docker/compose · error

service %q is not running container #%d

Error message

service %q is not running container #%d

What it means

getSpecifiedContainer lists containers for the project plus a com.docker.compose.container-number label filter for the requested index; when the filtered list is empty and an explicit index (>0) was requested, this specific error is returned. It is the backing error for index-addressed operations such as `docker compose exec --index N` and `docker compose logs --index N`.

Source

Thrown at pkg/compose/containers.go:105

	return f
}

func (s *composeService) getSpecifiedContainer(ctx context.Context, projectName string, oneOff oneOff, all bool, serviceName string, containerIndex int) (container.Summary, error) {
	defaultFilters := getDefaultFilters(projectName, oneOff, serviceName)
	if containerIndex > 0 {
		defaultFilters.Add("label", containerNumberFilter(containerIndex))
	}
	res, err := s.apiClient().ContainerList(ctx, client.ContainerListOptions{
		Filters: defaultFilters,
		All:     all,
	})
	if err != nil {
		return container.Summary{}, err
	}
	containers := res.Items
	if len(containers) < 1 {
		if containerIndex > 0 {
			return container.Summary{}, fmt.Errorf("service %q is not running container #%d", serviceName, containerIndex)
		}
		return container.Summary{}, fmt.Errorf("service %q is not running", serviceName)
	}

	// Sort by container number first, then put one-off containers at the end
	sort.Slice(containers, func(i, j int) bool {
		numberLabelX, _ := strconv.Atoi(containers[i].Labels[api.ContainerNumberLabel])
		numberLabelY, _ := strconv.Atoi(containers[j].Labels[api.ContainerNumberLabel])
		IsOneOffLabelTrueX := containers[i].Labels[api.OneoffLabel] == "True"
		IsOneOffLabelTrueY := containers[j].Labels[api.OneoffLabel] == "True"

		if IsOneOffLabelTrueX || IsOneOffLabelTrueY {
			return !IsOneOffLabelTrueX && IsOneOffLabelTrueY
		}

		return numberLabelX < numberLabelY
	})
	return containers[0], nil

View on GitHub (pinned to ddc4b044b6)

Solutions

1. Check the actual replica count and numbers: `docker compose ps web` (container numbers are in the names, e.g. web-2)
2. Scale up first (`docker compose up -d --scale web=3`) or drop --index to let Compose pick any running replica
3. If the target replica exists but is stopped, start it (`docker compose start web`) before the indexed command

Example fix

# before
docker compose exec --index 3 web sh   # only 2 replicas

# after
docker compose up -d --scale web=3
docker compose exec --index 3 web sh

// before exec --index N, confirm a container with that number label exists
list, _ := dockerCli.Client().ContainerList(ctx, client.ContainerListOptions{
    All: true,
    Filters: filters.NewArgs(
        filters.Arg("label", "com.docker.compose.project="+project),
        filters.Arg("label", "com.docker.compose.service="+service),
        filters.Arg("label", fmt.Sprintf("com.docker.compose.container-number=%d", index)),
    ),
})
if len(list.Items) == 0 { return fmt.Errorf("no replica #%d for %s", index, service) }

if err != nil && strings.Contains(err.Error(), "is not running container #") {
    // re-check replica count (compose ps) and retry without --index or after scaling up
}

When it happens

Trigger: `docker compose exec --index 3 web sh` when the service runs fewer than 3 replicas (or none); the container-number label filter matches no container because scaling decreased, the numbered container was recreated, or `--all` was not passed and that replica is stopped.

Common situations: Scripts hardcoding `--index` against autoscaled services; using --index right after `up --scale web=2` reduced replicas; addressing a stopped replica (needs All=true listing) that the default running-only filter hides.

Related errors

• deleting paths in %s: %w
• no container found for project %q: %w
• service %q is not running
• no container(s) found with the following name(s): %s
• not found

AI-assisted analysis of docker/compose@ddc4b044b6 (2026-08-15). Data as JSON: /api/errors/847aebca17e08e17. Report an issue: GitHub.