Multi-server deployments

Coolify can deploy the same application to a primary server and one or more additional standalone servers. This gives each server its own running instance of the application.

Adding deployment servers does not distribute traffic by itself. After the application is running on every server, configure a cloud load balancer or another external traffic layer in front of them.

Before you begin

Prepare the application and servers before attaching another deployment destination.

• Add and validate every server in Coolify. Follow Add Server for each new server.
• Use servers with the same CPU architecture, such as AMD64 or ARM64, so every server can run the same image.
• Make application state available outside the containers. Use shared or external services for databases, sessions, queues, caches, and uploaded files.
• Create a Docker registry repository that the primary server, any build server, and every additional server can access.
• Authenticate the SSH user configured in Coolify to that registry on every server that must push or pull the image. See Docker registries.

Configure the application image

1. Open the application in Coolify.

2. Select Configuration, then General.

3. In the Docker registry settings, enter the full registry repository in Docker Image. For example:

   ghcr.io/example/acme-web

4. Save the application settings.

Coolify requires Docker Image before it can deploy an application to additional servers. During a deployment, the primary server or configured build server builds the image and pushes it to the registry. The additional servers then pull the same image.

Add deployment servers

1. Open Configuration for the application.
2. Select Servers.
3. Under Add another server, select the server and network you want to attach.
4. Repeat the selection for each additional server.

The server originally selected for the application remains the Primary Server. Each attached server appears under Additional Server(s).

If no server is available to attach, confirm that the candidate server is validated, usable, belongs to the same team, and has a standalone Docker destination. A server already attached to the application is not shown again.

Deploy and verify

Deploy the application after attaching all required servers.

1. Select Deploy from the application page.
2. Follow the deployment logs. Confirm that Coolify pushes the built image to the configured registry and starts a deployment for each attached server.
3. Open Configuration > Servers and confirm that the primary and additional servers show a running status.
4. Test every server through the origin path you plan to use before adding it to a load balancer.

If an additional server cannot pull the image, sign in to the registry on that server with the same SSH user configured for the server in Coolify, then deploy again.

Manage deployment servers

The Servers page provides actions for each attached server:

• Deploy deploys the application to only that server.
• Stop stops the application on that server.
• Promote to Primary makes an additional server the primary deployment destination. The former primary server becomes an additional server.
• Remove from server stops the application on that server and removes the deployment destination after you confirm the server name.

Normal application-wide deploy, restart, and stop actions include the primary and additional servers. A pull request preview is not deployed to the additional destinations.

What multi-server deployment does not provide

Attaching servers gives you multiple application instances, but it does not create a complete highly available system. You must still configure:

• a load balancer with health checks
• DNS for the public domain
• firewall or security-group rules for the application servers
• shared data and session storage
• monitoring for the application and every server

Continue with Cloud Load Balancing to route traffic across the deployed instances.