cli: fix return code when job deployment succeeds (#19876)

When a job eval is blocked due to missing capacity, the `nomad job run`
command will monitor the deployment, which may succeed once additional
capacity is made available.

But the current implementation would return `2` even when the deployment
succeeded because it only took the first eval status into account.

This commit updates the eval monitoring logic to reset the scheduling
error state if the deployment eventually succeeds.

.changelog/19876.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+cli: Fix return code when `nomad job run` succeeds after a blocked eval
+```

command/monitor.go

@@ -306,6 +306,9 @@ func (m *monitor) monitor(evalID string) int {
 		if err != nil || status != api.DeploymentStatusSuccessful {
 			return 1
 		}
+		if status == api.DeploymentStatusSuccessful {
+			schedFailure = false
+		}
 	}
 
 	// Treat scheduling failures specially using a dedicated exit code.

command/monitor_test.go

@@ -4,14 +4,18 @@
 package command
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/hashicorp/nomad/api"
 	"github.com/hashicorp/nomad/ci"
+	"github.com/hashicorp/nomad/helper/pointer"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/mitchellh/cli"
+	"github.com/shoenig/test/must"
+	"github.com/shoenig/test/wait"
 	"github.com/stretchr/testify/require"
 )
 
@@ -223,6 +227,107 @@ func TestMonitor_Monitor(t *testing.T) {
 	}
 }
 
+func TestMonitor_MonitorBlockedEval(t *testing.T) {
+	ci.Parallel(t)
+
+	srv, client, _ := testServer(t, false, nil)
+	defer srv.Shutdown()
+
+	ui := cli.NewMockUi()
+	mon := newMonitor(ui, client, fullId)
+
+	// Submit a service job.
+	// Since there are no clients this will create a blocked eval.
+	job := testJob("job1")
+	job.Type = pointer.Of("service")
+	job.TaskGroups[0].Tasks[0].Config["run_for"] = "300s"
+
+	resp, _, err := client.Jobs().Register(job, nil)
+	must.NoError(t, err)
+
+	// Start monitoring the eval and collect return code.
+	var code int
+	doneCh := make(chan struct{})
+	go func() {
+		defer close(doneCh)
+		code = mon.monitor(resp.EvalID)
+	}()
+
+	// Helper function to check for eval and deployment status.
+	waitForEvalDeploymentStatusFunc := func(evalStatus string, deploymentStatus string) func() error {
+		return func() error {
+			// Verify most recent job eval is blocked.
+			evals, _, err := client.Jobs().Evaluations(*job.ID, nil)
+			if err != nil {
+				return fmt.Errorf("failed to fetch job evals: %w", err)
+			}
+			if len(evals) < 1 {
+				return fmt.Errorf("expected at least one eval, got %d", len(evals))
+			}
+
+			eval := evals[0]
+			if eval.Status != evalStatus {
+				return fmt.Errorf("expected eval to be %q, got %q", evalStatus, eval.Status)
+			}
+
+			// Verify job deployment is running.
+			ds, _, err := client.Jobs().Deployments(*job.ID, false, nil)
+			if err != nil {
+				return fmt.Errorf("failed to fetch job deployments: %w", err)
+			}
+			if len(ds) != 1 {
+				return fmt.Errorf("expected 1 deployment, found %d", len(ds))
+			}
+
+			d := ds[0]
+			if d.Status != deploymentStatus {
+				return fmt.Errorf("expected deployment to be %q, got %q", deploymentStatus, d.Status)
+			}
+			return nil
+		}
+	}
+
+	// Wait until job eval is blocked and deployment is running.
+	must.Wait(t,
+		wait.InitialSuccess(
+			wait.ErrorFunc(waitForEvalDeploymentStatusFunc(
+				api.EvalStatusBlocked,
+				api.DeploymentStatusRunning,
+			)),
+			wait.Timeout(3*time.Second),
+			wait.Gap(1*time.Second),
+		),
+		must.Sprintf("failed to wait for blocked deployment"),
+	)
+
+	// Add client to provide the necessary capacity and unblock the eval.
+	srvRPCAddr := srv.GetConfig().AdvertiseAddrs.RPC
+	testClient(t, "client1", newClientAgentConfigFunc("global", "classA", srvRPCAddr))
+
+	// Wait until job eval is complete and deployment is successful.
+	must.Wait(t,
+		wait.InitialSuccess(
+			wait.ErrorFunc(waitForEvalDeploymentStatusFunc(
+				api.EvalStatusComplete,
+				api.DeploymentStatusSuccessful,
+			)),
+			wait.Timeout(30*time.Second),
+			wait.Gap(1*time.Second),
+		),
+		must.Sprintf("failed to wait for blocked deployment"),
+	)
+
+	// Wait for command to complete.
+	select {
+	case <-doneCh:
+	case <-time.After(5 * time.Second):
+		t.Fatalf("eval monitor took too long")
+	}
+
+	// Verify status code is 0 since deployment was succesful.
+	must.Zero(t, code)
+}
+
 func TestMonitor_formatAllocMetric(t *testing.T) {
 	ci.Parallel(t)