All Products
Search

This Product

    Function Compute:Custom runtimes

    Document Center

    Function Compute:Custom runtimes

    Last Updated:Sep 05, 2025

    Function Compute provides built-in runtimes for popular programming languages such as Node.js, Python, PHP, Java, C#, and Go, allowing you to focus on coding your business logic without worrying about any additional configuration. However, in certain scenarios, you may need to use less common programming languages or specific versions of a language to fulfill your specific business requirements. In such cases, you can create a custom runtime to establish a tailored environment. For example, you can use programming languages like Rust, or specify a version of Node.js, like Node.js 16, in your custom runtime.

    We recommend that you use web functions with a custom runtime. This combination allows you to quickly set up various popular web application frameworks, making it easier to build and deploy HTTP-based applications and services. You can customize the startup command and listening port for your custom runtime, and instance-level concurrency is also supported.

    Container environments

    The following table lists the container environments supported by custom runtimes.

    Runtime

    Identifier

    Operating system

    Architecture

    Custom runtime (Debian 12) (in public preview)

    custom.debian12

    Debian 12

    x86_64

    Custom runtime (Debian 11)

    custom.debian11

    Debian 11

    x86_64

    Custom runtime (Debian 10)

    custom.debian10

    Debian 10

    x86_64

    Custom runtime (Debian 9)

    custom

    Debian 9

    x86_64

    Important

    Custom runtime (Debian 12) is supported in the following regions: China (Hangzhou), China (Qingdao), China (Beijing), China (Zhangjiakou), China (Hohhot), and China (Chengdu).

    Functions created after 00:00:00 on December 1, 2021

    • User permissions: Functions must be executed by root users.

    • Directory permissions: Data can be written to any directory.

    • Code location in the container: /code.

    Functions created before 00:00:00 on December 1, 2021

    • User permissions: Functions must be executed by non-root users.

    • Directory permissions: Data can only be written to the /tmp directory.

    • Code location in the container: /code.

    Environment information

    Built-in dependencies

    The built-in dependencies of a custom runtime are the same as those of a built-in runtime. For more information, see the following topics:

    When you create a web function with a custom runtime, the system automatically configures the corresponding public layer for the programming language you use. For example, a Flask layer is automatically configured when you create a web function in Python.

    Custom runtime (Debian 12)

    The following table shows the built-in programming language of custom runtime (Debian 12). You can write code for your custom runtime function directly in the following language without installing third-party interpreters or configuring layers.

    In some programming languages, you need to configure environment variables. Refer to the following table for details.

    Programming language

    Installation directory

    Version

    Environment variable

    Python 3.11

    /usr/bin/python3

    3.11.2

    No extra settings required

    Custom runtime (Debian 11)

    The following table shows the built-in programming language of custom runtime (Debian 11). You can write code for your custom runtime function directly in the following language without installing third-party interpreters or configuring layers.

    In some programming languages, you need to configure environment variables. Refer to the following table for details.

    Programming language

    Installation directory

    Version

    Environment variable

    Python 3.12

    /var/fc/lang/python3.12

    3.12.4

    PATH=/var/fc/lang/python3.12/bin:$PATH

    Custom runtime (Debian 10)

    The following table lists the built-in programming languages of custom runtime (Debian 10). You can write code for your custom runtime function directly in the following languages without installing third-party interpreters or configuring layers.

    In some programming languages, you need to configure environment variables. Refer to the following table for details.

    Programming language

    Installation directory

    Version

    Environment variable

    Node.js 20

    /var/fc/lang/nodejs20

    v20.10.0

    PATH=/var/fc/lang/nodejs20/bin:$PATH

    Node.js 18

    /var/fc/lang/nodejs18

    v18.19.0

    PATH=/var/fc/lang/nodejs18/bin:$PATH

    Python 3.10

    /var/fc/lang/python3.10

    3.10.9

    PATH=/var/fc/lang/python3.10/bin:$PATH

    Python 2.7

    Default installation directory

    2.7.16

    N/A

    Custom runtime (Debian 9)

    The following items list the built-in programming languages of custom runtime (Debian 9). You can write code for your custom runtime function directly in the following languages without installing third-party interpreters or configuring layers.

    • Python 3.7.4 (default Python version)

    • Node.js 10.16.2

    • OpenJDK 1.8.0

    • Ruby 2.7

    • Nginx 1.10.3

    • PHP 7.4.12

      Expand to see a list of built-in extensions of PHP 7.4.12.

      bcmath

      calendar

      Core

      ctype

      curl

      date

      dom

      exif

      FFI

      fileinfo

      filter

      ftp

      gd

      gettext

      hash

      iconv

      imagick

      imap

      intl

      json

      libxml

      mbstring

      mcrypt

      memcached

      mysqli

      mysqlnd

      openSSL

      pcntl

      pcre

      PDO

      pdo_mysql

      pdo_pgsql

      pdo_sqlite

      pgsql

      Phar

      posix

      protobuf

      readline

      redis

      Reflection

      session

      shmop

      SimpleXML

      soap

      sockets

      sodium

      SPL

      sqlite3

      standard

      swoole

      sysvmsg

      sysvsem

      sysvshm

      tokenizer

      xml

      xmlreader

      xmlrpc

      xmlwriter

      xsl

      Zend OPcache

      zip

      zlib

      None

    Use a non-built-in programming language

    Note

    We recommend that you use a public layer if you want to write function code in a non-built-in programming language. For more information, see Configure common layers in the Function Compute console.

    If you want to create a custom runtime by using a non-built-in programming language, you must package the interpreter or runtime for that language with your code file and deploy the package to Function Compute. For example, to create a Node.js 16 runtime, you must download the required interpreter, package it with your code, and then deploy the package to Function Compute. Perform the following steps:

    1. Download Node.js of a 64-bit Linux version to the code package directory. 

      wget http://mirrors.nju.edu.cn/nodejs/v16.14.2/node-v16.14.2-linux-x64.tar.gz -O node-v16.14.2-linux-x64.tar.gz && tar -zxvf node-v16.14.2-linux-x64.tar.gz && rm -rf node-v16.14.2-linux-x64.tar.gz

    2. Configure the startup command of Node.js in the custom runtime. 

      customRuntimeConfig:
  command:
    - /code/node-v16.14.2-linux-x64/bin/node
  args:
    - 'server.js'

# You can also configure the following environment variable for your function: PATH=/code/node-v16.14.2-linux-x64/bin:/usr/local/bin/apache-maven/bin:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/ruby/bin. 
# After the configuration is complete, you can use Node.js to start the HTTP server.

    Install dependencies

    For more information about how to install the dependencies of each programming language in a custom runtime, see the following topics:

    You can also use layers of Function Compute to install dependencies. We recommend that you use a public layer or build a dependency layer online. For more information, see the following topics: