This topic describes how to use a custom runtime to write functions in aFunction Compute.

Background information

Custom runtimes allow you to define runtime environments. In a custom runtime, you can define the runtime environment based on your requirements. For example, you can perform the following operations:
  • Customize personalized languages, such as Rust.
  • Use a runtime environment of the specified version for a programming language, such as Node.js 16.

Container environment

A custom runtime runs in the following container environment:
  • Operating system: Debian 9
  • Architecture: x86_64.
  • User permissions:
    • If functions are created at and after 00:00:00 December 1, 2021, the functions must be executed by the root user.
    • If functions are created before 00:00:00 December 1, 2021, the functions must be executed by a non-root user.
  • Directory permissions:
    • If functions are created at and after 00:00:00 December 1, 2021, all the directories are writable.
    • If functions are created before 00:00:00 December 1, 2021, only the /tmp directory is writable.
  • Directory location of the code in the container: /code.

Environment Information

A custom runtime supports the following built-in languages of the specified versions. You can create custom runtimes of the following languages without the need to install third-party interpreters:
  • Python 3.7.4
  • Node.js 10.16.2
  • OpenJDK 1.8.0
  • Ruby 2.7
  • PowerShell 7.1.0
  • Nginx 1.10.3
  • PHP 7.4.12
    Among them, PHP 7.4.12 built-in extensions list as follows:
    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

For more information about the built-in software of custom runtime, see Details.

Use non-built-in programming languages

If you plan to use a language to make a custom runtime, but the language is not a built-in language for the custom runtime, you need to package and deploy the language's parser or runtime and code files to the Function Compute to achieve your intended goals. For example, if the runtime environment is Node.js 16, you must download the interpreter of Node.js 16, compress the interpreter and your code file into a package, and then deploy the package in Function Compute. Perform the following steps:

  1. Download the Linux-x64 version of the node to the code package directory.
    wget -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. Set the node to use the custom runtime startup command.
        - /code/node-v16.14.2-linux-x64/bin/node
        - 'server.js'
    # You can also set the environment variable 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
    # In this way, you can directly use node to start the HTTP Server.