From 81804fc4641d279fec8f9bf48b21b22fc90cb891 Mon Sep 17 00:00:00 2001
From: Peter Hunt <pehunt@redhat.com>
Date: Fri, 15 Feb 2019 16:39:24 -0500
Subject: pod infra container is started before a container in a pod is run,
 started, or attached.

Prior, a pod would have to be started immediately when created, leading to confusion about what a pod state should be immediately after creation. The problem was podman run --pod ... would error out if the infra container wasn't started (as it is a dependency). Fix this by allowing for recursive start, where each of the container's dependencies are started prior to the new container. This is only applied to the case where a new container is attached to a pod.

Also rework container_api Start, StartAndAttach, and Init functions, as there was some duplicated code, which made addressing the problem easier to fix.

Signed-off-by: Peter Hunt <pehunt@redhat.com>
---
 libpod/container_graph.go | 97 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)

(limited to 'libpod/container_graph.go')

diff --git a/libpod/container_graph.go b/libpod/container_graph.go
index 44a1f1736..da93be77d 100644
--- a/libpod/container_graph.go
+++ b/libpod/container_graph.go
@@ -1,6 +1,9 @@
 package libpod
 
 import (
+	"context"
+	"strings"
+
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
@@ -169,3 +172,97 @@ func detectCycles(graph *containerGraph) (bool, error) {
 
 	return false, nil
 }
+
+// Visit a node on a container graph and start the container, or set an error if
+// a dependency failed to start. if restart is true, startNode will restart the node instead of starting it.
+func startNode(ctx context.Context, node *containerNode, setError bool, ctrErrors map[string]error, ctrsVisited map[string]bool, restart bool) {
+	// First, check if we have already visited the node
+	if ctrsVisited[node.id] {
+		return
+	}
+
+	// If setError is true, a dependency of us failed
+	// Mark us as failed and recurse
+	if setError {
+		// Mark us as visited, and set an error
+		ctrsVisited[node.id] = true
+		ctrErrors[node.id] = errors.Wrapf(ErrCtrStateInvalid, "a dependency of container %s failed to start", node.id)
+
+		// Hit anyone who depends on us, and set errors on them too
+		for _, successor := range node.dependedOn {
+			startNode(ctx, successor, true, ctrErrors, ctrsVisited, restart)
+		}
+
+		return
+	}
+
+	// Have all our dependencies started?
+	// If not, don't visit the node yet
+	depsVisited := true
+	for _, dep := range node.dependsOn {
+		depsVisited = depsVisited && ctrsVisited[dep.id]
+	}
+	if !depsVisited {
+		// Don't visit us yet, all dependencies are not up
+		// We'll hit the dependencies eventually, and when we do it will
+		// recurse here
+		return
+	}
+
+	// Going to try to start the container, mark us as visited
+	ctrsVisited[node.id] = true
+
+	ctrErrored := false
+
+	// Check if dependencies are running
+	// Graph traversal means we should have started them
+	// But they could have died before we got here
+	// Does not require that the container be locked, we only need to lock
+	// the dependencies
+	depsStopped, err := node.container.checkDependenciesRunning()
+	if err != nil {
+		ctrErrors[node.id] = err
+		ctrErrored = true
+	} else if len(depsStopped) > 0 {
+		// Our dependencies are not running
+		depsList := strings.Join(depsStopped, ",")
+		ctrErrors[node.id] = errors.Wrapf(ErrCtrStateInvalid, "the following dependencies of container %s are not running: %s", node.id, depsList)
+		ctrErrored = true
+	}
+
+	// Lock before we start
+	node.container.lock.Lock()
+
+	// Sync the container to pick up current state
+	if !ctrErrored {
+		if err := node.container.syncContainer(); err != nil {
+			ctrErrored = true
+			ctrErrors[node.id] = err
+		}
+	}
+
+	// Start the container (only if it is not running)
+	if !ctrErrored {
+		if !restart && node.container.state.State != ContainerStateRunning {
+			if err := node.container.initAndStart(ctx); err != nil {
+				ctrErrored = true
+				ctrErrors[node.id] = err
+			}
+		}
+		if restart && node.container.state.State != ContainerStatePaused && node.container.state.State != ContainerStateUnknown {
+			if err := node.container.restartWithTimeout(ctx, node.container.config.StopTimeout); err != nil {
+				ctrErrored = true
+				ctrErrors[node.id] = err
+			}
+		}
+	}
+
+	node.container.lock.Unlock()
+
+	// Recurse to anyone who depends on us and start them
+	for _, successor := range node.dependedOn {
+		startNode(ctx, successor, ctrErrored, ctrErrors, ctrsVisited, restart)
+	}
+
+	return
+}
-- 
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