Preview Environments

It is critical to have testing and staging environments accurately reflect production, but achieving this can be a major operational hassle. Most engineering teams use a single staging environment which makes it hard for developers to test their changes in isolation; the alternative is for devops teams to spin up new testing or staging environments manually and tear them down after testing is done.

Render’s preview environments solve this problem by automatically creating a fresh copy of your production environment (including services, databases, and environment groups) on every pull request, so you can test your changes with confidence without affecting staging or relying on devops teams to create and destroy infrastructure.

Render keeps your preview environments up to date on every commit and automatically destroys them when the original pull request is merged or closed. You can also set up an expiry time to automatically clean up preview environments after a period of inactivity.

Preview environments can be helpful in a lot of cases:

• Share your changes live in code reviews: no more Git diffs for visual changes!
• Get shareable links for upcoming features and collaborate more effectively with internal and external stakeholders.
• Run CI tests against a high fidelity copy of your production environment before merging.

Getting started

1. Make sure your services and databases are defined in a render.yaml file and synchronized in your Render Dashboard. See our Infrastructure as Code documentation for how to get started with render.yaml.
2. Set previewsEnabled: true at the top level of your render.yaml file to enable preview environments.

previewsEnabled: trueservices:
- type: web
...

You’re all set! Open a new pull request in your repository and see your preview environment deploy with status updates right in the pull request. You can visit the URL for your preview environment by clicking View deployment next to your web service deployment.

If you’d like to try this for yourself, fork our Preview Environments example repository, synchronize the render.yaml file in your dashboard, and open a new pull request.

Override preview instance types

You can override the billing instance type used for preview services by specifying a previewPlan that is different from the corresponding production value. See YAML instance type names for a list of valid values.

previewsEnabled: true
services:
- type: web
  plan: standard
  previewPlan: starter  name: express-server
  runtime: node
- type: redis
  plan: standard
  previewPlan: starter  name: private redis
  ipAllowList: [] # only allow internal connections
databases:
- name: my_test_db
  plan: standard
  previewPlan: starter

Environment variables

You can override environment variables in preview environments with previewValue. This can be useful if you need to override a production API key with a test key, or if you’d like to use a single database across all preview environments. Environment variable overrides are supported for web services, private services, and environment groups.

previewsEnabled: true
services:
- type: web
  plan: standard
  name: express-server
  runtime: node
  envVars:
  - key: MY_API_KEY
    value: production-api-key
    previewValue: test-api-key

Placeholder environment variables

Placeholder environment variables defined with sync: false will not be copied to preview environments. To share secret variables across preview environments:

1. Manually create an environment group in the Dashboard.
2. Add one or more environment variables.
3. Reference the environment group in your render.yaml file, as needed.

previewsEnabled: true
services:
- type: web
  plan: standard
  name: express-server
  runtime: node
  envVars:
  # The value for `MY_API_KEY` provided in the Dashboard will *not* be
  # copied to preview environments.
  - key: MY_API_KEY
    sync: false

  # Any values in this group will be copied to preview environments,
  # if `all-settings` exists and is *not* included in this file.
  - fromGroup: all-settings

Preview environment initialization

You may want to run custom initialization for your preview environment after it is created but not on subsequent deploys, for example to seed a newly created database or download files to disk. You can do this by specifying a command to run after the first successful deploy with initialDeployHook.

previewsEnabled: true
services:
- type: web
  plan: standard
  name: express-server
  runtime: node
  initialDeployHook: ./seed_database.sh

Automatic expiration

You can set the number of days a preview environment can exist without any new commits to help control costs. Set previewsExpireAfterDays to automatically delete the environment after the specified number of days of inactivity. The default is no expiry. The expiration time is reset with every push to the preview environment.

previewsEnabled: true
previewsExpireAfterDays: 3services:
- type: web
  plan: standard
  name: express-server
  runtime: node

Skipping a pull request

If you don’t want Render to create a preview environment for a particular pull request, include any of the following strings in the pull request’s title (not in a commit message):

• [skip render]
• [skip preview]
• [render skip]
• [preview skip]

Root directory and build filters

If you define the Root Directory or specify Build Filters for each service in your Blueprint Spec, Render will only create a preview environment if the files changed in a pull request match the Root Directory or Build Filter paths for at least one service.

Preview environment billing

Preview resources are billed just like regular Render services and are prorated by the second. See Render Pricing for service and instance type details.