How Deploys Work

Render makes deploying your application as easy as pushing your code to source control.

Automatic Git deploys

By default, Render automatically deploys a Git-backed service (any service connected to a GitHub/GitLab/Bitbucket repo) whenever changes are pushed or merged to the service’s linked branch.

You can skip an auto-deploy for a particular commit, or even disable auto-deploys entirely for your service.

Skipping an auto-deploy

Certain changes to your codebase might not merit a new deploy, such as edits to a README file. In these cases, you can include a skip phrase in your Git commit message to prevent the change from triggering an auto-deploy:

git commit -m "[skip render] Update README"

The skip phrase is one of [skip render] or [render skip]. You can also use one of the following in place of render:

• deploy
• cd

When an auto-deploy is skipped, a corresponding entry appears on your service’s Events page:

Disabling auto-deploys

If you always want to trigger deploys manually, you can disable auto-deploys in the Render Dashboard. Go to your service’s Settings page and set Auto-Deploy to No:

Don’t forget to save your changes!

Deploy steps

With each deploy, Render proceeds through the following commands for your service:

You specify these commands as part of creating your service in the Render Dashboard. You can modify these commands for an existing service from its Settings page:

Each command is described below.

Build command

Performs all compilation and dependency installation that’s necessary for your service to run. It usually resembles the command you use to build your project locally.

Example build commands for each runtime

Pre-deploy command

If defined, this command runs after your service’s build finishes, but before that build is deployed. Recommended for tasks that should always precede a deploy but are not tied to building your code, such as:

• Database migrations
• Uploading assets to a CDN

The pre-deploy command is available for paid web services, private services, and background workers.

If you don’t define a pre-deploy command for a service, Render proceeds directly from the build command to the start command.

Start command

Render runs this command to start your service when it’s ready to deploy.

Example start commands for each runtime

Canceling a deploy

You can cancel an in-progress deploy from the Render Dashboard.

1. Go to your service’s Events page and click the word Deploy in the corresponding event entry.

   • This opens the deploy’s details page.

2. Click Cancel deploy:

   

Restarting a service

If your service is misbehaving, you can restart it from the service’s page in the Render Dashboard. Click Manual Deploy > Restart service:

Note the following about restarting a service:

• When you restart your service, Render actually deploys a completely new instance and swaps over to it when it’s ready. The original running instance is then deprovisioned.
  • This makes restarting a zero-downtime action, similar to other deploys.
• If you restart a scaled service, Render performs a restart for every instance.
• If you restart a service, the new instance uses the same configuration as the original instance, including values of environment variables.
  • This means that if you’ve recently updated your service’s configuration but haven’t redeployed since then, restarting will not cause your service to incorporate those updates.

Zero-downtime deploys

Whenever you deploy a new version of your service, Render makes sure that the service remains up and available throughout the deploy process.

Here’s how it works:

1. When you push up a new version of your code, Render attempts to build it.

   • If the build fails, Render cancels the deploy, and your original service instance continues running without interruption.

2. If the build succeeds, Render attempts to spin up a new instance of your service running the new version of your code:

   • While the new instance is spinning up, your original instance continues to handle all incoming requests.

3. If the new instance spins up successfully (you can help verify this for web services by setting up health checks), Render updates its network configuration to start sending incoming requests to the new instance:

   • At this point, the new instance is receiving all incoming requests. The original instance is still running.

4. After 60 seconds, Render sends a SIGTERM signal to your app’s process on the original instance.

   • This signals your app to initiate a graceful shutdown.

5. If your app’s process doesn’t exit within a 30-second grace period after receiving the SIGTERM signal, Render sends a SIGKILL signal to force the process to terminate.

   • If you manage your service with a Blueprint, you can extend this grace period by setting the maxShutdownDelaySeconds field in your render.yaml file.

6. The zero-downtime deploy is complete.

For services that are scaled to multiple instances, Render performs steps 2-5 for one instance at a time. If any new instance fails to become healthy during this process, Render cancels the entire deploy and reverts to instances running the previous version of your service.

Health checks

You can (and should!) define a health check endpoint for every web service to help Render determine whether it’s ready to receive traffic. Render sends an HTTP request to this endpoint as part of zero-downtime deploys, and also every few seconds to verify the health of running services.

Set your health check endpoint path in the Render Dashboard from your web service’s Settings page:

If you manage your service with a Blueprint, instead set the healthCheckPath field in your render.yaml file.

Health check protocol

With every health check, Render sends an HTTP GET request to each service instance’s health check endpoint. If your service has at least one custom domain, Render sets one of those domains as the value of the Host header for the request. Otherwise, Render uses the service’s onrender.com subdomain.

• The check succeeds if your health check endpoint responds with a 2xx or 3xx status code. Render considers the instance healthy.
• The check fails in all other cases (including after a 5-second response timeout). Render considers the instance potentially unhealthy.

If a potentially unhealthy instance continues to fail its health checks, Render takes the following actions:

• During a zero-downtime deploy:
  • If a new instance fails all of its health checks for 15 consecutive minutes, Render cancels the deploy and continues routing traffic to existing instances.
• For an actively running service:
  • If an instance fails all of its health checks for 15 consecutive seconds, Render stops routing traffic to it to give it an opportunity to recover.
  • After 60 consecutive seconds of failed health checks, Render automatically restarts the service.

In the event of a canceled deploy or a service restart, Render notifies you according to your settings.