Google Cloud Run for serverless backend search

This document walks you through setting up a Google Cloud Run for serverless backend search. For more guidance on configuration options for full backend search check here.

1. Build the docker image:

   cd ./cmd/tempo-serverless && make build-docker-gcr
   

   This will create the Docker container image to be deployed to Google Cloud Run. The docker image will be named: tempo-serverless:latest and tempo-serverless:<branch>-<commit hash>. Here is an example of that name:

   $ docker images | grep tempo-serverless
   tempo-serverless                                                           cloud-run-3be4efa               146c9d9fa63c   58 seconds ago   47.9MB
   tempo-serverless                                                           latest                          146c9d9fa63c   58 seconds ago   47.9MB
   

2. Push the image to a Google Container Registry repo.

3. Provision the Google Cloud Run service. This example uses Terraform. Configuration values should be adjusted to meet the needs of your installation.

   locals {
     // this can be increased if you would like to use multiple functions
     count = 1
   }
   
   resource "google_cloud_run_service" "run" {
     count = local.count
   
     name     = "<service name>"
     location = "<appropriate region>"
   
     metadata {
       annotations = {
           "run.googleapis.com/ingress"      = "internal",     # this annotation can be used to limit connectivity to the service
       }
     }
   
     template {
       metadata {
         annotations = {
             "autoscaling.knative.dev/minScale"                   = "1",
             "autoscaling.knative.dev/maxScale"                   = "1000",
             "autoscaling.knative.dev/panic-threshold-percentage" = "110.0",  # default 200.0. how aggressively to go into panic mode and start scaling heavily
             "autoscaling.knative.dev/window"                     = "10s",    # default 60s. window over which to average metrics to make scaling decisions
         }
       }
       spec {
         container_concurrency = 4
         containers {
           image = "<container image created above>"
           resources {
             limits = {
                 cpu = "2"
                 memory = "1Gi"
             }
           }
           env {
             name = "TEMPO_GCS_BUCKET_NAME"
             value = "<gcs bucket where tempo data is stored>"
           }
           env {
             name = "TEMPO_BACKEND"
             value = "gcs"
           }
           env {
             name = "TEMPO_GCS_HEDGE_REQUESTS_AT"
             value = "400ms"
           }
           env {
             name = "TEMPO_GCS_HEDGE_REQUESTS_UP_TO"
             value = "2"
           }
           env {
             name = "GOGC"
             value = "400"
           }
         }
       }
     }
   
     traffic {
       percent         = 100
       latest_revision = true
     }
   }
   

4. Add the newly-created cloud run service as external endpoints in your querier configuration. The endpoint can be retrieved from the “details” tab in Google Cloud Run:

   querier:
     search:
       external_endpoints:
       - <trigger url from console>