package mirage

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Mirage combinators.

Mirage devices a set of devices and combinator to to define portable applications across all platforms that MirageOS supports.

Release v3.8.1

module Key : module type of struct include Mirage_key end

Configuration keys.

include Functoria_app.DSL


type _ typ = _ Functoria.typ =
  1. | Type : 'a -> 'a typ
  2. | Function : 'b typ * 'c typ -> ('b -> 'c) typ

The type for values representing module types.

val typ : 'a -> 'a typ

type t is a value representing the module type t.

val (@->) : 'a typ -> 'b typ -> ('a -> 'b) typ

Construct a functor type from a type and an existing functor type. This corresponds to prepending a parameter to the list of functor parameters. For example:

kv_ro @-> ip @-> kv_ro 

This describes a functor type that accepts two arguments -- a kv_ro and an ip device -- and returns a kv_ro.

type job = Functoria.job

Type for job values.

val job : job typ

job is the signature for user's application main module.

type 'a impl = 'a Functoria.impl

The type for values representing module implementations.

val ($) : ('a -> 'b) impl -> 'a impl -> 'b impl

m $ a applies the functor m to the module a.

type abstract_impl = Functoria.abstract_impl =
  1. | Abstract : _ impl -> abstract_impl

The type for abstract implementations.

val abstract : _ impl -> abstract_impl

abstract t is t but with its type variable abstracted. Useful for dependencies.


type key = Functoria_key.t

The type for command-line keys. See Functoria_key.t.

type context = Functoria_key.context

The type for keys' parsing context. See Functoria_key.context.

type 'a value = 'a Functoria_key.value

The type for values parsed from the command-line. See Functoria_key.value.

val if_impl : bool value -> 'a impl -> 'a impl -> 'a impl

if_impl v impl1 impl2 is impl1 if v is resolved to true and impl2 otherwise.

val match_impl : 'b value -> default:'a impl -> ('b * 'a impl) list -> 'a impl

match_impl v cases ~default chooses the implementation amongst cases by matching the v's value. default is chosen if no value matches.

module type KEY = Functoria.KEY

The signature for run-time and configure-time command-line keys.

Package dependencies

For specifying opam package dependencies, the type package is used. It consists of the opam package name, the ocamlfind names, and optional lower and upper bounds. The version constraints are merged with other modules.

type package = private Functoria.package = {
  1. opam : string;
  2. pin : string option;
  3. build : bool;
  4. ocamlfind : Astring.String.Set.t;
  5. min : Astring.String.Set.t;
  6. max : Astring.String.Set.t;

The type of a package

val package : ?build:bool -> ?sublibs:string list -> ?ocamlfind:string list -> ?min:string -> ?max:string -> ?pin:string -> string -> package

package ~build ~sublibs ~ocamlfind ~min ~max ~pin opam is a package. Build indicates a build-time dependency only, defaults to false. The ocamlfind name is by default the same as opam, you can specify ~sublibs to add additional sublibraries (e.g. ~sublibs:["mirage"] "foo" will result in the findlib names ["foo"; "foo.mirage"] . In case the findlib name is disjoint (or empty), use ~ocamlfind. Specifying both ~ocamlfind and ~sublibs leads to an invalid argument. Version constraints are given as min (inclusive) and max (exclusive). If pin is provided, a pin-depends is generated.

Application Builder

Values of type impl are tied to concrete module implementation with the foreign construct. Module implementations of type job can then be registered into an application builder. The builder is in charge if parsing the command-line arguments and of generating code for the final application. See Functoria_app for details.

val foreign : ?packages:package list -> ?keys:key list -> ?deps:abstract_impl list -> string -> 'a typ -> 'a impl

foreign name typ is the module name, having the module type typ.

  • If packages is set, then the given packages are installed before compiling the current application.
  • If keys is set, use the given keys to parse at configure and runtime the command-line arguments before calling name.connect.
  • If deps is set, the given list of abstract implementations is added as data-dependencies: they will be initialized before calling name.connect.

For a more flexible definition of packages, or for a custom configuration step, see the configurable class type and the foreign class.

module Info = Functoria.Info

Information about the final application.

class type 'ty configurable = object ... end

Signature for configurable module implementations. A configurable is a module implementation which contains a runtime state which can be set either at configuration time (by the application builder) or at runtime, using command-line arguments.

val impl : 'a configurable -> 'a impl

impl c is the implementation of the configurable c.

class base_configurable : object ... end

base_configurable pre-defining many methods from the configurable class. To be used as follow:

class 'a foreign : ?packages:package list -> ?keys:key list -> ?deps:abstract_impl list -> string -> 'a typ -> 'a configurable

This class can be inherited to define a configurable with an API similar to foreign.


val hash : 'a impl -> int

hash is the hash function on implementations. FIXME(samoht) expand on how it works.

val equal : 'a impl -> 'a impl -> bool

equal is the equality over implementations.

module ImplTbl = Functoria.ImplTbl

Hashtbl of implementations.

General mirage devices

type tracing

The type for tracing.

val tracing : tracing typ

Implementation of the tracing type.

val mprof_trace : size:int -> unit -> tracing impl

Use mirage-profile to trace the unikernel. On Unix, this creates and mmaps a file called "trace.ctf". On Xen, it shares the trace buffer with dom0.

  • parameter size:

    size of the ring buffer to use.

type qubesdb
val qubesdb : qubesdb typ

For the Qubes target, the Qubes database from which to look up * dynamic runtime configuration information.

val default_qubesdb : qubesdb impl

A default qubes database, guessed from the usual valid configurations.


type time

Abstract type for timers.

val time : time typ

Implementations of the Mirage_types.TIME signature.

val default_time : time impl

The default timer implementation.


type pclock

Abstract type for POSIX clocks.

val pclock : pclock typ

Implementations of the Mirage_types.PCLOCK signature.

val default_posix_clock : pclock impl

The default mirage-clock PCLOCK implementation.

type mclock

Abstract type for monotonic clocks

val mclock : mclock typ

Implementations of the Mirage_types.MCLOCK signature.

val default_monotonic_clock : mclock impl

The default mirage-clock MCLOCK implementation.

Log reporters

type reporter

The type for log reporters.

val reporter : reporter typ

Implementation of the log reporter type.

val default_reporter : ?clock:pclock impl -> ?ring_size:int -> ?level:Logs.level -> unit -> reporter impl

default_reporter ?clock ?level () is the log reporter that prints log messages to the console, timestampted with clock. If not provided, the default clock is default_posix_clock. level is the default log threshold. It is Logs.Info if not specified.

val no_reporter : reporter impl

no_reporter disable log reporting.


type random

Abstract type for random sources.

val random : random typ

Implementations of the Mirage_types.RANDOM signature.

val stdlib_random : random impl

Passthrough to the OCaml Random generator.

  • deprecated Mirage will always use a Fortuna PRNG.
val nocrypto_random : random impl

Passthrough to the Fortuna PRNG implemented in nocrypto.

  • deprecated Mirage will always use a Fortuna PRNG.
val default_random : random impl

Default PRNG device to be used in unikernels. It uses getrandom/getentropy on Unix, and a Fortuna PRNG on other targets.


type console

Abstract type for consoles.

val console : console typ

Implementations of the Mirage_types.CONSOLE signature.

val default_console : console impl

Default console implementation.

val custom_console : string -> console impl

Custom console implementation.

Block devices

type block

Abstract type for raw block device configurations.

val block : block typ

Implementations of the Mirage_types.BLOCK signature.

val block_of_file : string -> block impl

Use the given file as a raw block device.

val block_of_xenstore_id : string -> block impl

Use the given XenStore ID (ex: /dev/xvdi1 or 51760) as a raw block device.

val ramdisk : string -> block impl

Use a ramdisk with the given name.

val generic_block : ?group:string -> ?key:[ `XenstoreId | `BlockFile | `Ramdisk ] value -> string -> block impl

Static key/value stores

type kv_ro

Abstract type for read-only key/value store.

val kv_ro : kv_ro typ

Implementations of the Mirage_types.KV_RO signature.

val crunch : string -> kv_ro impl

Crunch a directory.

val archive : block impl -> kv_ro impl
val archive_of_files : ?dir:string -> unit -> kv_ro impl
val direct_kv_ro : string -> kv_ro impl

Direct access to the underlying filesystem as a key/value store. For Xen backends, this is equivalent to crunch.

val generic_kv_ro : ?group:string -> ?key:[ `Archive | `Crunch | `Direct | `Fat ] value -> string -> kv_ro impl

Generic key/value that will choose dynamically between fat, archive and crunch. To use a filesystem implementation, try kv_ro_of_fs.

If no key is provided, it uses Key.kv_ro to create a new one.

type kv_rw

Abstract type for read-write key/value store.

val kv_rw : kv_rw typ

Implementations of the Mirage_types.KV_RW signature.

val direct_kv_rw : string -> kv_rw impl

Direct access to the underlying filesystem as a key/value store. Only available on Unix backends.

val kv_rw_mem : ?clock:pclock impl -> unit -> kv_rw impl

An in-memory key-value store using mirage-kv-mem.


type fs

Abstract type for filesystems.

val fs : fs typ

Implementations of the Mirage_types.FS signature.

val fat : block impl -> fs impl

Consider a raw block device as a FAT filesystem.

val fat_of_files : ?dir:string -> ?regexp:string -> unit -> fs impl

fat_files dir ?dir ?regexp () collects all the files matching the shell pattern regexp in the directory dir into a FAT image. By default, dir is the current working directory and regexp is *

val kv_ro_of_fs : fs impl -> kv_ro impl

Consider a filesystem implementation as a read-only key/value store.

Network interfaces

type network

Abstract type for network configurations.

val network : network typ

Implementations of the Mirage_types.NETWORK signature.

val default_network : network impl

default_network is a dynamic network implementation * which attempts to do something reasonable based on the target.

val netif : ?group:string -> string -> network impl

A custom network interface. Exposes a Key.interface key.

Ethernet configuration

type ethernet
val ethernet : ethernet typ

Implementations of the Mirage_types.ETHERNET signature.

val etif : network impl -> ethernet impl

ARP configuration

type arpv4
val arpv4 : arpv4 typ

Implementation of the Mirage_types.ARPV4 signature.

val arp : ?time:time impl -> ethernet impl -> arpv4 impl

ARP implementation provided by the arp library

IP configuration

Implementations of the Mirage_types.IP signature.

type v4
type v6
type 'a ip

Abstract type for IP configurations.

type ipv4 = v4 ip
type ipv6 = v6 ip
val ipv4 : ipv4 typ

The Mirage_types.IPV4 module signature.

val ipv6 : ipv6 typ

The Mirage_types.IPV6 module signature.

type ipv4_config = {
  1. network : Ipaddr.V4.Prefix.t;
  2. gateway : Ipaddr.V4.t option;

Types for IPv4 manual configuration.

type ipv6_config = {
  1. addresses : Ipaddr.V6.t list;
  2. netmasks : Ipaddr.V6.Prefix.t list;
  3. gateways : Ipaddr.V6.t list;

Types for IP manual configuration.

val create_ipv4 : ?group:string -> ?config:ipv4_config -> ?random:random impl -> ?clock:mclock impl -> ethernet impl -> arpv4 impl -> ipv4 impl

Use an IPv4 address Exposes the keys and Key.V4.gateway. If provided, the values of these keys will override those supplied in the ipv4 configuration record, if that has been provided.

val ipv4_qubes : ?random:random impl -> ?clock:mclock impl -> qubesdb impl -> ethernet impl -> arpv4 impl -> ipv4 impl

Use a given initialized QubesDB to look up and configure the appropriate * IPv4 interface.

val create_ipv6 : ?random:random impl -> ?time:time impl -> ?clock:mclock impl -> ?group:string -> ethernet impl -> ipv6_config -> ipv6 impl

Use an IPv6 address. Exposes the keys Key.V6.ips, Key.V6.netmasks and Key.V6.gateways.

UDP configuration

type 'a udp
type udpv4 = v4 udp
type udpv6 = v6 udp
val udp : 'a udp typ

Implementation of the Mirage_types.UDP signature.

val udpv4 : udpv4 typ
val udpv6 : udpv6 typ
val direct_udp : ?random:random impl -> 'a ip impl -> 'a udp impl
val socket_udpv4 : ?group:string -> Ipaddr.V4.t option -> udpv4 impl

TCP configuration

type 'a tcp
type tcpv4 = v4 tcp
type tcpv6 = v6 tcp
val tcp : 'a tcp typ

Implementation of the Mirage_types.TCP signature.

val tcpv4 : tcpv4 typ
val tcpv6 : tcpv6 typ
val direct_tcp : ?clock:mclock impl -> ?random:random impl -> ?time:time impl -> 'a ip impl -> 'a tcp impl
val socket_tcpv4 : ?group:string -> Ipaddr.V4.t option -> tcpv4 impl

Network stack configuration

type stackv4
val stackv4 : stackv4 typ

Implementation of the Mirage_types.STACKV4 signature.

val direct_stackv4 : ?clock:mclock impl -> ?random:random impl -> ?time:time impl -> ?group:string -> network impl -> ethernet impl -> arpv4 impl -> ipv4 impl -> stackv4 impl

Direct network stack with given ip.

val socket_stackv4 : ?group:string -> Ipaddr.V4.t list -> stackv4 impl

Network stack with sockets. Exposes the key Key.V4.interfaces.

val qubes_ipv4_stack : ?group:string -> ?qubesdb:qubesdb impl -> ?arp:(ethernet impl -> arpv4 impl) -> network impl -> stackv4 impl

Build a stackv4 by looking up configuration information via QubesDB, * building an ipv4, then building a stack on top of that.

val dhcp_ipv4_stack : ?group:string -> ?random:random impl -> ?time:time impl -> ?arp:(ethernet impl -> arpv4 impl) -> network impl -> stackv4 impl

Build a stackv4 by obtaining a DHCP lease, using the lease to * build an ipv4, then building a stack on top of that.

val static_ipv4_stack : ?group:string -> ?config:ipv4_config -> ?arp:(ethernet impl -> arpv4 impl) -> network impl -> stackv4 impl

Build a stackv4 by checking the, and Key.V4.gateway keys * for ipv4 configuration information, filling in unspecified information from ?config, * then building a stack on top of that.

val generic_stackv4 : ?group:string -> ?config:ipv4_config -> ?dhcp_key:bool value -> ?net_key:[ `Direct | `Socket ] option value -> network impl -> stackv4 impl

Generic stack using a dhcp and a net keys: and Key.dhcp.

If a key is not provided, it uses or Key.dhcp (with the group argument) to create it.

Resolver configuration

type resolver
val resolver : resolver typ
val resolver_dns : ?ns:Ipaddr.V4.t -> ?ns_port:int -> ?random:random impl -> ?time:time impl -> ?mclock:mclock impl -> stackv4 impl -> resolver impl
val resolver_unix_system : resolver impl

Syslog configuration

Syslog exfiltrates log messages (generated by libraries using the logs library) via a network connection. The log level of the log sources is controlled via the Mirage_key.logs key. The functionality is provided by the logs-syslog package.

type syslog_config = {
  1. hostname : string;
  2. server : Ipaddr.V4.t option;
  3. port : int option;
  4. truncate : int option;
val syslog_config : ?port:int -> ?truncate:int -> ?server:Ipaddr.V4.t -> string -> syslog_config

Helper for constructing a syslog_config.

type syslog

The type for syslog

val syslog : syslog typ

Implementation of the syslog type.

val syslog_udp : ?config:syslog_config -> ?console:console impl -> ?clock:pclock impl -> stackv4 impl -> syslog impl

Emit log messages via UDP to the configured host.

val syslog_tcp : ?config:syslog_config -> ?console:console impl -> ?clock:pclock impl -> stackv4 impl -> syslog impl

Emit log messages via TCP to the configured host.

val syslog_tls : ?config:syslog_config -> ?keyname:string -> ?console:console impl -> ?clock:pclock impl -> stackv4 impl -> kv_ro impl -> syslog impl

Emit log messages via TLS to the configured host, using the credentials (private ekey, certificate, trust anchor) provided in the KV_RO using the keyname.


val nocrypto : job impl

Device that initializes the entropy. Deprecated and unused.

  • deprecated nocrypto is deprecated and not needed anymore.

Conduit configuration

type conduit
val conduit : conduit typ
val conduit_direct : ?tls:bool -> stackv4 impl -> conduit impl

HTTP configuration

type http
val http : http typ
val http_server : conduit impl -> http impl
  • deprecated `http_server` is deprecated. Please use `cohttp_server` or `httpaf_server` instead.
val cohttp_server : conduit impl -> http impl

cohttp_server starts a Cohttp server.

val httpaf_server : conduit impl -> http impl

httpaf_server starts a http/af server.

Argv configuration

val default_argv : Functoria_app.argv impl

default_argv is a dynamic argv implementation * which attempts to do something reasonable based on the target.

val no_argv : Functoria_app.argv impl

no_argv Disable command line parsing and set argv to |""|.

Other devices

val noop : job impl

noop is a job that does nothing, has no dependency and returns ()

type info

info is the type for module implementing Mirage_runtime.Info.

val info : info typ

info is the combinator to generate info values to use at runtime.

val app_info : info impl

app_info exports all the information available at configure time into a runtime Mirage.Info.t value.

Application registering

val register : ?argv:Functoria_app.argv impl -> ?tracing:tracing impl -> ?reporter:reporter impl -> ?keys:Key.t list -> ?packages:Functoria.package list -> string -> job impl list -> unit

register name jobs registers the application named by name which will executes the given jobs.

  • parameter packages

    The opam packages needed by this module.

  • parameter keys

    The keys related to this module.

  • parameter tracing

    Enable tracing.

  • parameter argv

    Configure command-line argument parsing. The default parser is default_argv. To disable command-line parsing, use no_argv.