a bracket and stop, e.g.
withConfig::Config-> (DB-> IO a) -> IO (EitherStartErrora)withConfigplan f =bracket(startConfigplan) (either memptystop) $ either (pure . Left) (fmap Right . f)
or just use withConfig. If you are calling startConfig you
probably want withConfig anyway.
Since: 1.15.0.0
Stop the postgres process and cleanup any temporary resources that
might have been created.
Since: 1.12.0.0
stopPostgres :: DB -> IO ExitCode Source #
Only stop the postgres process but leave any temporary resources.
Useful for testing backup strategies when used in conjunction with
restart or withRestart.
Since: 1.12.0.0
stopPostgresGracefully :: DB -> IO ExitCode Source #
Only stop the postgres process but leave any temporary resources.
In contrast to stopPostgres this function makes sure postgres
has time to properly write files to the data directory.
Since: 1.16.1.0
setupInitDbCache :: CacheConfig -> IO CacheResources Source #
Setup the initdb cache folder.
cleanupInitDbCache :: CacheResources -> IO () Source #
Cleanup the cache directory if it was Temporary.
Since: 1.20.0.0
Arguments
| :: DirectoryType | |
| -> DB | The handle. The |
| -> IO (Either StartError Snapshot) |
Shutdown the database and copy the directory to a folder.
Since: 1.20.0.0
cleanupSnapshot :: Snapshot -> IO () Source #
Cleanup any temporary resources used for the snapshot.
Since: 1.20.0.0
Main resource handle
Handle for holding temporary resources, the postgres process handle
and postgres connection information. The DB also includes the
final plan used to start initdb, createdb and
postgres. See toConnectionString or toConnectionOptions
for converting a DB to postgresql connection string.
Since: 1.12.0.0
DB accessors
toConnectionString :: DB -> ByteString Source #
Convert a DB to a connection string. Alternatively one can access the
Options using toConnectionOptions.
Since: 1.12.0.0
toConnectionOptions :: DB -> Options Source #
toDataDirectory :: DB -> FilePath Source #
Access the data directory. This was either generated or
specified explicitly when creating the Config
Since: 1.12.0.0
toTemporaryDirectory :: DB -> FilePath Source #
Get the directory that is used to create other temporary directories
Since: 1.12.0.0
DB modifiers
makeDataDirPermanent :: DB -> DB Source #
Make the data directory permanent. Useful for debugging.
If you are using with or withConfig this function will
not modify the DB that is passed for cleanup. You will
need to setup your own bracket like
bracket (fmapmakeDataDirPermanentstart) (either memptystop)
Since: 1.12.0.0
reloadConfig :: DB -> IO () Source #
Reload the configuration file without shutting down. Calls
pg_reload_conf().
Since: 1.12.0.0
DB debugging
Snapshot handle
A type to track a possibly temporary snapshot directory
Since: 1.20.0.0
Instances
| Generic Snapshot Source # | |
| NFData Snapshot Source # | |
Defined in Database.Postgres.Temp.Internal | |
| type Rep Snapshot Source # | |
Defined in Database.Postgres.Temp.Internal type Rep Snapshot = D1 (MetaData "Snapshot" "Database.Postgres.Temp.Internal" "tmp-postgres-1.20.0.1-LdMyT8l53A3BmReNfAX0t9" True) (C1 (MetaCons "Snapshot" PrefixI True) (S1 (MetaSel (Just "unSnapshot") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 CompleteDirectoryType))) | |
initdb cache handle
data CacheResources Source #
A handle to cache temporary resources and configuration.
Since: 1.20.0.0
Instances
| Generic CacheResources Source # | |
Defined in Database.Postgres.Temp.Internal Associated Types type Rep CacheResources :: Type -> Type # Methods from :: CacheResources -> Rep CacheResources x # to :: Rep CacheResources x -> CacheResources # | |
| NFData CacheResources Source # | |
Defined in Database.Postgres.Temp.Internal Methods rnf :: CacheResources -> () # | |
| type Rep CacheResources Source # | |
Defined in Database.Postgres.Temp.Internal type Rep CacheResources = D1 (MetaData "CacheResources" "Database.Postgres.Temp.Internal" "tmp-postgres-1.20.0.1-LdMyT8l53A3BmReNfAX0t9" False) (C1 (MetaCons "CacheResources" PrefixI True) (S1 (MetaSel (Just "cacheResourcesCow") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Bool) :*: S1 (MetaSel (Just "cacheResourcesDirectory") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 CompleteDirectoryType))) | |
Errors
data StartError Source #
A list of failures that can occur when starting. This is not and exhaustive list but covers the errors that the system catches for the user.
Since: 1.12.0.0
Constructors
| StartPostgresFailed ExitCode |
|
| InitDbFailed |
|
Fields | |
| CreateDbFailed |
|
Fields | |
| CompletePlanFailed String [String] | The |
| CompleteProcessConfigFailed String [String] | The |
| ConnectionTimedOut | Timed out waiting for |
| DeleteDbError SqlError | |
| EmptyDataDirectory | This will happen if a |
| CopyCachedInitDbFailed String ExitCode | This is called if copying a folder cache fails. |
| FailedToFindDataDirectory String | Failed to find a data directory when trying to get
a cached |
| SnapshotCopyFailed String ExitCode | We tried to copy a data directory to a snapshot folder and it failed |
Instances
| Eq StartError Source # | |
Defined in Database.Postgres.Temp.Internal.Core | |
| Show StartError Source # | |
Defined in Database.Postgres.Temp.Internal.Core Methods showsPrec :: Int -> StartError -> ShowS # show :: StartError -> String # showList :: [StartError] -> ShowS # | |
| Exception StartError Source # | |
Defined in Database.Postgres.Temp.Internal.Core Methods toException :: StartError -> SomeException # fromException :: SomeException -> Maybe StartError # displayException :: StartError -> String # | |
Configuration
Defaults
defaultConfig :: Config Source #
The default configuration. This will create a database called "postgres"
via initdb (it's default behavior).
It will create a temporary directory for the data and a temporary directory
for a unix socket on a random port.
Additionally it will use the following "postgresql.conf"
which is optimized for performance.
shared_buffers = 12MB fsync = off synchronous_commit = off full_page_writes = off log_min_duration_statement = 0 log_connections = on log_disconnections = on client_min_messages = ERROR
defaultConfig also passes the --no-sync flag to initdb.
If you would like to customize this behavior you can start with the
defaultConfig and overwrite fields or combine a defaultConfig with another Config
using <> (mappend).
Alternatively you can eschew defaultConfig altogether, however
your postgres might start and run faster if you use
defaultConfig.
The defaultConfig also disables the logging of internal Events.
To append additional lines to "postgresql.conf" file create a
custom Config like the following.
custom = defaultConfig <> mempty
{ plan = mempty
{ postgresConfigFile =
[ "wal_level = replica"
, "archive_mode = on"
, "max_wal_senders = 2"
, "fsync = on"
, "synchronous_commit = on"
]
}
}
Or using the provided lenses and your favorite lens library:
custom = defaultConfig &planL.postgresConfigFileL<>~ [ "wal_level = replica" , "archive_mode = on" , "max_wal_senders = 2" , "fsync = on" , "synchronous_commit = on" ]
This is common enough there is defaultPostgresConf which
is a helper to do this.
As an alternative to using defaultConfig one could create a
config from connections parameters using optionsToDefaultConfig.
Since: 1.12.0.0
defaultPostgresConf :: [String] -> Config Source #
mappend the defaultConfig with a Config that provides additional
"postgresql.conf" lines. Equivalent to:
defaultPostgresConfextra =defaultConfig<> mempty {plan= mempty {postgresConfigFile= extra } }
or with lenses:
defaultPostgresConfextra =defaultConfig&planL.postgresConfigFileL<>~ extra
Since: 1.12.0.0
standardProcessConfig :: ProcessConfig Source #
The standardProcessConfig sets the handles to stdin, stdout and
stderr and inherits the environment variables from the calling
process.
Since: 1.12.0.0
silentConfig :: Config Source #
The similar to defaultConfig but all the handles are set to /dev/null.
and uses a postgresql.conf which disables logging:
shared_buffers = 12MB fsync = off synchronous_commit = off full_page_writes = off log_min_messages = PANIC log_min_error_statement = PANIC log_statement = none client_min_messages = ERROR
See silentProcessConfig as well.
Since: 1.14.0.0
silentProcessConfig :: ProcessConfig Source #
silentProcessConfig sets the handles to /dev/null and
inherits the environment variables from the calling process.
Since: 1.12.0.0
defaultCacheConfig :: CacheConfig Source #
defaultCacheConfig attempts to determine if the cp on the path
supports "copy on write" flags and if it does, sets cacheUseCopyOnWrite
to True.
It sets cacheDirectoryType to Permanent ~/.tmp-postgres and
cacheTemporaryDirectory to /tmp (but this is not used when
Permanent is set).
Since: 1.19.0.0
snapshotConfig :: Snapshot -> Config Source #
Convert a snapshot into a Config that includes a copyConfig for copying the
snapshot directory to a temporary directory.
Since: 1.20.0.0
Custom Config builder helpers
Configuration Types
CacheConfig
data CacheConfig Source #
Configuration for the initdb data directory cache.
Since: 1.20.0.0
Constructors
| CacheConfig | |
Fields
| |