Introducing error package

Signed-off-by: apostasie <[email protected]>

pkg/errs/errors.go

@@ -0,0 +1,40 @@
+/*
+   Copyright The containerd Authors.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+       http://www.apache.org/licenses/LICENSE-2.0
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package nerderr
+
+import "errors"
+
+var (
+	// ErrSystemIsBroken should wrap all system-level errors (filesystem unexpected conditions, hosed files, misbehaving subsystems)
+	ErrSystemIsBroken = errors.New("system error")
+
+	// ErrInvalidArgument should wrap all cases where an argument does not match expected syntax,
+	// or prevents an operation from succeeding because of its value
+	ErrInvalidArgument = errors.New("invalid argument")
+
+	// ErrNotFound is the generic error describing that a requested resource could not be found
+	ErrNotFound = errors.New("could not find the requested resource")
+
+	// ErrNetworkCondition is meant to wrap network level errors - DNS, TCP, TLS errors
+	// but NOT http server level errors
+	ErrNetworkCondition = errors.New("network communication failed")
+
+	// ErrServerIsMisbehaving should wrap all server errors (eg: status code 50x)
+	// but NOT dns, tcp, or tls errors
+	ErrServerIsMisbehaving = errors.New("server error")
+
+	// ErrFailedPrecondition should wrap errors encountered when a certain operation cannot be performed because
+	// a precondition prevents it from completing. For example, removing a volume that is in use.
+	ErrFailedPrecondition = errors.New("unable to perform the requested operation")
+)