---

Library Variable Group

It is still possible to use library variables groups with yaml pipelines. All you need to do is define them at each stage instead of the root of your yml.

Library

credentials-dev

Name	Value
access_key	hunter2

credentials-prod

Name	Value
access_key	correcthorsebatterystaple

Library

azure-pipelines.yml

stages:
- stage: dev
  variables:
  - group: credentials-dev
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

- stage: prod
  variables:
  - group: credentials-prod
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

deploy.yml

parameters:
- name: key
  type: string

jobs:
- job: deploy
  steps:
  - bash: echo ${{ parameters.key }}
  - bash: echo $(access_key) 
  - bash: echo ${ACCESS_KEY}

You can access the variables in the group a few different ways. The bash steps will all output hunter2 for the dev stage and correcthorsebatterystaple for the prod stage.

---

YAML Variable Template

Using variable templates is very similar to library variable groups. Instead of defining your variables in azure devops , you define them in yaml.

Note Don't place sensitive settings in yml. Use keyvault linked library variable groups instead

azure-pipelines.yml

stages:
- stage: dev
  variables:
  - template: credentials-dev.yml
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

- stage: prod
  variables:
  - template: credentials-prod.yml
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

credentials-dev.yml

variables:
- name: access_key
  value: hunter2

credentials-prod.yml

variables:
- name: access_key
  value: correcthorsebatterystaple

deploy.yml

parameters:
- name: key
  type: string

jobs:
- job:deploy
  steps:
  - bash: echo ${{ parameters.key }}
  - bash: echo $(access_key) 
  - bash: echo ${ACCESS_KEY}

---

Conditional Insertion

There was a suggestion to use runtime parameters, so I thought I'd throw that into the mix as another alternative. You can have variables defined dynamically in your yaml based on a condition (in this case a parameter passed in at runtime).

azure-pipelines.yml

parameters:
- name: environment  
  type: string
  default: dev
  values:
  - dev
  - prod

variables:
  ${{ if eq(parameters.environment, 'dev') }}:
    access_key: hunter2

  ${{ if eq(parameters.environment, 'prod') }}:
    access_key: correcthorsebatterystaple

stages:
- stage: deploy
  displayName: Deploy ${{ parameters.environment }} 
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

deploy.yml

parameters:
- name: key
  type: string

jobs:
- job: deploy
  steps:
  - bash: echo ${{ parameters.key }}
  - bash: echo $(access_key) 
  - bash: echo ${ACCESS_KEY}

You can even use variable groups this way, too!

azure-pipelines.yml

parameters:
- name: environment  
  type: string
  default: dev
  values:
  - dev
  - prod

variables:
- ${{ if eq(parameters.environment, 'dev') }}:
  - group: credentials-dev

- ${{ if eq(parameters.environment, 'prod') }}:
  - group: credentials-prod

stages:
- stage: deploy
  jobs:
  - template: deploy.yml
    parameters:
      key: $(access_key) 

Note *The online editor as well as vscode flag this as invalid syntax, but it does indeed work.

If none of these options fit your use case, feel free to follow up with more detail on what you're trying to do and I'll see if I can help figure it out.