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.
![](https://support.huaweicloud.com/eu/functiongraph_faq/public_sys-resources/note_3.0-en-us.png)
- 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.
General FAQs FAQs
- What Is FunctionGraph?
- Do I Need to Apply for Any Compute, Storage, or Network Services When Using FunctionGraph?
- Do I Need to Deploy My Code After Programming?
- How Do I Obtain a Token?
- What Runtimes Does FunctionGraph Support?
- How Much Disk Space Is Allocated to Each FunctionGraph Function?
- Does FunctionGraph Support Function Versioning?
- How Does a Function Read or Write Files?
- How Do I Set a Proxy When Using CLI?
- Does FunctionGraph Support Function Extension?
- Which Permissions Are Required for an IAM User to Use FunctionGraph?
- How Can I Create an ODBC Drive-based Python Dependency Package for Database Query?
- What Is the Quota of FunctionGraph?
- What Chinese Fonts Does FunctionGraph Support?
- How Does FunctionGraph Resolve a Private DNS Domain Name?
- How Does a Container Image–based Function Resolve a Private DNS Domain Name?
- How Do I Use a Domain Name to Access an API Registered with API Gateway (Dedicated)?
- What Are the Common Application Scenarios of FunctionGraph?
- Why Can't the API Gateway Domain Name Bound to a Service Be Resolved During Function Invocation?
- Does FunctionGraph Support Synchronous Transmission at the Maximum Intranet Bandwidth?
- What If the VPC Quota Is Used Up?
- How Can I Print Info, Error, or Warn Logs?
- Can I Set the Domain Name of an API to My Own Domain Name?
- Can I Change the Runtime?
- Can I Change a Function's Name?
- Why Is Message "failed to mount exist system path" Displayed?
- How Do I Obtain Uploaded Files?
- Why Can't I Receive Responses for Synchronous Invocation?
- What Should I Do If the os.system("command &") Execution Logs Are Not Collected?
- Which Directories Can Be Accessed When a Custom Runtime Is Used?
- Which Minor Versions of Python 3.6 and 3.9 Are Supported?
- Which Actions Can Be Used Instead of a VPC Administrator Agency for VPC Access?
- What Are the Possible Causes for Function Timeout?
- How Do I Obtain the Code of a Function?
- Do You Have Sample Code for Initializers?
- How Do I Enable Structured Log Query?
- Can I Enable a Listening Port in a Function to Receive External TCP Requests via EIP?
- Does FunctionGraph Support Domain Name Resolution?
- How Do I Obtain the Source IP Address of an HTTP Request Initiated by a Function?
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