VMCache: check if vm_cache_endpoint file exists before VMCache server…

[teawater]

… runs

There is an issue that more than one VMCache server can run with same
vm_cache_endpoint file together.
The cause is factory try to remove vm_cache_endpoint file before VMCache
server runs.
Change it to check if vm_cache_endpoint file exists before VMCache server
runs to handle the issue.

Fixes: #1385

Signed-off-by: Hui Zhu teawater@hyper.sh

[teawater]

/test

[teawater]

/test

[teawater]

jenkins-ci-ARM-ubuntu-18-04 failed:

00:07:41 /home/jenkins/workspace/kata-containers-runtime-ARM-18.04-PR/go/src/github.com/kata-containers/runtime/virtcontainers/utils
00:07:58 virtcontainers/qemu.go:1494:6: `genericMemoryTopology` is unused (deadcode)
00:07:58 func genericMemoryTopology(memoryMb, hostMemoryMb uint64, slots uint8, memoryOffset uint32) govmmQemu.Memory {
00:07:58      ^
00:07:58 cli/kata-check.go:55:2: `genericCPUFlagsTag` is unused (deadcode)
00:07:58 	genericCPUFlagsTag    = "flags"      // nolint: varcheck, unused
00:07:58 	^
00:07:58 cli/kata-check.go:56:2: `genericCPUVendorField` is unused (deadcode)
00:07:58 	genericCPUVendorField = "vendor_id"  // nolint: varcheck, unused
00:07:58 	^
00:07:58 cli/kata-check.go:57:2: `genericCPUModelField` is unused (deadcode)
00:07:58 	genericCPUModelField  = "model name" // nolint: varcheck, unused
00:07:58 	^
00:07:58 cli/kata-check_test.go:31:6: `testCPUData` is unused (deadcode)
00:07:58 type testCPUData struct {
00:07:58      ^
00:07:58 cli/kata-check_test.go:151:6: `genericTestGetCPUDetails` is unused (deadcode)
00:07:58 func genericTestGetCPUDetails(t *testing.T, validVendor string, validModel string, validContents string, data []testCPUDetail) {
00:07:58      ^
00:08:10 Build step 'Execute shell' marked build as failure
00:08:10 Performing Post build task...
00:08:10 Match found for :.* : True
00:08:10 Logical operation result is TRUE
00:08:10 Running script  : #!/bin/bash

This a64 format issue is handled by #1433
So I think current PR does not relate to this fail.

[bergwolf]

There is no os.IsExist error for os.Stat.

[teawater]

There is no os.IsExist error for os.Stat.

Submit a new version according to your comments.

[teawater]

/test