Service Catalog Checks

Applies to @connectum/core 1.3.0.

Does this apply to you?

You need to act only if one of these is true:

• code matches Code.Unavailable on a ctx.call or ctx.stream to a service that is not mounted locally on a server that has no remoteResolver;
• you pass timeoutMs of 0, a negative number, NaN or Infinity in CallOptions;
• propagateHeaders holds a name that is not a valid HTTP header name, or is not an array;
• enabledServices holds a type name that is not in services (for example a typo read from an environment variable);
• your catalog is a hand-built map whose key differs from its descriptor's typeName;
• you call createCatalogClient() without a resolver, dnsResolver() without a template, or pass a non-object map to perServiceEnvResolver() or mapResolver();
• you define the same service twice, or a handler object has a member that is not a function, or a defineLazyService factory is async or returns something that is not an object.

Valid configurations behave as before.

What changed

Case	Before	From 1.3.0
ctx.call / ctx.stream to an unmounted service, no remoteResolver	Code.Unavailable, "the resolver returned null"	Code.FailedPrecondition, "not mounted locally and no remoteResolver is configured"
CallOptions.timeoutMs of 0, negative, NaN, Infinity	0 and negatives removed the inherited deadline; the others failed differently locally and remotely	Rejected with Code.InvalidArgument naming timeoutMs
Nested call after the inbound deadline passed	The callee ran without a deadline	Code.DeadlineExceeded
Invalid propagateHeaders entry	createServer() succeeded; every ctx.call threw a TypeError	createServer() throws a TypeError naming propagateHeaders and the entry
enabledServices entry that matches no supplied service	The server started with nothing mounted	start() rejects with CatalogConfigError
Catalog key different from the typeName	Accepted	createServer() / createCatalogClient() throw CatalogConfigError
Resolver returns a string, undefined or a Promise	transport.unary is not a function on every call; the value was cached	Code.Internal naming the service; not cached
Same service defined twice	The last definition won silently	CatalogConfigError
defineService / defineLazyService handler mistakes	Late or unnamed errors, or a service whose methods were all unimplemented	TypeError naming the service
endpoint: ""	The resolver saw { typeName, endpoint: "" } or { typeName } depending on call order	Always { typeName }
server.hasService() on a lazy service	Ran the factory and froze addService()	A lookup; nothing runs

Required changes

• Match the code that fits the cause. For a missing remoteResolver handle Code.FailedPrecondition (or better, configure the resolver or mount the service). Keep Code.Unavailable for a configured resolver that returns null.
• Drop non-positive timeouts. Omit timeoutMs to inherit the deadline, or pass a positive finite number to shorten it.
• Fix the names. Correct the header names, enabledServices entries and catalog keys the errors point at.
• Make factories synchronous. A defineLazyService factory returns the handlers object; do asynchronous setup before createServer().

Before and after

const server = createServer({
  services: [orders],
  catalog,
  enabledServices: [OrdersService.typeName],
  // no remoteResolver
});

// 1.2: ctx.call('inventory.v1.InventoryService/Check', ...) -> Code.Unavailable (retried by `retry`)
// 1.3: ctx.call('inventory.v1.InventoryService/Check', ...) -> Code.FailedPrecondition

Verify the upgrade

Start every server configuration you deploy, including the one that reads enabledServices from the environment. start() and createServer() now report the mistakes above before the first request.

Related

• Service catalog
• Resolvers