mirror of
https://github.com/openfaas/faas.git
synced 2025-06-17 12:46:59 +00:00
119 lines
2.9 KiB
Go
119 lines
2.9 KiB
Go
package handlers
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import (
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"context"
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"encoding/json"
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"io/ioutil"
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"log"
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"net/http"
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"strconv"
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"github.com/alexellis/faas/gateway/requests"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/client"
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)
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// DefaultMaxReplicas is the amount of replicas a service will auto-scale up to.
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const DefaultMaxReplicas = 20
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// MakeAlertHandler handles alerts from Prometheus Alertmanager
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func MakeAlertHandler(c *client.Client) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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log.Println("Alert received.")
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body, readErr := ioutil.ReadAll(r.Body)
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log.Println(string(body))
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if readErr != nil {
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log.Println(readErr)
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return
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}
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var req requests.PrometheusAlert
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err := json.Unmarshal(body, &req)
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if err != nil {
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log.Println(err)
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return
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}
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if len(req.Alerts) > 0 {
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if err := scaleService(req, c); err != nil {
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log.Println(err)
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w.WriteHeader(http.StatusInternalServerError)
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} else {
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w.WriteHeader(http.StatusOK)
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}
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}
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}
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}
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func scaleService(req requests.PrometheusAlert, c *client.Client) error {
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var err error
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serviceName := req.Alerts[0].Labels.FunctionName
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if len(serviceName) > 0 {
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opts := types.ServiceInspectOptions{
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InsertDefaults: true,
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}
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service, _, inspectErr := c.ServiceInspectWithRaw(context.Background(), serviceName, opts)
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if inspectErr == nil {
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currentReplicas := *service.Spec.Mode.Replicated.Replicas
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status := req.Status
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replicaLabel := service.Spec.TaskTemplate.ContainerSpec.Labels["com.faas.max_replicas"]
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maxReplicas := DefaultMaxReplicas
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if len(replicaLabel) > 0 {
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maxReplicas, err = strconv.Atoi(replicaLabel)
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if err != nil {
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log.Printf("Bad replica count: %s, should be uint.\n", replicaLabel)
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}
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}
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newReplicas := CalculateReplicas(status, currentReplicas, uint64(maxReplicas))
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if newReplicas == currentReplicas {
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return nil
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}
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log.Printf("Scaling %s to %d replicas.\n", serviceName, newReplicas)
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service.Spec.Mode.Replicated.Replicas = &newReplicas
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updateOpts := types.ServiceUpdateOptions{}
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updateOpts.RegistryAuthFrom = types.RegistryAuthFromSpec
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response, updateErr := c.ServiceUpdate(context.Background(), service.ID, service.Version, service.Spec, updateOpts)
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if updateErr != nil {
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err = updateErr
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}
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log.Println(response)
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} else {
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err = inspectErr
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}
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}
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return err
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}
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// CalculateReplicas decides what replica count to set depending on current/desired amount
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func CalculateReplicas(status string, currentReplicas uint64, maxReplicas uint64) uint64 {
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newReplicas := currentReplicas
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const step = 5
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if status == "firing" {
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if currentReplicas == 1 {
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// First jump is from 1 to "step" i.e. 1->5
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newReplicas = step
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} else {
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if currentReplicas+step > maxReplicas {
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newReplicas = maxReplicas
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} else {
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newReplicas = currentReplicas + step
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}
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}
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} else { // Resolved event.
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newReplicas = 1
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}
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return newReplicas
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}
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