How can I build multiple binaries with Cargo?

Question

I'd like to make a project with a daemon and a client, connecting through a unix socket.

A client and a daemon requires two binaries, so how do I tell Cargo to build two targets from two different sources?

To add a bit of fantasy, I'd like to have a library for the main part of the daemon, and just have a binary to wrap around it and communicate through sockets.

So, we have this kind of tree architecture:

├── Cargo.toml
├── target
|   └── debug
|       ├── daemon
│       └── client
└── src
    ├── daemon
    │   ├── bin
    │   │   └── main.rs
    │   └── lib
    │       └── lib.rs
    └── client
        └── bin
            └── main.rs

I could make one executable which manages both concerns, but that's not what I want to do, unless it's very good practice.

Highly relevant: [Rust package with both a library and a binary?](http://stackoverflow.com/q/26946646/155423). — Shepmaster, Apr 13 '16 at 17:18
In complement of [Dognert's](http://stackoverflow.com/questions/36604010/how-can-i-build-multiple-binaries-with-cargo/36604610#36604610) answer, they answer all the questions I got. Thank you a lot! — RallionRl, Apr 13 '16 at 17:45
this seems to be the relevant issue: https://github.com/rust-lang/cargo/issues/8294 — Bryan Larsen, Sep 30 '22 at 23:49

score 318 · Accepted Answer · edited Jul 01 '23 at 13:23

318

You can specify multiple binaries using [[bin]], as mentioned in the Cargo Book

[[bin]]
name = "daemon"
path = "src/daemon/bin/main.rs"

[[bin]]
name = "client"
path = "src/client/bin/main.rs"

You can run individual binaries with the cargo run command with the --bin <bin-name> option.

Tip: If you instead put these files in src/bin/daemon.rs and src/bin/client.rs, you'll get two executables named daemon and client as Cargo compiles all files in src/bin into executables with the same name automatically. You need to specify names and paths like in the snippet above only if you don't follow this convention.

edited Jul 01 '23 at 13:23

BinaryButterfly

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answered Apr 13 '16 at 16:39

Dogbert

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@AngelAngel you want to customize the output path? By default it'll be stored in `target/debug/$name` where `$name` is the `name` you specify in Cargo.toml. – Dogbert Apr 14 '16 at 11:48
I just wondered if you could say where to install a copy of the binary elsewhere other than the default. A copy in $name and another copy in another path. Not that it is trivial, just curious, thanks for your time. – Angel Angel Apr 14 '16 at 12:01
@AngelAngel I think you're looking for the `cargo install` command. Try reading the output of `cargo help install`. – Dogbert Apr 14 '16 at 12:09
1

This doesn't work if one of the `[[bin]]`s uses `required-features`. For that it seems like `cargo workspace` is the only solution? – Alex Moore-Niemi Jul 14 '21 at 14:37
How do you specify the default binary? ie say client should be default – Anatoly Bugakov Sep 09 '22 at 19:13
@AnatolyBugakov you mean setting the default for `cargo run`? See https://doc.rust-lang.org/cargo/reference/manifest.html#the-default-run-field. – Dogbert Sep 11 '22 at 09:23
It is worth noting that the line 'default-run = "a"' can be added under package in Cargo.toml to specify a default to run when using the form described in this answer. – Cameron Oct 18 '22 at 19:52
@Dogbert can these have different dependencies? I'd like to not include all deps of all bins into all bins – Benni May 26 '23 at 19:18

score 78 · Answer 2 · edited Oct 19 '20 at 18:07

78

Another way is to use the workspace feature. This will provide more flexibility due to the fact that we can have more than one library. Example project structure:

.
├── Cargo.toml
├── cli
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── core
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
├── daemon
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── gui
│   ├── Cargo.toml
│   └── src
│       └── main.rs
└── rpc
    ├── Cargo.toml
    └── src
        └── lib.rs

Contents of the root Cargo.toml:

[workspace]
members = ["cli", "core", "daemon", "gui", "rpc"]

edited Oct 19 '20 at 18:07

Shepmaster

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answered Aug 23 '19 at 17:00

UltimaWeapon

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I could not get this to work. I had to move the binary rust source in the src/ folder and specify another target in `[[bin]]`. Could you give more details about what you did to get this to work? I was getting the following error: `use ::engine::RuleEngine;` `could not find engine in {{root}}` – Kenny Bambridge May 03 '20 at 20:08
@KennyBambridge I have not worked on Rust for awhile. IIRC when I have created this answer I tried on my local machine and it work as intended. – UltimaWeapon Jun 22 '20 at 14:57
@KennyBambridge You do have to add crates in other workspaces as dependencies in the Cargo.toml where you want to use them. – Caesar Oct 17 '20 at 10:32
1

I saw filecoin use this code structure: https://github.com/filecoin-project/rust-fil-proofs – Eric Jun 20 '21 at 06:45
I got it working, but I ended up referring to different Workspace docs, i.e. the one in the Rust book: https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html – rv.kvetch Feb 17 '22 at 22:55

score 3 · Answer 3 · answered Sep 08 '19 at 00:13

Another format could be to replicate what the Crates.io source code has done, if you have a massive project, something like:

Main Library in src, with a Bin folder with your executables. Then make calls to your main library crate from your executables.

That way you library is centralized so easier to find things as it's cached.

How can I build multiple binaries with Cargo?

3 Answers3

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