Automated rollback of CF

alert_filter_and_condition

fetch cloud_function
| metric 'cloudfunctions.googleapis.com/function/execution_count'
| {
    filter status != 'ok'
    ;
    ident
}
| group_by drop[status], sliding(5m), .sum
| ratio
| scale '%'
| every (30s)
| condition val() > 20'%'

cf_version1.go

package example
 
import (
 "fmt"
 "net/http"

 "github.com/GoogleCloudPlatform/functions-framework-go/functions"
)

func init() {
   functions.HTTP("EventHandler", eventHandler)
}

// eventHandler always returns "pong" on "/ping"
// and returns 404 to other requests
func eventHandler(w http.ResponseWriter,
                  r *http.Request) {
  if r.URL.Path != "/ping" {
    http.NotFound(w, r)
    return
  }
  fmt.Fprint(w, "pong")
}

cf_version2.go

package example
 
import (
 "net/http"

 "github.com/GoogleCloudPlatform/functions-framework-go/functions"
)

func init() {
   functions.HTTP("EventHandler", eventHandler)
}

// eventHandler fails on "/ping" with 500
// and returns 404 to other requests
func eventHandler(w http.ResponseWriter,
                  r *http.Request) {
  if r.URL.Path != "/ping" {
    http.NotFound(w, r)
    return
  }
  http.Error(w, "simulated error", http.StatusInternalServerError)
}

cloudbuild.yaml

steps:
- name: 'gcr.io/cloud-builders/gcloud'
  env:
  - 'project_id=$PROJECT_ID'
  - 'function_name=$_FUNCTION_NAME'
  - 'function_region=$_FUNCTION_REGION'
  script: |
    #!/usr/bin/env bash
    echo "Reading bucket and object for $function_name in $function_region ..."
    read -r bucket object <<< $(gcloud functions describe "$function_name" --project="$project_id" --region="$function_region" --format="value(build_config.source.storage_source.bucket,build_config.source.storage_source.object)")
    echo "Loading version for gs://$bucket/$object ..."
    version=$(gcloud storage ls --all-versions "gs://$bucket/$object" --long | grep -v ^TOTAL | sort -r -k 2 | sed -n '2 p' | awk '{print $3}')
    if [[ -n "$version" ]]; then
      temp="gs://$bucket/temp.zip"
      gcloud storage cp "$version" "$temp"
      gcloud functions deploy "$function_name" --project="$project_id" --region="$function_region" --source="$temp"
      gcloud storage rm "$temp"
    else
      echo "Cannot rollback to previous version. Only one version of the function was found."
    fi

cloudbuild_trigger_substitutions

_FUNCTION_NAME=$(body.message.data.incident.resource.labels.function_name)
_FUNCTION_REGION=$(body.message.data.incident.resource.labels.region)

permissions.txt

Cloud Build Settings Enable it to work with Cloud Fuctions