sdjournal

package
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 Go to latest Published: Jan 25, 2016 License: Apache-2.0 Imports: 12 Imported by: 3

Documentation

Overview

Package sdjournal provides a low-level Go interface to the systemd journal wrapped around the sd-journal C API.

All public read methods map closely to the sd-journal API functions. See the sd-journal.h documentation[1] for information about each function.

To write to the journal, see the pure-Go "journal" package

[1] http://www.freedesktop.org/software/systemd/man/sd-journal.html

Index

Constants

View Source 
const (
	SD_JOURNAL_FIELD_SYSTEMD_UNIT = "_SYSTEMD_UNIT"
	SD_JOURNAL_FIELD_MESSAGE      = "MESSAGE"
	SD_JOURNAL_FIELD_PID          = "_PID"
	SD_JOURNAL_FIELD_UID          = "_UID"
	SD_JOURNAL_FIELD_GID          = "_GID"
	SD_JOURNAL_FIELD_HOSTNAME     = "_HOSTNAME"
	SD_JOURNAL_FIELD_MACHINE_ID   = "_MACHINE_ID"
)

Journal entry field strings which correspond to: http://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html

View Source 
const (
	SD_JOURNAL_NOP        = int(C.SD_JOURNAL_NOP)
	SD_JOURNAL_APPEND     = int(C.SD_JOURNAL_APPEND)
	SD_JOURNAL_INVALIDATE = int(C.SD_JOURNAL_INVALIDATE)
)

Journal event constants

View Source 
const (
	// IndefiniteWait is a sentinel value that can be passed to
	// sdjournal.Wait() to signal an indefinite wait for new journal
	// events. It is implemented as the maximum value for a time.Duration:
	// https://github.com/golang/go/blob/e4dcf5c8c22d98ac9eac7b9b226596229624cb1d/src/time/time.go#L434
	IndefiniteWait time.Duration = 1<<63 - 1
)

Variables

View Source 
var (
	ErrExpired = errors.New("Timeout expired")
)

Functions

func GetCatalogForMessageID 

func GetCatalogForMessageID(messageId string) (string, error)

GetCatalogForMessageID works similar to GetCatalog(), but the entry is looked up by the specified message ID (no open journal context is necessary for this), and no field substitution is performed.

Types

type Journal 

type Journal struct {
	// contains filtered or unexported fields
}

Journal is a Go wrapper of an sd_journal structure.

func NewJournal 

func NewJournal() (*Journal, error)

NewJournal returns a new Journal instance pointing to the local journal

func NewJournalFromDir 

func NewJournalFromDir(path string) (*Journal, error)

NewJournalFromDir returns a new Journal instance pointing to a journal residing in a given directory. The supplied path may be relative or absolute; if relative, it will be converted to an absolute path before being opened.

func (*Journal) AddConjunction 

func (j *Journal) AddConjunction() error

AddConjunction inserts a logical AND in the match list.

func (*Journal) AddDisjunction 

func (j *Journal) AddDisjunction() error

AddDisjunction inserts a logical OR in the match list.

func (*Journal) AddMatch 

func (j *Journal) AddMatch(match string) error

AddMatch adds a match by which to filter the entries of the journal.

func (*Journal) Close 

func (j *Journal) Close() error

Close closes a journal opened with NewJournal.

func (*Journal) FlushMatches 

func (j *Journal) FlushMatches()

FlushMatches flushes all matches, disjunctions and conjunctions.

func (*Journal) GetCatalog 

func (j *Journal) GetCatalog() (string, error)

GetCatalog retrieves a message catalog entry for the current journal entry. This will look up an entry in the message catalog by using the "MESSAGE_ID=" field of the current journal entry. Before returning the entry all journal field names in the catalog entry text enclosed in "@" will be replaced by the respective field values of the current entry. If a field name referenced in the message catalog entry does not exist, in the current journal entry, the "@" will be removed, but the field name otherwise left untouched.

func (*Journal) GetCursor 

func (j *Journal) GetCursor() (string, error)

GetCursor returns a cursor string for the current journal entry. A cursor is a serialization of the current journal position formatted as text. The string only contains printable characters and can be passed around in text form. The cursor identifies a journal entry globally and in a stable way and may be used to later seek to it via SeekCursor.

func (*Journal) GetData 

func (j *Journal) GetData(field string) (string, error)

GetData gets the data object associated with a specific field from the current journal entry.

func (*Journal) GetDataAll 

func (j *Journal) GetDataAll() (JournalEntry, error)

func (*Journal) GetDataValue 

func (j *Journal) GetDataValue(field string) (string, error)

GetDataValue gets the data object associated with a specific field from the current journal entry, returning only the value of the object.

func (*Journal) GetRealtimeUsec 

func (j *Journal) GetRealtimeUsec() (uint64, error)

GetRealtimeUsec gets the realtime (wallclock) timestamp of the current journal entry.

func (*Journal) GetUsage 

func (j *Journal) GetUsage() (uint64, error)

GetUsage returns the journal disk space usage, in bytes.

func (*Journal) Next 

func (j *Journal) Next() (int, error)

Next advances the read pointer into the journal by one entry.

func (*Journal) NextSkip 

func (j *Journal) NextSkip(skip uint64) (uint64, error)

NextSkip advances the read pointer by multiple entries at once, as specified by the skip parameter.

func (*Journal) Previous 

func (j *Journal) Previous() (uint64, error)

Previous sets the read pointer into the journal back by one entry.

func (*Journal) PreviousSkip 

func (j *Journal) PreviousSkip(skip uint64) (uint64, error)

PreviousSkip sets back the read pointer by multiple entries at once, as specified by the skip parameter.

func (*Journal) SeekCursor 

func (j *Journal) SeekCursor(cursor string) error

SeekCursor seeks to the entry located at the specified cursor string. If no entry matching the specified cursor is found the call will seek to the next closest entry (in terms of time) instead. SeekCursor returns true if it was able to seek to the exact postion, or false, if it was able to only seek to the next closest position. It returns an error if the operation failed completely

func (*Journal) SeekHead 

func (j *Journal) SeekHead() error

SeekHead seeks to the beginning of the journal, i.e. the oldest available entry.

func (*Journal) SeekMonotonicUsec 

func (j *Journal) SeekMonotonicUsec(boot_id string, usec uint64) error

SeekMonotonicUsec seeks to the entry with the specified monotonic timestamp, i.e. CLOCK_MONOTONIC. Since monotonic time restarts on every reboot a boot ID needs to be specified as well.

func (*Journal) SeekRealtimeUsec 

func (j *Journal) SeekRealtimeUsec(usec uint64) error

SeekRealtimeUsec seeks to the entry with the specified realtime (wallclock) timestamp, i.e. CLOCK_REALTIME.

func (*Journal) SeekTail 

func (j *Journal) SeekTail() error

SeekTail may be used to seek to the end of the journal, i.e. the most recent available entry.

func (*Journal) SetDataThreshold 

func (j *Journal) SetDataThreshold(threshold uint64) error

SetDataThresold sets the data field size threshold for data returned by GetData. To retrieve the complete data fields this threshold should be turned off by setting it to 0, so that the library always returns the complete data objects.

func (*Journal) TestCursor 

func (j *Journal) TestCursor(cursor string) (bool, error)

TestCursor may be used to check whether the current position in the journal matches the specified cursor. This is useful since cursor strings do not uniquely identify an entry: the same entry might be referred to by multiple different cursor strings, and hence string comparing cursors is not possible. Use this call to verify after an invocation of SeekCursor whether the entry being sought to was actually found in the journal or the next closest entry was used instead.

func (*Journal) Wait 

func (j *Journal) Wait(timeout time.Duration) int

Wait will synchronously wait until the journal gets changed. The maximum time this call sleeps may be controlled with the timeout parameter. If sdjournal.IndefiniteWait is passed as the timeout parameter, Wait will wait indefinitely for a journal change.

type JournalEntry 

type JournalEntry map[string]interface{}

JournalEntry is an alias for map[string]interface{}

type JournalReader 

type JournalReader struct {
	Journal *Journal
}

JournalReader is an io.ReadCloser which provides a simple interface for iterating through the systemd journal.

func NewJournalReader 

func NewJournalReader(config JournalReaderConfig) (*JournalReader, error)

NewJournalReader creates a new JournalReader with configuration options that are similar to the systemd journalctl tool's iteration and filtering features.

func (*JournalReader) Close 

func (r *JournalReader) Close() error

func (*JournalReader) Follow 

func (r *JournalReader) Follow(until <-chan time.Time, writer io.Writer) (err error)

Follow synchronously follows the JournalReader, writing each new journal entry to writer. The follow will continue until a single time.Time is received on the until channel.

func (*JournalReader) FollowJournal 

func (r *JournalReader) FollowJournal(until <-chan int, writer chan<- JournalEntry) (err error)

FollowJournal synchronously follows the JournalReader, writing each new journal entry to writer. The follow will continue until any int is received on the until channel. All Journal entries are pushed to the writer channel.

func (*JournalReader) Read 

func (r *JournalReader) Read(b []byte) (int, error)

func (*JournalReader) ReadEntry 

func (r *JournalReader) ReadEntry() (JournalEntry, error)

type JournalReaderConfig 

type JournalReaderConfig struct {
	// The Since and NumFromTail options are mutually exclusive and determine
	// where the reading begins within the journal.
	Since       time.Duration // start relative to a Duration from now
	NumFromTail uint64        // start relative to the tail

	// Show only journal entries whose fields match the supplied values. If
	// the array is empty, entries will not be filtered.
	Matches []Match
}

JournalReaderConfig represents options to drive the behavior of a JournalReader.

type Match 

type Match struct {
	Field string
	Value string
}

Match is a convenience wrapper to describe filters supplied to AddMatch.

func (*Match) String 

func (m *Match) String() string

String returns a string representation of a Match suitable for use with AddMatch.

Source Files

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