Provide basic string manupilation functions for template executions.

This change centralizes the template manipulation in a single package
and adds basic string functions to their execution.

Signed-off-by: David Calavera <david.calavera@gmail.com>
Upstream-commit: 8514880997bd1bc944769dcc41e52307bb01f7ff
Component: engine

components/engine/docs/admin/formatting.md

@@ -0,0 +1,66 @@
+<!--[metadata]>
++++
+title = "Format command and log output"
+description = "CLI and log output formatting reference"
+keywords = ["format, formatting, output, templates, log"]
+[menu.main]
+parent = "engine_admin"
+weight=-90
++++
+<![end-metadata]-->
+
+# Formatting reference
+
+Docker uses [Go templates](https://golang.org/pkg/text/template/) to allow users manipulate the output format
+of certain commands and log drivers. Each command a driver provides a detailed
+list of elements they support in their templates:
+
+- [Docker Images formatting](https://docs.docker.com/engine/reference/commandline/images/#formatting)
+- [Docker Inspect formatting](https://docs.docker.com/engine/reference/commandline/inspect/#examples)
+- [Docker Log Tag formatting](https://docs.docker.com/engine/admin/logging/log_tags/)
+- [Docker Network Inspect formatting](https://docs.docker.com/engine/reference/commandline/network_inspect/)
+- [Docker PS formatting](https://docs.docker.com/engine/reference/commandline/ps/#formatting)
+- [Docker Volume Inspect formatting](https://docs.docker.com/engine/reference/commandline/volume_inspect/)
+- [Docker Version formatting](https://docs.docker.com/engine/reference/commandline/version/#examples)
+
+## Template functions
+
+Docker provides a set of basic functions to manipulate template elements.
+This is the complete list of the available functions with examples:
+
+### Join
+
+Join concatenates a list of strings to create a single string.
+It puts a separator between each element in the list.
+
+	$ docker ps --format '{{join .Names " or "}}'
+
+### Json
+
+Json encodes an element as a json string.
+
+	$ docker inspect --format '{{json .Mounts}}' container
+
+### Lower
+
+Lower turns a string into its lower case representation.
+
+	$ docker inspect --format "{{lower .Name}}" container
+
+### Split
+
+Split slices a string into a list of strings separated by a separator.
+
+	# docker inspect --format '{{split (join .Names "/") "/"}}' container
+
+### Title
+
+Title capitalizes a string.
+
+	$ docker inspect --format "{{title .Name}}" container
+
+### Upper
+
+Upper turms a string into its upper case representation.
+
+	$ docker inspect --format "{{upper .Name}}" container