Preview Environments

Test proposed changes in a disposable copy of your production environment.

Preview environments require a Professional workspace or higher.

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.

A preview environment creates new instances of the services/postgresql defined in your Blueprint, they do not copy any data from existing services. If you need to run any initial setup (e.g. seeding the database) you can use Preview Environment Initialization.

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

Make sure your services and databases are defined in a render.yaml file and synchronized as a Blueprint in the Render Dashboard.
- For details, see Render Blueprints.
At the root level of your render.yaml file, enable preview environments by setting the previews.generation key to one of manual or automatic:
```
previews:  generation: automaticservices:
- type: web
...
```
For details on each option, see Manual vs. automatic preview environments.

Setting the deprecated field previewsEnabled: true is equivalent to setting this field to automatic.
Merge your changes to your Blueprint’s linked branch.

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.

preview environment deployment

As of this writing, GitLab does not support status updates on merge requests.

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.

If you explicitly set a branch for your services in render.yaml then that would be used to deploy a preview environment as well which may not be expected behavior. Typically, if you’re using preview environments you don’t need to specify a branch as we would use the branch the blueprint was created for initially and then the branch the pull request is against to create the preview environment.

Manual vs. automatic preview environments

Preview Mode Description

Preview Mode	Description
Manual	By default, Render does not create preview environments for PRs. To create a preview environment for a specific PR, include the string `[render preview]` in your PR’s title (not the commit message): `[render preview] Update homepage` You can also edit an existing PR’s title to add or remove `[render preview]`. If you do, Render provisions or deletes associated preview instances accordingly.
Automatic	By default, Render creates a preview environment for every PR against your Blueprint’s linked branch. To skip creating a preview environment for a specific PR, include any of the following strings in your PR’s title (not the commit message): `[skip preview]` `[skip render]` `[preview skip]` `[render skip]` You can also edit an existing PR’s title to add or remove one of these strings. If you do, Render provisions or deletes associated preview instances accordingly. Your pull request’s title might be included in the message for its associated merge commit. If you use `[skip render]` or `[render skip]`, this also skips the auto-deploy for the service when merged. To avoid this, instead use `[skip preview]` or `[preview skip]`.

Manual

By default, Render does not create preview environments for PRs.

To create a preview environment for a specific PR, include the string [render preview] in your PR’s title (not the commit message):

[render preview] Update homepage

You can also edit an existing PR’s title to add or remove [render preview]. If you do, Render provisions or deletes associated preview instances accordingly.

Automatic

By default, Render creates a preview environment for every PR against your Blueprint’s linked branch.

To skip creating a preview environment for a specific PR, include any of the following strings in your PR’s title (not the commit message):

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

You can also edit an existing PR’s title to add or remove one of these strings. If you do, Render provisions or deletes associated preview instances accordingly.

Your pull request’s title might be included in the message for its associated merge commit. If you use [skip render] or [render skip], this also skips the auto-deploy for the service when merged.

To avoid this, instead use [skip preview] or [preview skip].

Override preview instance types

Services in a preview environment can use a different instance type from their production counterparts. By using smaller instance types for preview environments, you can reduce costs.

For PostgreSQL databases and Redis instances, set the previewPlan field.
For all other service types, set the previews.plan field.

If your PostgreSQL database uses a new flexible plan, you cannot specify a non-flexible instance type for its previewPlan (or vice versa). See supported values.

See example render.yaml declarations below. For all supported values, see the Blueprint YAML Reference.

If you don’t specify a preview instance type for a service, Render uses the same instance type that you use in production.

previews:
  generation: automatic
services:
- type: web
  plan: standard
  previews:    plan: 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: pro-4gb
  previewPlan: basic-1gb  previewDiskSizeGB: 5

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.

previews:
  generation: automatic
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 are not copied to preview environments. To share secret variables across preview environments:

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

previews:
  generation: automatic
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

You can also use an environment group that’s managed by a Blueprint, if it’s not the same Blueprint that you’re using to manage your preview environments.

If you use the same Blueprint for both, a new environment group will be created for each preview environment. Placeholder environment variables will not be copied to these environment groups.

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.

previews:
  generation: automatic
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 manage costs. Set previews.expireAfterDays 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.

previews:
  generation: automatic
  expireAfterDays: 3services:
- type: web
  plan: standard
  name: express-server
  runtime: node

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.