Irmin - A distributed database built on the same principles as Git
Irmin is an OCaml library for building mergeable, branchable distributed data stores.
- Built-in snapshotting - backup and restore
- Storage agnostic - you can use Irmin on top of your own storage layer
- Custom datatypes - (de)serialization for custom data types
- Highly portable - runs anywhere from Linux to web browsers and Xen unikernels
- Git compatibility -
irmin-gituses an on-disk format that can be inspected and modified using Git
- Dynamic behavior - allows the users to define custom merge functions, use in-memory transactions (to keep track of reads as well as writes) and to define event-driven workflows using a notification mechanism
Documentation can be found online at https://mirage.github.io/irmin
To install Irmin, the command-line tool and all optional dependencies using opam:
opam install irmin-unix
A minimal installation, with no storage backends can be installed by running:
opam install irmin
To only install the in-memory storage backend:
opam install irmin-mem
The following packages have been made available on
irmin- the base package, no storage implementations
irmin-chunk- chunked storage
irmin-fs- filesystem-based storage using
irmin-git- Git compatible storage
irmin-http- a simple REST interface
irmin-mem- in-memory storage implementation
irmin-mirage- mirage compatibility
irmin-unix- unix compatibility
For more information about an individual package consult the online documentation
Below is a simple example of setting a key and getting the value out of a Git based, filesystem-backed store.
open Lwt.Infix (* Irmin store with string contents *) module Store = Irmin_unix.Git.FS.KV(Irmin.Contents.String) (* Database configuration *) let config = Irmin_git.config ~bare:true "/tmp/irmin/test" (* Commit author *) let author = "Example <firstname.lastname@example.org>" (* Commit information *) let info fmt = Irmin_unix.info ~author fmt let main = (* Open the repo *) Store.Repo.v config >>= (* Load the master branch *) Store.master >>= fun t -> (* Set key "foo/bar" to "testing 123" *) Store.set t ~info:(info "Updating foo/bar") ["foo"; "bar"] "testing 123" >>= fun () -> (* Get key "foo/bar" and print it to stdout *) Store.get t ["foo"; "bar"] >|= fun x -> Printf.printf "foo/bar => '%s'\n" x (* Run the program *) let () = Lwt_main.run main
To compile the example above, save it to a file called
example.ml and run:
$ ocamlfind ocamlopt example.ml -o example -package irmin-unix,lwt.unix -linkpkg $ ./example foo/bar => 'testing 123'
examples directory contains some more advanced examples. The build them, run:
$ jbuilder build examples/trees.exe $ _build/default/examples/trees.exe
The same thing can also be accomplished using
irmin, the command-line application installed with
irmin-unix, by running:
$ echo "root: ." > irmin.yml $ irmin init $ irmin set foo/bar "testing 123" $ irmin get foo/bar
irmin.yml allows for
irmin flags to be set on a per-directory basis. You can also set flags globally using
irmin help irmin.yml for further details.
irmin --help for list of all commands and either
irmin <command> --help or
irmin help <command> for more help with a specific command.
Feel free to to report any issues using the Github bugtracker.
See the LICENSE file.
Development of Irmin was supported in part by the EU FP7 User-Centric Networking project, Grant No. 611001.