DevOps Build Pipeline - Templates - Run from the same branch - azure-devops

Question

I am testing a POC build pipeline and I am trying to use templates as a sort of reference library, so I can reuse the same code in multiple pipelines, while also allowing for simpler editing/updating, if changes are required.
I want to be able to run the pipeline from a DevOps branch and refer to the same branch (or tag) when validating/running all the template pipelines in this build pipeline.
The ultimate goal is to pass multiple variables to the template (via a loop/for each) to create multiple build artifacts referencing public repositories (in this test a public terraform github repo). We could then maybe only need to maintain the variable data and not the source/reference code.
I thought DevOps did this 'OOTB', but realised that this was probably not the case. Something like this:
Repo: InfraAsData (all pipelines)
Branch: feature/sparse-clone-repo
Updated azure-pipeline.yaml and added template templates/sparse-clone.yaml (FYI - this template is untested as well)
azure-pipeline.yaml:
trigger: none
resources:
repositories:
- repository: InfraAsData #resource name to be used in the build pipeline
type: git #Azure git
name: 'IAC/InfraAsData'
refs: 'refs/heads/$(branch_name)'
parameters:
- name: branch
displayName: branch
type: string
default: $(Build.SourceBranch)
variables:
- name: branch_name
value: ${{ parameters.branch }}
- template: ./templates/variables/resource-groups.yaml#InfraAsData #variables template
pool:
vmImage: 'ubuntu-latest'
stages:
#sparse clone the target public repo blobs to build pipeline artifacts directory
- stage: Template-Sparse-Clone-To-Artifacts
displayName: 'Test Sparse Clone to Artifacts'
jobs:
- deployment: sparseCloneTfModule
displayName: 'Sparse Clone Terraform module to Artifacts'
environment: Test
strategy:
runOnce:
deploy:
steps:
- template: $(Build.SourceBranch)/templates/sparse-clone.yaml#InfraAsData #Create artifacts based on template variables
parameters: #module specific var from var template
repoUrl: '${{ variables[template.repoUrl] }}'
repoPath: '${{ variables[template.repoPath] }}'
artifactPath: '${{ variables[template.artifactPath] }}'
sparse-clone.yaml
parameters:
repoUrl: ''
repoPath: ''
artifactPath: ''
#testing
steps:
- script: |
md $(Build.BinariesDirectory)/$(parameters.artifactPath)
git clone --filter=blob:none --sparse $(parameters.repoUrl) $(parameters.artifactPath)
cd $(Build.BinariesDirectory)/$(parameters.artifactPath)
git sparse-checkout init --cone
git sparse-checkout set $(parameters.repoPath)
git checkout main
dir $(Build.BinariesDirectory)/$(parameters.artifactPath)
displayName: 'Clone Github Repo Subdirectory - filter blob none'
When I run this from the feature/sparse-clone-repo branch in DevOps I get an error that the new template does not exist in the main branch (it doesn't of course).
/build/test/azure-pipeline.yaml: File /templates/variables/resource-groups.yaml not found in repository https://dev.azure.com//IAC/_git/InfraAsData branch refs/heads/main version
I have also tried using no resources.repository, using $(Build.SourceBranch) $(Build.SourceBranchName) as refs value and as the template path reference (like in the 2nd template example).
EDIT:
If i remove the resource.repositories reference, then the correct branch is identified, but the azure-pipeline.yaml relative path is appended to the template path:
/build/test/azure-pipeline.yaml: File /build/test/$(Build.SourceBranch)/templates/variables/resource-groups.yaml not found in repository https://dev.azure.com//IAC/_git/InfraAsData branch refs/heads/feature/pipelines
So correct branch, but not the correct relative path.
EDIT 2:
I can remove the resources section and use a relative path
../../templates/variables/resource-groups.yaml
but this is not dynamic, to a 'root' reference, so would not work if the folder structure were to change (EG I moved the azure-pipeline.yaml up a level)
I'm sure I am missing something obvious or misunderstanding the docs (or pipeline templates). Any pointers gratefully received!

Answer 1

When I run this from the feature/sparse-clone-repo branch in DevOps I
get an error that the new template does not exist in the main branch
(it doesn't of course).
From your description, seems you thought the 'refs' of the resources determine the branch of the alias of the template part.
But it is not, the 'resources.repositories.repository' doesn't have a section named 'refs', only 'ref' is allowed.
In your situation, you used a section named 'refs' which doesn't exist. Pipeline will use the default branch of the repository to looking for the template YAML. So change the default branch of the repository or change the 'refs' to 'ref' will solve the first issue.
And I notice you were using variable in resources section, you have two mistakes.
One is '$()' can't use in compile time part. Another is even compile time variables are also not allowed in 'ref' section.
ref
string
ref name to checkout; defaults to 'refs/heads/main'. The branch
checked out by default whenever the resource trigger fires. Does not
accept variables.
You can use your pipeline like this:
trigger: none
resources:
repositories:
- repository: InfraAsData #resource name to be used in the build pipeline
type: git #Azure git
name: 'BowmanCP/template_branch'
ref: 'refs/heads/${{parameters.branch}}'
parameters:
- name: branch
displayName: branch
type: string
default: main2
pool:
vmImage: 'ubuntu-latest'
stages:
#sparse clone the target public repo blobs to build pipeline artifacts directory
- stage: Template_Sparse_Clone_To_Artifacts
displayName: 'Test Sparse Clone to Artifacts'
jobs:
- deployment: sparseCloneTfModule
displayName: 'Sparse Clone Terraform module to Artifacts'
environment: Test
strategy:
runOnce:
deploy:
steps:
- template: ./templates/sparse-clone.yaml#InfraAsData #Create artifacts based on template variables
parameters: #module specific var from var template
repoUrl: 'xxx'
repoPath: 'xxx'
artifactPath: 'xxx'
Basically, variables can't be used in your situation and there doesn't have a parameter reuse feature. That's everything.