telegraf/plugins/processors/strings/README.md

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# Strings Processor Plugin
The `strings` plugin maps certain go string functions onto measurement, tag, and field values. Values can be modified in place or stored in another key.
Implemented functions are:
- lowercase
- uppercase
- trim
- trim_left
- trim_right
- trim_prefix
- trim_suffix
Please note that in this implementation these are processed in the order that they appear above.
Specify the `measurement`, `tag` or `field` that you want processed in each section and optionally a `dest` if you want the result stored in a new tag or field. You can specify lots of transformations on data with a single strings processor.
### Configuration:
```toml
[[processors.strings]]
# [[processors.strings.uppercase]]
# tag = "method"
# [[processors.strings.lowercase]]
# field = "uri_stem"
# dest = "uri_stem_normalised"
## Convert a tag value to lowercase
# [[processors.strings.trim]]
# field = "message"
# [[processors.strings.trim_left]]
# field = "message"
# cutset = "\t"
# [[processors.strings.trim_right]]
# field = "message"
# cutset = "\r\n"
# [[processors.strings.trim_prefix]]
# field = "my_value"
# prefix = "my_"
# [[processors.strings.trim_suffix]]
# field = "read_count"
# suffix = "_count"
```
#### Trim, TrimLeft, TrimRight
The `trim`, `trim_left`, and `trim_right` functions take an optional parameter: `cutset`. This value is a string containing the characters to remove from the value.
#### TrimPrefix, TrimSuffix
The `trim_prefix` and `trim_suffix` functions remote the given `prefix` or `suffix`
respectively from the string.
### Example
**Config**
```toml
[[processors.strings]]
[[processors.strings.lowercase]]
field = "uri-stem"
[[processors.strings.trim_prefix]]
field = "uri_stem"
prefix = "/api/"
[[processors.strings.uppercase]]
field = "cs-host"
dest = "cs-host_normalised"
```
**Input**
```
iis_log,method=get,uri_stem=/API/HealthCheck cs-host="MIXEDCASE_host",referrer="-",ident="-",http_version=1.1,agent="UserAgent",resp_bytes=270i 1519652321000000000
```
**Output**
```
iis_log,method=get,uri_stem=healthcheck cs-host="MIXEDCASE_host",cs-host_normalised="MIXEDCASE_HOST",referrer="-",ident="-",http_version=1.1,agent="UserAgent",resp_bytes=270i 1519652321000000000
```