Documentation
¶
Overview ¶
Package logging contains logging related utilities.
Index ¶
- Variables
- func NewTestLogger(t testing.TB) *slog.Logger
- func Parse(query Query) (*cel.Ast, error)
- func Shorten(s string) string
- func ShortenComponent(component string) string
- func StderrLogger(opts Options) *slog.Logger
- type FileStore
- type LogHandler
- type Options
- type PrettyPrinter
- type Query
- type Reader
- type Source
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var DefaultLogDir = filepath.Join(os.TempDir(), "serviceweaver", "logs")
DefaultLogDir is the default directory where Service Weaver log files are stored.
Functions ¶
func NewTestLogger ¶
NewTestLogger returns a new logger for tests.
func ShortenComponent ¶
ShortenComponent shortens the given component name to be of the format <pkg>.<IfaceType>. (Recall that the full component name is of the format <path1>/<path2>/.../<pathN>/<IfaceType>.)
func StderrLogger ¶
StderrLogger returns a logger that pretty prints log entries to stderr.
Types ¶
type FileStore ¶
type FileStore struct {
// contains filtered or unexported fields
}
FileStore stores log entries in files.
func NewFileStore ¶
NewFileStore returns a LogStore that writes files to the specified directory.
type LogHandler ¶ added in v0.2.0
type LogHandler struct {
Opts Options // configures the log entries
Write func(entry *protos.LogEntry) // called on every log entry
}
LogHandler implements a custom slog.Handler.
func (*LogHandler) Handle ¶ added in v0.2.0
func (h *LogHandler) Handle(rec slog.Record) error
Handle implements the slog.Handler interface.
type Options ¶
type Options struct {
App string // Service Weaver application (e.g., "todo")
Deployment string // Service Weaver deployment (e.g., "36105c89-85b1...")
Component string // Service Weaver component (e.g., "Todo")
Weavelet string // Service Weaver weavelet id (e.g., "36105c89-85b1...")
// Pre-assigned attributes. These will be attached to each log entry
// generated by the logger. This slice will never be appended to in place.
Attrs []string
}
Options configures the log entries produced by a logger.
type PrettyPrinter ¶
type PrettyPrinter struct {
// contains filtered or unexported fields
}
PrettyPrinter pretty prints log entries. You can safely use a PrettyPrinter from multiple goroutines.
func NewPrettyPrinter ¶
func NewPrettyPrinter(color bool) *PrettyPrinter
NewPrettyPrinter returns a new PrettyPrinter. If color is true, the pretty printer colorizes its output using ANSII escape codes.
func (*PrettyPrinter) Format ¶
func (pp *PrettyPrinter) Format(e *protos.LogEntry) string
Format formats a log entry as a single line of human-readable text. Here are some examples of what pretty printed log entries look like:
I0921 10:07:31.733831 distributor 076cb5f1 distributor.go:164] Registering versions... I0921 10:07:31.759352 distributor 076cb5f1 anneal.go:155 ] Deploying versions... I0921 10:07:31.759696 manager 076cb5f1 manager.go:125 ] Starting versions... I0921 10:07:31.836563 manager 076cb5f1 manager.go:137 ] Success starting... I0921 10:07:31.849647 distributor 076cb5f1 anneal.go:184 ] Successfully deployed... I0921 10:07:31.862637 distributor 076cb5f1 distributor.go:169] Successfully registered... I0921 10:07:31.862754 controller 076cb5f1 anneal.go:331 ] Successfully distributed...
type Query ¶
type Query = string
Query is a filter for log entries.
Syntax ¶
Queries are written using a subset of the CEL language 1. Thus, every syntactically valid query is also a syntactically valid CEL program. Specifically, a query is a CEL program over the following fields:
- app: string
- version: string
- full_version: string
- component: string
- full_component: string
- node: string
- full_node: string
- time: timestamp
- level: string
- source: string
- msg: string
- attrs: map[string]string
A query is restricted to:
- boolean algebra (!, &&, ||),
- equalities and inequalities (==, !=, <, <=, >, >=),
- the string operations "contains" and "matches",
- map indexing (attrs["foo"]) and membership ("foo" in attrs), and
- constant strings, timestamps, and ints.
All equalities and inequalities must look like `app == "todo"` or `attrs["foo"] == "bar"`; i.e. a field or attribute on the left and a constant on the right.
Semantics ¶
Queries have the same semantics as CEL programs except for one small exception. An attribute expression like `attrs["foo"]` has an implicit membership test `"foo" in attrs`. For example, the query
attrs["foo"] == "bar"
is evaluated like the CEL program
"foo" in attrs && attrs["foo"] == "bar"
TODO(mwhittaker): Expand the set of valid queries. For example, we can allow more constant expressions on the right hand side of a comparison. We can also allow fields on the right and constants on the left.
type Reader ¶
type Reader interface {
// Read returns the next log entry, or io.EOF when there are no more log
// entries. Calling Read on a closed reader will return an error. If a
// non-nil error is returned, the returned entry is guaranteed to be nil.
Read(context.Context) (*protos.LogEntry, error)
// Close closes the Reader. Close can safely be called multiple times.
Close()
}
Reader is a log entry iterator. A Reader is not thread-safe; its methods cannot be called concurrently.
Example ¶
ctx := context.Background()
reader := getLogReader()
defer reader.Close()
for {
entry, err := reader.Read(ctx)
if errors.Is(err, io.EOF) {
// No more log entries.
return
} else if err != nil {
fmt.Fprintln(os.Stderr, err)
return
}
fmt.Println(entry)
}
Output:
type Source ¶
type Source interface {
// Query returns a log entry reader.
//
// Log entries produced by a single component replica are guaranteed to be
// returned in increasing timestamp order, but log entries across component
// replicas are interleaved in timestamp order only on a best-effort basis.
//
// If follow is true, then the returned reader follows logs like `tail -f`.
// Otherwise, log entries that are created during an executing query may or
// may not be returned. Similarly, the returned reader does not return old
// log entries that have been garbage collected.
Query(ctx context.Context, q Query, follow bool) (Reader, error)
}
Source is a log source. You can use a source to cat and follow logs, filtering log entries using a query. A Source can safely be used concurrently from multiple goroutines.
func FileSource ¶
FileSource returns a new Source that reads logs from files saved by a FileStore.
Source Files