container: workdir resolution must consider symlink if explicitly configured

While resolving `workdir` we mostly create a `workdir` when `stat`
fails with `ENOENT` or `ErrNotExist` however following cases are not
true when user explicitly specifies a `workdir` while `running` using
`--workdir` which tells `podman` to only use workdir if its exists on
the container. Following configuration is implicity set with other
`run` mechanism like `podman play kube`

Problem with explicit `--workdir` or similar implicit config in `podman play
kube` is that currently podman ignores the fact that workdir can also be
a `symlink` and actual `link` could be valid.

Hence following commit ensures that in such scenarios when a `workdir`
is not found and we cannot create a `workdir` podman must perform a
check to ensure that if `workdir` is a `symlink` and `link` is resolved
successfully and resolved link is present on the container then we
return as it is.

Docker performs a similar behviour.

Signed-off-by: Aditya R <arajan@redhat.com>

test/e2e/build/workdir-symlink/Dockerfile

@@ -0,0 +1,5 @@
+FROM alpine
+RUN mkdir /tmp/destination
+RUN ln -s /tmp/destination /tmp/link
+WORKDIR /tmp/link
+CMD ["echo", "hello"]

test/e2e/build_test.go

@@ -259,6 +259,19 @@ var _ = Describe("Podman build", func() {
 		Expect(session.OutputToString()).NotTo(ContainSubstring("io.podman.annotations.seccomp"))
 	})
 
+	It("podman build where workdir is a symlink and run without creating new workdir", func() {
+		session := podmanTest.Podman([]string{
+			"build", "-f", "build/workdir-symlink/Dockerfile", "-t", "test-symlink",
+		})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+
+		session = podmanTest.Podman([]string{"run", "--workdir", "/tmp/link", "test-symlink"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		Expect(session.OutputToString()).To(ContainSubstring("hello"))
+	})
+
 	It("podman build --http_proxy flag", func() {
 		os.Setenv("http_proxy", "1.2.3.4")
 		if IsRemote() {

test/e2e/play_kube_test.go

@@ -38,6 +38,21 @@ spec:
   hostname: unknown
 `
 
+var workdirSymlinkPodYaml = `
+apiVersion: v1
+kind: Pod
+metadata:
+  labels:
+    app: test-symlink
+  name: test-symlink
+spec:
+  containers:
+  - image: test-symlink
+    name: test-symlink
+    resources: {}
+  restartPolicy: Never
+`
+
 var podnameEqualsContainerNameYaml = `
 apiVersion: v1
 kind: Pod
@@ -1332,6 +1347,26 @@ var _ = Describe("Podman play kube", func() {
 		Expect(sharednamespaces).To(ContainSubstring("pid"))
 	})
 
+	It("podman play kube should be able to run image where workdir is a symlink", func() {
+		session := podmanTest.Podman([]string{
+			"build", "-f", "build/workdir-symlink/Dockerfile", "-t", "test-symlink",
+		})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+
+		err := writeYaml(workdirSymlinkPodYaml, kubeYaml)
+		Expect(err).To(BeNil())
+
+		kube := podmanTest.Podman([]string{"play", "kube", kubeYaml})
+		kube.WaitWithDefaultTimeout()
+		Expect(kube).Should(Exit(0))
+
+		logs := podmanTest.Podman([]string{"pod", "logs", "-c", "test-symlink-test-symlink", "test-symlink"})
+		logs.WaitWithDefaultTimeout()
+		Expect(logs).Should(Exit(0))
+		Expect(logs.OutputToString()).To(ContainSubstring("hello"))
+	})
+
 	It("podman play kube should not rename pod if container in pod has same name", func() {
 		err := writeYaml(podnameEqualsContainerNameYaml, kubeYaml)
 		Expect(err).To(BeNil())