PoC: Network simulation framework (#1555)

* simv2: wip

* simulation: exec adapter start/stop

* simulation: add node status to exec adapter

* simulation: initial simulation code

* simulation: exec adapter, configure path to executable

* simulation: initial docker adapter

* simulation: wip kubernetes adapter

* simulation: kubernetes adapter proxy

* simulation: implement GetAll/StartAll/StopAll

* simulation: kuberentes adapter - set env vars and resource limits

* simulation: discovery test

* simulation: remove port definitions within docker adapter

* simulation: simplify wait for healthy loop

* simulation: get nat ip addr from interface

* simulation: pull docker images automatically

* simulation: NodeStatus -> NodeInfo

* simulation: move discovery test to example dir

* simulation: example snapshot usage

* simulation: add goclient specific simulation

* simulation: add peer connections to snapshot

* simulation: close rpc client

* simulation: don't export kubernetes proxy server

* simulation: merge simulation code

* simulation: don't export nodemap

* simulation: rename SimulationSnapshot -> Snapshot

* simulation: linting fixes

* simulation: add k8s available helper func

* simulation: vendor

* simulation: fix 'no non-test Go files' when building

* simulation: remove errors from interface methods where non were returned

* simulation: run getHealthInfo check in parallel

vendor/github.com/containerd/continuity/fs/hardlink.go

@@ -0,0 +1,43 @@
+/*
+   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 fs
+
+import "os"
+
+// GetLinkInfo returns an identifier representing the node a hardlink is pointing
+// to. If the file is not hard linked then 0 will be returned.
+func GetLinkInfo(fi os.FileInfo) (uint64, bool) {
+	return getLinkInfo(fi)
+}
+
+// getLinkSource returns a path for the given name and
+// file info to its link source in the provided inode
+// map. If the given file name is not in the map and
+// has other links, it is added to the inode map
+// to be a source for other link locations.
+func getLinkSource(name string, fi os.FileInfo, inodes map[uint64]string) (string, error) {
+	inode, isHardlink := getLinkInfo(fi)
+	if !isHardlink {
+		return "", nil
+	}
+
+	path, ok := inodes[inode]
+	if !ok {
+		inodes[inode] = name
+	}
+	return path, nil
+}