micro/util/wrapper/wrapper.go

package wrapper

import (
	"context"

	"github.com/micro/go-micro/client"
	"github.com/micro/go-micro/metadata"
)

type clientWrapper struct {
	client.Client
	headers metadata.Metadata
}

var (
	HeaderPrefix = "Micro-"
)

func (c *clientWrapper) setHeaders(ctx context.Context) context.Context {
	// copy metadata
	mda, _ := metadata.FromContext(ctx)
	md := metadata.Copy(mda)

	// set headers
	for k, v := range c.headers {
		if _, ok := md[k]; !ok {
			md[k] = v
		}
	}

	return metadata.NewContext(ctx, md)
}

func (c *clientWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
	ctx = c.setHeaders(ctx)
	return c.Client.Call(ctx, req, rsp, opts...)
}

func (c *clientWrapper) Stream(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
	ctx = c.setHeaders(ctx)
	return c.Client.Stream(ctx, req, opts...)
}

func (c *clientWrapper) Publish(ctx context.Context, p client.Message, opts ...client.PublishOption) error {
	ctx = c.setHeaders(ctx)
	return c.Client.Publish(ctx, p, opts...)
}

// FromService wraps a client to inject From-Service header into metadata
func FromService(name string, c client.Client) client.Client {
	return &clientWrapper{
                c,
                metadata.Metadata{
                        HeaderPrefix + "From-Service": name,
                },
        }
}