Custom methods: URI suffix

This rule enforces that custom methods include the custom verb in the REST URI, as mandated in AIP-136.

Details

This rule looks at any method that is not a standard method, and tries to find the appropriate suffix at the end of the URI. More specifically:

• If the URI contains a name or parent variable, then it expects :verb at the end of the URI.
• Otherwise, it expects :verbNoun at the end of the URI.

Note: This rule will not run if the http-name-variable or http-parent-variable rules raise an issue, as a significant number of issues raised by this rule are actually violations of one of those.

Examples

Verb only

Incorrect code for this rule:

// Incorrect.
rpc CheckoutBook(CheckoutBookRequest) returns (CheckoutBookResponse) {
  option (google.api.http) = {
    // Should end with ":checkout", because the book is implied.
    post: "/v1/{name=publishers/*/books/*}:checkoutBook"
    body: "*"
  };
}

Correct code for this rule:

// Correct.
rpc CheckoutBook(CheckoutBookRequest) returns (CheckoutBookResponse) {
  option (google.api.http) = {
    post: "/v1/{name=publishers/*/books/*}:checkout"
    body: "*"
  };
}

Verb and noun

Incorrect code for this rule:

// Incorrect.
rpc SignContract(SignContractRequest) returns (SignContractResponse) {
  option (google.api.http) = {
    // Should end with ":signContract", because contract is not implied.
    post: "/v1/{publisher=publishers/*}:sign"
    body: "*"
  };
}

Correct code for this rule:

// Correct.
rpc SignContract(SignContractRequest) returns (SignContractResponse) {
  option (google.api.http) = {
    post: "/v1/{publisher=publishers/*}:signContract"
    body: "*"
  };
}

Known limitations

This rule naïvely assumes that the verb is always one word (the “noun” may be any number of words; they often include adjectives). This may cause some false positives, and the rule may be disabled in these situations.

Note: Before disabling the rule, consider whether the verb is properly represented as a single word. A common occurrence here is for words like “Signup”, “Rollout”, etc., which should prefer their single-word form.

Disabling

If you need to violate this rule, use a leading comment above the method. Remember to also include an aip.dev/not-precedent comment explaining why.

// (-- api-linter: core::0136::http-uri-suffix=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
rpc CheckoutBook(CheckoutBookRequest) returns (CheckoutBookResponse) {
  option (google.api.http) = {
    post: "/v1/{name=publishers/*/books/*}:checkoutBook"
    body: "*"
  };
}

If you need to violate this rule for an entire file, place the comment at the top of the file.