Cloud Run-based custom probers.

This repository contains a terraform module and Go library for deploying probers that perform custom probing logic to Google Cloud. The module packages a custom Go prober as a container image, deploys it to Cloud Run, and then configures an Uptime Check to periodically hit the Cloud Run URL.

Defining a custom prober

With the little Go library provided here, a probe can be defined with as little code as:

import (
	"context"
	"log"

	"github.com/chainguard-dev/terraform-google-prober/pkg/prober"
)

func main() {
	prober.Go(context.Background(), prober.Func(func(ctx context.Context) error {
		log.Print("Got a probe!")
		return nil
	}))
}

See our basic example.

Deploying a custom prober

With the terraform module provided here, a probe can be deployed with a little configuration as:

module "prober" {
  source  = "chainguard-dev/prober/google"
  version = "v0.1.2"

  name       = "basic-example"
  project_id = var.project_id

  importpath  = "github.com/chainguard-dev/terraform-google-prober/examples/basic"
  working_dir = path.module
}

See our basic example.

Passing additional configuration

You can pass additional configuration to your custom probes via environment variables passed to the prober application. These can be specified in the prober module:

  env = {
    "FOO" : "bar"
  }

See our complex example.

Multi-regional probers

By default, the probers run as a single-homed Cloud Run application, which is great for development, and virtually free, but to take advantage of the geographic distribution of GCP Uptime Checks, we need to deploy Cloud Run applications to multiple regions behind a Google Cloud Load Balancer (expensive!) with a TLS-terminated domain.

This can be done by specifying the following additional configuration:

  # Deploy to three regions behind GCLB with a Google-managed
  # TLS certificate under the provided domain.
  locations = [
    "us-east1",
    "us-central1",
    "us-west1",
  ]

  # The domain under which we will provision hostnames
  domain   = var.domain

  # The Google Cloud DNS Zone to use for directing prober hostnames to the GCLB
  # IP address.
  dns_zone = google_dns_managed_zone.prober_zone.name

See our complex example.

Requirements

No requirements.

Providers

Name	Version
cosign	n/a
google	n/a
ko	n/a
random	n/a

Modules

No modules.

Resources

Name	Type
cosign_sign.image	resource
google_cloud_run_service.probers	resource
google_cloud_run_service_iam_policy.noauths	resource
google_compute_backend_service.probers	resource
google_compute_global_address.static_ip	resource
google_compute_global_forwarding_rule.forwarding_rule	resource
google_compute_managed_ssl_certificate.prober_cert	resource
google_compute_region_network_endpoint_group.neg	resource
google_compute_target_https_proxy.prober	resource
google_compute_url_map.probers	resource
google_dns_record_set.prober_dns	resource
google_monitoring_alert_policy.uptime_alert	resource
google_monitoring_uptime_check_config.global_uptime_check	resource
google_monitoring_uptime_check_config.regional_uptime_check	resource
ko_build.image	resource
random_password.secret	resource
cosign_verify.base-image	data source
google_iam_policy.noauth	data source

Inputs

Name	Description	Type	Default	Required
alert_description	Alert documentation. Use this to link to playbooks or give additional context.	string	"An uptime check has failed."	no
cpu	The CPU limit for the prober.	string	"1000m"	no
dns_zone	The managed DNS zone in which to create prober record sets (required for multiple locations).	string	""	no
domain	The domain of the environment to probe (required for multiple locations).	string	""	no
enable_alert	If true, alert on failures. Outputs will return the alert ID for notification and dashboards.	bool	false	no
env	A map of custom environment variables (e.g. key=value)	map	{}	no
importpath	The import path that contains the prober application.	string	n/a	yes
locations	Where to run the Cloud Run services.	list(string)	[ "us-central1" ]	no
memory	The memory limit for the prober.	string	"512Mi"	no
name	Name to prefix to created resources.	string	n/a	yes
notification_channels	A list of notification channels to send alerts to.	list(string)	[]	no
period	The period for the prober in seconds.	string	"300s"	no
project_id	The project that will host the prober.	string	n/a	yes
repository	Container repository to publish images to.	string	""	no
service_account	The email address of the service account to run the service as.	string	n/a	yes
timeout	The timeout for the prober in seconds.	string	"60s"	no
working_dir	The working directory that contains the importpath.	string	n/a	yes

Outputs

Name	Description
alert_id	n/a
uptime_check	n/a
uptime_check_name	n/a