The first stage in my pipeline checks for what services have actually changed. This is in an effort to speed up the pipeline by avoiding rebuilding, retesting, redeploying services if there have been no changes.
This is the changed.yaml for that stage:
parameters:
- name: comparedTo
default: ''
stages:
- stage: Changed
displayName: Check for changes in services and configs...
jobs:
- job: Changes
displayName: Checking for changes in services and configs...
steps:
- bash: |
mapfile -t changed < <(git diff HEAD ${{ parameters.comparedTo }} --name-only | awk -F'/' 'NF!=1{print $1}' | sort -u)
servicesChanged=()
configChanged=()
echo ""
echo "Total Changed: ${#changed[@]}"
for i in "${changed[@]}"
do
echo $i
if [[ $i == 'admin' ]]; then
echo "##vso[task.setvariable variable=adminChanged;isOutput=True]true"
servicesChanged+=("admin")
elif [[ $i == 'admin-v2' ]]; then
echo "##vso[task.setvariable variable=adminV2Changed;isOutput=True]true"
servicesChanged+=("admin-v2")
elif [[ $i == 'api' ]]; then
echo "##vso[task.setvariable variable=apiChanged;isOutput=True]true"
servicesChanged+=("api")
elif [[ $i == 'client' ]]; then
echo "##vso[task.setvariable variable=clientChanged;isOutput=True]true"
servicesChanged+=("client")
elif [[ $i == 'k8s' ]]; then
echo "##vso[task.setvariable variable=k8sChanged;isOutput=True]true"
configsChanged+=("k8s")
elif [[ $i == 'pipelines' ]]; then
echo "##vso[task.setvariable variable=pipelineChanged;isOutput=True]true"
configsChanged+=("pipelines")
fi
done
echo ""
echo "Services Changed: ${#servicesChanged[@]}"
for i in "${servicesChanged[@]}"
do
echo $i
done
echo ""
echo "Configs Changed: ${#configsChanged[@]}"
for i in "${configsChanged[@]}"
do
echo $i
done
if [[ ${#servicesChanged[@]} > 0 ]]; then
echo ""
echo "Any services changed: True"
echo "##vso[task.setvariable variable=anyServicesChanged;isOutput=true]true"
echo "##vso[task.setvariable variable=servicesChanged;isOutput=true]${servicesChanged[@]}"
fi
if [[ ${#configsChanged[@]} > 0 ]]; then
echo ""
echo "Any configs changed: True"
echo "##vso[task.setvariable variable=anyConfigsChanged;isOutput=true]true"
echo "##vso[task.setvariable variable=configsChanged;isOutput=true]${configsChanged[@]}"
fi
echo ""
name: detectChanges
As you can see, it creates a number of task output variables:
# This just indicates if the service has changed: true/false
echo "##vso[task.setvariable variable=<service-name>;isOutput=True]true"
# This should be creating a an output variable that is an array of the services that have changed
echo "##vso[task.setvariable variable=servicesChanged;isOutput=true]${servicesChanged[@]}"
So I gave myself two options: just a true/false for each service or iterating (somewhow) through an array of the services that have changed.
Each stage basically has the following form:
# pr.yaml
...
- template: templates/unitTests.yaml
parameters:
services:
- api
- admin
- admin-v2
- client
...
parameters:
- name: services
type: object
default: []
stages:
- stage: UnitTests
displayName: Run unit tests on service...
dependsOn: Changed
condition: succeeded()
jobs:
- job: UnitTests
condition: or(eq(stageDependencies.Changed.Changes.outputs['detectChanges.anyServicesChanged'], true), eq(variables['Build.Reason'], 'Manual'))
displayName: Running unit tests...
steps:
- ${{ each service in parameters.services }}:
- bash: |
echo "Now running ${{ service }} unit tests..."
Here is what I've tried so far and the errors I get:
Adding each service conditionally to services array or adding the array of changed services:
- template: templates/changed.yaml
parameters:
comparedTo: origin/production
- template: templates/unitTests.yaml
dependsOn: Changed
parameters:
services:
- ${{ if eq(stageDependencies.Changed.Changes.outputs['detectChanges.apiChanged'], true) }}
- api
- ${{ if eq(stageDependencies.Changed.Changes.outputs['detectChanges.adminChanged'], true) }}
- admin
- ${{ if eq(stageDependencies.Changed.Changes.outputs['detectChanges.adminV2Changed'], true) }}
- admin-v2
- ${{ if eq(stageDependencies.Changed.Changes.outputs['detectChanges.clientChanged'], true) }}
- client
Or...
- template: templates/changed.yaml
parameters:
comparedTo: origin/production
- template: templates/unitTests.yaml
dependsOn: Changed
parameters:
services:
- ${{ if eq(dependencies.Changed.outputs['Changes.detectChanges.apiChanged'], true) }}
- api
- ${{ if eq(dependencies.Changed.outputs['Changes.detectChanges.adminChanged'], true) }}
- admin
- ${{ if eq(dependencies.Changed.outputs['Changes.detectChanges.adminV2Changed'], true) }}
- admin-v2
- ${{ if eq(dependencies.Changed.outputs['Changes.detectChanges.clientChanged'], true) }}
- client
Or...
- template: templates/changed.yaml
parameters:
comparedTo: origin/production
- template: templates/unitTests.yaml
dependsOn: Changed
parameters:
services:
- $[ stageDependencies.Changed.Changes.outputs['detectChanges.servicesChanged'] ]
This results in:
An error occurred while loading the YAML build pipeline. Object reference not set to an instance of an object.
I know variables: will only take strings and not arrays.
One solution would be to have a variables: for each of the true/false variables and then conditions based on the parameters.services and whether the task output variables is true.
Any suggestions?
Ref:
The template expression ${{}} is evaluated at compile-time(before the jobs run), which means it cannot access to the variables that are dynamically set at the runtime(after the jobs start). So you cannot use template expression ${{}} in above scenario. See below description from here.
Within a template expression, you have access to the parameters context that contains the values of parameters passed in. Additionally, you have access to the variables context that contains all the variables specified in the YAML file plus many of the predefined variables (noted on each variable in that topic). Importantly, it doesn't have runtime variables such as those stored on the pipeline or given when you start a run. Template expansion happens very early in the run, so those variables aren't available
You can use conditions as a workaround. You need to add multiple tasks to be executed on the conditions. See below example:
- template: templates/changed.yaml
parameters:
comparedTo: origin/production
- template: templates/unitTests.yaml
dependsOn: Changed
#unitTests.yaml
stages:
- stage: UnitTests
displayName: Run unit tests on service...
dependsOn: Changed
condition: succeeded()
jobs:
- job: UnitTests
condition: or(eq(stageDependencies.Changed.Changes.outputs['detectChanges.anyServicesChanged'], true), eq(variables['Build.Reason'], 'Manual'))
displayName: Running unit tests...
variables:
changedServices: $[stageDependencies.Changed.Changes.outputs['detectChanges.servicesChanged']]
steps:
- bash: |
echo "Now running api unit tests..."
name: Api-unit-test
condition: contains(variables['changedServices'], 'api')
- bash: |
echo "Now running admin unit tests..."
name: admin-unit-test
condition: contains(variables['changedServices'], 'admin')
- bash: |
echo "Now running client unit tests..."
name: client-unit-test
condition: contains(variables['changedServices'], 'client')
Another workaround is to separate your pipeline into two pipelines. The fist pipeline to run the Changed stage. And Then call rest api in a script task to trigger the second pipeline and pass the variables in the request body. See this similar thread.