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.
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.