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Writing easyconfig files: the basics

This page explains all the basic information about how to write easyconfig files.

For software builds that follow established build patterns, an easyconfig is all that you need to create in order to build and install the software and the corresponding module file.

Luckily, the majority of software delivery mechanisms are being designed around either autotools or CMake or, perhaps, some simple file extraction/copy pattern. In that case, a generic easyblock can be leveraged; see Overview of generic easyblocks.

Yet, in case the software build calls for more elaborate steps (scientific software never fails to surprise us in this regard), a software-specific easyblock may be required; see Implementing easyblocks.

What is an easyconfig (file)?

An easyconfig file serves as a build specification for EasyBuild.

It consists of a plain text file (in Python syntax) with mostly key-value assignment to define easyconfig parameters.

Easyconfigs typically follow a (fixed) strict naming scheme, i.e. <name>-<version>[-<toolchain>][<versionsuffix>].eb.

The -<toolchain> label (which includes the toolchain name and version) is omitted when a system toolchain is used. The <versionsuffix> label is omitted when the version suffix is empty.


the filename of an easyconfig is only important w.r.t. dependency resolution (--robot), see Enabling dependency resolution.


# easyconfig file for GCC v4.8.3
name = 'GCC'
version = '4.8.3'


Comments can be included in easyconfig files using the hash (#) character (just like in Python code).

Available easyconfig parameters

About 50 different (generic) easyconfig parameters are supported currently. An overview of all available easyconfig parameters is available via the -a command line option.

By default, the parameters specific to generic (default) easyblock ConfigureMake are included; using --easyblock/-e parameters that are specific to a particular easyblock can be consulted.

See Available easyconfig parameters for more details.


$ eb -a -e Binary
Available easyconfig parameters (* indicates specific for the Binary EasyBlock)
name:           Name of software (default: None)
install_cmd(*):     Install command to be used. (default: None)

Mandatory easyconfig parameters

A handful of easyconfig parameters are mandatory:

  • name, version: specify what software (version) to build
  • homepage, description: metadata (used for module help)
  • toolchain: specifies name and version of compiler toolchain to use
    • format: dictionary with name/version keys, e.g., {'name': 'foo', 'version': '1.2.3'}
    • a list of supported toolchains can be found here


  • some others are planned to be required in the future
    • docurls, software license, software license urls


name = 'HPL'
version = '2.0'

homepage = ''
description = "High Performance Computing Linpack Benchmark"

toolchain = {'name': 'goolf', 'version': '1.4.10'}

Common easyconfig parameters

This section includes an overview of some commonly used (optional) easyconfig parameters.

Source files, patches and checksums

  • sources: list of source files (filenames only)
  • source urls: list of URLs where sources can be downloaded
  • patches: list of patch files to be applied (.patch extension)
  • checksums: list of checksums for source and patch files


  • sources are downloaded (best effort), unless already available
  • proxy settings are taken into account, since the urllib2 Python package is used for downloading (since EasyBuild v2.0)
  • patches need to be EasyBuild-compatible
    • unified diff format (diff -ruN)
    • patched locations relative to unpacked sources
  • see Patches for more information on patches
  • see Checksums for more information on checksums
  • sources is usually specified as a list of strings representing filenames for source files, but other formats are supported too, see Alternative formats for sources


name = 'HPL'
version = '2.2'


source_urls = ['']
sources = ['hpl-%(version)s.tar.gz']

# fix Make dependencies, so parallel build also works
patches = ['HPL_parallel-make.patch']

checksums = ['ac7534163a09e21a5fa763e4e16dfc119bc84043f6e6a807aba666518f8df440']



Rather than hardcoding the version (and name) in the list of sources, a string template %(version)s can be used, see also Dynamic values for easyconfig parameters.


Patches can be provided via the patches easyconfig parameter (list). A patch can be defined as:

  • a string,
  • a tuple of 2 elements, or
  • a dict

The most straight-forward use-case is string, which contains the name of the patch file (and must have .patch extension).

A tuple adds the possibility to specify where patch should be applied. This is mostly needed if a patch file adds new files or it is generally not possible to determine the starting directory. The first element is the patch file and the second is either the patch level (as an integer) which is used in the patch command (patch -p<n>) or a directory relative to the unpacked source dir.


tuple also has a special use case if the patch file has any other extension than .patch. In this case, the first tuple argument is a file which should be copied to the unpacked source dir and the second tuple argument is the target path, where the files should be copied to (relative to the unpacked source dir). See below for an example of this use case.

A dict adds the ability to pass the patch command additional arguments. For example, the --binary flag is needed to patch files with CRLF endings. The dict has a required filename key, with level and opts being optional ones.


Specifying only filename in dict is the same as using a plain string definition. Specifying filename and level is same as using a tuple definition.


patches = [
  # a simple patch file

  # when creating only new files by patch file, you need to specify the level:
  ('name-versions-fix.patch', 1),

  # apply the patch in a (sub-)subdirectory inside the source tree
  ('name-versions-fix.patch', 'src/subfolder'),

  # copy file to target_path folder
  ('Makefile', 'target_path'),

  # specify patch file and optionally level and opts for patch command
  {'filename': 'name-versions-fix.patch', 'level': 1, 'opts': '-l'}


Checksums for source files and patches can be provided via the checksums easyconfig parameter.

EasyBuild does not enforce checksums to be available for all source files and patches. Provided checksums will be 'consumed' first for the specified sources (in order), and subsequently also for patches.

Nevertheless, providing checksums for all source files and patches is highly recommended.

If checksums are provided, the checksum of the corresponding source files and patches is verified to match.

The checksums easyconfig parameter is usually defined as a list of strings.

Until EasyBuild v3.3.0, only MD5 checksums could be provided through a list of strings. Since EasyBuild v3.3.0, the checksum type is determined by looking at the length of the string:

  • 32-character strings are considered to be MD5 checksums (md5)
  • 64-character strings are considered to be SHA256 checksums (sha256)
  • (other lengths will result in an error message)

The intention is to move towards making sha256 the recommended and default checksum type.

Other checksum types are also supported: adler32, crc32, sha1, sha512, size (filesize in bytes). To provide checksum values of a specific type, elements of the checksums list can also be 2-element tuples of the form ('<checksum type>', '<checksum value>'). For example:

checksums = [('sha512', 'f962008105639f58e9a4455c8057933ab0a5e2f43db8340ae1e1afe6dc2d24105bfca3b2e1f79cb242495ca4eb363c9820d8cea6084df9d62c4c3e5211d99266')]
Adding or replacing checksums using --inject-checksums

Using the --inject-checksums command line option, you can let EasyBuild add or update checksums in one or more easyconfig files (which is significantly more convenient than doing it manually).

With --inject-checksums, checksums are injected for all sources and patches (if any), as well as for all sources & patches of every extension listed in exts_list (if any, see Extensions).

If the sources (& patches) are not available yet, EasyBuild will try to download them first; i.e., the fetch step is run prior to computing & injecting the checksums.

A backup is created of every easyconfig file that is touched by --inject-checksums, to avoid accidental loss of information. Backups are given an additional extension of the form .bak_<year><month><day><hour><min><sec>.


To clean up backup easyconfig files, you can use this one-liner:

find . -name '*.eb.bak_*' | xargs rm -v

The -v option makes rm print the path of files that are being removed.

Do use this with care; just run find . -name '*.eb.bak_*' first in case of doubt!

Multiple easyconfigs can be specified when using --inject-checksums, they will be processed in sequence. In addition, you can also combine --inject-checksums with --robot, see Synergy between --inject-checksums and --robot.

Adding checksums when none are specified yet

If the easyconfig file does not specify any checksums yet, they are simply injected after the sources (or patches, if present) specification when --inject-checksums is used.

For example:

$ eb bzip2-1.0.6.eb --inject-checksums
== temporary log file in case of crash /tmp/eb-Vm6w3e/easybuild-cAVQl6.log
== injecting sha256 checksums in /example/bzip2-1.0.6.eb
== fetching sources & patches for bzip2-1.0.6.eb...
== backup of easyconfig file saved to /example/bzip2-1.0.6.eb.bak_20170824200906...
== injecting sha256 checksums for sources & patches in bzip2-1.0.6.eb...
== * bzip2-1.0.6.tar.gz: a2848f34fcd5d6cf47def00461fcb528a0484d8edef8208d6d2e2909dc61d9cd
== Temporary log file(s) /tmp/eb-Vm6w3e/easybuild-cAVQl6.log* have been removed.
== Temporary directory /tmp/eb-Vm6w3e has been removed.

The backup easyconfig file can be used to double-check the difference between the original easyconfig file and the one produced by --inject-checksums:

$ diff -u /example/bzip2-1.0.6.eb.bak_20170824200906 /example/bzip2-1.0.6.eb
diff --git a//example/bzip2-1.0.6.eb.bak_20170824200906 b/example/bzip2-1.0.6.eb
index 46b2debed..2eb73f15a 100644
--- a/example/bzip2-1.0.6.eb.bak_20170824200906
+++ b/example/bzip2-1.0.6.eb
@@ -9,8 +9,9 @@ compressors), whilst being around twice as fast at compression and six times fas
 toolchain = SYSTEM
 toolchainopts = {'pic': True}

-sources = [SOURCE_TAR_GZ]
 source_urls = ['']
+sources = [SOURCE_TAR_GZ]
+checksums = ['a2848f34fcd5d6cf47def00461fcb528a0484d8edef8208d6d2e2909dc61d9cd']

 buildopts = "CC=gcc CFLAGS='-Wall -Winline -O3 -fPIC -g $(BIGFILES)'"


Along with injecting checksums, EasyBuild will also reorder the source_urls, sources and patches specifications, in that order and if they are present, and include the checksums specification afterwards. This is done to facilitate working towards a uniform style in easyconfig files, which also applies to the order of specified easyconfig parameters.

Replacing existing checksums

When one or more checksums are already specified, EasyBuild requires the use of --force together with --inject-checksums to replace those checksums. A clear warning will be printed to notify that existing checksums will be replaced.

For example:

$ eb bzip2-1.0.6.eb --inject-checksums
== temporary log file in case of crash /tmp/eb-WhSwVH/easybuild-HCODnl.log
== injecting sha256 checksums in /example/bzip2-1.0.6.eb
== fetching sources & patches for bzip2-1.0.6.eb...
ERROR: Found existing checksums, use --force to overwrite them
$ eb bzip2-1.0.6.eb --inject-checksums --force
== temporary log file in case of crash /tmp/eb-dS2QLa/easybuild-JGxOzC.log
== injecting sha256 checksums in /example/bzip2-1.0.6.eb
== fetching sources & patches for bzip2-1.0.6.eb...

WARNING: Found existing checksums in bzip2-1.0.6.eb, overwriting them (due to use of --force)...

== backup of easyconfig file saved to /example/bzip2-1.0.6.eb.bak_20170824203850...
== injecting sha256 checksums for sources & patches in bzip2-1.0.6.eb...


Any existing checksums are blindly replaced when --inject-checksums --force is used: the existing checksums are not verified to be correct as during normal use of EasyBuild (since that would kind of defeat the purpose of --inject-checksums). In addition, it also doesn't matter whether or not checksums are available for all sources & patches: with --inject-checksums, checksums will be added for all sources and patches, including for extensions listed in exts_list (if any).

Synergy between --inject-checksums and --robot

When --inject-checksums is combined with --robot, checksums are injected for each easyconfig file in the dependency graph for which no module is available yet.

For example, to inject checksums in every easyconfig file required to build HPL 2.2 with the foss/2017a toolchain:

$ MODULEPATH= eb HPL-2.2-foss-2017a.eb --installpath /tmp/$USER/sandbox --inject-checksums --robot
== temporary log file in case of crash /tmp/eb-8HpJc3/easybuild-H35khM.log
== resolving dependencies ...
== injecting sha256 checksums in /example/GCCcore-6.3.0.eb
== injecting sha256 checksums in /example/OpenMPI-2.0.2-GCC-6.3.0-2.27.eb
== injecting sha256 checksums in /example/FFTW-3.3.6-gompi-2017a.eb
== injecting sha256 checksums in /example/HPL-2.2-foss-2017a.eb


We are clearing $MODULEPATH and specifying a custom (empty) location to --installpath to avoid that EasyBuild skips any easyconfig because a corresponding module is already available.

Type of checksum to inject

By default, --inject-checksums will compute & inject SHA256 checksums, but a different checksum type can be specified as an argument (e.g., --inject-checksums md5).


Because of the optional argument that can be passed to --inject-checksums, you should not specify an easyconfig file name directly after the --inject-checksums, since it will be assumed to specify a checksum type, which will result in an error message like:

$ eb --inject-checksums bzip2-1.0.6.eb
Usage: eb [options] easyconfig [...]

eb: error: option --inject-checksums: invalid choice: 'bzip2-1.0.6.eb' (choose from 'adler32', 'crc32', 'md5', 'sha1', 'sha256', 'sha512', 'size')

Alternative formats for sources

In some cases, it can be required to provide additional information next to the name of a source file, e.g., a custom extraction command (because the one derived from the file extension is not correct), or an altername filename that should be used to download the source file.

This can be specified using a Python dictionary value in the sources easyconfig parameter.

Since EasyBuild v3.3.0, three keys are supported:

  • filename (mandatory): filename of source file
  • download_filename: filename that should be used when downloading this source file; the downloaded file will be saved using the filename value
  • extract_cmd: custom extraction command for this source file
  • source_urls: source URLs to consider for downloading this source file
  • git_config: see Downloading from a Git repository

For example:

sources = [{
    'source_urls': [''],
    'filename': 'example-%(version)s.gz',
    'download_filename': 'example.gz',  # provided source tarball is not versioned...
    'extract_cmd': "tar xfvz %s",  # source file is actually a gzipped tarball (filename should be .tar.gz)


Custom extraction commands can also be specified as a 2-element tuple, but this format has been deprecated in favour of the Python dictionary format described above; see also Specifying source files as 2-element tuples to provide a custom extraction command.

Using download_instructions for user-side part of installation

In some cases, getting some of the files required for an installation cannot be automated. Reasons for this include:

  • there is a manual stage to combine multiple downloaded files into the required installation file
  • the file requires a login to download

You can use the download_instructions parameter to specify steps for the user to do. This parameter takes string value and prints it whenever build fails because any file needed was not found. If download_instructions is not specified, Easybuild prints the default message stating the paths that were tested.

download_instructions = """
  Step 1: Go to and download example.jar.
  Step 2: Install example.jar (ensure Java is installed).
  Step 3: Go to the installation directory and create Tarball of its contents (tar -czvf example.tar.gz *).
  Step 4: Move created Tarball into the same directory, where your easyconfig is located and run build again.

Downloading from a Git repository

Since EasyBuild v3.7.0, support for downloading directly from a Git repository is available.

When git_config is provided for a particular source file (see Alternative formats for sources), EasyBuild will create a source tarball after downloading the specified Git repository.

The value for git_config is a Python dictionary, where the following keys are mandatory:

  • url: the URL where the Git repository is located
  • repo_name: the name of the Git repository

The value for filename in the source specification must end in .tar.gz (because a gzipped tarball will be created from the cloned repository).

In addition, either of the following keys must also be defined:

  • tag: the specific tag to download
  • commit: the specific commit ID to download

If a recursive checkout should be made of the repository, the recursive key can be set to True.

To also retain the .git directory (which holds the Git metadata for the repository), you can set the keep_git_dir to True (supported since EasyBuild v4.2.0).

A different name for the top-level directory can be specified via clone_into; by default the name of the repository is used.


  • creating a source tarball named example-main.tar.gz of the main branch of a (fictional) test repository from, and use example-test as top-level directory name:

    sources = [{
        'filename': 'example-main.tar.gz',
        'git_config': {
            'url': '',
            'repo_name': 'test',
            'tag': 'main',
            'clone_into': 'example-test',
  • creating a source tarball named example-20180920.tar.gz of the recursive checkout of commit abcdef12 of the test repository from

    sources = [{
        'filename': 'example-20180920.tar.gz',
        'git_config': {
            'url': '',
            'repo_name': 'test',
            'commit': 'abcdef12',
            'recursive': True,
            'keep_git_dir': True,


Because the source tarball is created locally (by running tar cfvz on the directory containing the cloned repository), the (SHA256) checksum is not guaranteed to be the same across different systems.

Whenever you have the option to download a source tarball (or equivalent) directly (for example from GitHub, which also allows downloading a tarball of a specific commit), we strongly recommend you to do so, git_config is intended for other Git repos.



  • modules must exist for all (non-system) dependencies
  • (non-system) dependencies can be resolved via --robot
  • format: (<name>, <version>[, <versionsuffix>[, <toolchain>]])


name = 'GTI'
toolchain = {'name': 'goolf', 'version': '1.5.14'}
dependencies = [('PnMPI', '1.2.0')]
builddependencies = [('CMake', '2.8.12', '', ('GCC', '4.8.2'))]

For each of the specified (build) dependencies, the corresponding module will be loaded in the build environment defined by EasyBuild. For the runtime dependencies, module load statements will be included in the generated module file.


By default, EasyBuild will try to resolve dependencies using the same toolchain as specified for the software being installed. As of v3.0, if no easyconfig exists to resolve a dependency using the default toolchain EasyBuild will search for the dependency using a compatible subtoolchain.

A different toolchain can be specified on a per-dependency level (cfr. the CMake build dependency in the example above).

Alternatively, you can instruct EasyBuild to use the most minimal (sub)toolchain when resolving dependencies, see Using minimal toolchains for dependencies.

Loading of modules for dependencies with a system toolchain

When a system toolchain is used, the modules for each of the (build) dependencies are always loaded, regardless of the toolchain version (as opposed the behaviour with the dummy toolchain in EasyBuild versions prior to v4.0, see Motivation for deprecating the dummy toolchain).

Specifying dependencies using system toolchain

To make EasyBuild resolve a dependency using the system toolchain, simply use the SYSTEM template constant as the 4th value in the tuple representing the dependency specification.

For example, to specify PnMPI version 1.2.0 built with the system toolchain as a (runtime) dependency:

dependencies = [('PnMPI', '1.2.0', '', SYSTEM)]

Using external modules as dependencies

Since EasyBuild v2.1, specifying modules that are not provided via EasyBuild as dependencies is also supported. See Using external modules for more information.


Besides dependencies, which are found outside the software being built but are part of the site's EasyBuild installation, it is also possible to incorporate extensions to the software within the build. This is done via the exts_list array.

Each entry in exts_list is a three-component tuple, with the name and version number, and a dictionary of configuration options for the entry:

exts_list = [
    ('name', 'version', { 'option':'value', 'option':'value' })

The latter may contain essentially any of the full easyconfig parameters, including buildopts, installopts, etc. Among those options, the following exceptions and special cases should be noted:

  • nosource: If set True, no download will be done
  • source_tmpl: Template string for the file to be downloaded
    • default is '%(name)s-%(version)s.tar.gz'
    • %(name)s and %(version)s come from the exts_list entry (above)
  • sources: Dictionary specifying details of where to download the extension
    • equivalent to a single entry from the easyconfig sources list
    • preferred to use of source_tmpl
  • start_dir: If not set, will be derived; the easyconfig value will not be used
exts_list = [
    ('llvmlite', '0.26.0', {
        'source_urls': [''],
        'patches': ['llvmlite-0.26.0_fix-ffi-Makefile.patch'],
        'checksums': [
            '13e84fe6ebb0667233074b429fd44955f309dead3161ec89d9169145dbad2ebf',    # llvmlite-0.26.0.tar.gz
            '40e6fe6de48709b45daebf8082f65ac26f73a4afdf58fc1e8099b97c575fecae',    # llvmlite-0.26.0_fix-ffi-Makefile.patch
    ('singledispatch', '', {
        'source_urls': [''],
        'checksums': ['5b06af87df13818d14f08a028e42f566640aef80805c3b50c5056b086e3c2b9c'],
    (name, version, {
        'source_urls': [''],
        'checksums': ['c62121b2d384d8b4d244ef26c1cf8bb5cb819278a80b893bf41918ad6d391258'],

That third instance uses the name and version variables defined in the easyconfig file. Since EasyBuild v4.2.2, a single-entry sources dictionary (see Alternative formats for sources) may be included in an exts_list entry. For example, to download Git sources from a private repository and convert them to a tar-ball for installation:

exts_defaultclass = 'PythonPackage'
exts_list = [
    ('pyCAP', '0.1', {
        'sources': {
            'filename': '%(name)s-%(version)s.tar.gz',
            'git_config': {
                'url': 'ssh://',
                'repo_name': 'pyCAP',
                'tag': '%(version)s',

Here, the template strings %(name)s and %(version)s will be substituted from the exts_list entry elements ("pyCAP" and "0.1", respectively), not from the easyconfig values.

Configure/build/install command options

  • configopts: options for configure command
  • preconfigopts: options used as prefix for configure command

In analogy to configure, also build and install commands are tuneable:

  • buildopts, prebuildopts: options for build command
  • installopts, preinstallopts: options for install command


easyblock = 'ConfigureMake'
# configure with: ./ && ./configure CC="$CC" CFLAGS="$CFLAGS"
preconfigopts = "./ && "
buildopts = 'CC="$CC" CFLAGS="$CFLAGS"'
# install with: make install PREFIX=<installation prefix>
installopts = 'PREFIX=%(installdir)s'


For more details w.r.t. use of string templates like %(installdir)s, see Dynamic values for easyconfig parameters.

List of configure/build/install options

In some cases, the configure-build-install cycle must be executed multiple times during a single installation, using different options for one or more steps.

EasyBuild supports specifying a list of strings, each of which specifying a particular set of options to use.

For example, to perform the installation procedure with three different sets of configuration options:

configopts = [
    "--common-opt --one --one-more",
    "--common-opt --two",
    "--common-opt --three",

This way, EasyBuild will perform the configure-build-install cycle three times:

  • configure using --common-opt --one --one-more, build and install
  • configure using --common-opt --two, build and install on top of the existing installation
  • configure using --common-opt --three, build and install once more on top of what is installed already

During this process, the environment is reset and the build directory is cleaned up after each cycle, while the installation directory is left untouched (in order to not destroy the result of earlier cycles).

If several (pre){config|build|install}opts parameters are defined as being a list of strings, the number of items in the lists must be the same. Any of these parameters defined as a single string value are just reused for each of the cycles performed. For example:

easyblock = 'ConfigureMake'
configopts = ['--one', '--two', '--three']
buildopts = 'lib'
preinstallopts = ['TYPE=one', 'TYPE=two', 'TYPE=three']

would result in:

  • ./configure --prefix=... --one; make lib; TYPE=one make install
  • ./configure --prefix=... --two; make lib; TYPE=two make install
  • ./configure --prefix=... --three; make lib; TYPE=three make install

An example use case of this is building FFTW with different precisions, see the FFTW easyconfig files.

Sanity check

Custom paths and commands to be used in the sanity check step can be specified using the respective parameters. These are used to make sure that an installation didn't (partly) fail unnoticed.

  • sanity_check_paths: files/directories that must get installed
  • sanity_check_commands: (simple) commands that must work when the installed module is loaded


  • format: Python dictionary with (only) files/dirs keys
  • values must be lists of (tuples of) strings, one of both must be non-empty
    • paths are relative to installation directory
    • for a path specified as a tuple, only one of the specified paths must be available
  • default values:
    • paths: non-empty bin and lib or lib64 directories
    • commands: none


sanity_check_paths = {
    'files': ["bin/xhpl"],
    'dirs': [],

Easyblock specification

To make EasyBuild use a specific (usually generic) easyblock the easyblock parameter can be used.

By default, EasyBuild will assume that the easyblock to use can be derived from the software name. For example: for GCC, EasyBuild will look for an easyblock class named EB_GCC in the Python module easybuild.easyblocks.gcc.

A list of available easyblocks is available via --list-easyblocks (see also List of available easyblocks); generic easyblocks are the ones for which the name does not start with EB_.


easyblock = 'CMakeMake'
name = 'GTI'
version = '1.2.0'


It is highly recommended to use existing (generic) easyblocks, where applicable. This avoids the need for creating (and maintaining) new easyblocks. Typically, generic easyblocks support several custom easyconfig parameters which allow to steer their behavior (see also All available easyconfig parameters).


easyblock = 'Binary'
install_cmd = "./install.bin"

Module class

The category to which the software belongs to can be specified using the moduleclass easyconfig parameter. By default, the base module class is used (which should be replaced with a more appropriate category).

EasyBuild enforces that only known module classes can be specified (to avoid misclassification due to typos).

The default list of module classes is available via --show-default-moduleclasses; additional module classes can be defined via the --moduleclasses configure option.


name = 'GCC'
moduleclass = 'compiler'


By default, EasyBuild will create a symlink to the generated module file in a module class-specific path. This behavior is configurable through the module naming scheme being used.


The module class may play a significant role in other aspects. For example, the alternative (hierarchical) module naming scheme HierarchicalMNS heavily relies on the moduleclass parameter for discriminating compilers and MPI libraries.

Tweaking existing easyconfig files

The ability to modify easyconfig files on the fly with EasyBuild, provides a very powerful and flexible feature to describe builds, without having to manually create all the input files.

Tweaking existing easyconfigs can be done using the --try-* command lines options. See Tweaking existing easyconfig files for more details.


  • GCC version update:

    eb GCC-4.9.0.eb --try-software-version=4.9.1
  • install WRF + its dozen dependencies with a different toolchain (!):

    eb WRF-3.5.1-ictce-5.3.0-dmpar.eb --try-toolchain=intel,2014b -r

Dynamic values for easyconfig parameters

String templates are completed using the value of particular easyconfig parameters, typically name and/or version. These help to avoid hardcoding values in multiple locations.

A list of available string templates can be obtained using --avail-easyconfig-templates.

Additionally, constants that can be used in easyconfig files are available via --avail-easyconfig-constants.


name = 'GCC'
version = '4.8.3'
source_urls = [
sources = [SOURCELOWER_TAR_GZ]  # gcc-4.8.3.tar.gz


Proper use of string templates is important, in particular to avoid hardcoding the software version in multiple locations of an easyconfig file; this is critical to make --try-software-version behave as expected (see also Tweaking existing easyconfig files).

Version-specific documentation relevant to easyconfigs

Contributing easyconfigs

Contribute your working easyconfig files!

Share your expertise with the community, avoid duplicate work, especially if:

  • the software package is not supported yet
  • an existing easyconfig needs (non-trivial) changes for a different version/toolchain
  • it is a frequently used software package (compilers, MPI, etc.)

See Contributing for more information.