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Creating easyconfig files

We already know how to install easyconfig files that are included with EasyBuild, but what about installing software for which no easyconfig is available yet?

To do this we will need to create additional easyconfig files, since every software installation performed by EasyBuild is done based on an easyconfig file.

In this part of the tutorial we will look at the guts of easyconfig files and even create some ourselves!

Easyconfigs vs easyblocks

Before we dive into writing easyconfig files, let us take a brief look at how they relate to easyblocks.

As we discussed earlier, an easyconfig file (*.eb) is required for each installation performed by EasyBuild which specifies the details of the installation (which software version, toolchain, etc.), while the installation procedure is implemented in an easyblock (a Python module).

When can we leverage a generic easyblock, perhaps via a "fat" easyconfig file that includes a lot of carefully defined easyconfig parameters, and when should we use a minimal easyconfig file together with a custom software-specific easyblock?

This is not an easy question to answer in a general sense, since it depends on several factors: the complexity of the software you want to get installed, how much flexibility you want, how "intelligent" the installation procedure should be with respect to the compiler toolchain and dependencies that are used for the installation, etc.

In a nutshell, custom software-specific easyblocks are "do once and forget": they are central solution to peculiarities in the installation procedure of a particular software package.

Reasons to consider implementing a software-specific easyblock rather than using a generic easyblock include:

  • 'critical' values for easyconfig parameters required to make installation succeed;
  • toolchain-specific aspects of the build and installation procedure (e.g., configure options);
  • interactive commands that need to be run;
  • custom (configure) options for dependencies;
  • having to create or adjust specific (configuration) files;
  • 'hackish' usage of a generic easyblock;
  • complex or very non-standard installation procedure;

Implementing easyblocks is out of scope for this basic tutorial, for more information please consult the EasyBuild documentation.

Writing easyconfig files

Writing an easyconfig file boils down to defining a set of easyconfig parameters in a text file, which we give a '.eb' extension by convention. The name of an easyconfig file doesn't matter when using it directly to install software, but it does matter when EasyBuild needs to find it to resolve a dependency for example (as we discussed earlier).

The syntax for easyconfig files is Python syntax: you are basically defining a bunch of Python variables that correspond to easyconfig parameters.

The order in which the easyconfig parameters are defined doesn't matter, but we generally try to strick to a particular order which roughly corresponds to the order in which the easyconfig parameters are used during the installation. That is mostly helpful for humans staring at easyconfig files or comparing them.

Mandatory parameters

A limited number of easyconfig parameters are mandatory, they must be defined in every easyconfig file:

  • name: the name of the software to install;
  • version: the version of the software to install;
  • homepage: a URL to the website of the software;
  • description: a short description of the software;
  • toolchain: the compiler toolchain to use for the installation;

name, version

It should be no surprise that specifying the name and version of the software you want to install is mandatory. This information may influence the value of several other easyconfig parameters (like the name of the source file), and is also used to the determine the name of the module file to install.

name = 'example'
version = '1.0'

homepage, description

The homepage and description are included in the generated module file for the installation. That way the "module show" command provides some useful high-level information about the installation.

homepage = ''
description = "This is just an example."

Usually it does not matter whether you use single or double quotes to specify string values, but you will often see that single quotes are used for values that don't have spaces (words) and double quotes for values that do have spaces (sentences). There is no technical reason for this, it just feels more natural to some people. There are cases where it is important to use the right type of quotes however, we will get back to that later (keep it in mind for the exercises!).

For multi-line descriptions, you will need to use "triple quoting" (which is standard Python syntax):

description = """This is an example
 of a multi-line description.
 It is spread across multiple lines."""


EasyBuild also requires that the compiler toolchain is specified, via the toolchain easyconfig parameter.

This can either be the system toolchain, for which a constant named SYSTEM is available:

toolchain = SYSTEM

Usually we specify a 'proper' toolchain like the compiler-only toolchain GCC 10.2.0 which we used before, or the full toolchain foss 2020b. The name and version of the toolchain can be specified using a small Python dictionary, for example:

toolchain = {'name': 'GCC', 'version': '10.2.0'}

Commonly used parameters

You will often need to specify additional easyconfig parameters to get something useful done. We will cover the most commonly used ones here, but keep in mind that these are not mandatory.

A full overview of all known easyconfig parameters can be obtained via "eb --avail-easyconfig-params" or just "eb -a" for short, or can be consulted in the EasyBuild documentation.

Sources, patches, and checksums

In most easyconfig files you will see that a list of source files is specified via the sources easyconfig parameter, usually combined with one or more URLs where these sources can be downloaded specified via source_urls. There also may be patch files listed (specified via patches), and checksums for both the source files and patches (specified via checksums).

The sources easyconfig parameter is commonly defined but it is not mandatory, because some easyconfig files only specify bundles of software packages and hence only serve to generate a module file.

Here is an example of how these easyconfig parameters can be specified:

source_urls = [
sources = ['example-1.0-src.tar.gz']
patches = ['example-fix.patch']
checksums = [

Each of these require a list of values, so even if there is only a single source file or download URL you must use square brackets as shown in the example. The default value for each of these is an empty list ([]).

Some things worth pointing out here:

  • The download URLs specified via source_urls do not include the name of the file, that is added automatically by EasyBuild when it tries to download the file (only if it's not available already.)
  • If multiple download URLs are specified, they are each tried once in order until the download of the source file was successful. This can be useful to include backup locations where source files can be downloaded from.
  • Names of source files and patches should not include hardcoded software versions, they usually use a template value like %(version)s instead:
    sources = ['example-%(version)s-src.tar.gz']
    EasyBuild will use the value of the version easyconfig parameter to determine the actual name of the source file. This way the software version is only specified in one place and the easyconfig file is easier to update to other software versions. A list of template values can be consulted via the EasyBuild command line via the --avail-easyconfig-templates option, or in the EasyBuild documentation.
  • Source files can also be specified in ways other than just using a filename, see the EasyBuild documentation for more information.
  • Specified checksums are usually SHA256 checksum values, but other types are also supported.


The easyblock that should be used for the installation can be specified via the easyblock easyconfig parameter.

This is not mandatory however, because by default EasyBuild will determine the easyblock to use based on the name of the software. If 'example' is specified as software name, EasyBuild will try to locate a software-specific easyblock named EB_example (in a Python module named Software-specific easyblocks follow the convention that the class name starts with 'EB_', followed by the software name (where some characters are replaced, like '-' with '_minus_').

Generic easyblocks

Usually the easyblock value is the name of a generic easyblock, if it is specified. The name of a generic easyblock does not start with 'EB_', so you can easily distinguish it from a software-specific easyblock.

Here are a couple of commonly used generic easyblocks:

  • ConfigureMake: implements the standard ./configure, make, make install installation procedure;
  • CMakeMake: same as ConfigureMake, but with ./configure replaced with cmake for the configuration step;
  • PythonPackage: implements the installation procedure for a single Python package, by default using "python install" but other methods like using "pip install" are also supported;
  • Bundle: a simple generic easyblock to bundle a set of software packages together in a single installation directory;
  • PythonBundle: a customized version of the Bundle generic easyblock to install a bundle of Python packages in a single installation directory;

A full overview of the available generic easyblocks is available in the EasyBuild documentation. You can also consult the output of eb --list-easyblocks, which gives an overview of all known easyblocks, and how they relate to each other.

Custom easyconfig parameters

Most generic easyblocks provide additional easyconfig parameters to steer their behaviour. You can consult these via "eb -a --easyblock" or just "eb -a -e", which results in an additional "EASYBLOCK-SPECIFIC" section to be added. See the (partial) output of this command for example:

$ eb -a -e ConfigureMake
Available easyconfig parameters (* indicates specific to the ConfigureMake easyblock):
build_cmd*              Build command to use [default: "make"]
build_type*             Value to provide to --build option of configure script, e.g., x86_64-pc-linux-gnu (determined by config.guess shipped with EasyBuild if None, False implies to leave it up to the configure script) [default: None]
configure_cmd*          Configure command to use [default: "./configure"]
configure_cmd_prefix*   Prefix to be glued before ./configure [default: ""]
host_type*              Value to provide to --host option of configure script, e.g., x86_64-pc-linux-gnu (determined by config.guess shipped with EasyBuild if None, False implies to leave it up to the configure script) [default: None]
install_cmd*            Build command to use [default: "make install"]
prefix_opt*             Prefix command line option for configure script ('--prefix=' if None) [default: None]
tar_config_opts*        Override tar settings as determined by configure. [default: False]


You will often need to list one or more dependencies that are required to install or run the software. We distinguish between two main different types of dependencies: runtime dependencies and build dependencies.

Runtime dependencies are required for using the installed software, and may also have to be available during the installation. These dependencies can be specified via the dependencies easyconfig parameter. EasyBuild will load the modules for these dependencies when setting up the build environment, and will include load statements for them in the generated module file.

Build dependencies are only required during the installation of the software, not for using the software once it is installed. The modules for these dependencies will be loaded in the build environment set up by EasyBuild during the installation, but they will not be loaded by the generated module file. You can specify build dependencies via the builddependencies easyconfig parameter. One typical example of a build dependency is CMake, which is only needed for configuring the build.

Here is a simple example of specifying dependencies:

builddependencies = [('CMake', '3.18.4')]

dependencies = [
    ('Python', '3.8.2'),
    ('HDF5', '1.10.6'),
    ('SciPy-bundle', '2020.03', '-Python-%(pyver)s'),

Both builddependencies and dependencies require a list of tuples, each of which specifying one dependency. The name and version of a dependency is specified with a 2-tuple (a tuple with two string values).

In some cases additional information may have to be provided, as is shown in the example above for the SciPy-bundle dependency where a 3rd value is specified corresponding to the versionsuffix value of this dependency. If this is not specified, it is assumed to be the empty string ('').

Note how we use the '%(pyver)s' template value in the SciPy-bundle dependency specification, to avoid hardcoding the Python version in different places.

See also the EasyBuild documentation for additional options on specifying dependencies.

Version suffix

In some cases you may want to build a particular software package in different configurations, or include a label in the module name to highlight a particular aspect of the installation.

The versionsuffix easyconfig parameter can be used for this purpose. The name of this parameter implies that this label will be added after the software version (and toolchain label) in the standard module naming scheme.

If you are configuring the software to build with a particular non-default value, you can indicate this as follows for example:

versionsuffix = '-example-label'

This mechanism is used frequently to indicate that a software installation depends on a particular version of Python, where the %(pyver)s template comes in useful again:

versionsuffix = '-Python-%(pyver)s'
dependencies = [('Python', '2.7.18')]

Even though Python 2 is officially dead and buried some scientific software still requires it, and mixing modules where some use Python 2 and other use Python 3 doesn't work well. The versionsuffix label is helpful to inform the user that a particular Python version is required by the installation.

Customizing configure, build, test, and install commands

When using a generic easyblock like ConfigureMake or CMakeMake, you will often find yourself having to specify options to the configure, build, test, or install commands, or to inject additional commands right before them.

For this the following standard easyconfig parameters are available:

  • preconfigopts: string value that is glued before the configure command;
  • configopts: string value that is added after the configure command, which can be used to specify configuration options;

Equivalent easyconfig parameters are available for the build, test and install steps: prebuildopts, buildopts, pretestopts, testopts, preinstallopts, and installopts.

Here is a fictitious example of how they can be used:

easyblock = 'ConfigureMake'
dependencies = [('HDF5', '1.10.6')]
configopts = '--enable-hdf5-support'

prebuildopts = 'export HDF5_PREFIX="$EBROOTHDF5" && '

installopts = "PREFIX='%(installdir)s'"

Here we are:

  • Adding the --enable-hdf5-support configure option, to convince the ConfigureMake easyblock to run the following command during the configure step:

    ./configure --prefix ... --enable-hdf5-support
    (where the '...' represents the path to installation directory where the software should be installed).

  • Specifying that an additional command has to be run before running make in the build step. We use '&&' to glue the command to the make command, so make will only be run if the command we specified ran correctly. So, the build step will run something like:

    export HDF5_PREFIX="$EBROOTHDF5" &&  make -j 4
    The '4' value passed to the -j option shown here, which specifies how many commands make can run in parallel, is automatically determined by EasyBuild based on the number of available cores (taking into account ulimit settings, and cpuset and cgroup restrictions).

  • Passing the location where the software should be installed via the PREFIX argument to the make install command during the installation step. This results in the following command being run:

    make install PREFIX=...
    (where the '...' again represents the path to installation directory). Even though the installation directory is already specified in the configure command, it is apparently blatantly ignored by the software we are installing here, and we are expected to specify it this way instead. How rude!

The $EBROOTHDF5 environment variable that we are using in prebuildopts corresponds to the path of the installation directory of the HDF5 dependency. EasyBuild includes a statement to define an $EBROOT* environment variable like this in every environment module file it generates (see the output of "module show HDF5").

Sanity check

One seemingly trivial yet important aspect of the installation procedure that EasyBuild performs is the sanity check step.

By default EasyBuild does a simple sanity check that verifies whether there is a non-empty bin subdirectory in the installation, next to a non-empty lib or lib64 directory (either is sufficient).

It is recommended to customize the sanity check and check for something more specific, like a particular binary or directory, or making sure that a trivial command (like example -V or example --help) runs correctly.

To specify a custom set of files and/or directories to check, you can use the sanity_check_paths easyconfig parameter. The expected value is Python dictionary with two keys: files and dirs. For example:

sanity_check_paths = {
    'files': ['bin/example'],
    'dirs': ['examples/one', 'examples/two'],

In addition, you can specify one or more commands that should be working without a problem (that is, have a zero exit status) via the sanity_check_commands easyconfig parameter. These commands will be run just like a user would: after loading the module that was generated for this installation. Here is an example:

sanity_check_commands = [
    "example --version",
    "example --help",

Module class

Finally, you will usually see the moduleclass easyconfig parameter to be defined as well, for example:

moduleclass = 'lib'

This is done to categorize software, and it is used to group the generated module files into smaller sets (remember what we saw when installing software earlier).

Generating tweaked easyconfigs

Sometimes you may want to install software that differs only slightly from an existing easyconfig file, like a newer software version or using a different compiler toolchain. Do we need to create an easyconfig file for this too?

We do, but EasyBuild does provide some help so you don't need to manually create the easyconfig file. You can use one of the --try-* options provided by the eb command to make EasyBuild generate a new easyconfig file based on an existing one.

For example, to try installing a different software version you can use the --try-software-version option:

eb example-1.2.3.eb --try-software-version 1.2.4

Or, to try using a different compiler toolchain you can use --try-toolchain:

eb example-1.2.3-foss-2020b.eb --try-toolchain intel,2020b

It is important to keep in mind the "try" aspect here: while easyconfigs that are generated by EasyBuild via a --try-* option often do work fine, there is no strong guarantee they will. Newer software versions may come with changes to the installation procedure, additional dependencies that are required, etc. Using a different compiler toolchain may be as simple as just switching one for another, but it may require additional changes to be made to configure options, for example.

Copying easyconfigs

One additional handy command line option we want to highlight is --copy-ec, which can be used to copy easyconfig files to a specific location. That may sound trivial, but keep in mind that you can specify easyconfigs to the eb command using only the filename, and letting the robot search mechanism locate them.

So to copy an easyconfig file, we would have to use eb --search first to get the full location to it, copy-paste that, and then use the cp command.

It is a lot easier with --copy-ec:

$ eb --copy-ec SAMtools-1.11-GCC-10.2.0.eb SAMtools.eb
SAMtools-1.10-GCC-10.2.0.eb copied to SAMtools.eb

If you omit the target location, the easyconfig file will simply be copied to the current working directory, retaining the original filename.

You can copy multiple easyconfig files at once, as long as the target location is an existing directory.


By means of example, we are going to puzzle together an easyconfig file to install the example software package eb-tutorial.

The sources for eb-tutorial version 1.0.1 are available at:

You can consult the unpacked sources at


Make sure EasyBuild is properly configured before you start:

export EASYBUILD_PREFIX=$HOME/easybuild

and that the installed software in /easybuild is available:

module use /easybuild/modules/all

Mandatory parameters

Let's start by getting the mandatory easyconfig parameters defined in the easyconfig file:

name = 'eb-tutorial'
version = '1.0.1'

homepage = ''
description = "EasyBuild tutorial example"

If we try using this (very) minimal easyconfig file, EasyBuild will inform us that we failed to specify one of the mandatory easyconfig parameters: toolchain:

$ eb example.eb
== Temporary log file in case of crash /tmp/eb-90j723rl/easybuild-q21plqvx.log
== found valid index for /easybuild/software/EasyBuild/4.3.3/easybuild/easyconfigs, so using it...
ERROR: Failed to process easyconfig /home/example/example.eb: mandatory parameters not provided in pyheader: toolchain

We will use GCC/10.2.0 as toolchain, since we know it is already installed in /easybuild in the prepared environment, so we also define the toolchain easyconfig parameter:

toolchain = {'name': 'GCC', 'version': '10.2.0'}

In addition, we'll also specify the moduleclass. This is not required, but it is usually set to a sensible value:

moduleclass = 'tools'

The default value is 'base', at least 'tools' has some meaning.


Let us see what happens if we take our current easyconfig file for a spin:

$ eb example.eb
== temporary log file in case of crash /tmp/eb-8_vxjfn7/easybuild-k3aaoan2.log
ERROR: Failed to process easyconfig /home/example/example.eb:
No software-specific easyblock 'EB_eb_minus_tutorial' found for eb-tutorial

That didn't get us very far...

The error shows that there is no software-specific easyblock available for installing the software with the name 'eb-tutorial'. Does that mean we have to implement an easyblock?

In this simple case it doesn't, since we can leverage one of the available generic easyblocks. But, which one?

Build instructions are usually included in a README file, or in the documentation. In this case, there's indeed a minimal README file available, which tells us that we should use the cmake command to configure the installation, followed by make and make install.

We briefly discussed a generic easyblock that does exactly this: CMakeMake.

easyblock = 'CMakeMake'

The "easyblock =" line is usually at the top of the easyconfig file, but strictly speaking the order of the parameter definitions doesn't matter (unless one is defined in terms of another one).

CMake build dependency

Does using the CMakeMake generic easyblock help at all?

$ eb example.eb
== temporary log file in case of crash /tmp/eb-yutbor1p/easybuild-4jc9v1u9.log
== found valid index for /easybuild/software/EasyBuild/4.3.3/easybuild/easyconfigs, so using it...
== processing EasyBuild easyconfig /home/example/example.eb
== building and installing eb-tutorial/1.0.1-GCC-10.2.0...
== fetching files...
== creating build dir, resetting environment...
== unpacking...
== patching...
== preparing...
== configuring...
== FAILED: Installation ended unsuccessfully (build directory: /tmp/easybuild/ebtutorial/1.0.1/GCC-10.2.0):
build failed (first 300 chars): cmd " cmake -DCMAKE_INSTALL_PREFIX=/home/example/easybuild/software/eb-tutorial/1.0.1-GCC-10.2.0 -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER='gcc' -DCMAKE_C_FLAGS='-O2 -ftree-vectorize -march=native -fno-math-errno' -DCMAKE_CXX_COMPILER='g++' -DCMAKE_CXX_FLAGS='-O2 -ftree-vectorize -march=native  (took 0 sec)

It did help: EasyBuild made an attempt to configure the build using the cmake command, but that failed almost instantly. We need to dive into the log file to see the actual reason. By starting at the end of the log file and scrolling up, you should be able to locate the following error message:

/bin/bash: cmake: command not found

Ah, that explains it, cmake isn't even installed on this system. Or is it?

$ module avail CMake

--------------------------- /easybuild/modules/all ----------------------------

Since a module is available for CMake that is compatible with the toolchain we are using (GCC 10.2.0), we can use it as a dependency for the installation. It is only needed for building the software, not for running it, so it's only a build dependency:

builddependencies = [('CMake', '3.18.4')]

There is usually no need to specify toolchain for (build) dependencies, EasyBuild will automatically consider subtoolchains compatible with the specified toolchain to locate module for the dependencies.

You can verify this via eb -D (equivalent with eb --dry-run):

$ eb example.eb -D
 * [x] /easybuild/software/EasyBuild/4.3.3/easybuild/easyconfigs/g/GCC/GCC-10.2.0.eb (module: GCC/10.2.0)
 * [x] /easybuild/software/EasyBuild/4.3.3/easybuild/easyconfigs/c/CMake/CMake-3.18.4-GCCcore-10.2.0.eb (module: CMake/3.18.4-GCCcore-10.2.0)
 * [ ] /home/example/example.eb (module: eb-tutorial/1.0.1-GCC-10.2.0)


If you try again after adding CMake as a build dependency, you will see the installation fail again in the configuration step. Inspecting the log file reveals this:

CMake Error: The source directory "/tmp/example/ebtutorial/1.0.1/GCC-10.2.0" does not appear to contain CMakeLists.txt.

Wait, but there is a CMakeLists.txt, we can see it in the unpacked sources!

Let's inspect the build directory:

$ ls /tmp/$USER/ebtutorial/1.0.1/GCC-10.2.0
$ ls /tmp/$USER/ebtutorial/1.0.1/GCC-10.2.0/easybuild_obj

There's nothing there at all! And that's not strange because we didn't actually specify any sources in our easyconfig file...

The sources easyconfig parameter is commonly defined but it is not mandatory, because some easyconfig files only specify bundles of software packages and hence only serve to generate a module file.

So we need to specify one or more source files that should be used, via the sources easyconfig parameter which specifies a list of names of source files:

sources = ['eb-tutorial-1.0.1.tar.gz']

We can avoid hardcoding the version number here by using a template value:

sources = ['eb-tutorial-%(version)s.tar.gz']

And since this is a standard way of naming software files, there's even a constant available that we can use:

sources = [SOURCE_TAR_GZ]

That way, we only have the software version specified once in the easyconfig file, via the version easyconfig parameter. That will come in useful later (see Exercise 7.2)...

If now we try installing the easyconfig file again, EasyBuild complains that it can't find the specified source file anywhere:

Couldn't find file eb-tutorial-1.0.1.tar.gz anywhere, and downloading it didn't work either...

To let EasyBuild automatically download the source file if it is not available yet, we have to specify where it can be downloaded. This is done via source_urls:

source_urls = ['']
sources = [SOURCE_TAR_GZ]

Required configure option

With sources and source_urls defined, we can try again. Yet again we see the configure step fail. Is this a ruse to make you hate CMake with a passion? Maybe...

Here's what we find in the log file:

CMake Error at CMakeLists.txt:7 (message):
  EBTUTORIAL_MSG is not set!

Apparently the eb-tutorial software has a required configure option. It's almost as if that was done on purpose, how silly!

Options to the configure command can be specified by the configopts easyconfig parameter. To define the value of a CMake option, we need to use -DNAME_OF_OPTION, so:

configopts = "-DEBTUTORIAL_MSG='Hello from the EasyBuild tutorial!' "

We need to be a little bit careful with quotes here. If we use outer double quotes, we have to use single quotes to specify the actual value for the EBTUTORIAL_MSG configure option. That works fine here, but that's not always the case! In some cases we will have to use inner doubles quotes, for example to get environment variables expanded when the configure command is run (see Exercise 7.1).

Sanity check

Hopefully that brings us closer to getting the installation to work...

$ eb example.eb
== sanity checking...
== FAILED: Installation ended unsuccessfully (build directory: /tmp/easybuild/ebtutorial/1.0.1/GCC-10.2.0): build failed (first 300 chars):
Sanity check failed: no (non-empty) directory found at 'lib' or 'lib64' in /home/easybuild/easybuild/software/eb-tutorial/1.0.1-GCC-10.2.0 (took 2 sec)

It got all the way to the sanity check step, that's great!

The sanity check failed because no 'lib' or 'lib64' directory was found. Indeed:

$ ls $HOME/easybuild/software/eb-tutorial/1.0.1-GCC-10.2.0
$ ls $HOME/easybuild/software/eb-tutorial/1.0.1-GCC-10.2.0/bin

There is only a binary named eb-tutorial in the bin subdirectory. So we need to customize the standard sanity check:

sanity_check_paths = {
    'files': ['bin/eb-tutorial'],
    'dirs': [],

Since we want to obtain a working installation, we might as well try to run this eb-tutorial command as well:

sanity_check_commands = ['eb-tutorial']

Let us now retry, but use --module-only rather than redoing the whole installation. --module-only still sanity checks the installation, so if it creates a module, we know it will work as expected. By enabling trace mode via --trace we can get some more information too:

$ eb example.eb --module-only --trace
== sanity checking...
  >> file 'bin/eb-tutorial' found: OK
  >> running command 'eb-tutorial' ...
  >> result for command 'eb-tutorial': OK
== COMPLETED: Installation ended successfully (took 4 sec)

Yes, great success!

To convince yourself that the installation works as intended, try to load the eb-tutorial module and run the eb-tutorial command yourself:

$ module use $HOME/easybuild/modules/all
$ module load eb-tutorial
$ eb-tutorial
Hello from the EasyBuild tutorial!

Complete easyconfig

Here is the complete easyconfig we puzzled together for this example:

easyblock = 'CMakeMake'

name = 'eb-tutorial'
version = '1.0.1'

homepage = ''
description = "EasyBuild tutorial example"

toolchain = {'name': 'GCC', 'version': '10.2.0'}

source_urls = ['']
sources = [SOURCE_TAR_GZ]
checksums = ['d6cec2ea298f4092cb1b880cb017220ab191561da941e9e480639cf3354b7ef9']

builddependencies = [('CMake', '3.18.4')]

configopts = "-DEBTUTORIAL_MSG='Hello from the EasyBuild tutorial!' "

sanity_check_paths = {
    'files': ['bin/eb-tutorial'],
    'dirs': [],

sanity_check_commands = ['eb-tutorial']

moduleclass = 'tools'

One additional easyconfig parameter we defined here is checksums, which specifies SHA256 checksums for source (and patch) files, so EasyBuild can verify them before performing an installation.

You can let EasyBuild determine and inject these SHA256 checksums automatically via eb --inject-checksums:

$ eb example.eb --inject-checksums
== injecting sha256 checksums for sources & patches in example.eb...
== * eb-tutorial-1.0.1.tar.gz: d6cec2ea298f4092cb1b880cb017220ab191561da941e9e480639cf3354b7ef9


Exercise E.1 - Making eb-tutorial a bit more personal

Change the easyconfig file for eb-tutorial to make the message printed by the eb-tutorial command a bit more personal: include the username of the account that was used to install the software in it (using the $USER environment variable).

(click to show solution)

For this we need to change the value that is passed to the EBTUTORIAL_MSG configure option:

configopts = '-DEBTUTORIAL_MSG="Hello from the EasyBuild tutorial! I was installed by $USER." '
Here we have to use inner double quotes, to ensure that the $USER environment variable is expanded by the shell when running the cmake configure command.

When you run the eb-tutorial command yourself, you should get output like this (not a message that includes a literal '$USER' string):

Hello from the EasyBuild tutorial! I was installed by example.

To re-install the example.eb easyconfig, you will need to use eb --rebuild or eb --force.

Exercise E.2 - Installing eb-tutorial version 1.1.0

Install version 1.1.0 of the eb-tutorial example software, which is a trivial version bump compared to version 1.0.1.

The sources are available via:

You can leverage the eb-tutorial easyconfig file we have composed in the example above, but you should not make any manual changes to it!

(click to show solution)

You can use the --try-software-version option for this:

$ eb example.eb --try-software-version 1.1.0
== building and installing eb-tutorial/1.1.0-GCC-10.2.0...
== COMPLETED: Installation ended successfully (took 4 sec)
To test:
$ module use $HOME/easybuild/modules/all
$ module load eb-tutorial/1.1.0-GCC-10.2.0
$ eb-tutorial
I have a message for you:
Hello from the EasyBuild tutorial!
(eb-tutorial version 1.0.1 doesn't print "I have a message for you:")

Exercise E.3 - Installing py-eb-tutorial 1.0.0

Try composing an easyconfig file for the py-eb-tutorial example software, which is a tiny Python package. The source tarball can be downloaded from this link: py-eb-tutorial-1.0.0.tar.gz.

A couple of tips:

  • There is a generic easyblock available for installing Python packages, which will come in useful here.

  • By default EasyBuild performs an import check when install Python packages, using a Python module name that is derived from the software name by default, which will be incorrect in this case. You can specify the correct name to use in the import check by specifying it via the options easyconfig parameter in your easyconfig file:

    options = {'modulename': 'example'}
    (you will need to change 'example' here, of course)

  • Leverage the software that is already pre-installed in /easybuild in the prepared environment. Remember that some already installed modules may be a bundle of a couple of other software packages.

Please also take this into account:

  • Unfortunately this software doesn't come with documentation. That is done to make it an example that is representative for software that you may run into in the wild (it's not because we were lazy when preparing the exercises, really!). You can inspect the sources of this software here. Definitely take a look at the file, it includes some clues about the requirements to get this software installed.

  • Make sure the installation actually works, by checking that the py-eb-tutorial command runs correctly. Maybe you will need to make sure other required software is available as well, for it to work correctly...

(click to show solution)

Here is a complete working easyconfig file for py-eb-tutorial:

easyblock = 'PythonPackage'

name = 'py-eb-tutorial'
version = '1.0.0'
versionsuffix = '-Python-%(pyver)s'

homepage = ''
description = "EasyBuild tutorial Python example"

source_urls = ['']
sources = [SOURCE_TAR_GZ]
checksums = ['fcf73a9efc65527a210b993e8889d41ebf05977eef1f6a65ebac3188152cd496']

toolchain = {'name': 'foss', 'version': '2020b'}

dependencies = [
    ('Python', '3.8.6'),
    ('SciPy-bundle', '2020.11'),
    ('eb-tutorial', '1.0.1'),

use_pip = True

options = {'modulename': 'eb_tutorial'}

sanity_check_paths = {
    'files': ['bin/py-eb-tutorial'],
    'dirs': ['lib/python%(pyshortver)s/site-packages'],

sanity_check_commands = ["py-eb-tutorial"]

moduleclass = 'tools'

Some remarks:

  • We used the PythonPackage generic easyblock. There is also a PythonBundle easyblock for installing bundles of Python packages, which is used for SciPy-bundle for example. But we don't need that here, since we are only dealing with a single Python package.

  • The versionsuffix is not strictly needed, but it's common to tag Python packages with the Python version for which they were installed.

  • The SHA256 checksum for the source tarball was added automatically via eb py-eb-tutorial.eb --inject-checksums.

  • py-eb-tutorial only wants to be installed with pip install, so we had to set use_pip = True. You can consult the custom easyconfig parameters supported by the PythonPackage easyblock via "eb -a -e PythonPackage", see the EASYBLOCK-SPECIFIC part of the output. Even when the default installation mechanism used by PythonPackage (which consists of running python install) works fine, it is recommended to instruct EasyBuild to use pip install instead.

  • By default EasyBuild will try to import py_eb_tutorial, while the actual name of the Python package provided by py-eb-tutorial is just eb_tutorial. We fixed this by specifying the correct Python module name to use via options.

  • Strictly speaking we don't need to specify a custom sanity_check_paths, since the default used by Python package is already pretty decent (it will check for a non-empty lib/python3.8/site-packages directory in the installation). We also want to make sure the py-eb-tutorial command is available in the bin subdirectory however. Hardcoding to python3.8 can be avoided using the %(pyshortver)s template value.

  • A good way to check whether the py-eb-tutorial command works correctly is by running it as a sanity check command. If the eb-tutorial command is not available the py-eb-tutorial command will fail, since it basically just runs the eb-tutorial command. So we need to include eb-tutorial as a (runtime) dependency in the py-eb-tutorial easyconfig file.

Last update: April 21, 2022