Environment creation

Grid'5000 provides bare-metal as a service for experimenting on distributed computers, thanks to the kadeploy service. While kadeploy handles the efficient deployment of a user's customized system (also named environment in the Grid'5000 terminology) on many nodes, companion tools allow building such custom systems environments. Hence, this page describes the Grid'5000 environment creation processes, with the several methods for doing it, and helpful tools.

Introduction: the several ways for preparing a custom system environment

There are different ways to prepare a system environment for experiments:

• (1) A first way consists in deploying a provided environment, e.g. Grid'5000 supported debian10-x64-big, and adding software and custom configurations to it after the initial deployment. That every time a new experiment is run (new deploy job). While it can be relevant, it has an obvious bias: the post-deployment setup is not factorized and must be redone every time and on all nodes.
• (2) A second way consists in building a master system environment with all the wanted customizations, then deploying that pre-built environment on the experiment nodes. This way, the environment preparation is only done once for all times and all nodes: it is factorized.

Once again, building such a customized master system environment can be achieved in different ways:

• (2-a) A first way consists in deploying an already provided environment (such as one of the Grid'5000 supported reference environments) on one node, doing some customizations on that node, then finally saving the operating system of the node as a master environment image, to later allow deploying it on all the nodes of an experiment. This usually involves the tgz-g5k command to create the master environment image (tarball).
• (2-b) A second way consists in building the master environment to deploy on all the nodes of an experiment from a recipe which describes the whole system environment construction process (possibly from scratch). This obviously allows for the reconstructibility and sharing of the environment, hence it helps the reproducibility of the experiment. This involves the same build process that is used to produce the Grid'5000 reference environments, using the kameleon tool (Grid'5000 environment recipes are written in the kameleon recipe and Puppet languages).

Note

Even though it is somehow out of context in this page, we can also mention the use of the sudo-g5k command, which allows a user to gain right away the root privileges whenever needed in the production environment (available on machines by default), hence without requiring a deploy job and to actually deploy an environment with kadeploy beforehand. In the context of the creation of custom system environment, using sudo-g5k: can simplify (1), because it avoids requiring an initial deployment. The standard environment (currently debian10 std) is just used. can also simplify (2-a): after using sudo-g5k to modify the std environment as root, tgz-g5k can be used to export an environment image from the modified standard environment. In both cases, one must understand that this however has the some drawbacks: it limits to using the debian10 std environment as base system on the nodes of the experiment, which may include some unnecessary complexity or limitations

In the remaining of this page, (1) will not be detailed: it is let to the user to choose a tool to deploy software and configurations on running systems, such as clush, taktuk, ansible, etc.

About Grid'5000 supported environments

While building a system environment from scratch (only taking a generic OS installation media as a base) may be doable, it is technically extremely difficult (see the last section of this page). Most Grid'5000 users should rather create customized environments on top of existing works, already done for Grid'5000.

The Grid'5000 technical team provides several reference environments, which a user's customized environment can be built on top of.

	Note

Of course, a user can also build a new customized environment on top of another user's customized environment.

The next sections give detailed technical howtos for customizing existing Grid'5000 environments, first following way (2-a), then way (2-b).

Creating an environment images using tgz-g5k

In this section, following the (2-a) way described above, we explain how to extend an existing Grid'5000 environment by first deploying it on a machine with kadeploy3, then bringing customization to that machine, and finally archiving the operating system of the machine with tgz-g5k to create a new environment image.

Note that this method allows building environment in the format to be deployed with kadeploy3, not VM image to use for instance with qemu (but qcow2 VM disk image can be modified in place). Also note that the next section shows how to build a VM disk image from a recipe using kameleon.

1: deploy the existing environment on a machine

First, we have to create the deploy job, to reserve a machine on which we will deploy the existing environment of our choice, which our customized environment will be based on.

	Note
	At this stage, it is wise choosing a Grid'5000 site and cluster that is not too loaded, furthermore using rather old hardware is of special interest because newer hardware usually has significantly longer boot time → see the Hardware page.

We do an interactive job (-I), of the deploy type (-t deploy), on only one machine (-l host=1). We will give ourselves 3 hours with -l walltime=3.

frontend:

oarsub -I -t deploy -l host=1,walltime=3

The interactive job opens a new shell on the frontend (careful: the job ends when exiting that shell).

Since the hostname of the reserved machine is stored in the $OAR_FILE_NODES file, we can deploy the reference environment of our choice (or another user's environment that we would like to extend) with kadeploy3:

frontend:

kadeploy3 -k -e debian10-x64-base -f $OAR_FILE_NODES

(if the chosen environment is not registered in kaenv3, see the -a option of kadeploy3 to point to a environment description file).

2: customize the environment

Once the deployment has run successfully, we can connect to the machine using ssh as root without password, and do any customization using shell commands.

frontend:

ssh root@hostname

You can therefore update your environment (to add any missing library you need, remove any package that you don't need in order to sizes down the image and possibly speeds up the deployment process, etc.)

Note: When you are done with the customization, mind clearing temporary files or caches to save disk space.

3: archive the environment image

We can now archive the customized environment, using tgz-g5k to create a Grid'5000 environment image from the filesystem of the machine. The environment image is a tarball of the filesystem of the OS with some adaptations.

frontend:

tgz-g5k -m hostname -f ~/environment_image.tgz

This will create a file named environment_image.tgz in your home directory on the frontend.

Note

About tgz-g5k: If you want to create an image of a machine that run the Grid'5000 default environment (i.e. not in a deploy job) and that you modified after gaining the root privileges with using sudo-g5k, the -o option of tgz-g5k must be used so that the connection to the machine is done using oarsh/oarcp instead of ssh/scp. If you want tgz-g5k to access the machine with a custom user id, you can use -u username (default is root). More information on tgz-g5k in tgz-g5k -h or man tgz-g5k.

4: create the environment description file

The new environment image cannot be deployed directly: the image is only one part of an environment. An environment is described by a YAML document. To use the new image, it must be referred by an environment description, so that deploying that environment uses the new image. Note that the environment includes also other information such as the postinstall script and the kernel command line for instance, which can be changed independently from changing the environment image.

The easiest way to create a description for your new environment is to modify the description of the environment it is based on.

Since we used the debian10-x64-base reference environment, we can retrieve its description using the kaenv3 command and save it to a file. Then we'll use it as a base for the description of our customized environment.

frontend:

kaenv3 -p debian10-x64-base -u deploy > my-custom-environment.yaml

We now edit the file to change the environment name, version, description, author, and so on. The image file entry must of course be changed to point to our new environment image tarball file. Since it is stored locally in our home directory, the path can be a simple absolute path (remove the server:// prefix). Finally, the visibility line should be removed or its value changed to shared or private.

---
name: my-debian
version: 1
description: my customized environment based on debian 10 (buster) - base
author: john@doe.org
visibility: shared
destructive: false
os: linux
image:
  file: /home/jdoe/environment_image.tgz
  kind: tar
  compression: gzip
postinstalls:
- archive: server:///grid5000/postinstalls/g5k-postinstall.tgz
  compression: gzip
  script: g5k-postinstall --net debian
boot:
  kernel: "/vmlinuz"
  initrd: "/initrd.img"
  kernel_params:
filesystem: ext4
partition_type: 131
multipart: false

Once this is done, our customized environment is ready to be deployed (in a deploy job) using:

frontend:

kadeploy3 -k -f $OAR_NODEFILE -a my-custom-environment.yaml

(This kind of deployment is called anonymous deployment because the description is not yet in the Kadeploy3 environment registry. It is particularly useful when working by iteration on the environment, thus having to recreate the environment image several times. Otherwise, since registered environments are checksummed, changing the image file requires updating the registration every time with kaenv3)

Once your customized environment is ready, it's optionally the time to add it to the Kadeploy3 environment registry:

frontend:

kaenv3 -a my-custom-environment.yaml

Assuming you set the name field in the environment description to "my-debian", it will then be deployable using the following command:

frontend:

kadeploy3 -k -f $OAR_NODEFILE -e my-debian

If the visibility is set to shared, your environment will show up in the list of available registered environment for any user, using kaenv3 -l -u your_username.

	Warning
	The registration of the environment does not make a copy of the environment image and postinstall files! Do not remove them or the environment will be broken. Also, environments registered by users are not automatically replicated on all sites (there is one kadeploy registry per site).

Creating an environment from a recipe using kameleon

In this section, following the (2-b) way described above, we explain how to build environments from recipes describing the whole creation process, rather than doing interactive modifications in command-line then use tgz-g5k to export the system to an image. With the method, all steps requested to build the environment are written, which helps traceability, reconstructability, and sharing.

There are actually different ways of writing recipes. The recipes of the Grid'5000 reference environment for instance describe the whole process of installation of the operating system from scratch using the installer of the target Linux distribution. Also, the Debian stable environments which are provided in several variants use Puppet for most of the configuration of the system. However, while building from scratch and using Puppet may look very nice, it is also complex and longer to execute.

As a result, we present a method in this documentation that is simpler and closer to what is actually done when using tgz-g5k:

1. The recipe will first retrieve the operating system image (tarball) of an existing Grid'5000 environment and run it a VM. That's bootstrap stage.
2. Then, the recipe will allow any customizations of the VM's operating system in the setup stage.
3. Finally, the export stage will create a new environment from the customized operating system, ready to be consumed by kadeploy.

Recipes are written for and processed by a tool named kameleon, that do the actual build of the environment. Kameleon is a powerful utility to generate operating system images or environments in the Grid'5000 context from recipes.

A kameleon recipe is composed of a main YAML file: the recipe. That recipe possibly depends on other YAML files: some recipes it extends and some macro steps. It also depends on various other files: data, helper scripts,....

Kameleon provides features such as context isolation and interactive breakpoints. Context isolation means that kameleon can run a build process without altering the operating system from where the tool is called itself (kameleon typically uses qemu VMs for the build). Kameleon does not need to run as root.

See the Kameleon website for more information, notably a description of the recipe syntax (language) used in the YAML files.

Preparing the workspace to use kameleon

For the work with kameleon, we suggest creating a fresh directory that will contain our recipes and all dependencies. Optionally, that directory can of course be versioned in a new git project, in order to keep track of any changes made.

node:

mkdir ~/my_recipes && cd ~/my_recipes

Warning

In the remaining of this document, kameleon commands are always run on a Grid'5000 machine in a regular job (not of type deploy), not on the personal workstation, and never on Grid'5000 frontends. The root privilege is not required to build an environment with kameleon (except on PPC64 machines/the drac cluster where sudo-g5k ppc64_cpu --smt=off must be run to deactivate hyperthreading before running kameleon, because qemu on PPC64 does not support hyperthreading).

First we create an interactive job to reserve a node where to run the kameleon commands:

frontend:

oarsub -I

Kameleon is preinstalled on the nodes.

We then install the repository of Grid'5000 recipes:

node:

kameleon repository add grid5000 https://gitlab.inria.fr/grid5000/environments-recipes.git

In case you already installed the repository previously, you may want to update it. To do so, run the following command:

node:

kameleon repository update grid5000

You can then list the available recipe templates with:

node:

kameleon template list

As explained above:

• We see here the templates for Debian stable (9, 10, and 11) with their different variants.
• We also see the templates for other distributions with only the min variant.
• Finally, we see the template for a recipe that builds from an existing Grid'5000 environment → we use that one.

Create the new recipe

As explained above, we extend the grid5000/from_grid5000_environment/base recipe. To do so, we run the following command:

node ~/my_recipes:

kameleon new my_custom_environment grid5000/from_grid5000_environment/base

We can now edit the new recipe file: my_custom_environment.yaml, and look at the global section. A lot of comments are provided to help adapt the recipe to our needs. The most important information to provide in the recipe is what existing environment we want to base our recipe on. This information must be provided in the grid5000_environment_import_name global variable. It must be set to one of the environments that are shown when running kaenv3 -l on a frontend. For instance we may choose to use debiantesting-x64-min. Most other global variables are commented (line begin with a #) because default values may be just fine. However, we may want to change some of those variables for instance to specify the user and version for a specific environment.

## Environment to build from
grid5000_environment_import_name: "debiantesting-x64-min"
#grid5000_environment_import_user: "deploy"
#grid5000_environment_import_version: ""

Once done, the important part is to bring our customization steps for the setup of our environment in the setup section (bootstrap and export should not require any changes).

For example, let's assume we want to install the ffmpeg package in our environement.

We add a new step to the recipe, which is just a sequence of actions to execute. This basically gives a setup section in our recipe as follows:

setup:
 - install_more_packages:
    - install_ffmpeg:
      - exec_in : apt-get update && apt-get install -y ffmpeg

• exec_in means that the command will be executed with bash in the VM of the build process. See the kameleon documation for other commands.
• install_more_packages is a macrostep, it can group one or several microsteps
• install_ffmpeg is a microstep

It is mandatory to define the 2 levels of steps (macrostep and microstep) and respect the format of a correct YAML document, to have a working recipe.

Optionnaly a macrostep and its microsteps can also be defined in a separate file. For instance, we can create the ~/my_recipes/steps/setup/ directory hierarchy and the steps/setup/install_more_packages.yaml file inside, with the following content:

- install_ffmpeg:
    - exec_in : apt-get update && apt-get install -y ffmpeg

Then use it in the recipe with just:

setup:
 - install_more_packages

(no : after install_more_packages, since the macrostep is defined in a separate file).

You can find more information about the kameleon language in the kameleon documentation

To inpect our environment before launching the build:

• We can look at the information about the environment with kameleon info:

node ~/my_recipes:

kameleon info my_custom_environment

• We can look at what the build of the environment involves by running kameleon dryrun:

node ~/my_recipes:

kameleon dryrun my_custom_environment

If any error is raised with those commands, it probably come from a bad syntax in the recipe (e.g. bad YAML formating).

For more complex examples, you may look at the following tutorials:

• PMEM-environment
• ARM64-custom-environment

Build and test

Once the recipe is written, we can launch the build. To do so, we just have to run following command:

node ~/my_recipes:

kameleon build my_custom_environment

	Warning
	Depending on different factors (e.g. the size of the image you are about to create (what variant), the hardware used (SSD or HDD)), the build process can last from a few minutes to a lot longer.

We end up with a build directory that contains the freshly build files we are interested in:

File build/my_custom_environment/my_custom_environment.dsc

• This is the description file of the new environment (this is a YAML file, the file extension does not really matter, be it .dsc, .env or .yaml)
• It can be used either directly with kadeploy to run the deployment without registering the environment:

After creating a new job of type deploy, we run the following kadeploy command from the frontend:

frontend:

kadeploy -a ~/my_recipe/build/my_custom_environment/my_custom_environment.dsc

• Or to register the environment with kaenv3, for later use with kadeploy.

frontend:

kaenv3 -a ~/my_recipe/build/my_custom_environment/my_custom_environment.dsc

File build/my_custom_environment/my_custom_environment.tar.zst

• This is the tarball of our new environment, referred to in the environment description (previously debian11_custom.tgz because the compression was formerly gzip)

	Note
	The environment tarball can also be used directly, for instance with docker import After installing docker on a reserved node with g5k-setup-docker, run: node: zstdcat ~/my_recipe/build/my_custom_environment/my_custom_environment.tar.zst | docker import - debian11-x64-min Then run the docker container, for instance: node: docker run -ti debian11-g5k bash

Of course, writing recipes, building the environment, and testing it may be a trial and error process requiring to loop over the different stages.

Please note that kameleon provides an interactive debugging of the recipe in case of errors or when breakpoints are inserted in the recipe. See comments in the recipes which give the syntax to add a breakpoint.

About the recipes of the Grid'5000 reference environments

As explained above, recipes for Grid'5000 reference environments build from scratch using the target system installer, and use Puppet for the Debian stable environment. The section below shows how to use those recipes in case the previous method does not suit the need.

Extending a Grid'5000 recipe that uses Puppet

We present here how to extend a Grid'5000 recipe and use Puppet to bring some customizations in a traceable way.

As a reminder, Puppet is only used in the Debian stable environment recipes of Grid'5000. We will extend one of those.

The names of the Debian stable (Debian 9, 10 and 11) recipe templates end by a word after a dash: that's the variant name. Variants are min, base, nfs, xen, big, std (see above in this page for more details). Puppet is in charge of configuring the environment operating system with regard to the chosen variant. All variants are defined as Puppet classes that include each others in the following order:

min ⊂ base ⊂ nfs ⊂ big ⊂ std

Additionnaly, the xen class just includes the base class, so that the xen environment is just the base environment with Xen hypervisor and tools added.

This means that all changes made in the min class will affect all other variants. Changes made in the big class will affect the builds of both the big and std variants.

In this example we will extend the min environment recipe of Debian 11. To do so, we use the kameleon new command as follows:

node ~/my_recipes:

kameleon new debian11_custom grid5000/debian11-x64-min.yaml

This creates the ~/my_recipes/debian11_custom.yaml file which is our new recipe. Besides, kameleon took care of importing in the directory all the files for the new recipe depends on.

You can list the recipes which are present in your workspace using the list command:

node ~/my_recipes:

kameleon list

You can see your new debian11_custom recipe along with the recipes that it extends directly or indirectly.

You can look at the steps involved in the build of the recipes using the kameleon dryrun command:

node ~/my_recipes:

kameleon dryrun debian11_custom

We see that the setup section has setup and run steps for an orchestrator: what's the part that prepares everything to use Puppet in the recipe and run it.

Since we want to write our customization with the Puppet language, we do not have to modify the debian11_custom.yaml recipe file much. We may just change the environment description by editing the recipe file ~/my_recipes/debian11_custom.yaml, and changing the description field starting at line 4, for instance:

#==============================================================================
#
# DESCRIPTION: My Grid'5000 Debian Bullseye
#
#==============================================================================

Once done, we can close the file and look at the Puppet code.

Puppet is a software configuration management tool that includes its own declarative language to describe system configuration. It is a model-driven solution that requires limited programming knowledge to use.

The puppets modules used by the Grid'5000 reference environments are located in ~/my_recipes/grid5000/steps/data/setup/puppet/modules/env/manifests/.

For our use case, we can look at the commonpackages.pp file. This is a really simple file that requests packages to be installed.

We can install ffmpeg like this :

class env::commonpackages{
}
...
class env::commonpackages::ffmpeg{
  package{ 'ffmpeg':
    ensure => installed;
  }
}
...

In this quite simple use case, but if you have a package like postfix which requires more configuration, it could be more complex! You may look at the puppet classes to find out how it works. Puppet covers a lot of needs that we cannot describe in this documentation. To know more, please refer to the Puppet documentation.

Extending a Grid'5000 recipe without using Puppet

All Grid'5000 reference environments can also be extended to add modifications using the kameleon language.

Let's say we want to extend grid5000/debiantesting-x64-min. We run the following command:

node ~/my_recipes:

kameleon new my_custom_environment grid5000/debiantesting-x64-min

This creates the ~/my_recipes/my_custom_environment.yaml file, which this time directly describes that it extends grid5000/debiantesting-x64-min.

We can now edit the recipe file, our customizations of the environment operating system is to be written in the setup section (bootstrap and export should not require any changes as long as we work on customizing the environment for Grid'5000).

For example, just like in the previous section with Puppet, we describe below how to install the ffmpeg package (but in the kameleon language this time).

We add a new step to the recipe, which is just a sequence of actions to execute. This basically gives a setup section in our recipe as follows:

setup:
 - "@base"
 - install_more_packages:
    - install_ffmpeg:
      - exec_in : apt-get update && apt-get install -y ffmpeg

• "@base" means that the steps from the environment we extend should be executed before our new steps (a bit like when using super() in a constructor of a class in Java or Ruby to call the constructor of the inherited class).
• exec_in means that the command will be executed with bash in the VM of the build process. See the kameleon documation for other commands.
• install_more_packages is a macrostep, install_ffmpeg is a microstep: It is mandatory to define the 2 level of steps and respect the format of a correct YAML document.

Please notice that this is very similar to what we did when extending the grid5000/from_grid5000_environment/base recipe, but the @base is added, since we want the setup section of the extended recipe to be executed.

Again, to inspect our environment before launching the build:

• We can look at the information about the environment with kameleon info:

node ~/my_recipes:

kameleon info my_custom_environment

• We can look at what the build of the environment involves by running kameleon dryrun:

node ~/my_recipes:

kameleon dryrun my_custom_environment

If any error is raised with those commands, it probably come from a bad syntax in the recipe (e.g. bad YAML formating).

Build and test

Once the recipe is written, we can launch the build. To do so, we just have to run following command:

node ~/my_recipes:

kameleon build my_custom_environment

	Warning
	Depending on different factors (e.g. the size of the image you are about to create (what variant), the hardware used (SSD or HDD)), the build process can last from a few minutes to a lot longer.

We end up with a build directory that contains the freshly build files we are interested in:

File build/my_custom_environment/my_custom_environment.dsc

• This is the description file of the new environment (this is a YAML file, the file extension does not really matter, be it .dsc, .env or .yaml)
• It can be used either directly with kadeploy to run the deployment without registering the environment:

After creating a new job of type deploy, we run the following kadeploy command from the frontend:

frontend:

kadeploy -a ~/my_recipe/build/my_custom_environment/my_custom_environment.dsc

• Or to register the environment with kaenv3, for later use with kadeploy.

frontend:

kaenv3 -a ~/my_recipe/build/my_custom_environment/my_custom_environment.dsc

File build/my_custom_environment/my_custom_environment.tar.zst

• This is the tarball of our new environment, referred to in the environment description (previously debian11_custom.tgz because the compression was formerly gzip)
• It can also be used directly, for instance with docker import

After installing docker on a reserved node with g5k-setup-docker, run:

node:

zstdcat ~/my_recipe/build/my_custom_environment/my_custom_environment.tar.zst | docker import - debian11-x64-min

Then run the docker container, for instance:

node:

docker run -ti debian11-g5k bash

File build/my_custom_environment/my_custom_environment.qcow2

• It is a qcow2 version of the environment for use with qemu (as seen earlier, it is not built when extending grid5000/from_grid5000_environment/base).

Just run Qemu on the image:

node:

qemu-system-x86_64 -enable-kvm -m 2048 -cpu host ~/my_recipe/build/my_custom_environment/my_custom_environment.qcow2

Of course, writing recipes, building the environment, and testing it may be a trial and error process requiring to loop over the different stages.

Please note that kameleon provides an interactive debugging of the recipe in case of errors or when breakpoints are inserted in the recipe. See comments in the recipes which give the syntax to add a breakpoint.

Creating an environment for an unsupported Operating System

	Note
	This requires strong system administrator skills and a very good understanding of how the Grid'5000 bare metal deployment functions.

If an Operating System is not provided as a Grid'5000 environment already, please mind that kameleon recipe allows installation from scratch of any Linux systems:

• boot the OS installer in a VM and do an unattended installation
• run some additional setup
• finally export the built system ready to be consumed by kadeploy3.

Therefore please mind using kameleon. Please get in touch with the Grid'50000 technical team to explain your motivation and ideas and possibly to get some help.