router

Documentation

Index

• Constants
• func NewMutableRouter(logger *zap.Logger, handler *mux.Router) *mutableRouter
• func Start(logger *zap.Logger, port int, executorUrl string)
• type Analytics
  • func MakeAnalytics(url string) *Analytics
• type AnalyticsData
• type FunctionWeightDistribution
• type HTTPTriggerSet
  • func (mr HTTPTriggerSet) ServeHTTP(responseWriter http.ResponseWriter, request *http.Request)
• type RetryingRoundTripper
  • func (roundTripper *RetryingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error)

Constants

const (
	FORWARDED        = "Forwarded"
	X_FORWARDED_HOST = "X-Forwarded-Host"
)

const (
	HEADERS_FISSION_FUNCTION_PREFIX = "Fission-Function"
)

Functions

func NewMutableRouter

func NewMutableRouter(logger *zap.Logger, handler *mux.Router) *mutableRouter

func Start

func Start(logger *zap.Logger, port int, executorUrl string)

Types

type Analytics

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

func MakeAnalytics

func MakeAnalytics(url string) *Analytics

type AnalyticsData

type AnalyticsData struct {
	ID                string `json:"ID"`
	FunctionCallCount uint64 `json:"FunctionCallCount"`
}

type FunctionWeightDistribution

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

type HTTPTriggerSet

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

func (HTTPTriggerSet) ServeHTTP

func (mr HTTPTriggerSet) ServeHTTP(responseWriter http.ResponseWriter, request *http.Request)

type RetryingRoundTripper

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

A layer on top of http.DefaultTransport, with retries.

func (*RetryingRoundTripper) RoundTrip

func (roundTripper *RetryingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error)

RoundTrip is a custom transport with retries for http requests that forwards the request to the right serviceUrl, obtained from router's cache or from executor if router entry is stale.

It first checks if the service address for this function came from router's cache. If it didn't, it makes a request to executor to get a new service for function. If that succeeds, it adds the address to it's cache and makes a request to that address with transport.RoundTrip call. Initial requests to new k8s services sometimes seem to fail, but retries work. So, it retries with an exponential back-off for maxRetries times.

Else if it came from the cache, it makes a transport.RoundTrip with that cached address. If the response received is a network dial error (which means that the pod doesn't exist anymore), it removes the cache entry and makes a request to executor to get a new service for function. It then retries transport.RoundTrip with the new address.

At any point in time, if the response received from transport.RoundTrip is other than dial network error, it is relayed as-is to the user, without any retries.

While this RoundTripper handles the case where a previously cached address of the function pod isn't valid anymore (probably because the pod got deleted somehow), by making a request to executor to get a new service for this function, it doesn't handle a case where a newly specialized pod gets deleted just after the GetServiceForFunction succeeds. In such a case, the RoundTripper will retry requests against the new address and give up after maxRetries. However, the subsequent http call for this function will ensure the cache is invalidated.

If GetServiceForFunction returns an error or if RoundTripper exits with an error, it get's translated into 502 inside ServeHttp function of the reverseProxy. Earlier, GetServiceForFunction was called inside handler function and fission explicitly set http status code to 500 if it returned an error.