adding docs for filebase64 function

website/content/docs/templates/hcl_templates/functions/file/filebase64.mdx

@@ -0,0 +1,46 @@
+---
+page_title: filebase64 - Functions - Configuration Language
+description: |-
+  The filebase64 function reads the contents of the file at the given path and
+  returns them as a base64-encoded string.
+---
+
+# `filebase64` Function
+
+`filebase64` reads the contents of a file at the given path and returns them as
+a base64-encoded string.
+
+```hcl
+filebase64(path)
+```
+
+The result is a Base64 representation of the raw bytes in the given file.
+Strings in the Packer language are sequences of Unicode characters, so
+Base64 is the standard way to represent raw binary data that cannot be
+interpreted as Unicode characters. Resource types that operate on binary
+data will accept this data encoded in Base64, thus avoiding the need to
+decode the result of this function.
+
+Packer uses the "standard" Base64 alphabet as defined in
+[RFC 4648 section 4](https://tools.ietf.org/html/rfc4648#section-4).
+
+This function can be used only with functions that already exist as static
+files on disk at the beginning of a Packer run. Language functions do not
+participate in the dependency graph, so this function cannot be used with
+files that are generated dynamically during a Packer operation.
+
+## Examples
+
+```
+> filebase64("${path.module}/hello.txt")
+SGVsbG8gV29ybGQ=
+```
+
+## Related Functions
+
+* [`file`](/packer/docs/templates/hcl_templates/functions/file/file) also reads the contents of a given file,
+  but interprets the data as UTF-8 text and returns the result directly
+  as a string, without any further encoding.
+* [`base64decode`](/packer/docs/templates/hcl_templates/functions/encoding/base64decode) can decode a Base64 string representing
+  bytes in UTF-8, but in practice `base64decode(filebase64(...))` is equivalent
+  to the shorter expression `file(...)`.