mirror

README

caddy-mirror

A basic request mirroring/shadowing middleware for Caddy 2

---

This module provides an HTTP handler which mirrors matching requests to an additional target.

It was written to solve two shortcomings with ngx_http_mirror_module - mirror requests were tied to the lifecycle of the main requests, and could not reuse connections.

Because the module is a minimum viable product, it has several of it's own shortcomings:

• Request bodies are not currently supported
• Requests are not identical to reverse_proxied requests
• Error logging is slow and spammy

Usage

example.com {
	route /hello {
		mirror http://mirror_server
		reverse_proxy http://hello_backend
	}
	
	route /world {
	    mirror http://mirror_server {
	        # Mirror half of all incoming requests
	        sample 0.5
	        # Use two goroutines/connections to send requests
	        concurrency 2
	        # Queue of 1024 requests shared between goroutines
	        backlog 1024
	    }
	    reverse_proxy http://world_backend
    }
}

Todo

• Add tests
• Add a circuit breaker for upstreams
• Try to adapt Caddy's reverse proxy as a transport

Documentation

Index

• type Mirror
  • func (*Mirror) CaddyModule() caddy.ModuleInfo
  • func (m *Mirror) Cleanup() error
  • func (m *Mirror) EnsureDefaults()
  • func (m *Mirror) Provision(ctx caddy.Context) error
  • func (m *Mirror) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error
  • func (m *Mirror) UnmarshalCaddyfile(d *caddyfile.Dispenser) error
  • func (m *Mirror) Validate() error
• type Request

Types

type Mirror

type Mirror struct {
	SamplingRate       float64       `json:"sampling_rate,omitempty"`
	RequestConcurrency int           `json:"request_concurrency,omitempty"`
	MaxBacklog         int           `json:"max_backlog,omitempty"`
	TargetServer       string        `json:"target,omitempty"`
	RequestTimeout     time.Duration `json:"request_timeout,omitempty"`
	AlertInterval      time.Duration `json:"alert_interval,omitempty"`
	// contains filtered or unexported fields
}

func (*Mirror) CaddyModule

func (*Mirror) CaddyModule() caddy.ModuleInfo

CaddyModule returns the Caddy module information.

func (*Mirror) Cleanup

func (m *Mirror) Cleanup() error

func (*Mirror) EnsureDefaults

func (m *Mirror) EnsureDefaults()

func (*Mirror) Provision

func (m *Mirror) Provision(ctx caddy.Context) error

func (*Mirror) ServeHTTP

func (m *Mirror) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error

func (*Mirror) UnmarshalCaddyfile

func (m *Mirror) UnmarshalCaddyfile(d *caddyfile.Dispenser) error

func (*Mirror) Validate

func (m *Mirror) Validate() error

type Request

type Request struct {
	// contains filtered or unexported fields
}