compute_ctl: Add endpoint that allows extensions to be installed (#9344)

Adds endpoint to install extensions:

**POST** `/extensions`
```
{"extension":"pg_sessions_jwt","database":"neondb","version":"1.0.0"}
```

Will be used by `local-proxy`.
Example, for the JWT authentication to work the database needs to have
the pg_session_jwt extension and also to enable JWT to work in RLS
policies.

---------

Co-authored-by: Conrad Ludgate <conradludgate@gmail.com>

libs/compute_api/src/requests.rs

@@ -1,8 +1,7 @@
 //! Structs representing the JSON formats used in the compute_ctl's HTTP API.
-
 use crate::{
     privilege::Privilege,
-    spec::{ComputeSpec, PgIdent},
+    spec::{ComputeSpec, ExtVersion, PgIdent},
 };
 use serde::Deserialize;
 
@@ -16,6 +15,13 @@ pub struct ConfigurationRequest {
     pub spec: ComputeSpec,
 }
 
+#[derive(Deserialize, Debug)]
+pub struct ExtensionInstallRequest {
+    pub extension: PgIdent,
+    pub database: PgIdent,
+    pub version: ExtVersion,
+}
+
 #[derive(Deserialize, Debug)]
 pub struct SetRoleGrantsRequest {
     pub database: PgIdent,

libs/compute_api/src/responses.rs

@@ -8,7 +8,7 @@ use serde::{Deserialize, Serialize, Serializer};
 
 use crate::{
     privilege::Privilege,
-    spec::{ComputeSpec, Database, PgIdent, Role},
+    spec::{ComputeSpec, Database, ExtVersion, PgIdent, Role},
 };
 
 #[derive(Serialize, Debug, Deserialize)]
@@ -172,6 +172,11 @@ pub struct InstalledExtensions {
     pub extensions: Vec<InstalledExtension>,
 }
 
+#[derive(Clone, Debug, Default, Serialize)]
+pub struct ExtensionInstallResult {
+    pub extension: PgIdent,
+    pub version: ExtVersion,
+}
 #[derive(Clone, Debug, Default, Serialize)]
 pub struct SetRoleGrantsResponse {
     pub database: PgIdent,

libs/compute_api/src/spec.rs

@@ -16,6 +16,9 @@ use remote_storage::RemotePath;
 /// intended to be used for DB / role names.
 pub type PgIdent = String;
 
+/// String type alias representing Postgres extension version
+pub type ExtVersion = String;
+
 /// Cluster spec or configuration represented as an optional number of
 /// delta operations + final cluster state description.
 #[derive(Clone, Debug, Default, Deserialize, Serialize)]