Add dataUri and dataUriToString functions

docs/reference/schemas/config/functions/dataUri.md

@@ -0,0 +1,191 @@
+---
+description: Reference for the 'dataUri' DSC configuration document function
+ms.date:     12/20/2025
+ms.topic:    reference
+title:       dataUri
+---
+
+# dataUri
+
+## Synopsis
+
+Converts a value to a data URI.
+
+## Syntax
+
+```Syntax
+dataUri(<stringToConvert>)
+```
+
+## Description
+
+The `dataUri()` function converts a string value to a [data URI][01] format. The function encodes
+the input string as base64 and returns it as a data URI with the `text/plain` media type and
+`utf8` charset.
+
+Data URIs are useful for embedding small text content directly in configuration documents,
+especially when the content needs to be passed through systems that expect URI-formatted data.
+
+## Examples
+
+### Example 1 - Encode a script for transport
+
+Encoding a PowerShell script as a data URI ensures safe transport through systems that may have
+issues with special characters or line breaks.
+
+```yaml
+# dataUri.example.1.dsc.config.yaml
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+parameters:
+  scriptContent:
+    type: string
+    defaultValue: "Write-Host 'Hello, World!'"
+resources:
+  - name: Encode script as data URI
+    type: Microsoft.DSC.Debug/Echo
+    properties:
+      output:
+        originalScript: "[parameters('scriptContent')]"
+        encodedScript: "[dataUri(parameters('scriptContent'))]"
+```
+
+```bash
+dsc config get --file dataUri.example.1.dsc.config.yaml
+```
+
+```yaml
+results:
+- name: Encode script as data URI
+  type: Microsoft.DSC.Debug/Echo
+  result:
+    actualState:
+      output:
+        originalScript: Write-Host 'Hello, World!'
+        encodedScript: data:text/plain;charset=utf8;base64,V3JpdGUtSG9zdCAnSGVsbG8sIFdvcmxkISc=
+messages: []
+hadErrors: false
+```
+
+### Example 2 - Encode JSON configuration for embedding
+
+The configuration encodes a JSON configuration string as a data URI, which is useful when passing
+structured data through systems that expect URI-formatted content.
+
+```yaml
+# dataUri.example.2.dsc.config.yaml
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+  - name: Encode JSON config as data URI
+    type: Microsoft.DSC.Debug/Echo
+    properties:
+      output: "[dataUri('{\"setting\":\"value\",\"enabled\":true}')]"
+```
+
+```bash
+dsc config get --file dataUri.example.2.dsc.config.yaml
+```
+
+```yaml
+results:
+- name: Encode JSON config as data URI
+  type: Microsoft.DSC.Debug/Echo
+  result:
+    actualState:
+      output: data:text/plain;charset=utf8;base64,eyJzZXR0aW5nIjoidmFsdWUiLCJlbmFibGVkIjp0cnVlfQ==
+messages: []
+hadErrors: false
+```
+
+### Example 3 - Compare base64 and dataUri encoding
+
+Unlike the [`base64()`][02] function which returns only the encoded content, `dataUri()` adds
+the data URI prefix with media type information. Use `dataUri()` when the target system expects
+the full data URI format.
+
+```yaml
+# dataUri.example.3.dsc.config.yaml
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+  - name: Compare encoding methods
+    type: Microsoft.DSC.Debug/Echo
+    properties:
+      output:
+        base64Only: "[base64('Hello')]"
+        fullDataUri: "[dataUri('Hello')]"
+```
+
+```bash
+dsc config get --file dataUri.example.3.dsc.config.yaml
+```
+
+```yaml
+results:
+- name: Compare encoding methods
+  type: Microsoft.DSC.Debug/Echo
+  result:
+    actualState:
+      output:
+        base64Only: SGVsbG8=
+        fullDataUri: data:text/plain;charset=utf8;base64,SGVsbG8=
+messages: []
+hadErrors: false
+```
+
+### Example 4 - Encode multiline content
+
+Multiline content like configuration files or scripts can be encoded as a data URI to preserve
+line breaks during transport.
+
+```yaml
+# dataUri.example.4.dsc.config.yaml
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+  - name: Encode multiline content
+    type: Microsoft.DSC.Debug/Echo
+    properties:
+      output: "[dataUri('line1\nline2\nline3')]"
+```
+
+```bash
+dsc config get --file dataUri.example.4.dsc.config.yaml
+```
+
+```yaml
+results:
+- name: Encode multiline content
+  type: Microsoft.DSC.Debug/Echo
+  result:
+    actualState:
+      output: data:text/plain;charset=utf8;base64,bGluZTEKbGluZTIKbGluZTM=
+messages: []
+hadErrors: false
+```
+
+## Parameters
+
+### stringToConvert
+
+The `dataUri()` function expects a single string as input. The function converts the value into a
+data URI representation. If the value isn't a string, DSC raises an error when validating the
+configuration document.
+
+```yaml
+Type:         string
+Required:     true
+MinimumCount: 1
+MaximumCount: 1
+```
+
+## Output
+
+The `dataUri()` function returns a data URI string in the format
+`data:text/plain;charset=utf8;base64,<encoded-content>` where `<encoded-content>` is the base64
+representation of the **stringToConvert** value.
+
+```yaml
+Type: string
+```
+
+<!-- Link reference definitions -->
+[01]: https://en.wikipedia.org/wiki/Data_URI_scheme
+[02]: base64.md