Python function to construct a ZIP archive with stream processing - without having to store the entire ZIP in memory or disk
Project description
stream-zip 
Python function to construct a ZIP archive on the fly - without having to store the entire ZIP in memory or disk. This is useful in memory-constrained environments, or when you would like to start returning compressed data before you've even retrieved all the uncompressed data. Generating ZIPs on-demand in a web server is a typical use case for stream-zip.
Offers similar functionality to zipfly, but with a different API, and does not use Python's zipfile module under the hood.
To unZIP files on the fly try stream-unzip.
Installation
pip install stream-zip
Usage
from datetime import datetime
from stream_zip import ZIP64, ZIP, NO_COMPRESSION, stream_zip
def unzipped_files():
modified_at = datetime.now()
perms = 0o600
def file_1_data():
yield b'Some bytes'
def file_2_data():
yield b'Some bytes'
def file_3_data():
yield b'Some bytes'
# ZIP64 mode
yield 'my-file-1.txt', modified_at, perms, ZIP64, file_1_data()
# ZIP mode
yield 'my-file-1.txt', modified_at, perms, ZIP, file_2_data()
# No compression
yield 'my-file-2.txt', modified_at, perms, NO_COMPRESSION, file_3_data()
for zipped_chunk in stream_zip(unzipped_files()):
print(zipped_chunk)
Limitations
It's not possible to completely stream-write ZIP files. Small bits of metadata for each member file, such as its name, must be placed at the end of the ZIP. In order to do this, stream-unzip buffers this metadata in memory until it can be output.
No compression is supported via the NO_COMPRESSION constant as in the above examples. However in this case the entire contents of these are buffered in memory, and so this should not be used for large files. This is because for uncompressed data, its size and CRC32 must be before it in the ZIP file.
It doesn't seem possible to automatically choose ZIP64 based on file sizes if streaming, since the specification of ZIP vs ZIP64 must be before the compressed data of each file in the final stream, and so before the sizes are known. Hence the onus is on client code to choose. ZIP has greater support but is limited to 4GiB (gibibyte), while ZIP64 has less support, but has a much greater limit of 16EiB (exbibyte). These limits apply to the compressed size of each member file, the uncompressed size of each member file, and to the size of the entire archive.
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