Volume Mapping (On-premise)

When you need to read and write files from an on-premise disk, you need to know the path in which the data is stored and make sure that the docker container in your runtime(s) running has access to this path. There are several ways of dealing with this challenge. First, this microlearning will discuss the various alternatives and best approaches in these scenarios.

Should you have any questions, please contact academy@emagiz.com.

1. Prerequisites

• Basic knowledge of the eMagiz platform

2. Key concepts

This microlearning centers around learning how to set up your volume mapping correctly so you can exchange file-based data on-premise.

By volume mapping, we mean: Creating a configuration through which the docker container can read and write data on a specific path on an on-premise machine.

There are several options for volume mapping for your on-premise machine.

• Volume
• Bind mount
• Temporary file system
• Named pipe

3. Volume Mapping (On-premise)

When you need to read and write files from an on-premise disk, you need to know the path in which the data is stored and make sure that the docker container in your runtime(s) running has access to this path. There are several ways of dealing with this challenge. First, this microlearning will discuss the various alternatives and best approaches in these scenarios.

There are several options for volume mapping for your on-premise machine.

• Machine volume
• Bind mount
• Network volume
• Temporary file system
• Named pipe

Below we will explain the differences between the various options available for your volume mapping. But before we do, we first explain how to set up this configuration within eMagiz. Then, you must navigate to Deploy -> Architecture on the model level. In this overview, you can access the Volume mapping per runtime deployed on-premise. To do so, you can right-click on the runtime to access the context menu.

When you click this option, you will see the following pop-up. In this pop-up, you can define the machine-level, runtime-level volumes and network-level volumes. More on that later. This is the starting point for configuring your volume mapping. We will walk through each available option and explain how they work and should be configured.

3.1 Volume

The first Type available to you is Volume. With this option, you create one or more folders on Docker relevant to that runtime to read and write persistent data. To configure this Type, you need to link the runtime volume to a machine volume (or network volume) you can create within the same pop-up. This means you can re-use a "Machine volume" or a "Network volume" over multiple runtimes (i.e., containers).

3.1.1 Link to Machine Volume

So, we first open the tab called "Machine volume." Then, by pressing the "New" button, we can define a new "Machine volume." In the pop-up that follows, we can specify the name of a machine volume and tell whether the Volume already exists on your docker installation or not.

Once you have done so, we press "Save" and switch back to the "Runtime volumes" tab.

In here, we push the "New" button to create a new "Runtime volume." In the following pop-up, we first need to select the Type we want to use. For this example, we use the Type called "Volume."

The first thing we need to select is the "Machine volume." Once we have chosen our "Machine volume," we must set the Target specific for this runtime. This target defines the second part of the path to which the runtime will gain access. For example, when you fill in "/target", we can combine this with the "Machine volume" name to arrive at the correct directory from which eMagiz needs to read data (or write data to). So in our case, this would be "/file-directory/target."

The last setting we need to configure is to define which rights we will grant our runtime on the Volume we are creating. The default setting is read/write rights for the runtime, which is sufficient in most cases. The result of following these steps will be the following.

3.1.2 Link to Network Volume

So, we first open the tab called "Network volume." Then, by pressing the "New" button, we can define a new "Network volume." In the pop-up that follows, we can specify the name of a machine volume and configure the relevant information for a network volume.

Once you have done so, we press "Save" and switch back to the "Runtime volumes" tab.

In here, we push the "New" button to create a new "Runtime volume." In the following pop-up, we first need to select the Type we want to use. For this example, we use the Type called "Volume."

The first thing we need to select is the "Machine volume." Once we have chosen our "Machine volume," we must set the Target specific for this runtime. This target defines the second part of the path to which the runtime will gain access. For example, when you fill in "/target", we can combine this with the "Machine volume" name to arrive at the correct directory from which eMagiz needs to read data (or write data to). So in our case, this would be "/file-directory/target."

The last setting we need to configure is to define which rights we will grant our runtime on the Volume we are creating. The default setting is read/write rights for the runtime, which is sufficient in most cases. The result of following these steps will be the following.

3.2 Bind mount

An alternative option to read and write persistent data is to use the "Bind mount" option. In general, we advise using the "Volume" option because they have better performance, and bind mounts depend on the host machine's directory structure and OS. However, only some external systems can adapt to this that easily. For example, the "Bind mount" option can interest your use case.

To configure a "Bind mount," you need to define a source and a target directory linked to each other. The source directory represents the directory on your local system (that might already be used currently to exchange files). The target directory defines a directory on your docker installation that the runtime can access.

3.3 Temporary file system

The temporary file system option is for you if you do not want to work with persistent data but require non-persistent data. This way, you can increase the container's performance by avoiding writing into the container's writable layer.

To configure this option, you need a target location. On top of that, you can define the maximum size of the temporary file system. 

3.4 Named pipe

The named pipe option can be selected, but we yet have to see a valid use case within the context of eMagiz for using this option. Therefore we won't discuss this option further in this microlearning.

4. Assignment

Navigate to Deploy -> Architecture and look at the Volume mapping options, read the help texts, and play around with the settings (if it is not a customer environment).
This assignment can be completed with the help of the (Academy) project you created/used in the previous assignment.

5. Key takeaways

• File-based communication on-premise changes in the new runtime architecture
• There are two ways to store persistent data
  • Volume
  • Bind mount
• The Volume option is considered the best alternative because they have better performance, and bind mounts are dependent on the directory structure and OS of the host machine
• When you want to deal with non-persistent data, the Temporary file storage option is the way to go.

6. Suggested Additional Readings

If you are interested in this topic and want more information, please read the help text provided by eMagiz.

7. Silent demonstration video

This video demonstrates how you could have handled the assignment and gives context to what you have just learned.

TBA