unable to upload non-image artifacts with cloud build - docker

Question

I have a very simple container (effectively the Cloud Build quickstart sample code) that generates a file. I'm trying to extend this container to upload said file to a bucket via the documentation on storing non-image artifacts with Cloud Build.
My Dockerfile builds a trivial container and executes a single script:
FROM alpine
WORKDIR /app
COPY . /app # the only file present is quickstart.sh
CMD ["./quickstart.sh"]
The script (quickstart.sh) generates a simple timestamp file:
#!/bin/sh
echo "Creating file 'time.txt'"
echo "The time is $(date)" > time.txt
## for debugging:
# pwd
# ls
# cat time.txt
My cloudbuild.yaml file is basically copy-pasted from the aforementioned docs, and is configured to upload the file:
steps:
- name: 'gcr.io/cloud-builders/docker'
args: [ 'build', '-t', 'gcr.io/$PROJECT_ID/quickstart-image', '.' ]
artifacts:
objects:
location: 'gs://my-bucket/'
paths: ['*.txt']
images:
- 'gcr.io/$PROJECT_ID/quickstart-image'
However, the file fails to upload and the build fails as a result. When I run the build command
gcloud builds submit --config cloudbuild.yaml .
All logs are successful until the end:
Artifacts will be uploaded to gs://my-bucket using gsutil cp
*.txt: Uploading path....
CommandException: No URLs matched: *.txt
CommandException: 1 file/object could not be transferred.
ERROR
ERROR: could not upload *.txt to gs://my-bucket/; err = exit status 1
Where gsutil is claiming no matching file can be found. However, if I build manually and generate the file, I can use gsutil cp *.txt gs://my-bucket/ to upload the file with no problem. So it's almost as if the file is wiped before Cloud Build reaches the "upload artifacts" step, but that does not seem like it would make sense. I imagine this is a pretty common use case but I'm not making any progress with the documentation alone. Any ideas? Thanks.

Answer 1

The issue here is that with the current steps, you are just building the container and not running it so the time.txt file doesn't get created. Even if you run the container, then the file gets created inside the container so you need to fetch it from inside the container so that gsutil can "see" the file.
I added 2 steps in the cloudbuild.yaml file to do this:
steps:
- name: 'gcr.io/cloud-builders/docker'
args: [ 'build', '-t', 'gcr.io/$PROJECT_ID/quickstart-image', '.' ]
- name: 'gcr.io/cloud-builders/docker'
args: [ 'run', '--name', 'containername', 'gcr.io/$PROJECT_ID/quickstart-image']
- name: 'gcr.io/cloud-builders/docker'
args: [ 'cp', 'containername:/app/time.txt, './time.txt']
artifacts:
objects:
location: 'gs://mybucket/'
paths: ['*.txt']
images:
- 'gcr.io/$PROJECT_ID/quickstart-image'
I hope this works for you.