Skip to content

Traffic ingress

Our boilerplate prefers the use of Cloud Run to host web applications. Applications hosted via Cloud run can use two different services to connect traffic from the outside world to them: Cloud Load Balancers and Domain Mappings. This page documents when and how to use both.

Our Cloud Run module

We have a standard module which we use to configure applications hosted in Cloud Run. This module can be used to configure both domain mapping and load balancer ingress. See the module's documentation for more details.

Which ingress to use

This section helps you select which ingress style to use.

No ingress

If no ingress style is specified and the application is marked as being public, a URL will be generated for the application under the domain. This is unlikely to be a human-friendly name but may suffice for test or development instances.

Domain mapping

Deprecation notice

Domain Mapping in Cloud Run has been in Pre-GA for multiple years. Due to latency issues, Google states that this feature is not fit for production use. Therefore, since version 9.0.0 of our Google Cloud Run terraform module, we only support custom domains when using a Cloud Load balancer.

The Cloud Run domain mapping ingress is simple to configure:

  1. Verify a DNS domain for the application.
  2. Specify the DNS domain via our standard module's dns_names variable.
  3. Add DNS records for that domain according to the dns_resource_records output from our standard module.

The application will then be served from the DNS domain provided. There are some restrictions surrounding domain mapping of which the most pressing is that applications hosted in europe-west2 (London) cannot use domain mapping. De facto this restricts our more modern applications to use load balancing or the "no ingress" configuration above.

Load balancer

A Cloud Load Balancer is appropriate when there are complex needs. Such needs include:

  • Using non-managed TLS certificates. This is often the case if one is transitioning a service fom on-premises to Cloud.
  • Using Cloud Identity Aware Proxy to restrict resources to particular identities.
  • The need to shape or otherwise filter traffic via Cloud Armour rules or backend weighting.

Our standard module comes with a basic Load Balancer configuration. For advanced use you may find that you need to configure it yourself. Examples of manually configured load balancers are:

  • The Raven Core IdP configuration (DevOps only) configures a basic load balancer. This was done ahead of support in our standard module and so provides a "minimal" configuration example with no fancy features.
  • The Raven Admin API configuration includes an example of configuring Cloud Identity Aware Proxy to restrict certain resources to individual service accounts.

Load Balancers incur additional costs when used and so domain mapping should be used in preference if possible.

When not to use an ingress

Sometimes you will not need to use either a load balancer nor domain mapping ingress. This is usually for services which are only ever called by resources within the parent Google project. A typical example of this is a service which is used in combination with Cloud Scheduler to perform actions at regular intervals.

In these cases our standard module may not prove sufficient as it assumes the application you are hosting is public.


In summary:

  • Ingresses should be used for externally available production applications or internal applications which need to make use of Identity Aware Proxy policies.
  • Our standard Cloud Run module can configure domain mapping or load balancer ingresses.
  • Domain mapping ingresses are easy to use but are inflexible.
  • Load balancer ingresses are flexible but may require additional configuration.
  • Load balancer ingresses should be used when:
    • the application is hosted in a region not supported by domain mappings,
    • custom TLS certificates need to be used, or
    • custom access and routing policies are required.
  • Custom access policies for Load balancers can be implemented via Cloud Armour policies.
  • There are cost implications with using load balancers which means their use should be considered carefully.