Azure yaml pipeline using "extends" - azure

Question

I am trying to use extends as part of my pipeline. I am trying to get the first basic step working from Azure docs ie
# pythonparameter-template.yml
parameters:
- name: usersteps
type: stepList
default: []
steps:
- ${{ each step in parameters.usersteps }}
- ${{ step }}
# azure-pipelines.yml
trigger: none
resources:
repositories:
- repository: CI-CD-Templates
type: git
name: /CI-CD-Templates
ref: refs/heads/master
extends:
template: /pythonparameter-template.yml#CI-CD-Templates
parameters:
usersteps:
- script: echo This is my first step
- script: echo This is my second step
I keep getting the below error:
The directive 'each' is not allowed in this context. Directives are not supported for expressions that are embedded within a string. Directives are only supported when the entire value is an expression
Unexpected value '${{ each step in parameters.usersteps }} - ${{ step }}'
Also after I extend from a template can azure-pipelines.yml also have it's own custom steps ie
# azure-pipelines.yml
resources:
repositories:
- repository: templates
type: git
name: MyProject/MyTemplates
ref: tags/v1
extends:
template: template.yml#templates
parameters:
usersteps:
- script: echo This is my first step
- script: echo This is my second step
steps:
- template: /validation-template.yml#CI-CD-Templates
parameters:
commitMessage: $(commitMessage)
- template: /shared-template.yml#CI-CD-Templates
parameters:
buildArtifactDir: $(buildArtifactDir)

Answer 1

Update
Please refer the response in this DC link-- Yaml extends feature erroring out when looping through steps.
​The YAML has a validation task in #pythonparameter-template.yml
Comment out these 2 lines and your YAML will succeed. The template shown here is preventing any tasks to be used. This could be a scenario for someone with specific security requirements.
${{ if eq(pair.key, 'task') }}:
'${{ pair.value }}': error
Are you trying to combine two yml pythonparameter-template.yml azure-pipelines.yml in the same file? It's not supported.
parameters:
- name: usersteps
type: stepList
default: []
steps:
- ${{ each step in parameters.usersteps }}
- ${{ step }}
According to the error Directives are not supported for expressions that are embedded within a string. Directives are only supported when the entire value is an expression Unexpected value '${{ each step in parameters.usersteps }} - ${{ step }}'
You maybe use the wrong format. About the formats you could refer our official doc here--
Template types & usage
Besides, you can make azure-pipelines.yml also have it's own custom steps. But you need to put them under parameters in the pipeline, not like the way you use.
azure-pipelines.yml
trigger:
- master
extends:
template: pythonparameter-template.yml
parameters:
buildSteps:
- bash: echo Test #Passes
displayName: succeed
- bash: echo "Test"
displayName: succeed
- script: echo "Script Test"
displayName: Fail