“Long-running plugins” are the name given to the implementations of Ketrew's
backends, e.g. Daemonize
, Yarn
, or PBS
.
The long-running plugins must:
LONG_RUNNING
interface;`Long_running (name, serialized_state)
;Ketrew.Plugin.register_long_running_plugin
.There are (for now) four long-running methods in the library, see
Ketrew.Lsf
,
Ketrew.Yarn
,
Ketrew.Pbs
, and
Ketrew.Daemonize
.
They all use the module Ketrew.Long_running_utilities
which provides a few
helpers for plugin writers.
Moreover, the tests contain a “dynamically linked plugin” that uses the
implementation of Ketrew.Daemonize
and adds a (stupid) custom runtime-query:
src/test/dummy-plugin/dummy_plugin.ml
.src/test/dummy_plugin_user.ml
.By default, Ketrew expects long-running plugins to be compiled to native
dynamically loadable modules (.cmxs
files).
Modules are then loaded from the configuration file thanks to the ~plugins
optional argument of Ketrew.Configuration.create
. Plugins can be direct
(preferably absolute) paths to .cmxs
files or names of OCamlfind packages:
let plugins = [ `OCamlfind "long_running_plugin_package"; `Compiled "$PATH/to/custom_long_running_plugin.cmxs"; ] let () = output [ profile "server-with-plugins" (create ~debug_level ~plugins (* ... *)
Plugins will be loaded in the order given in the list and can have dependencies (that Ketrew will load).
Note that if Ketrew is compiled to bytecode one has to use .cmo
or .cma
files instead of .cmxs
.
Dynamic linking can be annoying: for instance, some libraries do not install
.cmxs
files, and some architectures do not support native dynlink, …
Luckily, there is an alternative, one can link plugins statically with
src/app/main.ml
(or another
version of that), see the documentation.