RoutingRule

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