Use variables in Azure DevOps Pipeline templates - azure

Question

We have a collection of Azure DevOps pipeline templates that we re-use across multiple repositories. Therefore we wanted to have a file that contains variables for all of our templates.
The repo structure looks like this
template repo
├── template-1.yml
├── template-2.yml
└── variables.yml
project repo
├── ...
└── azure-pipelines.yml
The variables.yml looks like this
...
variables:
foo: bar
In template-1.yml we are importing the variables.yml as described in here
variables:
- template: variables.yml
In the azure-pipelines.yml we are using the template like this
resources:
repositories:
- repository: build-scripts
type: git
name: project-name/build-scripts
steps:
...
- template: template-1.yml#build-scripts
When we now try to run the pipeline, we get the following error message:
template-1.yml#build-scripts (Line: 10, Col: 1): Unexpected value 'variables'

Answer 1

The issue is because you used variable template at steps scope. And variables simply doesn't exists at that level. This should work for you:
resources:
repositories:
- repository: build-scripts
type: git
name: project-name/build-scripts
variables:
- template: template-1.yml#build-scripts
steps:
...
this is available to use at any place where variables are possible to use. So for instance you can use this in that way:
jobs:
- job: myJob
timeoutInMinutes: 10
variables:
- template: template-1.yml # Template reference
pool:
vmImage: 'ubuntu-16.04'
steps:
- script: echo My favorite vegetable is ${{ variables.favoriteVeggie }}.

Answer 2

If your template file only has variables, you can refer to Krzysztof Madej's answer.
If your template file has both variables and steps as shown below, it can only be used by extends.
# File: template-1.yml
variables: ...
steps: ...
Or you can write them in a stage, as shown below.
# File: template-1.yml
stages:
- stage: {stage}
variables: ...
jobs:
- job: {job}
steps: ...
Then insert it as a separate stage.
# azure-pipelines.yml
stages:
- stage: ...
- template: template-1.yml

Answer 3

Replying as I think there was something missed in the original explanations:
First:
If you are referencing variables in a template then you must ensure that you are extending that template when you call it. Calling a template that defines variables that is not extended will result in a failed pipeline execution.
template-1.yml#build-scripts (Line: 10, Col: 1): Unexpected value 'variables'
Second: When referencing variables in multiple templates do not use:
${{ variables.foo }} #even though this is seen in templates examples.
but rather use the normal variable syntax
$(foo) #this works
So for the originally reference example the following should work.
Variables.yml:
variables:
foo: bar
template-1.yml:
variables:
- template: variables.yml
....
steps:
...
- task: CmdLine#2
displayName: Display Variable
inputs:
script: |
echo $(foo)
azure-pipelines.yml:
resources:
repositories:
- repository: build-scripts
type: git
name: project-name/build-scripts
extends:
template: template-1.yml#build-scripts
template-2.yml
steps:
...
- task: CmdLine#2
displayName: Display Variable
inputs:
script: |
echo $(foo)

Answer 4

This approach can help someone, so I decided to post it here.
One more kind of "workaround" for that case, maybe a bit "dirty" since you need to specify the parameters explicitly each time you execute template, which is not a good idea if you have a lot of parameters to pass. (actually, there is a way, read below improved version) But, if you really want or you have not that much parameters, this should work:
the logic is: you have all your parameters in variables template, like templates/vars.yml:
variables:
- name: myVar1
value: MyValue1
- name: myVar2
value: MyValue2
and since you have everything you need in the variables, probably there is no need to importing variables into template itself, because template will be executed in pipeline, which will have your variables imported and you can substitute it explicitly, like in the example below:
templates/my-template-setup-env.yml's content (without variables inside it):
steps:
- script: |
echo "$(myVar3)"
my-azure-pipeline.yml's content (with importing variables template):
name: my-cute-CI-name
trigger:
- main
pool:
vmImage: ubuntu-18.04
variables:
- template: templates/vars.yml # importing your variables from templates
stages:
- stage: RunTheStage
displayName: 'Run first stage'
jobs:
- job: RunTheJob
displayName: 'Run your job'
steps:
- template: templates/my-template-setup-env.yml # your template
parameters:
myVar3: $(myVar1) # substitute value from vars.yml, so myVar1 will be used in templated and printed
Improved version
But, if you have unique naming of your params and variables across all pipelines and templates, you are in safe to not specify it explicitly during template usage, that will work as well:
edited and shortened version of my-azure-pipeline.yml (in case you have the same name of your variable and parameter in template):
variables:
- template: templates/vars.yml
...
steps:
- template: templates/my-template-setup-env.yml # env preparation
# parameters:
# myVar2: $(myVar2) # you don't need to pass any parameters explicitly to the template since you have same name of variable
templates/my-template-setup-env.yml then should be like this:
steps:
- script: |
echo "$(myVar2)" # not myVar3, since myVar3 is not in initial variables file templates/vars.yml
or you need to add remaining variables (myVar3 in our first case) into templates/vars.yml file as well.