exec-wasi.md

Exec Wasi

The exec_wasi input plugin, allows to execute WASM program that is WASI target like as external program and collects event logs from there.

Configuration Parameters

The plugin supports the following configuration parameters:

Key	Description
WASI_Path	The place of a WASM program file.
Parser	Specify the name of a parser to interpret the entry as a structured message.
Accessible_Paths	Specify the whitelist of paths to be able to access paths from WASM programs.
Interval_Sec	Polling interval (seconds).
Interval_NSec	Polling interval (nanosecond).
Wasm_Heap_Size	Size of the heap size of Wasm execution. Review unit sizes for allowed values.
Wasm_Stack_Size	Size of the stack size of Wasm execution. Review unit sizes for allowed values.
Buf_Size	Size of the buffer (check unit sizes for allowed values)
Oneshot	Only run once at startup. This allows collection of data precedent to fluent-bit's startup (bool, default: false)
Threaded	Indicates whether to run this input in its own thread. Default: false.

Configuration Examples

Here is a configuration example. in_exec_wasi can handle parser. To retrieve from structured data from WASM program, you have to create parser.conf:

Note that Time_Format should be aligned for the format of your using timestamp. In this documents, we assume that WASM program should write JSON style strings into stdout.

[PARSER]
    Name        wasi
    Format      json
    Time_Key    time
    Time_Format %Y-%m-%dT%H:%M:%S.%L %z

Then, you can specify the above parsers.conf in the main fluent-bit configuration:

[SERVICE]
    Flush        1
    Daemon       Off
    Parsers_File parsers.conf
    Log_Level    info
    HTTP_Server  Off
    HTTP_Listen  0.0.0.0
    HTTP_Port    2020

[INPUT]
    Name exec_wasi
    Tag  exec.wasi.local
    WASI_Path /path/to/wasi/program.wasm
    Accessible_Paths .,/path/to/accessible
    Parser wasi

[OUTPUT]
    Name  stdout
    Match *