podman healthcheck run (phase 1)

Add the ability to manually run a container's healthcheck command.
This is only the first phase of implementing the healthcheck.
Subsequent pull requests will deal with the exposing the results and
history of healthchecks as well as the scheduling.

Signed-off-by: baude <bbaude@redhat.com>

libpod/healthcheck.go

@@ -0,0 +1,92 @@
+package libpod
+
+import (
+	"os"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// HealthCheckStatus represents the current state of a container
+type HealthCheckStatus int
+
+const (
+	// HealthCheckSuccess means the health worked
+	HealthCheckSuccess HealthCheckStatus = iota
+	// HealthCheckFailure means the health ran and failed
+	HealthCheckFailure HealthCheckStatus = iota
+	// HealthCheckContainerStopped means the health check cannot
+	// be run because the container is stopped
+	HealthCheckContainerStopped HealthCheckStatus = iota
+	// HealthCheckContainerNotFound means the container could
+	// not be found in local store
+	HealthCheckContainerNotFound HealthCheckStatus = iota
+	// HealthCheckNotDefined means the container has no health
+	// check defined in it
+	HealthCheckNotDefined HealthCheckStatus = iota
+	// HealthCheckInternalError means somes something failed obtaining or running
+	// a given health check
+	HealthCheckInternalError HealthCheckStatus = iota
+	// HealthCheckDefined means the healthcheck was found on the container
+	HealthCheckDefined HealthCheckStatus = iota
+)
+
+// HealthCheck verifies the state and validity of the healthcheck configuration
+// on the container and then executes the healthcheck
+func (r *Runtime) HealthCheck(name string) (HealthCheckStatus, error) {
+	container, err := r.LookupContainer(name)
+	if err != nil {
+		return HealthCheckContainerNotFound, errors.Wrapf(err, "unable to lookup %s to perform a health check", name)
+	}
+	hcStatus, err := checkHealthCheckCanBeRun(container)
+	if err == nil {
+		return container.RunHealthCheck()
+	}
+	return hcStatus, err
+}
+
+// RunHealthCheck runs the health check as defined by the container
+func (c *Container) RunHealthCheck() (HealthCheckStatus, error) {
+	var newCommand []string
+	hcStatus, err := checkHealthCheckCanBeRun(c)
+	if err != nil {
+		return hcStatus, err
+	}
+	hcCommand := c.HealthCheckConfig().Test
+	if len(hcCommand) > 0 && hcCommand[0] == "CMD-SHELL" {
+		newCommand = []string{"sh", "-c"}
+		newCommand = append(newCommand, hcCommand[1:]...)
+	} else {
+		newCommand = hcCommand
+	}
+	// TODO when history/logging is implemented for healthcheck, we need to change the output streams
+	// so we can capture i/o
+	streams := new(AttachStreams)
+	streams.OutputStream = os.Stdout
+	streams.ErrorStream = os.Stderr
+	streams.InputStream = os.Stdin
+	streams.AttachOutput = true
+	streams.AttachError = true
+	streams.AttachInput = true
+
+	logrus.Debugf("executing health check command %s for %s", strings.Join(newCommand, " "), c.ID())
+	if err := c.Exec(false, false, []string{}, newCommand, "", "", streams, 0); err != nil {
+		return HealthCheckFailure, err
+	}
+	return HealthCheckSuccess, nil
+}
+
+func checkHealthCheckCanBeRun(c *Container) (HealthCheckStatus, error) {
+	cstate, err := c.State()
+	if err != nil {
+		return HealthCheckInternalError, err
+	}
+	if cstate != ContainerStateRunning {
+		return HealthCheckContainerStopped, errors.Errorf("container %s is not running", c.ID())
+	}
+	if !c.HasHealthCheck() {
+		return HealthCheckNotDefined, errors.Errorf("container %s has no defined healthcheck", c.ID())
+	}
+	return HealthCheckDefined, nil
+}