Environment

Environment variablesEnvironment variables

The table provides a list of environment variables defined in the Cloud Functions runtime and available to a function. You cannot override these.

You can add other environment variables when creating a function version. The limit for maximum environment variable size, including variable names, is 4 KB.

You cannot calculate environment variables. Environment variable values are string constants. You can only calculate these within function code.

You can retrieve environment variables using standard programming language tools.

Use casesUse cases

• Status monitoring of geographically distributed devices
• Sensor reading monitoring and event notifications
• Deploying a fault-tolerant architecture with preemptible VMs

Certificate for accessing managed databasesCertificate for accessing managed databases

The environment has an SSL certificate available for accessing managed databases from your code. The certificate is stored in the /usr/local/share/ca-certificates/yandex-internal-ca.crt file.

User filesUser files

User files are stored in two directories:

• /function/code: User's working directory. It contains all the code of your function and all the files uploaded as a ZIP archive. You can use a relative path to access it.

• /tmp: Directory for temporary files. It is used by the service to optimize repeat function calls that are sequentially processed by one of its instances. When a function instance ceases to operate, the data is deleted from /tmp. The maximum size of temporary files is limited to 512 MB.

  When creating a function version, you can allocate some of the function instance's RAM for the tmp directory. The specified amount of RAM will thus be mounted as a RAM disk to the /tmp directory. A function version needs at least 1 GB of RAM.

  If you enable Allocate memory for the /tmp directory, preloaded runtime environments start as regular ones.

Dynamic librariesDynamic libraries

If a function requires dynamic libraries to operate, these can be uploaded as a ZIP archive, in the /shared-libs directory at the root of the archive. The directory will be added to the LD_LIBRARY_PATH environment variable.

The dynamic libraries must be assembled on Ubuntu 18.04 LTS and linked with libc 2.27.