Commit/Push Changes to Azure DevOps Repository At End of Build

Question

As part of our build process we update version numbers and we want to commit and push the changes back to the main repository. This is a git repo hosted on azure devops and using get sources as the first step:

I added a command line task at the end of the pipeline with following code. There appears to be something wrong, how can I do this properly? Thank you.

git config --global user.email "my@email.address.com"
git config --global user.name "VSTS Admin"
git status

ECHO SOURCE BRANCH IS %BUILD_SOURCEBRANCH%

ECHO ADDING MODIFIED FILES
git add *.cs
git add *.build
git add *.wxs

ECHO CREATING COMMIT
git commit -m "Update version numbers for Build %BUILD_BUILDNUMBER%"
git push origin master

here are the results:

##[section]Starting: Commit/Push Changes To Git Repo
==============================================================================
Task         : Command Line
Description  : Run a command line script using cmd.exe on Windows and bash on macOS and Linux.
Version      : 2.148.0
Author       : Microsoft Corporation
Help         : [More Information](https://go.microsoft.com/fwlink/?LinkID=613735)
==============================================================================
Generating script.
========================== Starting Command Output ===========================
##[command]"C:\windows\system32\cmd.exe" /D /E:ON /V:OFF /S /C "CALL "D:\a\_temp\8b19361b-8f47-4d31-834d-132fedb0b386.cmd""
HEAD detached at e7a1479d
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   ../../../Properties/AssemblyInfo.cs
        .. (more files modified)

SOURCE BRANCH IS refs/heads/master
ADDING MODIFIED FILES
CREATING COMMIT
[detached HEAD 5c1bf6dc] Update version numbers for Build myBuildNumber_5.1.001
 2 files changed, 2 insertions(+), 2 deletions(-)
error: src refspec master does not match any
error: failed to push some refs to     'https://{org}@dev.azure.com/{projectName}/_git/{reponame}'
##[error]Cmd.exe exited with code '1'.
##[section]Finishing: Commit/Push Changes To Git Repo

Answer 1

Things to note are:

1. Azure Pipeline does git checkout on commit which triggered the pipeline.
   Ex: git checkout <commit-hash-SHA1>
2. This is called as detached HEAD state since the repository's head instead of pointing to any valid branch it now points to the commit itself. (ie HEAD is detached)
3. Since we are in detached HEAD state, we can't push back directly and instead one can use the following approach which pushes directly to the target branch.
   Ex: git push <remote-repo-url> HEAD:refs/heads/<target-branch> could be origin or fully qualified repo-url
   or git push url_with_pat HEAD:refs/heads/<target-branch> (url can also contain the PAT (personal access token to Github - with write access to target repo) of format:
   https://<username>:<PAT>@github.com/<username>/<repo>.git
   By doing this way we are appending the current pipeline local commit history in detached state, to whatever target branch we want.
4. Since still we require target branch(or source branch which triggered the build) we can use environment variable $(Build.SourceBranch) which is of format /refs/head/<branch> since its in detached state mode (uses refs-heads)

This is particularly useful if for whatever reason you are trying not to checkout a branch

If the above method is not required, then still a direct checkout of specific branch can be made using classical git checkout -b <branch>

NOTE: can be substituted with trimmed $(Build.SourceBranch) where prefixing /refs/heads/ can be removed before using

Answer 2

"src refspec master does not match any" means the re is no local master branch to push.

That is because the commit has been created in a detached HEAD (no branch)

You must create first the master branch with git checkout -b master before adding and committing.
More precisely, as I mentioned here:

git checkout master 2>/dev/null || git checkout -b master;

The OP dan confirms in the comments:

when it got sources in previous step it checked out to different branch than master (git checkout --progress --force e7a1479dc5d2139be5247a027721e2a88b44a890)

A checkout of a commit directly results by definition in a detached HEAD.