Accessing File Systems from Running Functions

Find out how to access file systems from running functions deployed to OCI Functions.

A function you've deployed to OCI Functions can access the file system of the container in which it's running as follows:

  • the function can read files from all directories
  • the function can write files to the /tmp directory

For example, you might want a function to download an Excel file and then read its contents. To meet this requirement, you might create a function that writes the file to the /tmp directory in the container's filesystem, and then subsequently reads the file.

When writing files to the /tmp directory, the /tmp directory is generally always writable. However, the maximum allowable size of the /tmp directory depends on the maximum memory threshold specified for the function:

Maximum memory threshold for the function (MB) Maximum allowed size of /tmp (MB) Maximum allowed number of files (inodes) in /tmp
128 MB 32 MB 1024
256 MB 64 MB 2048
512 MB 128 MB 4096
1024 MB 256 MB 8192
2048 MB 512 MB 16384

Note that the /tmp directory might be shared by successive invocations of the function. A file written by an earlier invocation of a function could still exist when the function is invoked a second time. It is your responsibility to delete any files to avoid unexpected behavior.