Advanced Usage of Resources

In a pipeline, the role of a resource goes beyond inputs and outputs. Here are several other ways in which you can use resources in your pipeline.

Using Resources Values in Environment Variables

A step that specifies a resource can access the resource and its attributes through environment variables.

These environment variables have a standard naming convention: res_<resource name>_<tag>
This can be extended further to access an integration that is specified in the resource: res_<resource_name>_<integration tag name>_<tag>

Example

If the definition of a GitRepo resource named app_gitrepo is as follows:GitRepo

GitRepo Resource Definition

resources:
  - name: app_gitRepo
    type: GitRepo
    configuration:
      path: user1/repo1
      gitProvider: myGitProvider

The environment variable definition would be as follows:

Environment Variable	Result	Description
`res_app_gitRepo_path`	user1/repo1	Returns the `path` attribute of the `app_gitRepo` resource
`res_app_gitRepo_gitProvider_url`		Returns `url` of the Git Provider of the `app_gitRepo` resource

Then the following environment variables will be available to a step that uses the app_gitRepo resource as an input:

Environment Variables

steps:
  - name: build_app
    type: MvnBuild
    configuration:
      sourceLocation: .
      mvnCommand: clean install
      configFileLocation: .
      inputResources:
        - name: app_gitRepo             # Use the app_gitRepo resource
   execution:
     onSuccess:
       - send_notification notifySlack --text "Maven build completed for $res_app_gitRepo_path at $res_app_gitRepo_gitProvider_url"
     onFailure:
       - send_notification notifySlack --text "Maven build FAILED for $res_app_gitRepo_path at $res_app_gitRepo_gitProvider_url"

Using Arrays

Certain resources, such as Aql, DistributionRule, and VmCluster have arrays in their configuration.

For arrays within resources ( VmCluster):

res_<resource name>_<array heading>_len (this tells you how many entries in array)

res_<resource name>_<array heading>_0

res_<resource name>_<array heading>_1

res_<resource name>_<array heading>_2

For object arrays within resources ( DistributionRule):

res_<resource name>_<array heading>_len (this tells you how many entries in array)

res_<resource name>_<array heading>_0_<tag>

res_<resource name>_<array heading>_1_<tag>

Using Stateful Resources

Resources are stateful entities and persist across pipelines, enabling passing of information between pipelines. This is especially useful when creating a pipeline of pipelines.

Steps can store any key-value pair data in a resource using the write_outpututility function. These values can then be referenced as environment variables by any subsequent cuting step that uses that resource as an input. Therefore, a step can pass information to another step in the run of the pipeline.

The environment variable for the stored value is of the form res_<resource name>_<key name>.

Example

The following example creates three properties in the resource myImage.

Using write_output

write_output myImage sport="baseball" equipment="bat" field="diamond"

When the resource is specified in a step's inputResources, these properties can be accessed as the following environment variables:

Environment Variables

$ printenv res_myImage_sport
baseball
$ printenv res_myImage_equipment
bat
$ printenv res_myImage_field
diamond

For more information, see Creating Stateful Pipelines.

Using Extension Resources

Extension resources enable Pipelines users to extend the Pipelines DSL by specifying their own resource types. After an extension resource is loaded, it can be used by any step in a pipeline. For more information, see Pipelines Extension Resource Model.