Changing stacks

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You can restage apps on a new stack. Here is a description of stacks and lists of stacks that are supported on Cloud Foundry v4-0.

To restage a Windows app on a new Windows stack, see Changing Windows stacks.

You can also use the Stack Auditor plug-in for the Cloud Foundry Command Line Interface (cf CLI) when changing stacks. See Using the Stack Auditor plug-in.

Overview

A stack is a prebuilt root file system (rootfs) that supports a specific operating system. For example, Linux-based systems need /usr and /bin directories at their root. The stack works in tandem with a buildpack to support apps running in compartments. Under Diego architecture, cell VMs can support multiple stacks.

Note Docker apps do not use stacks.

Available stacks

Cloud Foundry v4-0 includes support for cflinuxfs3. The Linux cflinuxfs3 stack is derived from Ubuntu Bionic 18.04. For more information about supported libraries, see the GitHub stacks page.

The latest versions of Cloud Foundry include support for cflinuxfs4 which is derived from Ubuntu 22.04 LTS (Jammy Jellyfish). For more information, see GitHub cflinuxfs4 stack receipt.

You can also build your own custom stack. For more information, see Adding a Custom Stack.

Restaging apps on a new stack

For security, stacks receive regular updates to address Common Vulnerabilities and Exposures (CVEs). Apps pick up on these stack changes through new releases of Cloud Foundry. However, if your app links statically to a library provided in the rootfs, you might have to manually restage it to pick up the changes.

It can be difficult to know what libraries an app statically links to, and it depends on the languages you are using. One example is an app that uses a Ruby or Python binary, and links out to part of the C standard library. If the C library requires an update, you might need to recompile the app and restage it.

To restage an app on a new stack:

1. Use the cf stacks command to list the stacks available in a deployment.

   $ cf stacks
   Getting stacks in org MY-ORG / space development as developer@example.com...
   OK
   
   name         description
   cflinuxfs3   Cloud Foundry Linux-based filesystem (Ubuntu 18.04)
   cflinuxfs4   Cloud Foundry Linux-based filesystem (Ubuntu 22.04)
   

2. To change your stack and restage your app, run:

   cf push MY-APP -s STACK-NAME
   

   Where:

   • MY-APP is the name of the app.
   • STACK-NAME is the name of the new stack.

   For example, to restage your app on the stack cflinuxfs4, run cf push MY-APP -s cflinuxfs4:

       $ cf push MY-APP -s cflinuxfs4
       Using stack cflinuxfs4...
       OK
       Creating app MY-APP in org MY-ORG / space development as developer@example.com...
       OK
       ...
       requested state: started
       instances: 1/1
       usage: 1G x 1 instances
       urls: MY-APP.cfapps.io
       last uploaded: Wed 17 Jul 22:57:04 UTC 2024
           state     since                  cpu    memory        disk           logging         cpu entitlement   details
       #0  running   2024-07-17T22:57:22Z   0.3%   49.5M of 1G   130.2M of 1G   0B/s of 16K/s   2.4%
       

Stacks API

For API information, see the Stacks section of the Cloud Foundry API Documentation.