Saving image file on filesystem on Google App Engine with Python Flask - google-app-engine

Question

I have a Flask app where a user can upload an image and the image is saved on a static folder on the filesystem.
Currently, I'm using Google App Engine for hosting and found that it's not possible to save to the static folder on the standard environment. Here is the code
def save_picture(form_picture,name):
picture_fn = name + '.jpg'
picture_path = os.path.join(app.instance_path, 'static/image/'+ picture_fn)
output_size = (1000,1000)
i = Image.open(form_picture)
i.thumbnail(output_size)
i.save(picture_path)
return picture_path
#app.route('/image/add', methods=['GET', 'POST'])
def addimage():
form = Form()
if form.validate_on_submit():
name = 'randomname'
try:
picture_file = save_picture(form.image.data,name)
return redirect(url_for('addimage'))
except:
flash("unsuccess")
return redirect(url_for('addimage'))
My question is if I change from standard to flex environment would it be possible to save to a static folder? If not what are the other hosting options that I should consider? Do you have any suggestions?
Thanks in advance.
following your's advice I'm changing to use Cloud Storage. i'm wondering what should i use from upload_from_file(), upload_from_filename() or upload_from_string(). the source_file takes data from form.photo.data from flask-wtform. i'm not successfully saving on the cloud storage yet. this is my code:
def upload_blob(bucket_name, source_file, destination_blob_name):
storage_client = storage.Client()
bucket = storage_client.get_bucket(bucket_name)
blob = bucket.blob(destination_blob_name)
blob.upload_from_filename(source_file)
return destination_blob_name
#app.route('/image/add', methods=['GET', 'POST'])
def addimage():
form = Form()
if form.validate_on_submit():
name = 'randomname'
try:
filename = 'foldername/'+ name + '.jpg'
picture_file = upload_blob('mybucketname', form.photo.data, filename)
return redirect(url_for('addimage'))
except:
flash("unsuccess")
return redirect(url_for('addimage'))
I have successfully able to save file on google cloud storage by changing the save_picture function just in case anyone have trouble with this in the future:
app.config['BUCKET'] = 'yourbucket'
app.config['UPLOAD_FOLDER'] = '/tmp'
def save_picture(form_picture,name):
picture_fn = secure_filename(name + '.jpg')
picture_path = os.path.join(app.config['UPLOAD_FOLDER'], picture_fn)
output_size = (1000,1000)
i = Image.open(form_picture)
i.thumbnail(output_size)
i.save(picture_path)
storage_client = storage.Client()
bucket = storage_client.get_bucket(app.config['BUCKET'])
blob = bucket.blob('static/image/'+ picture_fn)
blob.upload_from_filename(picture_path)
return picture_path

Answer 1

The problem with storing it to some folder is that it would live on that one instance and other instances would not be able to access it. Furthermore, instances in GAE come and go, so you would lose the image eventually.
You should use Google Cloud Storage for this:
from google.cloud import storage
client = storage.Client()
bucket = client.get_bucket('bucket-id-here')
blob = bucket.get_blob('remote/path/to/file.txt')
blob.upload_from_string('New contents!')
https://googleapis.dev/python/storage/latest/index.html

Answer 2

With Flask and Appengine, Python3.7, I save files to a bucket in the following way, because I want to loop it for many files:
for key, upload in request.files.items():
file_storage = upload
content_type = None
identity = str(uuid.uuid4()) # or uuid.uuid4().hex
try:
upload_blob("f00b4r42.appspot.com", request.files[key], identity, content_type=upload.content_type)
The helper function:
from google.cloud import storage
def upload_blob(bucket_name, source_file_name, destination_blob_name, content_type="application/octet-stream"):
"""Uploads a file to the bucket."""
storage_client = storage.Client()
bucket = storage_client.get_bucket(bucket_name)
blob = bucket.blob(destination_blob_name)
blob.upload_from_file(source_file_name, content_type=content_type)
blob.make_public()
print('File {} uploaded to {}.'.format(
source_file_name,
destination_blob_name))

Answer 3

Changing from Google App Engine Standard Environment to Google App Engine Flexible Environment will allow you to write to disk, as well as to choose a Compute Engine machine type with more memory for your specific application [1]. If you are interested on following this path find all the relevant documentation from migrating a Python app here.
Nonetheless, as it was explained by user #Alex on his provided answer as instances are created (the number of instances is scaled up) or deleted (the number of instances is scaled down) according to your load, the better option in your particular case would be to use Cloud Storage. Find an example for uploading objects to Cloud Storage with Python here.