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?. — Shepmaster
– Shepmaster, Commented Apr 13, 2016 at 17:18
In complement of Dognert's answer, they answer all the questions I got. Thank you a lot! — RallionRl
– RallionRl, Commented Apr 13, 2016 at 17:45
this seems to be the relevant issue: github.com/rust-lang/cargo/issues/8294 — Bryan Larsen
– Bryan Larsen, Commented Sep 30, 2022 at 23:49

Nikita Fedyashev · Accepted Answer · 2023-07-01 13:23:45Z

385

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 1, 2023 at 13:23

Nikita Fedyashev

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answered Apr 13, 2016 at 16:39

Dogbert

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10 Comments

Angel Angel Over a year ago

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.

Alex Moore-Niemi Over a year ago

This doesn't work if one of the [[bin]]s uses required-features. For that it seems like cargo workspace is the only solution?

Anatoly Bugakov Over a year ago

How do you specify the default binary? ie say client should be default

Cameron Over a year ago

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.

Benni Over a year ago

@Dogbert can these have different dependencies? I'd like to not include all deps of all bins into all bins

|

Shepmaster · Accepted Answer · 2020-10-19 18:07:29Z

100

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, 2020 at 18:07

Shepmaster

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answered Aug 23, 2019 at 17:00

user1829232

6 Comments

Kenny Bambridge Over a year ago

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}}

user1829232 Over a year ago

@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.

Caesar Over a year ago

@KennyBambridge You do have to add crates in other workspaces as dependencies in the Cargo.toml where you want to use them.

Eric Over a year ago

I saw filecoin use this code structure: github.com/filecoin-project/rust-fil-proofs

Wizard.Ritvik Over a year ago

I got it working, but I ended up referring to different Workspace docs, i.e. the one in the Rust book: doc.rust-lang.org/book/ch14-03-cargo-workspaces.html

|

Robust Systems 8472-1488 · Accepted Answer · 2019-09-08 00:13:43Z

7

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.

answered Sep 8, 2019 at 0:13

Robust Systems 8472-1488

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