runlabel: run any command

As discussed [1], the runlabel command should execute any command
specified in a label.  The reasoning behind is that we cannot restrict
which options are passed to Podman which thereby has full access to the
host (runlabels must be used with care).

With the updated semantics, runlabel will substitute the commands with a
basepath equal to "docker" or "podman" with "/proc/self/exe", and
otherwise leave the command unchanged to execute any other command on
the host.

[1] https://github.com/containers/libpod/pull/1607#issuecomment-428321382

Signed-off-by: Valentin Rothberg <vrothberg@suse.com>

test/e2e/runlabel_test.go

@@ -0,0 +1,68 @@
+package integration
+
+import (
+	"fmt"
+	"os"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var PodmanDockerfile = `
+FROM  alpine:latest
+LABEL RUN podman --version`
+
+var LsDockerfile = `
+FROM  alpine:latest
+LABEL RUN ls -la`
+
+var _ = Describe("podman container runlabel", func() {
+	var (
+		tempdir    string
+		err        error
+		podmanTest PodmanTest
+	)
+
+	BeforeEach(func() {
+		tempdir, err = CreateTempDirInTempDir()
+		if err != nil {
+			os.Exit(1)
+		}
+		podmanTest = PodmanCreate(tempdir)
+		podmanTest.RestoreAllArtifacts()
+	})
+
+	AfterEach(func() {
+		podmanTest.Cleanup()
+		f := CurrentGinkgoTestDescription()
+		timedResult := fmt.Sprintf("Test: %s completed in %f seconds", f.TestText, f.Duration.Seconds())
+		GinkgoWriter.Write([]byte(timedResult))
+
+	})
+
+	It("podman container runlabel (podman --version)", func() {
+		image := "podman-runlabel-test:podman"
+		podmanTest.BuildImage(PodmanDockerfile, image, "false")
+
+		result := podmanTest.Podman([]string{"container", "runlabel", "RUN", image})
+		result.WaitWithDefaultTimeout()
+		Expect(result.ExitCode()).To(Equal(0))
+
+		result = podmanTest.Podman([]string{"rmi", image})
+		result.WaitWithDefaultTimeout()
+		Expect(result.ExitCode()).To(Equal(0))
+	})
+
+	It("podman container runlabel (ls -la)", func() {
+		image := "podman-runlabel-test:ls"
+		podmanTest.BuildImage(LsDockerfile, image, "false")
+
+		result := podmanTest.Podman([]string{"container", "runlabel", "RUN", image})
+		result.WaitWithDefaultTimeout()
+		Expect(result.ExitCode()).To(Equal(0))
+
+		result = podmanTest.Podman([]string{"rmi", image})
+		result.WaitWithDefaultTimeout()
+		Expect(result.ExitCode()).To(Equal(0))
+	})
+})