382 lines
11 KiB
Protocol Buffer
382 lines
11 KiB
Protocol Buffer
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syntax = "proto3";
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option go_package = "hclspec";
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/* Spec allows exposing the specification for an HCL body, allowing for parsing and
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validation.
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Certain expressions within a specification may use the following functions.
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The documentation for each spec type above specifies where functions may
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be used.
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* `abs(number)` returns the absolute (positive) value of the given number.
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* `coalesce(vals...)` returns the first non-null value given.
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* `concat(lists...)` concatenates together all of the given lists to produce a new list.
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* `hasindex(val, idx)` returns true if the expression `val[idx]` could succeed.
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* `int(number)` returns the integer portion of the given number, rounding towards zero.
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* `jsondecode(str)` interprets the given string as JSON and returns the resulting data structure.
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* `jsonencode(val)` returns a JSON-serialized version of the given value.
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* `length(collection)` returns the number of elements in the given collection (list, set, map, object, or tuple).
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* `lower(string)` returns the given string with all uppercase letters converted to lowercase.
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* `max(numbers...)` returns the greatest of the given numbers.
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* `min(numbers...)` returns the smallest of the given numbers.
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* `reverse(string)` returns the given string with all of the characters in reverse order.
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* `strlen(string)` returns the number of characters in the given string.
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* `substr(string, offset, length)` returns the requested substring of the given string.
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* `upper(string)` returns the given string with all lowercase letters converted to uppercase.
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## Type Expressions
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Type expressions are used to describe the expected type of an attribute, as
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an additional validation constraint.
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A type expression uses primitive type names and compound type constructors.
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A type constructor builds a new type based on one or more type expression
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arguments.
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The following type names and type constructors are supported:
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* `any` is a wildcard that accepts a value of any type. (In HCL terms, this
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is the _dynamic pseudo-type_.)
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* `string` is a Unicode string.
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* `number` is an arbitrary-precision floating point number.
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* `bool` is a boolean value (`true` or `false`)
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* `list(element_type)` constructs a list type with the given element type
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* `set(element_type)` constructs a set type with the given element type
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* `map(element_type)` constructs a map type with the given element type
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* `object({name1 = element_type, name2 = element_type, ...})` constructs
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an object type with the given attribute types.
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* `tuple([element_type, element_type, ...])` constructs a tuple type with
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the given element types. This can be used, for example, to require an
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array with a particular number of elements, or with elements of different
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types.
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`null` is a valid value of any type, and not a type itself.
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*/
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package hashicorp.nomad.plugins.shared.hclspec;
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// Spec defines the available specification types.
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message Spec {
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oneof block {
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Object object = 1;
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Array array = 2;
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Attr Attr = 3;
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Block block_value = 4;
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BlockList block_list = 5;
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BlockSet block_set = 6;
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BlockMap block_map = 7;
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Default default = 8;
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Literal literal = 9;
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}
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}
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/* Attr spec type reads the value of an attribute in the current body
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and returns that value as its result. It also creates validation constraints
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for the given attribute name and its value.
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```hcl
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Attr {
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name = "document_root"
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type = string
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required = true
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}
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```
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`Attr` spec blocks accept the following arguments:
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* `name` (required) - The attribute name to expect within the HCL input file.
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This may be omitted when a default name selector is created by a parent
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`Object` spec, if the input attribute name should match the output JSON
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object property name.
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* `type` (optional) - A [type expression](#type-expressions) that the given
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attribute value must conform to. If this argument is set, `hcldec` will
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automatically convert the given input value to this type or produce an
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error if that is not possible.
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* `required` (optional) - If set to `true`, `hcldec` will produce an error
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if a value is not provided for the source attribute.
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`Attr` is a leaf spec type, so no nested spec blocks are permitted.
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*/
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message Attr {
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string name = 1;
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string type = 2;
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bool required = 3;
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}
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/* Block spec type applies one nested spec block to the contents of a
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block within the current body and returns the result of that spec. It also
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creates validation constraints for the given block type name.
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```hcl
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Block {
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name = "logging"
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Object {
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Attr "level" {
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type = string
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}
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Attr "file" {
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type = string
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}
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}
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}
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```
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`Block` spec blocks accept the following arguments:
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* `name` (required) - The block type name to expect within the HCL
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input file. This may be omitted when a default name selector is created
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by a parent `Object` spec, if the input block type name should match the
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output JSON object property name.
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* `required` (optional) - If set to `true`, `hcldec` will produce an error
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if a block of the specified type is not present in the current body.
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`Block` creates a validation constraint that there must be zero or one blocks
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of the given type name, or exactly one if `required` is set.
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`Block` expects a single nested spec block, which is applied to the body of
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the block of the given type when it is present.
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*/
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message Block {
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string name = 1;
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bool required = 2;
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Spec nested = 3;
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}
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/* BlockList spec type is similar to `Block`, but it accepts zero or
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more blocks of a specified type rather than requiring zero or one. The
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result is a JSON array with one entry per block of the given type.
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```hcl
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BlockList {
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name = "log_file"
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Object {
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Attr "level" {
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type = string
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}
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Attr "filename" {
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type = string
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required = true
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}
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}
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}
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```
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`BlockList` spec blocks accept the following arguments:
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* `name` (required) - The block type name to expect within the HCL
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input file. This may be omitted when a default name selector is created
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by a parent `Object` spec, if the input block type name should match the
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output JSON object property name.
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* `min_items` (optional) - If set to a number greater than zero, `hcldec` will
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produce an error if fewer than the given number of blocks are present.
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* `max_items` (optional) - If set to a number greater than zero, `hcldec` will
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produce an error if more than the given number of blocks are present. This
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attribute must be greater than or equal to `min_items` if both are set.
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`Block` creates a validation constraint on the number of blocks of the given
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type that must be present.
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`Block` expects a single nested spec block, which is applied to the body of
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each matching block to produce the resulting list items.
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*/
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message BlockList {
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string name = 1;
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uint64 min_items = 2;
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uint64 max_items = 3;
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Spec nested = 4;
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}
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/* BlockSet spec type behaves the same as BlockList except that
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the result is in no specific order and any duplicate items are removed.
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```hcl
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BlockSet {
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name = "log_file"
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Object {
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Attr "level" {
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type = string
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}
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Attr "filename" {
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type = string
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required = true
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}
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}
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}
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```
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The contents of `BlockSet` are the same as for `BlockList`.
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*/
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message BlockSet {
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string name = 1;
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uint64 min_items = 2;
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uint64 max_items = 3;
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Spec nested = 4;
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}
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/* BlockMap spec type is similar to `Block`, but it accepts zero or
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more blocks of a specified type rather than requiring zero or one. The
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result is a JSON object, or possibly multiple nested JSON objects, whose
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properties are derived from the labels set on each matching block.
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```hcl
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BlockMap {
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name = "log_file"
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labels = ["filename"]
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Object {
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Attr "level" {
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type = string
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required = true
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}
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}
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}
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```
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`BlockMap` spec blocks accept the following arguments:
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* `name` (required) - The block type name to expect within the HCL
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input file. This may be omitted when a default name selector is created
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by a parent `Object` spec, if the input block type name should match the
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output JSON object property name.
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* `labels` (required) - A list of user-oriented block label names. Each entry
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in this list creates one level of object within the output value, and
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requires one additional block header label on any child block of this type.
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Block header labels are the quoted strings that appear after the block type
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name but before the opening `{`.
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`Block` creates a validation constraint on the number of labels that blocks
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of the given type must have.
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`Block` expects a single nested spec block, which is applied to the body of
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each matching block to produce the resulting map items.
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*/
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message BlockMap {
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string name = 1;
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repeated string labels = 2;
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Spec nested = 3;
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}
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/* Literal spec type returns a given literal value, and creates no
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validation constraints. It is most commonly used with the `Default` spec
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type to create a fallback value, but can also be used e.g. to fill out
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required properties in an `Object` spec that do not correspond to any
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construct in the input configuration.
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```hcl
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Literal {
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value = "hello world"
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}
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```
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`Literal` spec blocks accept the following argument:
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* `value` (required) - The value to return. This attribute may be an expression
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that uses [functions](#spec-definition-functions).
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`Literal` is a leaf spec type, so no nested spec blocks are permitted.
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*/
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message Literal {
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string value = 1;
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}
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/* Default spec type evaluates a sequence of nested specs in turn and
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returns the result of the first one that produces a non-null value.
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It creates no validation constraints of its own, but passes on the validation
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constraints from its first nested block.
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```hcl
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Default {
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Attr {
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name = "private"
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type = bool
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}
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Literal {
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value = false
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}
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}
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```
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A `Default` spec block must have at least one nested spec block, and should
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generally have at least two since otherwise the `Default` wrapper is a no-op.
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The second and any subsequent spec blocks are _fallback_ specs. These exhibit
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their usual behavior but are not able to impose validation constraints on the
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current body since they are not evaluated unless all prior specs produce
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`null` as their result.
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*/
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message Default {
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Spec primary = 1;
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Spec default = 2;
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}
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/* Object spec type is the most commonly used at the root of a spec file.
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Its result is a JSON object whose properties are set based on any nested
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spec blocks:
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```hcl
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Object {
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Attr "name" {
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type = "string"
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}
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Block "address" {
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Object {
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Attr "street" {
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type = "string"
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}
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# ...
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}
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}
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}
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```
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Nested spec blocks inside `Object` must always have an extra block label
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`"name"`, `"address"` and `"street"` in the above example) that specifies
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the name of the property that should be created in the JSON object result.
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This label also acts as a default name selector for the nested spec, allowing
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the `Attr` blocks in the above example to omit the usually-required `name`
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argument in cases where the HCL input name and JSON output name are the same.
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An `Object` spec block creates no validation constraints, but it passes on
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any validation constraints created by the nested specs.
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*/
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message Object {
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map<string, Spec> attributes = 1;
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}
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/* Array spec type produces a JSON array whose elements are set based on
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any nested spec blocks:
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```hcl
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Array {
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Attr {
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name = "first_element"
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type = "string"
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}
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Attr {
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name = "second_element"
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type = "string"
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}
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}
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```
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An `Array` spec block creates no validation constraints, but it passes on
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any validation constraints created by the nested specs.
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*/
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message Array {
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repeated Spec values = 1;
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}
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