SparkleFormation CLI commands

The sfn command provides a collection of subcommands to handle stack lifecycles as well as subcommands to aid in inspection of existing stacks.

Lifecycle commands

Stack create

Stacks can be created via sfn using SparkleFormation templates or raw JSON templates.

$ sfn create my-stack

sfn will prompt for selection of a template to build for this new stack. To disable this prompting behavior, you can provide the path or name of the desired template:

$ sfn create my-stack --file my_template

By default sfn will process and build SparkleFormation templates. To build a JSON template, disable processing in the configuration file, or via flag:

$ sfn create my-stack --file ./my_template.json --no-processing

The create command is only responsible for initiating the stack creation with the remote provider API. This does not report back the success or failure of the actual stack creation. To provide this behavior, the create command will automatically poll the stack’s resource events. Once the stack as reached a completed state, the create command can properly notify of a success or failed state and exit with the proper status code. The automatic polling behavior can be disabled:

$ sfn create my-stack --file my_template --no-poll
Apply stack

The --apply-stack option allows providing the name of an existing stack when creating or updating. Applying stacks is simply fetching the outputs from the applied stacks and automatically defaulting the set parameter of the new or updated stack. Outputs are matched by name to the parameters of the target stack. This allows an easy way to use values from existing stacks when building new stacks.

Example:

StackA:

...
  "Outputs": {
    "LoadBalancerAddress": {
      "Description": "Address of Load Balancer",
      "Value": {
        "Fn::GetAtt": [
          "LoadBalancerResource",
          "DNSName"
        ]
      }
    }
  }
...

StackB:

...
  "Parameters": {
    "LoadBalancerAddress": {
      "Type": "String",
      "Default": "unset"
    }
  }
...

When creating StackB, if we use the --apply-stack option:

$ sfn create StackB --apply-stack StackA

when prompted for the stack parameters, we will find the parameter value for LoadBalancerAddress to be filled in with the output provided from StackA.

Remote location apply stack

Stacks that are defined in a different region, or within a different provider, can be applied by prefixing stack names with the configured location name. Using the defined .sfn configuration:

Configuration.new do
  ...
  credentials do
    provider :aws
    aws_access_key_id ENV['AWS_ACCESS_KEY_ID']
    aws_secret_access_key ENV['AWS_SECRET_ACCESS_KEY']
    aws_region 'us-west-2'
  end
  locations do
    ca_west do
      provider :aws
      aws_access_key_id ENV['AWS_ACCESS_KEY_ID']
      aws_secret_access_key ENV['AWS_SECRET_ACCESS_KEY']
      aws_region 'us-west-1'
    end
  end
end

Now, when creating a new stack (which uses the configured credentials targeting us-west-2) a stack from the us-west-1 region can be applied by prefixing the location name to the stack name:

$ sfn create StackB --apply-stack ca_west__StackA

NOTE: Location providers are not required to be common.

Example of stack creation:

stack create

Stack update

Existing stacks can be updated via sfn:

$ sfn update my-stack

This will start an “in place” update. Only the parameters of the stack are updated. To update the template of the stack as well:

$ sfn update my-stack --file my_template

The update command behaves like the create command. It is only responsible for initiating the request with the remote provider API. It will poll the stack events to detect final stack state. The polling can be disabled:

$ sfn update my-stack --file my_template --no-poll

Example of stack update:

stack update

Stack destroy

Existing stacks can be destroyed via sfn:

$ sfn destroy my-stack

By default a confirmation prompt will be provided prior to destroying an existing stack. This can be disabled by automatically confirming:

$ sfn destroy my-stack --yes

The destroy command will poll the stack resource events until the stack has been successfully deleted, or has reached a “complete” state (which would indicate a failure to destroy). The polling can be disabled:

$ sfn destroy my-stack --yes --no-poll

The destroy command also provides glob support when specifying stack names. This can make cleanup very easy when multiple testing stacks may exist:

$ sfn destroy my-stack-*

This will destroy all stacks whose name start with my-stack-. The command will prompt for confirmation and provide a list of all matching stacks prior to destruction.

Example of stack destroy:

stack destroy

Inspection and Information commands

Stack list

To list existing stacks:

$ sfn list

Example of a stack list:

stack list

Stack describe

A description of an existing stack will display resources allocated to the stack and any outputs that were defined within the stack’s template:

$ sfn describe my-stack

If the stack contains nested stacks, it will display the resources and outputs for those stacks as well.

To describe only resources:

$ sfn describe my-stack --resources

To describe only outputs:

$ sfn describe my-stack --outputs

Example of a stack describe:

stack describe

Stack events

List the events genereted by the resources allocated to an existing stack:

$ sfn events my-stack

If the resources within the stack are currently being modified (via a create, update, or destroy) command, the events can be polled until the stack reaches a completed state:

$ sfn events my-stack --poll

Example of stack events:

stack events

Stack inspection

Existing stacks can have their resources inspected via sfn using the miasma model API. The inspect command provides the ability to directly access resource information where the miasma library has modeling support enabled.

One builtin helper for the inspect command is listing all compute resources available within a stack. This includes standalone compute instances as well as compute instances attached to auto-scaling groups defined within the stack.

$ sfn inspect my-stack --nodes

Example of stack node inspection:

stack inspect nodes

When run with no options, the inspect command will output the data model information of the stack:

$ sfn inspect my-stack

Individual items can be displayed using the attribute flag:

$ sfn inspect my-stack --attribute template

The attribute flag is gets applied to the miasma data model and will output the result of request. For example, if the stack consisted of one resource, and that resource was a compute instance, we could view the resource information from the orchestration API point of view:

$ sfn inspect my-stack --attribute "resources.all.first"

The information here will be sparse because the orchestration API only keeps a reference to the actual resource within its own system. Because the miasma library has compute modeling defined, we can utilize the library to automatically load the compute instance:

$ sfn inspect my-stack --attribute "resources.all.first.expand"

If only the addresses allocated to the compute instance were desired, that can be requested:

$ sfn inspect my-stack --attribute "resources.all.first.expand.addresses"

Example of stack attribute inspection

stack inspect attribute

Template print

To display a generated template:

$ sfn print --file my_template

Template validation

Templates can be validated with the remote provide API prior to creation:

$ sfn validate --file my_template

If the template is a JSON style template, disable processing:

$ sfn validate --file my_template --no-processing

Example of stack validate:

stack validate

Template diff

Template updates can be diff’ed against an existing stack’s template to display information about what resource modifications will be introduced by the new template:

$ sfn diff my-stack --file my_template

Example of stack diff:

stack diff

Template graphs

Creation or dependency graphs can be created via sfn. Two styles of the graph can be generated:

  • "creation" - Resource creation flow (default)
  • "dependency" - Resource dependency composition

To generate a graph:

$ sfn graph --file my_template --graph-style dependency

By default the graph command will create a Graphviz compatible dot format file. If Graphviz is installed on the local system, an image can be generated directly:

$ sfn graph --file my_template --graph-type png

Configuration commands

To aid setup and configuration, sfn provides a configuration helper:

$ sfn conf

This will display the current configuration. If no configuration file is present, the user can have one automatically generated for them:

$ sfn conf --generate