Gitlab CI Child pipeline - gitlab

Question

I have a problem with gitlab ci child pipelines.
Need to trigger ci pipeline automatically after each commit in repo that have more than one app. Need to configure to detect which folder/files were modified in order to know which app pipeline to trigger
Example of structure
Main/
---- applicationsA/
-------- appA1/
-------- appA2/
-------- appA3/
---- applicationsB/
-------- appB1/
-------- appB2/
-------- appB3/
Main ".gitlab-ci.yml" is:
workflow:
rules:
- if: ‘$CI_PIPELINE_SOURE == “web”’
variables:
APPNAME: $APPNAME
stages:
- child-pipelines
appA1:
stage: child-pipelines
trigger:
include:
- local: applicationA/appA1/gitlab-ci.yml
strategy: depend
rules:
- if: $APPNAME == “appA1” && $CI_PIPELINE_SOURE == “web”
appA2:
stage: child-pipelines
trigger:
include:
- local: applicationA/appA2/gitlab-ci.yml
strategy: depend
rules:
- if: $APPNAME == “appA1” && $CI_PIPELINE_SOURE == “web”
...
appA1 ".gitlab-ci.yml" is:
stages:
- build
- test
build-appA1:
stage: build
script:
- echo "Execute appA1 build!"
publish-appA1:
stage: build
script:
- echo "Execute appA1 publish!"
appA2 ".gitlab-ci.yml" is:
stages:
- build
- test
build-appA2:
stage: build
script:
- echo "Execute appA1 build!"
publish-appA2:
stage: build
script:
- echo "Execute appA1 publish!"
The purpose of this configuration is that , for example, when i change a file inside app**, the pipeline detects the changes and build the app**.

Answer 1

You can use rules:changes with a glob pattern and only run a certain job if anything changes in the specific app folder:
appA1:
stage: child-pipelines
trigger:
include:
- local: applicationA/appA1/gitlab-ci.yml
strategy: depend
rules:
- if: '$APPNAME == "appA1" && $CI_PIPELINE_SOURE == "web"'
changes:
- Main/applicationsA/appA1/**/*