Cannot use folder as output artifact in master branch

[duboisf]

Is this a BUG REPORT or FEATURE REQUEST?:

Bug report

What happened:

We updated argo to master branch (4bfbb20) and tried our workflow and it couldn't save an artifact from a folder.

What you expected to happen:

To be able to save a folder as an artifact like in version 2.2.1

How to reproduce it (as minimally and precisely as possible):

cat <<EOF | argo --serviceaccount=basic-workflow submit --watch -
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: folder-artifact-
spec:
  entrypoint: artifact
  templates:
  - name: artifact
    steps:
    - - name: generate-artifact
        template: whalesay

  - name: whalesay
    container:
      image: docker/whalesay:latest
      command: [sh, -c]
      args: ["
        mkdir /tmp/result;
        cowsay hello world | tee /tmp/result/hello_world.txt;
        stat /tmp/result/hello_world.txt;
      "]
    outputs:
      artifacts:
      - name: hello-art
        path: /tmp/result
EOF
Name:                folder-artifact-qbvq9
Namespace:           argo
ServiceAccount:      basic-workflow
Status:              Failed
Message:             child 'folder-artifact-qbvq9-3898948278' failed
Created:             Thu Mar 21 13:15:05 -0400 (3 seconds ago)
Started:             Thu Mar 21 13:15:05 -0400 (3 seconds ago)
Finished:            Thu Mar 21 13:15:08 -0400 (now)
Duration:            3 seconds

STEP                      PODNAME                           DURATION  MESSAGE
 ✖ folder-artifact-qbvq9                                              child 'folder-artifact-qbvq9-3898948278' failed
 └---⚠ generate-artifact  folder-artifact-qbvq9-3898948278  2s        failed to save outputs: File or Artifact does not exist. /tmp/result

$ argo logs folder-artifact-qbvq9-3898948278
 _____________ 
< hello world >
 ------------- 
    \
     \
      \     
                    ##        .            
              ## ## ##       ==            
           ## ## ## ##      ===            
       /""""""""""""""""___/ ===        
  ~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ /  ===- ~~~   
       \______ o          __/            
        \    \        __/             
          \____\______/   
  File: '/tmp/result/hello_world.txt'
  Size: 399             Blocks: 8          IO Block: 4096   regular file
Device: 10302h/66306d   Inode: 9445939     Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-03-21 17:15:06.071716789 +0000
Modify: 2019-03-21 17:15:06.123717175 +0000
Change: 2019-03-21 17:15:06.123717175 +0000
 Birth: -

Environment:

• Argo version:
  v2.2.1-92-g4bfbb20b
• Kubernetes version :

$ kubectl version -o yaml
clientVersion:
  buildDate: 2019-01-16T18:24:45Z
  compiler: gc
  gitCommit: 51dd616cdd25d6ee22c83a858773b607328a18ec
  gitTreeState: clean
  gitVersion: v1.12.5
  goVersion: go1.10.7
  major: "1"
  minor: "12"
  platform: linux/amd64
serverVersion:
  buildDate: 2019-02-28T18:40:05Z
  compiler: gc
  gitCommit: 4e209c9383fa00631d124c8adcc011d617339b3c
  gitTreeState: clean
  gitVersion: v1.11.8
  goVersion: go1.10.8
  major: "1"
  minor: "11"
  platform: linux/amd64

Other debugging information (if applicable):

• executor logs:

$ kubectl logs folder-artifact-qbvq9-3898948278 -c wait
time="2019-03-21T17:15:06Z" level=info msg="Creating a docker executor"
time="2019-03-21T17:15:06Z" level=info msg="Executor (version: v2.3.0+4bfbb20.dirty, build_date: 2019-03-19T19:56:58Z) initialized with template:\narchiveLocation:\n  s3:\n    accessKeySecret:\n
 key: accessKey\n      name: artifacts-repo\n    bucket: ***********\n    key: argo/2019/03/21/folder-artifact-qbvq9/folder-artifact-qbvq9-3898948278\n    region: us-east-1\n    secretKeySecret:\n      key: secretKey\n      name: artifacts-repo\ncontainer:\n  args:\n  - ' mkdir /tmp/result; cowsay hello world | tee /tmp/result/hello_world.txt; stat\n    /tmp/result/hello_world.txt; '\n  command:\n  - sh\n  - -c\n  image: docker/whalesay:latest\n  name: \"\"\n  resources: {}\ninputs: {}\nmetadata: {}\nname: whalesay\noutputs:\n
artifacts:\n  - name: hello-art\n    path: /tmp/result\n"
time="2019-03-21T17:15:06Z" level=info msg="Waiting on main container"
time="2019-03-21T17:15:07Z" level=info msg="main container started with container ID: 309868c3f02b062f313d4db24918286150a348c4a64797394791c63c0402220c"
time="2019-03-21T17:15:07Z" level=info msg="Starting annotations monitor"
time="2019-03-21T17:15:07Z" level=info msg="docker wait 309868c3f02b062f313d4db24918286150a348c4a64797394791c63c0402220c"
time="2019-03-21T17:15:07Z" level=info msg="Starting deadline monitor"
time="2019-03-21T17:15:07Z" level=info msg="Main container completed"
time="2019-03-21T17:15:07Z" level=info msg="No sidecars"
time="2019-03-21T17:15:07Z" level=info msg="No output parameters"
time="2019-03-21T17:15:07Z" level=info msg="Saving output artifacts"
time="2019-03-21T17:15:07Z" level=info msg="Saving artifact: hello-art"
time="2019-03-21T17:15:07Z" level=info msg="Archiving 309868c3f02b062f313d4db24918286150a348c4a64797394791c63c0402220c:/tmp/result to /argo/outputs/artifacts/hello-art.tgz"
time="2019-03-21T17:15:07Z" level=info msg="sh -c docker cp -a 309868c3f02b062f313d4db24918286150a348c4a64797394791c63c0402220c:/tmp/result - | gzip > /argo/outputs/artifacts/hello-art.tgz"
time="2019-03-21T17:15:07Z" level=info msg="Annotations monitor stopped"
time="2019-03-21T17:15:07Z" level=warning msg="File or Artifact does not exist. /tmp/result"
time="2019-03-21T17:15:07Z" level=info msg="Alloc=3188 TotalAlloc=10850 Sys=70078 NumGC=4 Goroutines=7"
time="2019-03-21T17:15:07Z" level=fatal msg="File or Artifact does not exist. /tmp/result\ngithub.com/argoproj/argo/errors.New\n\t/go/src/github.com/argoproj/argo/errors/errors.go:49\ngithub.com/argoproj/argo/errors.InternalError\n\t/go/src/github.com/argoproj/argo/errors/errors.go:60\ngithub.com/argoproj/argo/workflow/executor/docker.(*DockerExecutor).CopyFile\n\t/go/src/github.com/argoproj/argo/workflow/executor/docker/docker.go:59\ngithub.com/argoproj/argo/workflow/executor.(*WorkflowExecutor).saveArtifact\n\t/go/src/github.com/argoproj/argo/workflow/executor/executor.go:233\ngithub.com/argoproj/argo/workflow/executor.(*WorkflowExecutor).SaveArtifacts\n\t/go/src/github.com/argoproj/argo/workflow/executor/executor.go:212\ngithub.com/argoproj/argo/cmd/argoexec/commands.waitContainer\n\t/go/src/github.com/argoproj/argo/cmd/argoexec/commands/wait.go:50\ngithub.com/argoproj/argo/cmd/argoexec/commands.glob..func4\n\t/go/src/github.com/argoproj/argo/cmd/argoexec/commands/wait.go:19\ngithub.com/spf13/cobra.(*Command).execute\n\t/go/src/github.com/spf13/cobra/command.go:766\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/go/src/github.com/spf13/cobra/command.go:852\ngithub.com/spf13/cobra.(*Command).Execute\n\t/go/src/github.com/spf13/cobra/command.go:800\nmain.main\n\t/go/src/github.com/argoproj/argo/cmd/argoexec/main.go:17\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:201\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1333"