# Configure service options From the menu select **Services** then select the service you want to configure.

## Service details In this section you can: * View a summary of the details about the service. * Configure the number of replicas. * Toggle the [service webhook](webhooks.md) on or off. * View the [service logs](logs.md). * Update, [roll back](rollback.md) or delete the service.

## Container specification configuration options ### Change container image Here you can replace the container image with a different image. Select the registry, enter the image name, then click **Apply changes**.

### Environment variables It's best to set environment variables when you [create a container](../containers/add.md) and before deployment. You can still set or edit these variables after deployment if you wish.

### Container labels Labels give you a way to record information about a container, such as the way it's configured. Labels can also be used by Portainer to [hide containers from the interface](../../../admin/settings/#hidden-containers).

### Mounts You have the option to either mount or bind volumes in Portainer, and you can also make them read only. To add a mount, first select either **Volume** or **Bind** from the **Type** dropdown. #### For volume mounts: Select the volume from the **Source** dropdown, enter the container path in the **Target** field tick **Read only** if required then click **Apply changes**.

#### For bind mounts: Enter the source path in the **Source** field, enter the container path in the **Target** field, tick **Read only** if required then click **Apply changes**.

## Networks & ports configuration options ### Networks You can define one or more networks for a service either before or after deployment. Simply select the network from the dropdown then click **Apply changes**.

### Published ports Use this setting to publish ports so they can access a container from outside of the host. You can either add new ports or update existing ports.

### Hosts file entries Lets you manually specify a hostname or URL and associate the URL to an internal or external IP address.

## Service specification settings ### Resource limits and reservations Sets limits on resource utilization, such as memory, CPU reservation and CPU limit.

### Placement constraints Use placement constraints to control which nodes a service can be assigned to.

### Placement preferences While placement constraints limit the nodes a service can run on, placement preferences attempt to place tasks on appropriate nodes in an algorithmic way (by default they are spread evenly).

### Restart policy Docker's restart policies ensure that linked containers are restarted in the correct order, and control the conditions under which they are restarted: * **Any**: Restart the container under any conditions (restarted host or Docker daemon). * **On Failure**: Restart the container if it exits due to an error which manifests as a non-zero exit code. * **None**: Do not automatically restart the container. You can also adjust the restart delay, maximum attempts and restart window.

### Update configuration Updates a service according to the parameters you specify. The parameters specified here are the same as `docker service create` (see [Docker's own documentation](https://docs.docker.com/engine/reference/commandline/service\_create/) for more information). Normally, updating a service will only cause the service’s tasks to be replaced with new ones if a change to the service requires recreating the tasks for it to take effect.

### Logging driver Docker includes logging mechanisms called _logging drivers_ that get information from the containers and services you're running. Each Docker daemon has a default logging driver which each container will use, unless you configure them to use a different logging driver.

### Service labels Lets you add metadata to containers using Docker labels either via an array or a dictionary. We recommend that you use reverse-DNS notation to stop labels from conflicting with those used by other software.

### Configs Docker 17.06 introduced Swarm service configs. These allow you to store non-sensitive information such as configuration files outside a service’s image or running containers. This keeps images as generic as possible and removes the need to bind-mount configuration files into containers or use environment variables.

### Secrets In the context of Docker Swarm services, a secret is a blob of data such as a password, SSH private key, SSL certificate, or another piece of data that should not be transmitted over a network or stored unencrypted in a Dockerfile or in your application’s source code.