disable healthchecks automatically on non systemd systems

The podman healthchecks are implemented using systemd timers, this works
great but it will never work on non systemd distros. Currently the logic
always assumes systemd is available and will fail with an error, so users
are forced to always run with `--no-healthcheck` to disable healthchecks
that are defined in an image for example. This is annoying and IMO
unnecessary, we should just default to no healthcheck on these systems.

First, use the systemd build tag to disable it at build time if this tag
is not used.
Second, use make sure systemd is used as init before trying
to use healthchecks. This could be the case when we are run in a container.

[NO NEW TESTS NEEDED] We do not have any non systemd VMs in CI AFAIK.

Fixes #16644

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

libpod/healthcheck.go

@@ -432,27 +432,3 @@ func (c *Container) healthCheckStatus() (string, error) {
 
 	return results.Status, nil
 }
-
-func (c *Container) disableHealthCheckSystemd(isStartup bool) bool {
-	if os.Getenv("DISABLE_HC_SYSTEMD") == "true" {
-		return true
-	}
-	if isStartup {
-		if c.config.StartupHealthCheckConfig.Interval == 0 {
-			return true
-		}
-	}
-	if c.config.HealthCheckConfig.Interval == 0 {
-		return true
-	}
-	return false
-}
-
-// Systemd unit name for the healthcheck systemd unit
-func (c *Container) hcUnitName(isStartup bool) string {
-	unitName := c.ID()
-	if isStartup {
-		unitName += "-startup"
-	}
-	return unitName
-}

libpod/healthcheck_linux.go

@@ -1,3 +1,6 @@
+//go:build systemd
+// +build systemd
+
 package libpod
 
 import (
@@ -10,6 +13,7 @@ import (
 	"github.com/containers/podman/v4/pkg/errorhandling"
 	"github.com/containers/podman/v4/pkg/rootless"
 	"github.com/containers/podman/v4/pkg/systemd"
+	"github.com/containers/podman/v4/utils"
 	"github.com/sirupsen/logrus"
 )
 
@@ -132,3 +136,27 @@ func (c *Container) removeTransientFiles(ctx context.Context, isStartup bool) er
 
 	return errorhandling.JoinErrors(stopErrors)
 }
+
+func (c *Container) disableHealthCheckSystemd(isStartup bool) bool {
+	if !utils.RunsOnSystemd() || os.Getenv("DISABLE_HC_SYSTEMD") == "true" {
+		return true
+	}
+	if isStartup {
+		if c.config.StartupHealthCheckConfig.Interval == 0 {
+			return true
+		}
+	}
+	if c.config.HealthCheckConfig.Interval == 0 {
+		return true
+	}
+	return false
+}
+
+// Systemd unit name for the healthcheck systemd unit
+func (c *Container) hcUnitName(isStartup bool) string {
+	unitName := c.ID()
+	if isStartup {
+		unitName += "-startup"
+	}
+	return unitName
+}

libpod/healthcheck_nosystemd_linux.go

@@ -0,0 +1,24 @@
+//go:build !systemd
+// +build !systemd
+
+package libpod
+
+import (
+	"context"
+)
+
+// createTimer systemd timers for healthchecks of a container
+func (c *Container) createTimer(interval string, isStartup bool) error {
+	return nil
+}
+
+// startTimer starts a systemd timer for the healthchecks
+func (c *Container) startTimer(isStartup bool) error {
+	return nil
+}
+
+// removeTransientFiles removes the systemd timer and unit files
+// for the container
+func (c *Container) removeTransientFiles(ctx context.Context, isStartup bool) error {
+	return nil
+}