Struct RoutingRule

pub struct RoutingRule {
    pub routing_parameters: Vec<RoutingParameter>,
}

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. In the examples below I am skipping the percent-encoding for readablity.

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

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.

Trait Implementations

impl Clone for RoutingRule

fn clone(&self) -> RoutingRule

Returns a copy 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<(), Error>

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 encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

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