Upload CodeBuild artifacts *if* they exist - amazon-web-services

Question

I have a simple CodeBuild spec that defines artifacts to be uploaded after tests run:
artifacts:
files:
- cypress/**/*.png
discard-paths: yes
These artifacts are only generated if the test-action fails (a screenshot is captured of the failing test screen) and are being successfully uploaded to S3.
In the case that tests succeed, no .png files will be generated and the CodeBuild action fails:
[Container] 2018/09/21 20:06:34 Expanding cypress/**/*.png
[Container] 2018/09/21 20:06:34 Phase complete: UPLOAD_ARTIFACTS Success: false
[Container] 2018/09/21 20:06:34 Phase context status code: CLIENT_ERROR Message: no matching artifact paths found
Is there a way to conditionally upload files if they exist in the buildspec?
Alternatively I could use the s3 cli -- in which case I would need a way to easily access the bucket name and artifact key.

Answer 1

To get around this, I'm creating a placeholder file that matches the glob pattern if build succeeds:
post_build:
commands:
- if [ -z "$CODEBUILD_BUILD_SUCCEEDING" ]; then echo "Build failing, no need to create placeholder image"; else touch cypress/0.png; fi
artifacts:
files:
- cypress/**/*.png
discard-paths: yes

Answer 2

If any one still looking for solution base on tgk answer.
in my cas I wanna upload the artifact only in master ENV , so other than master I create a place holder and upload in a TMP folder.
post_build:
commands:
#creating a fake file to workaround fail upload in non prod build
- |
if [ "$ENV" = "master" ]; then
export FOLDERNAME=myapp-$(date +%Y-%m-%d).$((BUILD_NUMBER))
else
touch myapp/0.tmp;
export FOLDERNAME="TMP"
fi
artifacts:
files:
- myapp/build/outputs/apk/prod/release/*.apk
- myapp/*.tmp
discard-paths: yes
name: $FOLDERNAME