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A stack is a prebuilt root file system (rootfs) that supports a specific operating system. For example, Linux-based systems need
/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.
PAS 2.4 includes support for the following stacks:
- cflinuxfs3: The Linux
cflinuxfs3stack is derived from Ubuntu Bionic 18.04. Refer to the GitHub stacks page for supported libraries.
- cflinuxfs2: The Linux
cflinuxfs2stack is derived from Ubuntu Trusty 14.04. Refer to the GitHub stacks page for supported libraries.
Breaking Change: Support for Ubuntu Trusty 14.04 ends in April 2019. Future versions of PAS may remove support for
cflinuxfs2. Push all new apps using
cflinuxfs3and migrate existing apps to
cflinuxfs3as soon as possible. For more information about the Ubuntu support lifecycle, see the Canonical documentation.
For security, stacks receive regular updates to address Common Vulnerabilities and Exposures (CVEs). Apps pick up on these stack changes through new releases of PAS. However, if your app links statically to a library provided in the rootfs, you may 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 may need to recompile the app and restage it as follows:
Use the cf stacks command to list the stacks available in a deployment.
$ cf stacks Getting stacks in org MY-ORG / space development as email@example.com... OK name description cflinuxfs2 Cloud Foundry Linux-based filesystem - Ubuntu Trusty 14.04 LTS cflinuxfs3 Cloud Foundry Linux-based filesystem - Ubuntu Bionic 18.04 LTS
To change your stack and restage your app, use the cf push command. For example, to restage your app on the stack
cflinuxfs3you can run
cf push MY-APP -s cflinuxfs3:
$ cf push MY-APP -s cflinuxfs3 Using stack cflinuxfs3... OK Creating app MY-APP in org MY-ORG / space development as firstname.lastname@example.org... OK ... requested state: started instances: 1/1 usage: 1G x 1 instances urls: MY-APP.cfapps.io last uploaded: Wed Apr 8 23:40:57 UTC 2015 state since cpu memory disk #0 running 2015-04-08 04:41:54 PM 0.0% 57.3M of 1G 128.8M of 1G
To specify a different stack, replace
cflinuxfs3with the name of the stack in the
-s STACKNAMEparameter of the command.
For API information, review the Stacks section of the Cloud Foundry API Documentation.