First version of admin API (#298)

**Spec:**

- [x] Start writing
- [x] Specify all layout endpoints
- [x] Specify all endpoints for operations on keys
- [x] Specify all endpoints for operations on key/bucket permissions
- [x] Specify all endpoints for operations on buckets
- [x] Specify all endpoints for operations on bucket aliases

View rendered spec at <https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/admin-api/doc/drafts/admin-api.md>

**Code:**

- [x] Refactor code for admin api to use common api code that was created for K2V

**General endpoints:**

- [x] Metrics
- [x] GetClusterStatus
- [x] ConnectClusterNodes
- [x] GetClusterLayout
- [x] UpdateClusterLayout
- [x] ApplyClusterLayout
- [x] RevertClusterLayout

**Key-related endpoints:**

- [x] ListKeys
- [x] CreateKey
- [x] ImportKey
- [x] GetKeyInfo
- [x] UpdateKey
- [x] DeleteKey

**Bucket-related endpoints:**

- [x] ListBuckets
- [x] CreateBucket
- [x] GetBucketInfo
- [x] DeleteBucket
- [x] PutBucketWebsite
- [x] DeleteBucketWebsite

**Operations on key/bucket permissions:**

- [x] BucketAllowKey
- [x] BucketDenyKey

**Operations on bucket aliases:**

- [x] GlobalAliasBucket
- [x] GlobalUnaliasBucket
- [x] LocalAliasBucket
- [x] LocalUnaliasBucket

**And also:**

- [x] Separate error type for the admin API (this PR includes a quite big refactoring of error handling)
- [x] Add management of website access
- [ ] Check that nothing is missing wrt what can be done using the CLI
- [ ] Improve formatting of the spec
- [x] Make sure everyone is cool with the API design

Fix #231
Fix #295

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/298
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

2 files changed, 18 insertions, 28 deletions

diff --git a/src/web/error.rs b/src/web/error.rs
index 55990e9d..bd8f17b5 100644
--- a/src/web/error.rs
+++ b/src/web/error.rs
@@ -2,57 +2,47 @@ use err_derive::Error;
 use hyper::header::HeaderValue;
 use hyper::{HeaderMap, StatusCode};
 
-use garage_util::error::Error as GarageError;
+use garage_api::generic_server::ApiError;
 
 /// Errors of this crate
 #[derive(Debug, Error)]
 pub enum Error {
 	/// An error received from the API crate
 	#[error(display = "API error: {}", _0)]
-	ApiError(#[error(source)] garage_api::Error),
-
-	// Category: internal error
-	/// Error internal to garage
-	#[error(display = "Internal error: {}", _0)]
-	InternalError(#[error(source)] GarageError),
+	ApiError(garage_api::s3::error::Error),
 
 	/// The file does not exist
 	#[error(display = "Not found")]
 	NotFound,
 
-	/// The request contained an invalid UTF-8 sequence in its path or in other parameters
-	#[error(display = "Invalid UTF-8: {}", _0)]
-	InvalidUtf8(#[error(source)] std::str::Utf8Error),
-
-	/// The client send a header with invalid value
-	#[error(display = "Invalid header value: {}", _0)]
-	InvalidHeader(#[error(source)] hyper::header::ToStrError),
-
 	/// The client sent a request without host, or with unsupported method
 	#[error(display = "Bad request: {}", _0)]
 	BadRequest(String),
 }
 
+impl<T> From<T> for Error
+where
+	garage_api::s3::error::Error: From<T>,
+{
+	fn from(err: T) -> Self {
+		Error::ApiError(garage_api::s3::error::Error::from(err))
+	}
+}
+
 impl Error {
 	/// Transform errors into http status code
 	pub fn http_status_code(&self) -> StatusCode {
 		match self {
 			Error::NotFound => StatusCode::NOT_FOUND,
 			Error::ApiError(e) => e.http_status_code(),
-			Error::InternalError(
-				GarageError::Timeout
-				| GarageError::RemoteError(_)
-				| GarageError::Quorum(_, _, _, _),
-			) => StatusCode::SERVICE_UNAVAILABLE,
-			Error::InternalError(_) => StatusCode::INTERNAL_SERVER_ERROR,
-			_ => StatusCode::BAD_REQUEST,
+			Error::BadRequest(_) => StatusCode::BAD_REQUEST,
 		}
 	}
 
 	pub fn add_headers(&self, header_map: &mut HeaderMap<HeaderValue>) {
 		#[allow(clippy::single_match)]
 		match self {
-			Error::ApiError(e) => e.add_headers(header_map),
+			Error::ApiError(e) => e.add_http_headers(header_map),
 			_ => (),
 		}
 	}
diff --git a/src/web/web_server.rs b/src/web/web_server.rs
index 867adc51..c30d8957 100644
--- a/src/web/web_server.rs
+++ b/src/web/web_server.rs
@@ -18,9 +18,11 @@ use opentelemetry::{
 
 use crate::error::*;
 
-use garage_api::error::{Error as ApiError, OkOrBadRequest, OkOrInternalError};
 use garage_api::helpers::{authority_to_host, host_to_bucket};
 use garage_api::s3::cors::{add_cors_headers, find_matching_cors_rule, handle_options_for_bucket};
+use garage_api::s3::error::{
+	CommonErrorDerivative, Error as ApiError, OkOrBadRequest, OkOrInternalError,
+};
 use garage_api::s3::get::{handle_get, handle_head};
 
 use garage_model::garage::Garage;
@@ -207,7 +209,7 @@ async fn serve_file(garage: Arc<Garage>, req: &Request<Body>) -> Result<Response
 		Method::OPTIONS => handle_options_for_bucket(req, &bucket),
 		Method::HEAD => handle_head(garage.clone(), req, bucket_id, &key, None).await,
 		Method::GET => handle_get(garage.clone(), req, bucket_id, &key, None).await,
-		_ => Err(ApiError::BadRequest("HTTP method not supported".into())),
+		_ => Err(ApiError::bad_request("HTTP method not supported")),
 	}
 	.map_err(Error::from);
 
@@ -290,9 +292,7 @@ fn path_to_key<'a>(path: &'a str, index: &str) -> Result<Cow<'a, str>, Error> {
 	let path_utf8 = percent_encoding::percent_decode_str(path).decode_utf8()?;
 
 	if !path_utf8.starts_with('/') {
-		return Err(Error::BadRequest(
-			"Path must start with a / (slash)".to_string(),
-		));
+		return Err(Error::BadRequest("Path must start with a / (slash)".into()));
 	}
 
 	match path_utf8.chars().last() {