file

Writes messages to files on disk based on a chosen codec.

# Config fields, showing default values
output:
  label: ""
  file:
    path: ""
    codec: lines

Messages can be written to different files by using interpolation functions in the path field. However, only one file is ever open at a given time, and therefore when the path changes the previously open file is closed.

Batches and Multipart Messages

When writing multipart (batched) messages using the lines codec the last message ends with double delimiters. E.g. the messages "foo", "bar" and "baz" would be written as:

foo\n
bar\n
baz\n

Whereas a multipart message [ "foo", "bar", "baz" ] would be written as:

foo\n
bar\n
baz\n\n

This enables consumers of this output feed to reconstruct the original batches. However, if you wish to avoid this behaviour then add a split processor before messages reach this output.

Fields

path

The file to write to, if the file does not yet exist it will be created. This field supports interpolation functions.

Type: string
Default: ""
Requires version 3.33.0 or newer

# Examples

path: /tmp/data.txt

path: /tmp/${! timestamp_unix() }.txt

path: /tmp/${! json("document.id") }.json

codec

The way in which the bytes of messages should be written out into the output data stream. It's possible to write lines using a custom delimiter with the delim:x codec, where x is the character sequence custom delimiter.

Type: string
Default: "lines"
Requires version 3.33.0 or newer

Option	Summary
all-bytes	Only applicable to file based outputs. Writes each message to a file in full, if the file already exists the old content is deleted.
append	Append each message to the output stream without any delimiter or special encoding.
lines	Append each message to the output stream followed by a line break.
delim:x	Append each message to the output stream followed by a custom delimiter.

# Examples

codec: lines

codec: "delim:\t"

codec: delim:foobar