Attempting to build Chat example - no "secio" feature in "libp2p"

[brandonmarzolf]

I'm attempting to build the chat example to learn the libp2p library.

I'm on Ubuntu, I installed the protobuf compiler, added all the features, including "secio" to the feature flags list in the Cargo.toml file, and my attempt to compile has me stuck on this error:

error: failed to select a version for libp2p.
... required by package chat v0.1.0 (...src/examples/chat)
versions that meet the requirements ^0.51.0 are: 0.51.0

the package chat depends on libp2p, with features: secio but libp2p does not have these features.

failed to select a version for libp2p which could resolve this conflict

From what investigation I've been able to do, being new to the library, it does indeed look like there is no "secio" feature. That has me wondering if the example is broken.

What can I do to resolve this? Is this a broken example, or is something else wrong?

[thomaseizinger]

Secio has been removed 2.5 years ago and I cannot find any references to it in the repository. Where does it say you should add the secio feature?

[brandonmarzolf]

@thomaseizinger Given the last part of my reply, perhaps it is best to close this question, if you agree that I have gone down the wrong path and the error in question is irrelevant? Then I will ask a new question, specific to how to go about building the examples? Does this sound good to you?

[thomaseizinger]

You mean like this: #3509? :)

They are all in one place, but they don't build individually as they are dependent on the libp2p in the project itself.

They are built as part of our CI so yes they do build individually. That was one of the main reasons I wanted them separate. They are now copy-pastable.

when I switch this out to the latest version released on crates.io which is necessary if I'm to build a standalone project

That isn't gonna work, sorry. But that is not specific to our project, this won't reliably work in any Rust project. If you look at examples, I'd advise you to always look at the released Git tag or specify a Git dependency in your project:

libp2p = { git = "https://github.com/libp2p/rust-libp2p" }

Perhaps I need to back up and instead ask: How are the examples intended to be built?

In terms of selecting features, the easiest is to just specify full. Before #3509, we also used that for the examples:

rust-libp2p/Cargo.toml

Lines 183 to 185 in 2c10cd8

	[[example]]
	name = "chat"
	required-features = ["full"]

Now, with #3509 we can finally be more fine-granular and specify the individual features for each example.

In your specific case, you should also be able to copy the feature-list from the chat example and depend on the latest released version from crates.io (because we haven't made any changes to features since the last release). Let me know if that works.

In regards to your other compile errors with async_std etc, you should also be a long way if you look at the Cargo.toml of the new examples.

[thomaseizinger]

diff --git a/examples/chat-example/Cargo.toml b/examples/chat-example/Cargo.toml
index bfd2d7e0..06c59736 100644
--- a/examples/chat-example/Cargo.toml
+++ b/examples/chat-example/Cargo.toml
@@ -10,4 +10,4 @@ async-std = { version = "1.12", features = ["attributes"] }
 async-trait = "0.1"
 env_logger = "0.10.0"
 futures = "0.3.26"
-libp2p = { path = "../../libp2p", features = ["async-std", "dns", "gossipsub", "mdns", "mplex", "noise", "macros", "tcp", "websocket", "yamux"] }
+libp2p = { version = "0.51", features = ["async-std", "dns", "gossipsub", "mdns", "mplex", "noise", "macros", "tcp", "websocket", "yamux"] }

I just applied the above patch to master and cargo run --bin chat-example worked without problems. If you get version conflicts, I'd suggest you nuke your Cargo.lock and try again.

[brandonmarzolf]

Thank you for all of that.

Since the latest release doesn't have the examples in their own projects, I copied the chat.rs example from the latest release tag, and then I copied the dependencies from the latest release.

This didn't work.

So then, instead of trying to figure out what features to enable, I just enabled "full" as you recommended and that built, and appears to be working.

Thank you for all your help in this!

[thomaseizinger]

Glad you got it working. You should be able to replace full with the list of features that is now listened in examples/chat-example/Cargo.toml. That would likely reduce (initial) compile times a bit.