manifest.toml
NAME
manifest.toml - declarative environment configuration format
SYNOPSIS
The manifest.toml file is a declarative format for specifying the
packages installed in an environment, environment variables to make
available to the environment, a shell script to run upon activation of
the environment, and other options to change the behavior of the
environment.
DESCRIPTION
Flox environments come with a declarative manifest in TOML format. An environment can be defined entirely by this one file. The file is divided into just a few sections that are represented as TOML tables:
[install]
The [install] table is the core of the environment, specifying which
packages you’d like installed in the environment. An example of the
[install] table is shown below:
Since this is TOML, equivalent ways of writing this would be
or
[install.ripgrep]
pkg-path = "ripgrep"
[install.pip]
pkg-path = "python310Packages.pip"
Flox will use the first format by default when automatically editing the manifest.
Package names
Packages are organized in a hierarchical structure such that certain
packages are found at the top level (e.g. ripgrep), and other packages
are found under package sets (e.g. python310Packages.pip). We call
this location within the catalog the “pkg-path”.
The pkg-path is searched when you execute a flox search command. The
pkg-path is what’s shown by flox show. Finally, the pkg-path appears
in your manifest after a flox install.
Package descriptors
Each entry in the [install] table is a key-value pair. The key in the
key-value pair (e.g. ripgrep, pip) is referred to as an “install
ID”, and represents the name by which you will refer to a particular
package e.g. if you wanted to uninstall or upgrade the package. Install
IDs are inferred from the last attribute in the pkg-path, but may also
be specified either at install-time via the -i option or interactively
via flox-edit(1).
The value in the key-value pair is called a “package descriptor”. A
package is specified by a number of available options which are separate
from the install ID, so you are free to change them independently of one
another. This allows you to change package details while keeping a
stable install ID, for example upgrading from gcc.pkg-path = "gcc12"
to gcc.pkg-path = "gcc13".
Most package descriptors will be catalog descriptors, which allow specifying packages from the Flox catalog. A second format, flake descriptors, is also supported, which allows specifying software to install from an arbitrary Nix flake.
Catalog descriptors
The full list of catalog descriptor options is:
Descriptor ::= {
pkg-group = null | <STRING>
, version = null | <STRING>
, systems = null | [<STRING>, ...]
, pkg-path = <STRING>
, priority = null | <INT>
}
Only pkg-path is required.
By specifying some of these options you create a set of requirements that the installed program must satisfy, otherwise installation will fail.
By default, all packages belong to the same pkg-group, which means
providing specific versions for two different packages can quickly lead
to installation failures. To avoid such failures, either give a looser
version constraint, or move one of the packages to a different package
group.
Each option is described below:
pkg-group
Marks a package as belonging to a pkg-group.
The pkg-group is a collection of software that is known to work together at a point in time. Adding packages to a pkg-group enables packages in the pkg-group to share the same libraries and dependencies, which ensures maximum compatibility and minimizes the size of the environment.
Packages are marked as belonging to a pkg-group simply by setting this option to the name of the pkg-group. Packages that do not have a pkg-group specified belong to the same group.
Multiple pkg-groups may resolve to the same version of the catalog.
Pkg-groups are upgraded as a unit, ensuring that the packages within the
pkg-group continue to work together. See
flox-upgrade(1) for more details on how
pkg-groups and packages interact during upgrades.
version
Requires that the package match either an exact version or a semver
range.
The semantic version can be specified with the typical qualifiers such
as ^, >=, etc. Semantic versions that do not specify all three
fields (MAJOR.MINOR.PATCH) will treat the unspecified fields as
wildcards. This instructs Flox to find the latest versions for those
fields. For example version = "1.2" would select the latest version in
the 1.2.X series.
systems
A list of systems on which to install this package. When omitted this
defaults to the same systems that the manifest specifies that it
supports via options.systems.
pkg-path
The abbreviated location of a package within a catalog. A pkg-path is a
sequence of one or more attributes joined by a delimiter. For example,
both ripgrep and python310Packages.pip are pkg-paths. A pkg-path
that contains more than one attribute can be represented as either a
single string that contains a ‘.’-delimited sequence of the attributes,
or it can be represented as a TOML array of strings where each string is
an attribute. For example, both "python310Packages.pip" and
["python310Packages", "pip"] are equivalent for the pkg-path option.
This option is mutually exclusive with abs-path.
priority
A priority used to resolve file conflicts where lower values indicate
higher priority.
Each package internally has /bin, /man, /include, and other
directories for the files they provide. These directories from all
packages in the environment are merged when building the environment.
Two packages that provide the same /bin/foo file cause a conflict, and
it’s ambiguous which file should ultimately be placed into the
environment. Such conflicts can be resolved by assigning different
priorities to the conflicting packages.
The default priority is 5. Packages with a lower priority value will
take precedence over packages with higher priority values.
Flake descriptors
Flake descriptors allow installing software from an arbitrary Nix flake.
The full list of flake descriptor options is:
Descriptor ::= {
flake = <STRING>
, systems = null | [<STRING>, ...]
, priority = null | <INT>
}
Only flake is required. systems and priority behave the same as
described above for catalog descriptors, and flake is described below:
flake
Specifies a Nix flake installable, which Nix refers to as a flake output
attribute and documents at
https://nix.dev/manual/nix/2.17/command-ref/new-cli/nix#flake-output-attribute.
Flake installables are of the form flakeref[#attrpath], where flakeref
is a flake reference and attrpath is an optional attribute path.
Flox tries to use the same fallback behavior as Nix; if no attrpath is
specified, the flake is checked for containing
packages.$system.default or defaultPackage.$system. If an attrpath
is specified, it is checked whether packages.$system.$attrpath or
legacyPackages.$system.$attrpath exist.
[vars]
The [vars] section allows you to define environment variables for your
environment that are set during environment activation. The environment
variables specified here cannot reference one another. The names and
values of the environment variables are copied verbatim into the
activation script, so capitalization will be preserved.
Example:
[hook]
The on-activate script in the [hook] section is useful for
performing initialization in a predictable Bash shell environment.
on-activate
The on-activate script is sourced from a bash shell, and it can be
useful for spawning processes, dynamically setting environment
variables, and creating files and directories to be used by the
subsequent profile scripts, commands, and shells.
Hook scripts inherit environment variables set in the [vars] section,
and variables set here will in turn be inherited by the [profile]
scripts described below.
Any output written to stdout in a hook script is redirected to
stderr to avoid it being mixed with the output of profile section
scripts that write to stdout for “in-place” activations.
[hook]
on-activate = """
# Interact with the tty as you would in any script
echo "Starting up $FLOX_ENV_DESCRIPTION environment ..."
read -e -p "Favourite colour or favorite color? " value
# Set variables, create files and directories
venv_dir="$(mktemp -d)"
export venv_dir
# Perform initialization steps, e.g. create a python venv
python -m venv "$venv_dir"
# Invoke apps that configure the environment via stdout
eval "$(ssh-agent)"
"""
The on-activate script is not re-run when activations are nested. A
nested activation can occur when an environment is already active and
either eval "$(flox activate)" or flox activate -- CMD is run. In
this scenario, on-activate is not re-run. Currently, environment
variables set by the first run of the on-activate script are captured
and then later set by the nested activation, but this behavior may
change.
The on-activate script may be re-run by other commands; we may create
ephemeral activations and thus run the script multiple times for
commands such as services start. For this reason, it’s best practice
to make on-activate idempotent. However, the environment of your
current shell is only affected by the initial run of the script for the
first activation for your shell.
It’s also best practice to write hooks defensively, assuming the user is using the environment from any directory on their machine.
script - DEPRECATED
This field was deprecated in favor of the profile section.
[profile]
Scripts defined in the [profile] section are sourced by your shell
and inherit environment variables set in the [vars] section and by the
[hook] scripts. The profile.common script is sourced for every
shell, and special care should be taken to ensure compatibility with all
shells, after which exactly one of profile.{bash,fish,tcsh,zsh} is
sourced by the corresponding shell.
These scripts are useful for performing shell-specific customizations such as setting aliases or configuring the prompt.
[profile]
common = """
echo "it's gettin' flox in here"
"""
bash = """
source $venv_dir/bin/activate
alias foo="echo bar"
set -o vi
"""
zsh = """
source $venv_dir/bin/activate
alias foo="echo bar"
bindkey -v
"""
fish = """
source $venv_dir/bin/activate.fish
alias foo="echo bar"
fish_vi_key_bindings
"""
Profile scripts are re-run for nested activations. A nested activation
can occur when an environment is already active and either
eval "$(flox activate)" or flox activate -- CMD is run. In this
scenario, profile scripts are run a second time. Re-running profile
scripts allows aliases to be set in subshells that inherit from a parent
shell with an already active environment.
[services]
The [services] section of the manifest allows you to describe the
services you would like to run as part of your environment e.g. a web
server or a database. The services you define here use the packages
provided by the [install] section and any variables you’ve defined in
the [vars] section or hook.on-activate script.
The [services] section is a table of key-value pairs where the keys
determine the service names, and the values (service descriptors)
determine how to configure and run the services.
An example service definition is shown below:
[services.database]
command = "postgres start"
vars.PGUSER = "myuser"
vars.PGPASSWORD = "super-secret"
vars.PGDATABASE = "mydb"
vars.PGPORT = "9001"
This would define a service called database that configures and starts
a PostgreSQL database.
The full set of options is show below:
ServiceDescriptor ::= {
command = STRING
, vars = null | Map[STRING, STRING]
, is-daemon = null | BOOL
, shutdown = null | Shutdown
}
Shutdown ::= {
command = STRING
}
command
The command to run (interpreted by a Bash shell) to start the service.
This command can use any environment variables that were set in the
[vars] section, the hook.on-activate script, or the service-specific
vars table.
vars
A table of environment variables to set for the invocation of this
specific service. Nothing outside of this service will observe these
environment variables.
is-daemon
Whether this service spawns a daemon when it starts. Some commands start
a background process and then terminate instead of themselves running
for an extended period of time. These programs need special handling
when it comes time to shut down the services, so you must mark them with
the is-daemon field. If this field is set to true you must also
specify the shutdown.command field, otherwise the process will
continue to run after calling flox services stop or after exiting the
last activation of the environment.
shutdown.command
A command to run to shut down the service instead of delivering the
SIGTERM signal to the process. Some programs require special handling to
shut down properly e.g. a program that spawns a server process and uses
a client to tell the server to shut down. Sending a SIGTERM to a client
in that case may not shut down the server. In those cases you may
provide a specific shutdown command to run instead of relying on the
default behavior of sending a SIGTERM to the service. This field is
required if the is-daemon field is true.
[options]
The [options] section of the manifest details settings for the
environment itself.
The full set of options are listed below:
Options ::= {
systems = null | [<STRING>, ...]
, allow = null | Allows
, semver = null | Semver
, cuda-detection = null | <BOOL>
}
Allows ::= {
unfree = null | <BOOL>
, broken = null | <BOOL>
, licenses = null | [<STRING>, ...]
}
Semver ::= {
allow-pre-releases = <BOOL>
}
systems
The allowlist of systems that this environment supports. Valid values
are x86_64-linux, aarch64-linux, x86_64-darwin, and
aarch64-darwin. flox init automatically populates
this list with the current system type. A user that attempts to pull an
environment from FloxHub when their environment isn’t explicitly
supported will be prompted whether to automatically add their system to
this list. See flox-pull(1) for more details.
allow.unfree
Allows packages with unfree licenses to be installed and appear in
search results. The default is false.
allow.broken
Allows packages that are marked broken in the catalog to be installed
and appear in search results. The default is false.
allow.licenses
An allowlist of software licenses to allow in search results in
installs. Valid entries are SPDX
Identifiers.
semver.allow-pre-releases
Whether to allow pre-release software for package installations. The
default is false. Setting this value to true would allow a package
version 4.2.0-pre rather than 4.1.9.
cuda-detection
Whether to detect CUDA libraries and provide them to the environment.
The default is true. When enabled, Flox will detect if you have an
Nvidia device and attempt to locate libcuda in well-known paths. Then
it will symlink the libraries into .flox/lib and add that path to
FLOX_ENV_LIB_DIRS.