Can I substring a variable in Azure Pipelines? - azure-devops

Question

I'm looking for a way to define a variable in my azure-pipelines.yml file where I can substring the 'Build.SourceVersion' -> Use the first 7 characters only.
Seems like there is no build-in function that can do such string operations in the documentation. Is there something I'm missing?
My other approach would be to use a bash task and overwrite the variable there but finding something build-in that can do this would be way better solution.

Answer 1

My other approach would be to use a bash task and overwrite the variable there but finding something build-in that can do this would be way better solution.
I agree with Lucas. There is no such built-in task to get the first 7 characters of $(Build.SourceVersion) in Azure DevOps.
We could use the command line/powershell task to split long sha into short sha:
echo $(Build.SourceVersion)
set TestVar=$(Build.SourceVersion)
set MyCustomVar=%TestVar:~0,7%
echo %MyCustomVar%
echo ##vso[task.setvariable variable=ShortSourceVersion]%MyCustomVar%
In this case, we could get the short versions of Build.SourceVersion and set it as environment variable.
Then we could set this command line task as a task group:
So, we could use this task to set the ShortSourceVersion directly.
Hope this helps.

Answer 2

Here is the shortest version that I use for this job;
- bash: |
longcommithash=$(Build.SourceVersion)
echo "##vso[task.setvariable variable=shorthash;]$(echo ${longcommithash::9})"
It gives you the output as shown below;

Answer 3

On Azure devops it's possible to be done using batch technique indeed - like other answers propose in here - however I wanted to remove string from the end of string - and with batch this gets more complex ( See following link ).
Then I've concluded to use Azure's built-in expressions, for example like this:
- name: sourceBranchName
value: ${{ replace(variables['Build.SourceBranch'], 'refs/heads/') }}
replace will have similar effect to substring - so it will remove unnecessary part from original string.
If however you want to concatenate some string and then remove it from original name - it's possible to be done using for instance format function:
- name: originBranchName
value: ${{ replace(variables.sourceBranchName, format('-to-{0}', variables.dynamicvar ) ) }}
If dynamicvar is a - then function will remove -to-a from branch name.

Answer 4

You are right, there is no native way to do it. You will have to write a script to transform the variable.
Here is an example:
trigger:
- master
resources:
- repo: self
stages:
- stage: Build
displayName: Build image
jobs:
- job: Build
displayName: Build
pool:
vmImage: 'ubuntu-latest'
steps:
- task: CmdLine#2
inputs:
script: ' x=`echo "$(Build.SourceVersion)" | head -c 7`; echo "##vso[task.setvariable variable=MyVar]$x"'
- task: CmdLine#2
inputs:
script: 'echo "$(MyVar)"'

Answer 5

Sure you can! If you absolutely must. Here is a runtime computation taking the first 7 characters of the Build.SourceVersion variable.
variables:
example: ${{ format('{0}{1}{2}{3}{4}{5}{6}', variables['Build.SourceVersion'][0], variables['Build.SourceVersion'][1], variables['Build.SourceVersion'][2], variables['Build.SourceVersion'][3], variables['Build.SourceVersion'][4], variables['Build.SourceVersion'][5], variables['Build.SourceVersion'][6]) }}
NB: I can't get it to work with $[...] syntax as the variable is apparently empty at the initial.