Safe Haskell	None
Language	Haskell2010

Systemd.Journal

Contents

Writing to the journal
- Standard systemd journal fields
- Custom journal fields
Reading the journal

Synopsis

Writing to the journal

sendMessage :: Text -> IO () #

Send a message to the systemd journal.

sendMessage t == sendJournalFields (message t)

sendMessageWith :: Text -> JournalFields -> IO () #

Send a message and supply extra fields.

Note: The MESSAGE field will be replaced with the first parameter to this function. If you don't want this, use sendJournalFields

sendJournalFields :: JournalFields -> IO () #

Send an exact set of fields to the systemd journal.

type JournalFields = HashMap JournalField ByteString #

A structured object of all the fields in an entry in the journal. You generally don't construct this yourself, but you use the monoid instance and smart constructors below.

For example,

sendJournalFields (message "Oh god, it burns!" <> priority Emergency)

Standard systemd journal fields

message :: Text -> JournalFields #

The human readable message string for this entry. This is supposed to be the primary text shown to the user. It is usually not translated (but might be in some cases), and is not supposed to be parsed for meta data.

messageId :: UUID -> JournalFields #

A 128bit message identifier ID for recognizing certain message types, if this is desirable. Developers can generate a new ID for this purpose with journalctl --new-id.

priority :: Priority -> JournalFields #

A priority value compatible with syslog's priority concept.

data Priority :: * #

Log messages are prioritized with one of the following levels:

>>> [minBound..maxBound] :: [Priority]
[Emergency,Alert,Critical,Error,Warning,Notice,Info,Debug]

The Ord instance for Priority considers the more urgent level lower than less urgent ones:

>>> Emergency < Debug
True
>>> minimum [minBound..maxBound] :: Priority
Emergency
>>> maximum [minBound..maxBound] :: Priority
Debug

Constructors

Emergency	the system is unusable
Alert	action must be taken immediately
Critical	critical conditions
Error	error conditions
Warning	warning conditions
Notice	normal but significant condition
Info	informational
Debug	debug-level messages

Instances

Bounded Priority
Methods minBound :: Priority # maxBound :: Priority #
Enum Priority
Methods succ :: Priority -> Priority # pred :: Priority -> Priority # toEnum :: Int -> Priority # fromEnum :: Priority -> Int # enumFrom :: Priority -> [Priority] # enumFromThen :: Priority -> Priority -> [Priority] # enumFromTo :: Priority -> Priority -> [Priority] # enumFromThenTo :: Priority -> Priority -> Priority -> [Priority] #
Eq Priority
Methods (==) :: Priority -> Priority -> Bool # (/=) :: Priority -> Priority -> Bool #
Ord Priority
Methods compare :: Priority -> Priority -> Ordering # (<) :: Priority -> Priority -> Bool # (<=) :: Priority -> Priority -> Bool # (>) :: Priority -> Priority -> Bool # (>=) :: Priority -> Priority -> Bool # max :: Priority -> Priority -> Priority # min :: Priority -> Priority -> Priority #
Read Priority
Methods readsPrec :: Int -> ReadS Priority # readList :: ReadS [Priority] # readPrec :: ReadPrec Priority # readListPrec :: ReadPrec [Priority] #
Show Priority
Methods showsPrec :: Int -> Priority -> ShowS # show :: Priority -> String # showList :: [Priority] -> ShowS #
Generic Priority
Associated Types type Rep Priority :: * -> * # Methods from :: Priority -> Rep Priority x # to :: Rep Priority x -> Priority #
type Rep Priority
type Rep Priority = D1 (MetaData "Priority" "System.Posix.Syslog.Priority" "hsyslog-5.0.1-LTNaZ9tlet5J4kQ1BXverf" False) ((:+:) ((:+:) ((:+:) (C1 (MetaCons "Emergency" PrefixI False) U1) (C1 (MetaCons "Alert" PrefixI False) U1)) ((:+:) (C1 (MetaCons "Critical" PrefixI False) U1) (C1 (MetaCons "Error" PrefixI False) U1))) ((:+:) ((:+:) (C1 (MetaCons "Warning" PrefixI False) U1) (C1 (MetaCons "Notice" PrefixI False) U1)) ((:+:) (C1 (MetaCons "Info" PrefixI False) U1) (C1 (MetaCons "Debug" PrefixI False) U1))))

codeFile :: FilePath -> JournalFields #

The source code file generating this message.

codeLine :: Int -> JournalFields #

The source code line number generating this message.

codeFunc :: Text -> JournalFields #

The source code function name generating this message.

errno :: Int -> JournalFields #

The low-level Unix error number causing this entry, if any. Contains the numeric value of errno(3).

syslogFacility :: Facility -> JournalFields #

Syslog compatibility field.

syslogIdentifier :: Text -> JournalFields #

Syslog compatibility field.

syslogPid :: CPid -> JournalFields #

Syslog compatibility field.

Custom journal fields

data JournalField #

Instances

Eq JournalField #
Methods (==) :: JournalField -> JournalField -> Bool # (/=) :: JournalField -> JournalField -> Bool #
Data JournalField #
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> JournalField -> c JournalField # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c JournalField # toConstr :: JournalField -> Constr # dataTypeOf :: JournalField -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c JournalField) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c JournalField) # gmapT :: (forall b. Data b => b -> b) -> JournalField -> JournalField # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> JournalField -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> JournalField -> r # gmapQ :: (forall d. Data d => d -> u) -> JournalField -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> JournalField -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> JournalField -> m JournalField # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> JournalField -> m JournalField # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> JournalField -> m JournalField #
Ord JournalField #
Methods compare :: JournalField -> JournalField -> Ordering # (<) :: JournalField -> JournalField -> Bool # (<=) :: JournalField -> JournalField -> Bool # (>) :: JournalField -> JournalField -> Bool # (>=) :: JournalField -> JournalField -> Bool # max :: JournalField -> JournalField -> JournalField # min :: JournalField -> JournalField -> JournalField #
Read JournalField #
Methods readsPrec :: Int -> ReadS JournalField # readList :: ReadS [JournalField] # readPrec :: ReadPrec JournalField # readListPrec :: ReadPrec [JournalField] #
Show JournalField #
Methods showsPrec :: Int -> JournalField -> ShowS # show :: JournalField -> String # showList :: [JournalField] -> ShowS #
IsString JournalField #
Methods fromString :: String -> JournalField #
Monoid JournalField #
Methods mempty :: JournalField # mappend :: JournalField -> JournalField -> JournalField # mconcat :: [JournalField] -> JournalField #
Hashable JournalField #
Methods hashWithSalt :: Int -> JournalField -> Int # hash :: JournalField -> Int #

mkJournalField :: Text -> JournalField #

Construct a JournalField by converting to uppercase, as required by the journal.

journalField :: JournalField -> Text #

Extract the name of a JournalField.

Reading the journal

openJournal #

Arguments

:: MonadSafe m
=> [JournalFlag]	A list of flags taken under logical disjunction (or) to specify which journal files to open.
-> Start	Where to begin reading journal entries from.
-> Maybe Filter	An optional filter to apply the journal. Only entries satisfying the filter will be emitted.
-> Maybe Integer	The data field size threshold, or Nothing for no field size limit
-> Producer' JournalEntry m ()

Opens the journal for reading, optionally filtering the journal entries. Filters are defined as arbitrary binary expression trees, which are then rewritten to be in conjunctive normal form before filtering with systemd to comply with systemd's rule system.

data Start #

Where to begin reading the journal from.

Constructors

FromStart	Begin reading from the start of the journal.
FromEnd Direction	Begin reading from the end of the journal.
FromCursor JournalEntryCursor Direction	From a `JournalEntryCursor`.

data Direction #

In which direction to read the journal.

Constructors

Forwards	Read towards the end.
Backwards	Read towards the beginning.

Instances

Eq Direction #
Methods (==) :: Direction -> Direction -> Bool # (/=) :: Direction -> Direction -> Bool #

data JournalEntry #

An entry that has been read from the systemd journal.

Instances

Eq JournalEntry #
Methods (==) :: JournalEntry -> JournalEntry -> Bool # (/=) :: JournalEntry -> JournalEntry -> Bool #
Show JournalEntry #
Methods showsPrec :: Int -> JournalEntry -> ShowS # show :: JournalEntry -> String # showList :: [JournalEntry] -> ShowS #

type JournalEntryCursor = ByteString #

journalEntryFields :: JournalEntry -> JournalFields #

A map of each JournalField to its value.

journalEntryCursor :: JournalEntry -> JournalEntryCursor #

A JournalCursor can be used as marker into the journal stream. This can be used to re-open the journal at a specific point in the future, and JournalCursors can be serialized to disk.

journalEntryRealtime :: JournalEntry -> Word64 #

The time (in microseconds since the epoch) when this journal entry was received by the systemd journal.

data JournalFlag #

Flags to specify which journal entries to read.

Constructors

LocalOnly	Only journal files generated on the local machine will be opened.
RuntimeOnly	Only volatile journal files will be opened, excluding those which are stored on persistent storage.
SystemOnly	Only journal files of system services and the kernel (in opposition to user session processes) will be opened.

Instances

Bounded JournalFlag #
Methods minBound :: JournalFlag # maxBound :: JournalFlag #
Enum JournalFlag #
Methods succ :: JournalFlag -> JournalFlag # pred :: JournalFlag -> JournalFlag # toEnum :: Int -> JournalFlag # fromEnum :: JournalFlag -> Int # enumFrom :: JournalFlag -> [JournalFlag] # enumFromThen :: JournalFlag -> JournalFlag -> [JournalFlag] # enumFromTo :: JournalFlag -> JournalFlag -> [JournalFlag] # enumFromThenTo :: JournalFlag -> JournalFlag -> JournalFlag -> [JournalFlag] #
Eq JournalFlag #
Methods (==) :: JournalFlag -> JournalFlag -> Bool # (/=) :: JournalFlag -> JournalFlag -> Bool #
Ord JournalFlag #
Methods compare :: JournalFlag -> JournalFlag -> Ordering # (<) :: JournalFlag -> JournalFlag -> Bool # (<=) :: JournalFlag -> JournalFlag -> Bool # (>) :: JournalFlag -> JournalFlag -> Bool # (>=) :: JournalFlag -> JournalFlag -> Bool # max :: JournalFlag -> JournalFlag -> JournalFlag # min :: JournalFlag -> JournalFlag -> JournalFlag #

data Filter #

A logical expression to filter journal entries when reading the journal.

Constructors

Match JournalField ByteString	A binary exact match on a given `JournalField`.
And Filter Filter	Logical conjunction of two filters. Will only show journal entries that satisfy both conditions.
Or Filter Filter	Logical disjunction of two filters. Will show journal entries that satisfy either condition.

Instances

Eq Filter #
Methods (==) :: Filter -> Filter -> Bool # (/=) :: Filter -> Filter -> Bool #
Data Filter #
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Filter -> c Filter # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Filter # toConstr :: Filter -> Constr # dataTypeOf :: Filter -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c Filter) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Filter) # gmapT :: (forall b. Data b => b -> b) -> Filter -> Filter # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Filter -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Filter -> r # gmapQ :: (forall d. Data d => d -> u) -> Filter -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Filter -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Filter -> m Filter # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Filter -> m Filter # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Filter -> m Filter #
Show Filter #
Methods showsPrec :: Int -> Filter -> ShowS # show :: Filter -> String # showList :: [Filter] -> ShowS #