Struct RoutingRule 

#[non_exhaustive]
pub struct RoutingRule {
    pub routing_parameters: Vec<RoutingParameter>,
    /* private fields */
}

Specifies the routing information that should be sent along with the request in the form of routing header. NOTE: All service configuration rules follow the “last one wins” order.

The examples below will apply to an RPC which has the following request type:

Message Definition:

message Request {
  // The name of the Table
  // Values can be of the following formats:
  // - `projects/<project>/tables/<table>`
  // - `projects/<project>/instances/<instance>/tables/<table>`
  // - `region/<region>/zones/<zone>/tables/<table>`
  string table_name = 1;

  // This value specifies routing for replication.
  // It can be in the following formats:
  // - `profiles/<profile_id>`
  // - a legacy `profile_id` that can be any string
  string app_profile_id = 2;
}

Example message:

{
  table_name: projects/proj_foo/instances/instance_bar/table/table_baz,
  app_profile_id: profiles/prof_qux
}

The routing header consists of one or multiple key-value pairs. Every key and value must be percent-encoded, and joined together in the format of key1=value1&key2=value2. The examples below skip the percent-encoding for readability.

Example 1

Extracting a field from the request to put into the routing header unchanged, with the key equal to the field name.

annotation:

option (google.api.routing) = {
  // Take the `app_profile_id`.
  routing_parameters {
    field: "app_profile_id"
  }
};

result:

x-goog-request-params: app_profile_id=profiles/prof_qux

Example 2

Extracting a field from the request to put into the routing header unchanged, with the key different from the field name.

annotation:

option (google.api.routing) = {
  // Take the `app_profile_id`, but name it `routing_id` in the header.
  routing_parameters {
    field: "app_profile_id"
    path_template: "{routing_id=**}"
  }
};

result:

x-goog-request-params: routing_id=profiles/prof_qux

Example 3

Extracting a field from the request to put into the routing header, while matching a path template syntax on the field’s value.

NB: it is more useful to send nothing than to send garbage for the purpose of dynamic routing, since garbage pollutes cache. Thus the matching.

Sub-example 3a

The field matches the template.

annotation:

option (google.api.routing) = {
  // Take the `table_name`, if it's well-formed (with project-based
  // syntax).
  routing_parameters {
    field: "table_name"
    path_template: "{table_name=projects/*/instances/*/**}"
  }
};

result:

x-goog-request-params:
table_name=projects/proj_foo/instances/instance_bar/table/table_baz

Sub-example 3b

The field does not match the template.

annotation:

option (google.api.routing) = {
  // Take the `table_name`, if it's well-formed (with region-based
  // syntax).
  routing_parameters {
    field: "table_name"
    path_template: "{table_name=regions/*/zones/*/**}"
  }
};

result:

<no routing header will be sent>

Sub-example 3c

Multiple alternative conflictingly named path templates are specified. The one that matches is used to construct the header.

annotation:

option (google.api.routing) = {
  // Take the `table_name`, if it's well-formed, whether
  // using the region- or projects-based syntax.

  routing_parameters {
    field: "table_name"
    path_template: "{table_name=regions/*/zones/*/**}"
  }
  routing_parameters {
    field: "table_name"
    path_template: "{table_name=projects/*/instances/*/**}"
  }
};

result:

x-goog-request-params:
table_name=projects/proj_foo/instances/instance_bar/table/table_baz

Example 4

Extracting a single routing header key-value pair by matching a template syntax on (a part of) a single request field.

annotation:

option (google.api.routing) = {
  // Take just the project id from the `table_name` field.
  routing_parameters {
    field: "table_name"
    path_template: "{routing_id=projects/*}/**"
  }
};

result:

x-goog-request-params: routing_id=projects/proj_foo

Example 5

Extracting a single routing header key-value pair by matching several conflictingly named path templates on (parts of) a single request field. The last template to match “wins” the conflict.

annotation:

option (google.api.routing) = {
  // If the `table_name` does not have instances information,
  // take just the project id for routing.
  // Otherwise take project + instance.

  routing_parameters {
    field: "table_name"
    path_template: "{routing_id=projects/*}/**"
  }
  routing_parameters {
    field: "table_name"
    path_template: "{routing_id=projects/*/instances/*}/**"
  }
};

result:

x-goog-request-params:
routing_id=projects/proj_foo/instances/instance_bar

Example 6

Extracting multiple routing header key-value pairs by matching several non-conflicting path templates on (parts of) a single request field.

Sub-example 6a

Make the templates strict, so that if the table_name does not have an instance information, nothing is sent.

annotation:

option (google.api.routing) = {
  // The routing code needs two keys instead of one composite
  // but works only for the tables with the "project-instance" name
  // syntax.

  routing_parameters {
    field: "table_name"
    path_template: "{project_id=projects/*}/instances/*/**"
  }
  routing_parameters {
    field: "table_name"
    path_template: "projects/*/{instance_id=instances/*}/**"
  }
};

result:

x-goog-request-params:
project_id=projects/proj_foo&instance_id=instances/instance_bar

Sub-example 6b

Make the templates loose, so that if the table_name does not have an instance information, just the project id part is sent.

annotation:

option (google.api.routing) = {
  // The routing code wants two keys instead of one composite
  // but will work with just the `project_id` for tables without
  // an instance in the `table_name`.

  routing_parameters {
    field: "table_name"
    path_template: "{project_id=projects/*}/**"
  }
  routing_parameters {
    field: "table_name"
    path_template: "projects/*/{instance_id=instances/*}/**"
  }
};

result (is the same as 6a for our example message because it has the instance information):

x-goog-request-params:
project_id=projects/proj_foo&instance_id=instances/instance_bar

Example 7

Extracting multiple routing header key-value pairs by matching several path templates on multiple request fields.

NB: note that here there is no way to specify sending nothing if one of the fields does not match its template. E.g. if the table_name is in the wrong format, the project_id will not be sent, but the routing_id will be. The backend routing code has to be aware of that and be prepared to not receive a full complement of keys if it expects multiple.

annotation:

option (google.api.routing) = {
  // The routing needs both `project_id` and `routing_id`
  // (from the `app_profile_id` field) for routing.

  routing_parameters {
    field: "table_name"
    path_template: "{project_id=projects/*}/**"
  }
  routing_parameters {
    field: "app_profile_id"
    path_template: "{routing_id=**}"
  }
};

result:

x-goog-request-params:
project_id=projects/proj_foo&routing_id=profiles/prof_qux

Example 8

Extracting a single routing header key-value pair by matching several conflictingly named path templates on several request fields. The last template to match “wins” the conflict.

annotation:

option (google.api.routing) = {
  // The `routing_id` can be a project id or a region id depending on
  // the table name format, but only if the `app_profile_id` is not set.
  // If `app_profile_id` is set it should be used instead.

  routing_parameters {
    field: "table_name"
    path_template: "{routing_id=projects/*}/**"
  }
  routing_parameters {
     field: "table_name"
     path_template: "{routing_id=regions/*}/**"
  }
  routing_parameters {
    field: "app_profile_id"
    path_template: "{routing_id=**}"
  }
};

result:

x-goog-request-params: routing_id=profiles/prof_qux

Example 9

Bringing it all together.

annotation:

option (google.api.routing) = {
  // For routing both `table_location` and a `routing_id` are needed.
  //
  // table_location can be either an instance id or a region+zone id.
  //
  // For `routing_id`, take the value of `app_profile_id`
  // - If it's in the format `profiles/<profile_id>`, send
  // just the `<profile_id>` part.
  // - If it's any other literal, send it as is.
  // If the `app_profile_id` is empty, and the `table_name` starts with
  // the project_id, send that instead.

  routing_parameters {
    field: "table_name"
    path_template: "projects/*/{table_location=instances/*}/tables/*"
  }
  routing_parameters {
    field: "table_name"
    path_template: "{table_location=regions/*/zones/*}/tables/*"
  }
  routing_parameters {
    field: "table_name"
    path_template: "{routing_id=projects/*}/**"
  }
  routing_parameters {
    field: "app_profile_id"
    path_template: "{routing_id=**}"
  }
  routing_parameters {
    field: "app_profile_id"
    path_template: "profiles/{routing_id=*}"
  }
};

result:

x-goog-request-params:
table_location=instances/instance_bar&routing_id=prof_qux

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

routing_parameters: Vec<RoutingParameter>

A collection of Routing Parameter specifications. NOTE: If multiple Routing Parameters describe the same key (via the path_template field or via the field field when path_template is not provided), “last one wins” rule determines which Parameter gets used. See the examples for more details.

Implementations

impl RoutingRule

pub fn new() -> Self

pub fn set_routing_parameters<T, V>(self, v: T) -> Self

where T: IntoIterator<Item = V>, V: Into<RoutingParameter>,

Sets the value of routing_parameters.

Trait Implementations

impl Clone for RoutingRule

fn clone(&self) -> RoutingRule

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for RoutingRule

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for RoutingRule

fn default() -> RoutingRule

Returns the “default value” for a type.

impl Message for RoutingRule

fn typename() -> &'static str

The typename of this message.

impl PartialEq for RoutingRule

fn eq(&self, other: &RoutingRule) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for RoutingRule