How Does a Function Read or Write Files?

Background

A function can read files in the code directory. The working directory of a function is the upper-level directory of the handler file. Assume that you have uploaded a folder named backend. To read its test.conf file in the same level of directory as the handler file, use relative path code/backend/test.conf or use a full path (that is, the value of the RUNTIME_CODE_ROOT environment variable). To write a file (for example, to create or download a file), go to the /tmp directory or use the file system mounting feature provided by FunctionGraph.

• If containers are reclaimed, file read/written content will become invalid.
• Currently, FunctionGraph does not support instance persistence.

Typical Scenarios

• Download files stored in Object Storage Service (OBS) to the /tmp directory for processing.
• To store function execution data in OBS, create a file in the /tmp directory, write the data into the file, and then upload the file to OBS.