Stemcell Handling

What is Stemcell Handling?

In Ops Manager, every product uploaded and staged needs to be given a stemcell in order to operate. By default, every stemcell uploaded to Ops Manager will automatically associate with any new or existing products. Using the automation tasks, this default can be overridden to not have a stemcell associate with any products, and can be manually assigned as deemed necessary by the user.

Why do your Stemcell Handling Manually?

Unless there is a specific need to manually handle the stemcells in Ops Manager, it is recommended to use the default. A common use case for manual stemcell handling is updating the product stemcells one at a time to minimize downtime during apply changes. This is particularly beneficial in environments with large numbers of tiles that share the same stemcell.

How to use the Stemcell Handling Tasks in Automation

Platform Automation Toolkit has tasks that will assist in the manual handling of stemcells within Ops Manager. These tasks, in order, are:

• download-product
• upload-product
• stage-product
• upload-stemcell
• assign-stemcell

1. download-product:

   Create a config.yml for this task using the example provided.

   After running the task, a file named assign-stemcell.yml is outputted. The task will put a config file with two values, product and stemcell into the assign-stemcell-config output directory. This can be used with assign-stemcell to ensure the latest stemcell is used with that product.

2. Run the upload-product and stage-product tasks to get the resources into Ops Manager.

3. Run the upload-stemcell task.

   To upload the stemcell to Ops Manager without associating it with any product, the upload-stemcell task will need to be executed with the FLOATING_STEMCELL: false flag set.

   An example of this, in a pipeline:

- task: upload-stemcell
  image: platform-automation-image
  file: platform-automation-tasks/tasks/upload-stemcell.yml
  input_mapping:
    env: configuration
    stemcell: downloaded-stemcell
  params:
    ENV_FILE: ((foundation))/env/env.yml
    FLOATING_STEMCELL: false

Warning

upload-stemcell should not be run until after the stage-product task has completed. When the two tasks are run in the opposite order, the stemcell will still auto-associate with the product.

4. Run the assign-stemcell task to associate the stemcell with the staged product. If using the download-product task before doing this within the same job, you must assign the config using the input_mapping key to assign the outputted config to the config that assign-stemcell is expecting. Upon successful completion, the stemcell specified in the config will be associated with the product specified in the config, and no other product will be associated with that stemcell.

   An example of this, in a pipeline:

- task: assign-stemcell
  image: platform-automation-image
  file: platform-automation-tasks/tasks/assign-stemcell.yml
  input_mapping:
    env: configuration
    config: assign-stemcell-config
  params:
    ENV_FILE: ((foundation))/env/env.yml

5. Configure Product and Apply Changes can then be run on the product as normal.

How to Download a Specific Stemcell

Platform Automation Toolkit can be used to download a specific stemcell. In order to do so, create a config.yml for this task using the example provided.

[activate-certificate-authority]: ../tasks.md#activate-certificate-authority