Add podman pod top

Using the vendored changes from psgo, incorporate JoinNamespaceAndProcessInfoByPids to get process information for each pid namespace of running containers in the pod. Also added a man page, and tests.

Signed-off-by: haircommander <pehunt@redhat.com>

Closes: #1298
Approved by: mheon

2 files changed, 63 insertions, 0 deletions

diff --git a/libpod/pod_top_linux.go b/libpod/pod_top_linux.go
new file mode 100644
index 000000000..f49e28c9d
--- /dev/null
+++ b/libpod/pod_top_linux.go
@@ -0,0 +1,55 @@
+// +build linux
+
+package libpod
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/containers/psgo"
+)
+
+// GetPodPidInformation returns process-related data of all processes in
+// the pod.  The output data can be controlled via the `descriptors`
+// argument which expects format descriptors and supports all AIXformat
+// descriptors of ps (1) plus some additional ones to for instance inspect the
+// set of effective capabilities.  Eeach element in the returned string slice
+// is a tab-separated string.
+//
+// For more details, please refer to github.com/containers/psgo.
+func (p *Pod) GetPodPidInformation(descriptors []string) ([]string, error) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	pids := make([]string, 0)
+	ctrsInPod, err := p.allContainers()
+	if err != nil {
+		return nil, err
+	}
+	for _, c := range ctrsInPod {
+		c.lock.Lock()
+
+		if err := c.syncContainer(); err != nil {
+			c.lock.Unlock()
+			return nil, err
+		}
+		if c.state.State == ContainerStateRunning {
+			pid := strconv.Itoa(c.state.PID)
+			pids = append(pids, pid)
+		}
+		c.lock.Unlock()
+	}
+	// TODO: psgo returns a [][]string to give users the ability to apply
+	//       filters on the data.  We need to change the API here and the
+	//       varlink API to return a [][]string if we want to make use of
+	//       filtering.
+	output, err := psgo.JoinNamespaceAndProcessInfoByPids(pids, descriptors)
+	if err != nil {
+		return nil, err
+	}
+	res := []string{}
+	for _, out := range output {
+		res = append(res, strings.Join(out, "\t"))
+	}
+	return res, nil
+}
diff --git a/libpod/pod_top_unsupported.go b/libpod/pod_top_unsupported.go
new file mode 100644
index 000000000..d44470523
--- /dev/null
+++ b/libpod/pod_top_unsupported.go
@@ -0,0 +1,8 @@
+// +build !linux
+
+package libpod
+
+// GetPodPidInformation is exclusive to linux
+func (p *Pod) GetPodPidInformation(descriptors []string) ([]string, error) {
+	return nil, ErrNotImplemented
+}