Reference manual

File Structure Setup

To use FaaSr, you need to organize your project files as follows:

your-project/
├── workflow.json              # Your FaaSr workflow configuration (you will be passing this path)
├── faasr_data/                # Created automatically by faasr_test()
│   ├── functions/             # (Optional) User R functions
│   ├── files/                 # Simulated S3 storage
│   ├── logs/                  # Log files
│   └── temp/                  # Temporary execution files
└── my_functions.R             # (Optional) Your R functions

Key Components:

1. Workflow JSON file: Your FaaSr workflow configuration (can be anywhere; you pass the path to faasr_test())

2. R Functions: Your workflow functions can be stored in several locations:

   • In the package’s inst/extdata/functions/ directory (for package development)
   • In faasr_data/functions/ in your working directory
   • As standalone R files that you source before calling faasr_test()

3. faasr_data folder: Automatically created by faasr_test() to simulate cloud infrastructure:

   • files/ - Simulates S3 bucket storage for file operations
   • logs/ - Stores execution logs from faasr_log() calls
   • temp/ - Temporary workspace for function execution

Creating a Workflow Configuration

The workflow JSON configuration file is described by the FaaSr JSON schema.

Recommended approach: Use the FaaSr workflow builder to create and manage your workflow configuration files with a visual interface.

faasr_test

Usage: faasr_test(json_path)

json_path is a required argument and specifies the path of a FaaSr workflow configuration file

This is the only function that you need to call in order to run this local test. It loads the JSON-formatted workflow configuration file from the path specified by json_path and execute the functions in the order specified in the workflow.

faasr_put_file

Usage: faasr_put_file(server_name = NULL, local_folder = ".", local_file, remote_folder = "", remote_file)

Uploads a file from the local filesystem to the local FaaSr storage (simulating S3 bucket upload).

Parameters: - server_name: String specifying the server name (ignored in local implementation) - local_folder: String path to the local folder containing the file to upload (default: “.”) - local_file: String name of the local file to upload (required) - remote_folder: String path to the remote folder where the file will be stored (default: ““) - remote_file: String name for the file in remote storage (required)

Example:

faasr_put_file(local_file="output.csv", remote_folder="myfolder", remote_file="myoutput.csv")

faasr_get_file

Usage: faasr_get_file(server_name = NULL, remote_folder = "", remote_file, local_folder = ".", local_file)

Downloads a file from the local FaaSr storage to the local filesystem (simulating S3 bucket download).

Parameters: - server_name: String specifying the server name (ignored in local implementation) - remote_folder: String path to the remote folder containing the file to download (default: ““) - remote_file: String name of the remote file to download (required) - local_folder: String path to the local folder where the file will be saved (default:”.”) - local_file: String name for the file in local storage (required)

Example:

faasr_get_file(remote_folder="myfolder", remote_file="myinput1.csv", local_file="input1.csv")
faasr_get_file(server_name="My_Minio_Bucket", remote_file="myinput2.csv", local_file="input2.csv")

faasr_delete_file

Usage: faasr_delete_file(server_name = NULL, remote_folder = "", remote_file)

Deletes a file from the local FaaSr storage (simulating S3 bucket file deletion).

Parameters: - server_name: Character string specifying the server name (ignored in local implementation) - remote_folder: Character string path to the remote folder containing the file to delete (default: ““) - remote_file: Character string name of the remote file to delete (required)

Example:

faasr_delete_file(remote_folder="myfolder", remote_file="myoutput.csv")
faasr_delete_file(server_name="My_Minio_Bucket", remote_file="myoutput.csv")

faasr_get_folder_list

Usage: faasr_get_folder_list(server_name = NULL, faasr_prefix = "")

Lists all files in the local FaaSr storage, optionally filtered by a prefix (simulating S3 bucket listing).

Parameters: - server_name: Character string specifying the server name (ignored in local implementation) - faasr_prefix: Character string prefix to filter file names (optional, default: ““)

Returns: Character vector of file names matching the criteria

Example:

mylist1 <- faasr_get_folder_list(server_name="My_Minio_Bucket", faasr_prefix="myfolder")
mylist2 <- faasr_get_folder_list(server_name="My_Minio_Bucket", faasr_prefix="myfolder/mysubfolder")

faasr_log

Usage: faasr_log(log_message)

Appends a log message with timestamp to the local FaaSr log file. This is useful for debugging and tracking workflow execution.

Parameters: - log_message: Character string message to log (required)

Example:

log_msg <- paste0('Function compute_sum finished; output written to ', folder, '/', output, ' in default S3 bucket')
faasr_log(log_msg)

faasr_rank

Usage: faasr_rank()

Returns the current rank information for the executing function in a parallel workflow. This is useful when functions are executed in parallel and need to know their position in the execution order.

Returns: List containing rank and max_rank, or empty list if no rank information is available

Example:

# Get current rank information
rank_info <- faasr_rank()
if (length(rank_info) > 0) {
  cat("Current rank:", rank_info$rank, "of", rank_info$max_rank, "\n")
}

faasr_invocation_id

Usage: faasr_invocation_id()

Returns the invocation ID for the current workflow execution. This unique identifier can be used to track and correlate logs and outputs from a specific workflow run.

Returns: Character string invocation ID, or NULL if not available

Example:

# Get current invocation ID
inv_id <- faasr_invocation_id()
if (!is.null(inv_id)) {
  cat("Invocation ID:", inv_id, "\n")
}