Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

plugins/processors/strings/README.md

@@ -0,0 +1,186 @@
+# 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
+- titlecase
+- trim
+- trim_left
+- trim_right
+- trim_prefix
+- trim_suffix
+- replace
+- left
+- base64decode
+- valid_utf8
+
+Please note that in this implementation these are processed in the order that
+they appear above.
+
+Specify the `measurement`, `tag`, `tag_key`, `field`, or `field_key` 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.
+
+If you'd like to apply the change to every `tag`, `tag_key`, `field`,
+`field_key`, or `measurement`, use the value `"*"` for each respective
+field. Note that the `dest` field will be ignored if `"*"` is used.
+
+If you'd like to apply multiple processings to the same `tag_key` or
+`field_key`, note the process order stated above. See the second example below
+for an example.
+
+## Global configuration options <!-- @/docs/includes/plugin_config.md -->
+
+In addition to the plugin-specific configuration settings, plugins support
+additional global and plugin configuration settings. These settings are used to
+modify metrics, tags, and field or create aliases and configure ordering, etc.
+See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
+
+[CONFIGURATION.md]: ../../../docs/CONFIGURATION.md#plugins
+
+## Configuration
+
+```toml @sample.conf
+# Perform string processing on tags, fields, and measurements
+[[processors.strings]]
+  ## Convert a field value to lowercase and store in a new field
+  # [[processors.strings.lowercase]]
+  #   field = "uri_stem"
+  #   dest = "uri_stem_normalised"
+
+  ## Convert a tag value to uppercase
+  # [[processors.strings.uppercase]]
+  #   tag = "method"
+
+  ## Convert a field value to titlecase
+  # [[processors.strings.titlecase]]
+  #   field = "status"
+
+  ## Trim leading and trailing whitespace using the default cutset
+  # [[processors.strings.trim]]
+  #   field = "message"
+
+  ## Trim leading characters in cutset
+  # [[processors.strings.trim_left]]
+  #   field = "message"
+  #   cutset = "\t"
+
+  ## Trim trailing characters in cutset
+  # [[processors.strings.trim_right]]
+  #   field = "message"
+  #   cutset = "\r\n"
+
+  ## Trim the given prefix from the field
+  # [[processors.strings.trim_prefix]]
+  #   field = "my_value"
+  #   prefix = "my_"
+
+  ## Trim the given suffix from the field
+  # [[processors.strings.trim_suffix]]
+  #   field = "read_count"
+  #   suffix = "_count"
+
+  ## Replace all non-overlapping instances of old with new
+  # [[processors.strings.replace]]
+  #   measurement = "*"
+  #   old = ":"
+  #   new = "_"
+
+  ## Trims strings based on width
+  # [[processors.strings.left]]
+  #   field = "message"
+  #   width = 10
+
+  ## Decode a base64 encoded utf-8 string
+  # [[processors.strings.base64decode]]
+  #   field = "message"
+
+  ## Sanitize a string to ensure it is a valid utf-8 string
+  ## Each run of invalid UTF-8 byte sequences is replaced by the replacement string, which may be empty
+  # [[processors.strings.valid_utf8]]
+  #   field = "message"
+  #   replacement = ""
+```
+
+### 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.
+
+### Replace
+
+The `replace` function does a substring replacement across the entire
+string to allow for different conventions between various input and output
+plugins. Some example usages are eliminating disallowed characters in
+field names or replacing separators between different separators.
+Can also be used to eliminate unneeded chars that were in metrics.
+If the entire name would be deleted, it will refuse to perform
+the operation and keep the old name.
+
+## Example
+
+A sample configuration:
+
+```toml
+[[processors.strings]]
+  [[processors.strings.lowercase]]
+    tag = "uri_stem"
+
+  [[processors.strings.trim_prefix]]
+    tag = "uri_stem"
+    prefix = "/api/"
+
+  [[processors.strings.uppercase]]
+    field = "cs-host"
+    dest = "cs-host_normalised"
+```
+
+Sample input:
+
+```text
+iis_log,method=get,uri_stem=/API/HealthCheck cs-host="MIXEDCASE_host",http_version=1.1 1519652321000000000
+```
+
+Sample output:
+
+```text
+iis_log,method=get,uri_stem=healthcheck cs-host="MIXEDCASE_host",http_version=1.1,cs-host_normalised="MIXEDCASE_HOST" 1519652321000000000
+```
+
+### Second Example
+
+A sample configuration:
+
+```toml
+[[processors.strings]]
+  [[processors.strings.lowercase]]
+    tag_key = "URI-Stem"
+
+  [[processors.strings.replace]]
+    tag_key = "uri-stem"
+    old = "-"
+    new = "_"
+```
+
+Sample input:
+
+```text
+iis_log,URI-Stem=/API/HealthCheck http_version=1.1 1519652321000000000
+```
+
+Sample output:
+
+```text
+iis_log,uri_stem=/API/HealthCheck http_version=1.1 1519652321000000000
+```