Files
fn-serverless/api/runnerpool/runner_pool.go
Tolga Ceylan f24172aa9d fn: introducing lb placer basic metrics (#1058)
* fn: introducing lb placer basic metrics

This change adds basic metrics to naive and consistent
hash LB placers. The stats show how many times we scanned
the full runner list, if runner pool failed to return a
runner list or if runner pool returned an empty list.

Placed and not placed status are also tracked along with
if TryExec returned an error or not. Most common error
code, Too-Busy is specifically tracked.

If client cancels/times out, this is also tracked as
a client cancel metric.

For placer latency, we would like to know how much time
the placer spent on searching for a runner until it
successfully places a call. This includes round-trip
times for NACK responses from the runners until a successful
TryExec() call. By excluding last successful TryExec() latency,
we try to exclude function execution & runner container
startup time from this metric in an attempt to isolate
Placer only latency.

* fn: latency and attempt tracker

Removing full scan metric. Tracking number of
runners attempted is a better metric for this
purpose.

Also, if rp.Runners() fail, this is an unrecoverable
error and we should bail out instead of retrying.

* fn: typo fix, ch placer finalize err return

* fn: enable LB placer metrics in WithAgentFromEnv if prometheus is enabled
2018-06-12 13:36:05 -07:00

50 lines
1.3 KiB
Go

package runnerpool
import (
"context"
"io"
"net/http"
"github.com/fnproject/fn/api/models"
)
// Placer implements a placement strategy for calls that are load-balanced
// across runners in a pool
type Placer interface {
PlaceCall(rp RunnerPool, ctx context.Context, call RunnerCall) error
}
// RunnerPool is the abstraction for getting an ordered list of runners to try for a call
type RunnerPool interface {
// returns an error for unrecoverable errors that should not be retried
Runners(call RunnerCall) ([]Runner, error)
Shutdown(ctx context.Context) error
}
// PKIData encapsulates TLS certificate data
type PKIData struct {
Ca string
Key string
Cert string
}
// MTLSRunnerFactory represents a factory method for constructing runners using mTLS
type MTLSRunnerFactory func(addr, certCommonName string, pki *PKIData) (Runner, error)
// Runner is the interface to invoke the execution of a function call on a specific runner
type Runner interface {
TryExec(ctx context.Context, call RunnerCall) (bool, error)
Close(ctx context.Context) error
Address() string
}
// RunnerCall provides access to the necessary details of request in order for it to be
// processed by a RunnerPool
type RunnerCall interface {
SlotHashId() string
RequestBody() io.ReadCloser
ResponseWriter() http.ResponseWriter
StdErr() io.ReadWriteCloser
Model() *models.Call
}