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Modular Diplonat (with the option to disable useless modules) #8

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adrien wants to merge 12 commits from adrien/diplonat:feature/modular-config into main
pull from: adrien/diplonat:feature/modular-config
merge into: Deuxfleurs:main
Conversation 4 Commits 12 Files changed 11 +45 -17
1 changed files with 45 additions and 17 deletions
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Showing only changes of commit f5ac36e21f - Show all commits

60
src/config/runtime.rs
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@ -62,10 +62,14 @@ impl RuntimeConfig {
impl RuntimeConfigConsul {
pub(super) fn new(opts: ConfigOptsConsul) -> Result<Self> {
let node_name = opts
.node_name
.expect("'DIPLONAT_CONSUL_NODE_NAME' is required");
let url = opts.url.unwrap_or(super::CONSUL_URL.to_string());
let node_name = match opts.node_name {
Some(n) => n,
_ => return Err(anyhow!("'DIPLONAT_CONSUL_NODE_NAME' is required")),
quentin commented 2021-09-20 15:51:11 +00:00
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cf my following comment on DIPLONAT_ACME_EMAIL

cf my following comment on `DIPLONAT_ACME_EMAIL`
};
let url = match opts.url {
Some(url) => url,
_ => super::CONSUL_URL.to_string(),
};
Ok(Self { node_name, url })
}
@ -75,11 +79,16 @@ impl RuntimeConfigAcme {
pub fn new(opts: ConfigOptsAcme) -> Result<Option<Self>> {
if !opts.enable {
return Ok(None)
}
};
quentin commented 2021-09-20 15:49:07 +00:00
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I know this is not linked to this specific pull request but when your function returns a Result, there is no reason to panic with expect.

Instead, replace it with:

let email = opts
  .email
  .context("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled")?;

Please do it for the whole file :)

I know this is not linked to this specific pull request but when your function returns a Result, there is no reason to panic with expect. Instead, replace it with: ```rust let email = opts .email .context("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled")?; ``` Please do it for the whole file :)
adrien commented 2021-09-22 11:13:56 +00:00
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.context(...) is not a method of Option.

There's sense in doing so: when a parameter is invalid (like here), the method should panic or return an Err(..).

I'm still modifying the calls to return errors instead of panicking straight away. Using match for better clarity ;)

`.context(...)` is not a method of `Option`. There's sense in doing so: when a parameter is invalid (like here), the method should panic or return an Err(..). I'm still modifying the calls to return errors instead of panicking straight away. Using `match` for better clarity ;)
quentin commented 2021-09-23 05:27:22 +00:00
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You can convert an Option to an Error with ok_or: https://doc.rust-lang.org/std/option/enum.Option.html#method.ok_or

But we need an Error to map to the None. It is a bit challenging as it will be our first error in Diplonat, previously we were relaying only on errors generated by our dependencies.

For now, let's keep it simple, our error library provides us a simple macro to create an error from a string. Just a simple example:

return Err(anyhow!("Missing attribute: {}", missing))

So you can write:

let email = opts
  .email
  .ok_or(anyhow!("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled"))?;

For your information, context allows to enrich an existing error with some context. Indeed, here it is not appropriate as we have no error at all. But in the case where your library throw a cryptic error, you can enrich this error with some context in your program and your users will thank you many times later.

You made the following point:

There's sense in doing so: when a parameter is invalid (like here), the method should panic or return an Err(..).

First, you're right, when a parameter is invalid, we must handle this as an error. It was what I was suggesting to you in my first comment but I thought the return type of opts.email would be a Result and not an Option.

Second, we are writing Rust and we are in a library: in this situation, it is not acceptable to panic. As there is no clean way to recover from a panic, we terminate the program from a library without giving the program a chance to recover from the error. Even if we are not a "standalone library" and are writing the main program, we might change our mind the future. We should panic! only when there is no option. To illustrate my point, we could think that later, we would allow our main program to reload its configuration and retry the initialization if one actor fails.

Third, I am not sure we discussed it but ? is syntaxic sugar for:

let err = anyhow!("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled")

match opts.email.ok_or(err) {
  Ok(email) => {
    // our logic
  }
  Err(e) => return Err(e)
}

So in fact, what I suggest is that we return from the function with an Error if this parameter has not be provided.

You can convert an Option to an Error with `ok_or`: https://doc.rust-lang.org/std/option/enum.Option.html#method.ok_or But we need an Error to map to the None. It is a bit challenging as it will be our first error in Diplonat, previously we were relaying only on errors generated by our dependencies. For now, let's keep it simple, our error library provides us a simple macro to create an error from a string. Just a simple example: ```rust return Err(anyhow!("Missing attribute: {}", missing)) ``` So you can write: ```rust let email = opts .email .ok_or(anyhow!("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled"))?; ``` For your information, `context` allows to enrich an existing error with some context. Indeed, here it is not appropriate as we have no error at all. But in the case where your library throw a cryptic error, you can enrich this error with some context in your program and your users will thank you many times later. You made the following point: > There's sense in doing so: when a parameter is invalid (like here), the method should panic or return an Err(..). First, you're right, when a parameter is invalid, we must handle this as an error. It was what I was suggesting to you in my first comment but I thought the return type of `opts.email` would be a `Result` and not an `Option`. Second, we are writing Rust and we are in a library: in this situation, it is not acceptable to panic. As there is no clean way to recover from a panic, we terminate the program from a library without giving the program a chance to recover from the error. Even if we are not a "standalone library" and are writing the main program, we might change our mind the future. We should `panic!` only when there is no option. To illustrate my point, we could think that later, we would allow our main program to reload its configuration and retry the initialization if one actor fails. Third, I am not sure we discussed it but `?` is syntaxic sugar for: ```rust let err = anyhow!("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled") match opts.email.ok_or(err) { Ok(email) => { // our logic } Err(e) => return Err(e) } ``` So in fact, what I suggest is that we return from the function with an Error if this parameter has not be provided.
adrien commented 2021-09-23 08:01:08 +00:00
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Here's my new RuntimeConfigAcme implementation in full (in commit f5ac36e). Do you find it better?

impl RuntimeConfigAcme {
  pub fn new(opts: ConfigOptsAcme) -> Result<Option<Self>> {
    if !opts.enable {
      return Ok(None)
    };

    let email = match opts.email {
      Some(email) => email,
      _ => {
        return Err(anyhow!(
          "'DIPLONAT_ACME_EMAIL' is required if ACME is enabled"
        ))
      }
    };

    Ok(Some(Self { email }))
  }
}

We do return an error instead of panicking. But I may have overdone it with using match, but I didn't find any nice shorthand in Option methods (I checked ok_or). At least the intent is clear!

PS: Quite puzzled by the fact that Rust allows putting a return inside a match arm, which should be an expression returning a String (in this case). Welp, gotta get used to it!

Here's my new RuntimeConfigAcme implementation in full (in commit `f5ac36e`). Do you find it better? ```rust impl RuntimeConfigAcme { pub fn new(opts: ConfigOptsAcme) -> Result<Option<Self>> { if !opts.enable { return Ok(None) }; let email = match opts.email { Some(email) => email, _ => { return Err(anyhow!( "'DIPLONAT_ACME_EMAIL' is required if ACME is enabled" )) } }; Ok(Some(Self { email })) } } ``` We do return an error instead of panicking. But I may have overdone it with using match, but I didn't find any nice shorthand in `Option` methods (I checked `ok_or`). At least the intent is clear! PS: Quite puzzled by the fact that Rust allows putting a `return` inside a `match` arm, which should be an expression returning a String (in this case). Welp, gotta get used to it!
quentin commented 2021-09-23 12:26:17 +00:00
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Sorry, I was not clear enough ><

About handling error, I want to avoid expect and unwrap because they make our program panic, ie. the program is killed.

But unwrap_or is totally fine as it does not make the program panic.
And when the case is simple enough we can use one of these keywords: unwrap_or on Result or ok_or on Options instead of a match, it is totally ok.

So, I don't think you should replace your unwrap_or with a match in f5ac36e.

I have written a small example on how to use ok_or to convert an Option into a Result and checked that it compiles here: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=5bc6046485bab0cd4ae694b94d2ba1db

See the code without leaving gitea 
use std::{
  fmt,
  error::Error
};

#[derive(Debug)]
struct RequiredParameterError;
impl Error for RequiredParameterError {}
impl fmt::Display for RequiredParameterError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "A required parameter is not defined")
    }
}

fn foo(param: Option<String>) -> Result<String, RequiredParameterError> {
  let email = param.ok_or(RequiredParameterError{})?;
  return Ok("maito:".to_string() + &email)
}

fn main() {
  let user_param1 = Some("hello@example.org".to_string());
  let user_param2 = None;

  assert!(foo(user_param1).is_ok());
  assert!(foo(user_param2).is_err());
}

So, you may ask why I was advocating for match?
Because in fw_actors.rs you were using again unwrap() that can cause a panic in the program and we can't replace it by these simple keywords that are ok_or, unwrap_or, etc.

To sum up, I think we can define the following rules:

  1. Never write unwrap() or expect() (yes, never is too brutal, but it should be an exception)
  2. Replace them, when possible, by an appropriate small function if it exists
  3. Otherwise, if your case is too specific, use a match

I hope that this time I will be more clear.
I know that when we start coding together, it takes some times to align our minds but once it will be done, it will be easier :)

Sorry, I was not clear enough >< About handling error, I want to avoid `expect` and `unwrap` because they make our program panic, ie. the program is killed. But `unwrap_or` is totally fine as it does not make the program panic. And when the case is simple enough we can use one of these keywords: `unwrap_or` on `Result` or `ok_or` on Options instead of a `match`, it is totally ok. So, I don't think you should replace your `unwrap_or` with a `match` in `f5ac36e`. I have written a small example on how to use `ok_or` to convert an `Option` into a `Result` and checked that it compiles here: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=5bc6046485bab0cd4ae694b94d2ba1db <details> <summary>See the code without leaving gitea</summary> ```rust use std::{ fmt, error::Error }; #[derive(Debug)] struct RequiredParameterError; impl Error for RequiredParameterError {} impl fmt::Display for RequiredParameterError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "A required parameter is not defined") } } fn foo(param: Option<String>) -> Result<String, RequiredParameterError> { let email = param.ok_or(RequiredParameterError{})?; return Ok("maito:".to_string() + &email) } fn main() { let user_param1 = Some("hello@example.org".to_string()); let user_param2 = None; assert!(foo(user_param1).is_ok()); assert!(foo(user_param2).is_err()); } ``` </details> <br/> So, you may ask why I was advocating for `match`? Because in `fw_actors.rs` you were using again `unwrap()` that can cause a panic in the program and we can't replace it by these simple keywords that are `ok_or`, `unwrap_or`, etc. To sum up, I think we can define the following rules: 1. Never write `unwrap()` or `expect()` (yes, never is too brutal, but it should be an exception) 2. Replace them, when possible, by an appropriate small function if it exists 3. Otherwise, if your case is too specific, use a match I hope that this time I will be more clear. I know that when we start coding together, it takes some times to align our minds but once it will be done, it will be easier :)
let email = opts
.email
.expect("'DIPLONAT_ACME_EMAIL' is required if ACME is enabled");
let email = match opts.email {
Some(email) => email,
_ => {
return Err(anyhow!(
"'DIPLONAT_ACME_EMAIL' is required if ACME is enabled"
))
}
};
Ok(Some(Self { email }))
}
@ -91,7 +100,13 @@ impl RuntimeConfigFirewall {
return Ok(None)
}
let refresh_time = Duration::from_secs(opts.refresh_time.unwrap_or(super::REFRESH_TIME).into());
let refresh_time = Duration::from_secs(
match opts.refresh_time {
Some(t) => t,
_ => super::REFRESH_TIME,
}
.into(),
);
Ok(Some(Self { refresh_time }))
}
@ -103,16 +118,29 @@ impl RuntimeConfigIgd {
return Ok(None)
}
let private_ip = opts
.private_ip
.expect("'DIPLONAT_IGD_PRIVATE_IP' is required if IGD is enabled");
let private_ip = match opts.private_ip {
Some(ip) => ip,
_ => {
return Err(anyhow!(
"'DIPLONAT_IGD_PRIVATE_IP' is required if IGD is enabled"
))
}
};
let expiration_time = Duration::from_secs(
opts
.expiration_time
.unwrap_or(super::EXPIRATION_TIME)
match opts.expiration_time {
Some(t) => t.into(),
_ => super::EXPIRATION_TIME,
}
.into(),
);
let refresh_time = Duration::from_secs(
match opts.refresh_time {
Some(t) => t,
_ => super::REFRESH_TIME,
}
.into(),
);
let refresh_time = Duration::from_secs(opts.refresh_time.unwrap_or(super::REFRESH_TIME).into());
if refresh_time.as_secs() * 2 > expiration_time.as_secs() {
return Err(anyhow!(