correlation

README

package correlation

Package correlation provides a set of tools to add correlation ID to the context at certain levels (transport, endpoint) of the application.

Note: Currently only server side middleware are implemented.

Usage

Get correlation ID from transport headers

Transport level middleware (HTTPToContext, GRPCToContext) read the correlation ID from headers and add it to the context (if there is any).

// HTTP example
httptransport.NewServer(
    ctx,
    endpoint,
    decoder,
    encoder,
    httptransport.ServerBefore(correlation.HTTPToContext()),
)

// gRPC example
grpctransport.NewServer(
    ctx,
    endpoint,
    decoder,
    encoder,
    grpctransport.ServerBefore(correlation.GRPCToContext()),
)

Generate a correlation ID if none is found in the context

When clients don't pass a correlation ID to the server, one should be generated early of the request lifecycle.

endpoint = correlation.Middleware()(endpoint)

Make sure to seed the global random number generator:

import (
    "math/rand"
    "time"
)

rand.Seed(time.Now().UnixNano())

Documentation

Overview

Package correlation provides a set of tools to add correlation ID to the context at certain levels (transport, endpoint) of the application.

Index

• func FromContext(ctx context.Context) (string, bool)
• func GRPCToContext(headers ...string) grpc.ServerRequestFunc
• func HTTPToContext(headers ...string) http.RequestFunc
• func Middleware() endpoint.Middleware
• func ToContext(ctx context.Context, id string) context.Context

Functions

func FromContext

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

FromContext returns the correlation ID from the context (if any). Returns false as the second parameter if none is found.

func GRPCToContext

func GRPCToContext(headers ...string) grpc.ServerRequestFunc

GRPCToContext moves a correlation ID from request header to context (if any).

func HTTPToContext

func HTTPToContext(headers ...string) http.RequestFunc

HTTPToContext moves a correlation ID from request header to context (if any).

func Middleware

func Middleware() endpoint.Middleware

Middleware creates a new middleware that ensures the context contains a correlation ID.

func ToContext

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

ToContext returns a new context annotated with a correlation ID.