Documentation
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Overview ¶
Package logger provides line-buffered prefix writers and log target forwarding.
Index ¶
Constants ¶
const DefaultPrefix = "service timestamp"
DefaultPrefix is the default log prefix format: service name followed by timestamp.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type PrefixWriter ¶
type PrefixWriter struct {
// contains filtered or unexported fields
}
PrefixWriter is a line-buffered io.Writer that prefixes each line with configurable components (timestamp and/or service name):
[service-name] 2021-05-13T03:16:51.001Z output line here
The prefix format is controlled by a space-separated token string:
- "service timestamp" (default): [name] then timestamp
- "timestamp service": timestamp then [name]
- "timestamp": timestamp only
- "service": [name] only
- "none" or "": no prefix
Partial lines are buffered until a newline. Supports subscribers for live streaming and a ring buffer for recent history.
func NewPrefixWriter ¶
func NewPrefixWriter(dest io.Writer, name, prefix string) *PrefixWriter
NewPrefixWriter creates a new PrefixWriter. The prefix string controls which components appear and in what order. See DefaultPrefix for the default format.
func (*PrefixWriter) AddTarget ¶
func (pw *PrefixWriter) AddTarget(w io.Writer)
AddTarget adds an additional writer that receives the same prefixed output.
func (*PrefixWriter) ClearTargets ¶
func (pw *PrefixWriter) ClearTargets()
ClearTargets removes all additional writers registered via AddTarget, used during reload before re-wiring new ones. Nil (not extra[:0]) releases the backing array so stale writer references become GC-eligible immediately.
func (*PrefixWriter) Flush ¶
func (pw *PrefixWriter) Flush()
Flush writes any remaining buffered content (for shutdown).
func (*PrefixWriter) Recent ¶
func (pw *PrefixWriter) Recent() [][]byte
Recent returns a deep copy of recent prefixed log lines from the ring buffer. Each returned slice is an independent copy so concurrent ring writes cannot overwrite the bytes that callers (e.g. the logs command handler) are reading.
func (*PrefixWriter) Subscribe ¶
func (pw *PrefixWriter) Subscribe() (<-chan []byte, func())
Subscribe returns a channel that receives new prefixed log lines and an unsubscribe function. The channel is buffered to avoid blocking writes.
Received slices alias a reused per-subscription buffer; consumers must consume each synchronously before the next receive. Holding a slice past the next receive risks observing torn writes once the writer reuses the slot.
func (*PrefixWriter) Write ¶
func (pw *PrefixWriter) Write(p []byte) (int, error)
Write implements io.Writer. Peak per-Write memory is bounded to ~maxBufSize: p is consumed in chunks that never grow pw.buf beyond the cap, and a synthetic newline is injected when the cap is reached with no natural newline, so a multi-megabyte newline-free chunk cannot allocate len(p) bytes before the size check fires.
type Target ¶
type Target struct {
Writer io.WriteCloser
// contains filtered or unexported fields
}
Target wraps a log forwarding destination.
func NewTarget ¶
func NewTarget(name string, cfg TargetConfig) (*Target, error)
NewTarget creates a new log target from config.
type TargetConfig ¶
type TargetConfig struct {
// Labels are prepended to every forwarded line as logfmt-style key=value
// pairs (sorted by key), so syslog/file consumers can filter or attribute
// lines by target metadata. Empty = no label prefix.
Labels map[string]string
Type string // "syslog" or "file"
Location string // e.g. "udp://logs.example.com:514" or "/var/log/app.log"
// MaxSize is a human-readable byte size (e.g. "10MiB") at which a file
// target rotates. Empty = no rotation. File targets only; ignored for syslog.
MaxSize string
Services []string // filter: only these service names
// MaxFiles is the number of rotated files to keep. Values <= 0 default to
// defaultMaxFiles when MaxSize is set.
MaxFiles int
// Compress enables gzip compression of rotated files. Only meaningful for
// file targets with MaxSize set.
Compress bool
}
TargetConfig defines a log forwarding target.
Source Files