[gateway] turn API into a trait (#6145)

Somewhat large, but with no functional changes -- this is pure code movement.

In a few spots I had to move away from `From` impls, so that gateway-types does
not depend on gateway-sp-comms. I think those changes are for the best.

As a bonus, sp-sim no longer has to depend on omicron-gateway, cutting down the
number of build units for it from 600 to 468. That's a really nice improvement.

Cargo.toml

@@ -30,9 +30,11 @@ members = [
     "dns-server",
     "dns-server-api",
     "end-to-end-tests",
+    "gateway",
+    "gateway-api",
     "gateway-cli",
     "gateway-test-utils",
-    "gateway",
+    "gateway-types",
     "illumos-utils",
     "installinator-api",
     "installinator-common",
@@ -133,9 +135,11 @@ default-members = [
     "dns-server-api",
     # Do not include end-to-end-tests in the list of default members, as its
     # tests only work on a deployed control plane.
+    "gateway",
+    "gateway-api",
     "gateway-cli",
     "gateway-test-utils",
-    "gateway",
+    "gateway-types",
     "illumos-utils",
     "installinator-api",
     "installinator-common",
@@ -315,10 +319,12 @@ flume = "0.11.0"
 foreign-types = "0.3.2"
 fs-err = "2.11.0"
 futures = "0.3.30"
+gateway-api = { path = "gateway-api" }
 gateway-client = { path = "clients/gateway-client" }
 gateway-messages = { git = "https://github.com/oxidecomputer/management-gateway-service", rev = "c85a4ca043aaa389df12aac5348d8a3feda28762", default-features = false, features = ["std"] }
 gateway-sp-comms = { git = "https://github.com/oxidecomputer/management-gateway-service", rev = "c85a4ca043aaa389df12aac5348d8a3feda28762" }
 gateway-test-utils = { path = "gateway-test-utils" }
+gateway-types = { path = "gateway-types" }
 gethostname = "0.4.3"
 glob = "0.3.1"
 guppy = "0.17.5"

clients/gateway-client/src/lib.rs

@@ -35,6 +35,17 @@ pub use gateway_messages::SpComponent;
 // If the format of inventory data desired by wicket or nexus changes such that
 // it is no longer useful to directly expose the JsonSchema types, we can go
 // back to reusing `omicron_common`.
+//
+// As another alternative, since the `derives` and `patch` directives were
+// introduced, these types have moved to living in gateway-types. This means
+// that we can choose to use `replace` on them. That hasn't felt necessary so
+// far, but it's an option if it becomes desirable in the future. (One reason
+// to do that might be that currently, `nexus-types` depends on
+// `gateway-client`. Generally we expect the `-client` layer to depend on the
+// `-types` layer to avoid a circular dependency, and we've had to resolve a
+// rather thorny one between Nexus and sled-agent. But Nexus and sled-agent
+// call into each other. Since `gateway` is a lower-level service and never
+// calls into Nexus, the current scheme is okay.)
 progenitor::generate_api!(
     spec = "../../openapi/gateway.json",
     inner_type = slog::Logger,

dev-tools/openapi-manager/Cargo.toml

@@ -17,6 +17,7 @@ clap.workspace = true
 dns-server-api.workspace = true
 dropshot.workspace = true
 fs-err.workspace = true
+gateway-api.workspace = true
 indent_write.workspace = true
 installinator-api.workspace = true
 nexus-internal-api.workspace = true

dev-tools/openapi-manager/src/spec.rs

@@ -14,25 +14,36 @@ use openapiv3::OpenAPI;
 /// All APIs managed by openapi-manager.
 pub fn all_apis() -> Vec<ApiSpec> {
     vec![
+        ApiSpec {
+            title: "Bootstrap Agent API",
+            version: "0.0.1",
+            description: "Per-sled API for setup and teardown",
+            boundary: ApiBoundary::Internal,
+            api_description:
+                bootstrap_agent_api::bootstrap_agent_api_mod::stub_api_description,
+            filename: "bootstrap-agent.json",
+            extra_validation: None,
+        },
         ApiSpec {
             title: "CockroachDB Cluster Admin API",
             version: "0.0.1",
-            description: "API for interacting with the Oxide control plane's \
-                CockroachDB cluster",
+            description: "API for interacting with the Oxide \
+                control plane's CockroachDB cluster",
             boundary: ApiBoundary::Internal,
             api_description:
                 cockroach_admin_api::cockroach_admin_api_mod::stub_api_description,
             filename: "cockroach-admin.json",
             extra_validation: None,
         },
         ApiSpec {
-            title: "Bootstrap Agent API",
+            title: "Oxide Management Gateway Service API",
             version: "0.0.1",
-            description: "Per-sled API for setup and teardown",
+            description: "API for interacting with the Oxide \
+                control plane's gateway service",
             boundary: ApiBoundary::Internal,
             api_description:
-                bootstrap_agent_api::bootstrap_agent_api_mod::stub_api_description,
-            filename: "bootstrap-agent.json",
+                gateway_api::gateway_api_mod::stub_api_description,
+            filename: "gateway.json",
             extra_validation: None,
         },
         ApiSpec {

gateway-api/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "gateway-api"
+version = "0.1.0"
+edition = "2021"
+license = "MPL-2.0"
+
+[lints]
+workspace = true
+
+[dependencies]
+dropshot.workspace = true
+gateway-types.workspace = true
+omicron-common.workspace = true
+omicron-uuid-kinds.workspace = true
+omicron-workspace-hack.workspace = true
+schemars.workspace = true
+serde.workspace = true
+uuid.workspace = true