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>

1 files changed, 177 insertions, 0 deletions

diff --git a/src/api/common_error.rs b/src/api/common_error.rs
new file mode 100644
index 00000000..20f9f266
--- /dev/null
+++ b/src/api/common_error.rs
@@ -0,0 +1,177 @@
+use err_derive::Error;
+use hyper::StatusCode;
+
+use garage_util::error::Error as GarageError;
+
+/// Errors of this crate
+#[derive(Debug, Error)]
+pub enum CommonError {
+	// ---- INTERNAL ERRORS ----
+	/// Error related to deeper parts of Garage
+	#[error(display = "Internal error: {}", _0)]
+	InternalError(#[error(source)] GarageError),
+
+	/// Error related to Hyper
+	#[error(display = "Internal error (Hyper error): {}", _0)]
+	Hyper(#[error(source)] hyper::Error),
+
+	/// Error related to HTTP
+	#[error(display = "Internal error (HTTP error): {}", _0)]
+	Http(#[error(source)] http::Error),
+
+	// ---- GENERIC CLIENT ERRORS ----
+	/// Proper authentication was not provided
+	#[error(display = "Forbidden: {}", _0)]
+	Forbidden(String),
+
+	/// Generic bad request response with custom message
+	#[error(display = "Bad request: {}", _0)]
+	BadRequest(String),
+
+	// ---- SPECIFIC ERROR CONDITIONS ----
+	// These have to be error codes referenced in the S3 spec here:
+	// https://docs.aws.amazon.com/AmazonS3/latest/API/ErrorResponses.html#ErrorCodeList
+	/// The bucket requested don't exists
+	#[error(display = "Bucket not found: {}", _0)]
+	NoSuchBucket(String),
+
+	/// Tried to create a bucket that already exist
+	#[error(display = "Bucket already exists")]
+	BucketAlreadyExists,
+
+	/// Tried to delete a non-empty bucket
+	#[error(display = "Tried to delete a non-empty bucket")]
+	BucketNotEmpty,
+
+	// Category: bad request
+	/// Bucket name is not valid according to AWS S3 specs
+	#[error(display = "Invalid bucket name: {}", _0)]
+	InvalidBucketName(String),
+}
+
+impl CommonError {
+	pub fn http_status_code(&self) -> StatusCode {
+		match self {
+			CommonError::InternalError(
+				GarageError::Timeout
+				| GarageError::RemoteError(_)
+				| GarageError::Quorum(_, _, _, _),
+			) => StatusCode::SERVICE_UNAVAILABLE,
+			CommonError::InternalError(_) | CommonError::Hyper(_) | CommonError::Http(_) => {
+				StatusCode::INTERNAL_SERVER_ERROR
+			}
+			CommonError::BadRequest(_) => StatusCode::BAD_REQUEST,
+			CommonError::Forbidden(_) => StatusCode::FORBIDDEN,
+			CommonError::NoSuchBucket(_) => StatusCode::NOT_FOUND,
+			CommonError::BucketNotEmpty | CommonError::BucketAlreadyExists => StatusCode::CONFLICT,
+			CommonError::InvalidBucketName(_) => StatusCode::BAD_REQUEST,
+		}
+	}
+
+	pub fn aws_code(&self) -> &'static str {
+		match self {
+			CommonError::Forbidden(_) => "AccessDenied",
+			CommonError::InternalError(
+				GarageError::Timeout
+				| GarageError::RemoteError(_)
+				| GarageError::Quorum(_, _, _, _),
+			) => "ServiceUnavailable",
+			CommonError::InternalError(_) | CommonError::Hyper(_) | CommonError::Http(_) => {
+				"InternalError"
+			}
+			CommonError::BadRequest(_) => "InvalidRequest",
+			CommonError::NoSuchBucket(_) => "NoSuchBucket",
+			CommonError::BucketAlreadyExists => "BucketAlreadyExists",
+			CommonError::BucketNotEmpty => "BucketNotEmpty",
+			CommonError::InvalidBucketName(_) => "InvalidBucketName",
+		}
+	}
+
+	pub fn bad_request<M: ToString>(msg: M) -> Self {
+		CommonError::BadRequest(msg.to_string())
+	}
+}
+
+pub trait CommonErrorDerivative: From<CommonError> {
+	fn internal_error<M: ToString>(msg: M) -> Self {
+		Self::from(CommonError::InternalError(GarageError::Message(
+			msg.to_string(),
+		)))
+	}
+
+	fn bad_request<M: ToString>(msg: M) -> Self {
+		Self::from(CommonError::BadRequest(msg.to_string()))
+	}
+
+	fn forbidden<M: ToString>(msg: M) -> Self {
+		Self::from(CommonError::Forbidden(msg.to_string()))
+	}
+}
+
+/// Trait to map error to the Bad Request error code
+pub trait OkOrBadRequest {
+	type S;
+	fn ok_or_bad_request<M: AsRef<str>>(self, reason: M) -> Result<Self::S, CommonError>;
+}
+
+impl<T, E> OkOrBadRequest for Result<T, E>
+where
+	E: std::fmt::Display,
+{
+	type S = T;
+	fn ok_or_bad_request<M: AsRef<str>>(self, reason: M) -> Result<T, CommonError> {
+		match self {
+			Ok(x) => Ok(x),
+			Err(e) => Err(CommonError::BadRequest(format!(
+				"{}: {}",
+				reason.as_ref(),
+				e
+			))),
+		}
+	}
+}
+
+impl<T> OkOrBadRequest for Option<T> {
+	type S = T;
+	fn ok_or_bad_request<M: AsRef<str>>(self, reason: M) -> Result<T, CommonError> {
+		match self {
+			Some(x) => Ok(x),
+			None => Err(CommonError::BadRequest(reason.as_ref().to_string())),
+		}
+	}
+}
+
+/// Trait to map an error to an Internal Error code
+pub trait OkOrInternalError {
+	type S;
+	fn ok_or_internal_error<M: AsRef<str>>(self, reason: M) -> Result<Self::S, CommonError>;
+}
+
+impl<T, E> OkOrInternalError for Result<T, E>
+where
+	E: std::fmt::Display,
+{
+	type S = T;
+	fn ok_or_internal_error<M: AsRef<str>>(self, reason: M) -> Result<T, CommonError> {
+		match self {
+			Ok(x) => Ok(x),
+			Err(e) => Err(CommonError::InternalError(GarageError::Message(format!(
+				"{}: {}",
+				reason.as_ref(),
+				e
+			)))),
+		}
+	}
+}
+
+impl<T> OkOrInternalError for Option<T> {
+	type S = T;
+	fn ok_or_internal_error<M: AsRef<str>>(self, reason: M) -> Result<T, CommonError> {
+		match self {
+			Some(x) => Ok(x),
+			None => Err(CommonError::InternalError(GarageError::Message(
+				reason.as_ref().to_string(),
+			))),
+		}
+	}
+}