This topic describes how to use the Stack Auditor plugin for the Cloud Foundry Command Line Interface (cf CLI).
Stack Auditor is a cf CLI plugin that provides commands for listing apps and their stacks, migrating apps to a new stack, and deleting a stack.
One use case for Stack Auditor is when you must migrate a large number of apps to a new stack. This includes moving from cflinuxfs2 to cflinuxfs3 in preparation to upgrade your deployment to a version that does not contain cflinuxfs2. The following table describes the workflow you can use:
| Stage | Description |
|---|---|
| 1 | Operator audits stack usage to determine which apps need to be migrated. See List Apps and Their Stacks. |
| 2 | Operator communicates with developers that they must migrate their existing apps to a new stack and begin pushing all new apps to the a new stack. |
| 3 | Developers migrate their apps to a new stack. See Change Stacks. |
| 4 | Operator confirms apps have been migrated. |
| 5 | Operator deletes buildpacks associated with the old stack. |
| 6 | Operator deletes the old stack. See Delete a Stack. Note: If you upgrade your deployment to a version that contains the stack you deleted, the stack returns on upgrade. |
| 7 | If applicable, operator upgrades the deployment to the version that does not contain the old stack. |
To install Stack Auditor, do the following:
Download the Stack Auditor binary for your OS from Buildpack Extensions on VMware Tanzu Network.
Unzip the binary file you downloaded:
tar xvzf PATH-TO-BINARY
Install the plugin with the cf CLI:
cf install-plugin PATH-TO-BINARY
The sections below describe how to use Stack Auditor.
This section describes how to see the apps in each org and space and what stack they are using.
To see which apps are using which stack, run the following command. It lists apps for each org you have access to. To see all the apps in your deployment, ensure that you are logged in to the cf CLI as a user who can access all orgs.
cf audit-stack
See the following example output:
$ cf audit-stack first-org/development/first-app cflinuxfs2 first-org/staging/first-app cflinuxfs2 first-org/production/first-app cflinuxfs2 second-org/development/second-app cflinuxfs3 second-org/staging/second-app cflinuxfs3 second-org/production/second-app cflinuxfs3 ...
This section describes how to change the stack that an app uses. Stack Auditor rebuilds the app onto the new stack without a change in the source code of the app. If you want to move the app to a new stack with updated source code, follow the procedure in the Changing Stacks topic.
Warning: After successfully staging the app on cflinuxfs3, Stack Auditor attempts to restart the app on cflinuxfs3. This causes brief downtime. To avoid this brief downtime, use a blue-green strategy. See Using Blue-Green Deployment to Reduce Downtime and Risk.
To change the stack an app uses, do the following:
Target the org and space of the app:
cf target ORG SPACE
Where: * ORG is the org the app is in * SPACE is the space the app is in
Run the following command:
Note: If the app is in a stopped state, it remains stopped after changing stacks.
Note: When attempting to change stacks, your app is stopped. If the app fails on cflinuxfs3, Stack Auditor attempts to restage your app on cflinuxfs2.
cf change-stack APP-NAME STACK-NAME
Where: * APP-NAME is the app that you want to move to a new stack * STACK-NAME is the stack you want to move the app to
See the following example output:
$ cf change-stack my-app cflinuxfs3 Attempting to change stack to cflinuxfs3 for my-app... Starting app my-app in org pivotal-pubtools / space pivotalcf-staging as ljarzynski@pivotal.io... Downloading staticfile_buildpack... . . . requested state: started instances: 1/1 usage: 64M x 1 instance urls: example.com last uploaded: Thu Mar 28 17:44:46 UTC 2019 stack: cflinuxfs3 buildpack: staticfile_buildpack state since cpu memory disk details #0 running 2019-04-02 03:18:57 PM 0.0% 8.2M of 64M 6.9M of 1G Application my-app was successfully changed to Stack cflinuxfs3
This section describes how to delete a stack from your deployment. You must be an admin user to complete this step.
To delete a stack, run the following command. This action cannot be undone, with the following exception: If you upgrade your deployment to a version that contains the stack you deleted, the stack returns on upgrade.
cf delete-stack STACK-NAME
Where STACK-NAME is the name of the stack you want to delete.
$ cf delete-stack cflinuxfs2 Are you sure you want to remove the cflinuxfs2 stack? If so, type the name of the stack [cflinuxfs2] >cflinuxfs2 Deleting stack cflinuxfs2... Stack cflinuxfs2 has been deleted.
If you have any apps still running on cflinuxfs2, the command returns the following error:
Failed to delete stack cflinuxfs2 with error: Please delete the app associations for your stack.
