metadata

Documentation

Overview

Package metadata provides a request-scoped key-value map that propagates through RPC and REST call chains. It is the gofly equivalent of gRPC metadata, stored in context.Context and safe for concurrent read-only use.

Package metadata provides a request-scoped key-value map that propagates through RPC and REST call chains.

Index

• Constants
• func Append(ctx context.Context, kv ...string) context.Context
• func EnsureRequestID(ctx context.Context) (context.Context, string)
• func NewContext(ctx context.Context, md MD) context.Context
• func NewRequestID() string
• func RequestIDFromContext(ctx context.Context) string
• func WithRequestID(ctx context.Context, id string) context.Context
• type MD
  • func FromContext(ctx context.Context) (MD, bool)
  • func New(kv ...string) MD
  • func (md MD) Clone() MD
  • func (md MD) Get(key string) string

Constants

const RequestIDKey = "request_id"

RequestIDKey is the metadata key for request identifiers.

Functions

func Append

func Append(ctx context.Context, kv ...string) context.Context

Append adds key/value pairs to the MD stored in ctx, creating a new MD if none exists. Keys are overwritten on duplicate.

func EnsureRequestID

func EnsureRequestID(ctx context.Context) (context.Context, string)

EnsureRequestID returns ctx unchanged when it already carries a request id, or a derived context with a freshly generated id otherwise. The second return value is the resolved id.

func NewContext

func NewContext(ctx context.Context, md MD) context.Context

NewContext returns a new context carrying md. The stored value is a clone of the supplied map.

func NewRequestID

func NewRequestID() string

NewRequestID returns a 32-hex-character random identifier. Falls back to a base-36 timestamp if the system RNG fails.

func RequestIDFromContext

func RequestIDFromContext(ctx context.Context) string

RequestIDFromContext extracts the request_id stored in the context metadata. Returns an empty string when absent.

func WithRequestID

func WithRequestID(ctx context.Context, id string) context.Context

WithRequestID returns a derived context carrying the given request id in its metadata. If id is empty a fresh id is generated.

Types

type MD

type MD map[string]string

MD is a string-to-string metadata map.

func FromContext

func FromContext(ctx context.Context) (MD, bool)

FromContext extracts MD from ctx. The returned MD is a clone and safe to mutate without affecting the stored value.

func New

func New(kv ...string) MD

New creates an MD from alternating key/value strings.

func (MD) Clone

func (md MD) Clone() MD

Clone returns a shallow copy of md.

func (MD) Get

func (md MD) Get(key string) string

Get returns the value for key or "" if md is nil or the key is absent.