Feature request

I would like to get meaningful errors when I pass configuration (via JSON, ENV vars or both) to Iroha 2.

Consider the following cases that currently occur:

• I have passed PUBLIC_KEY and PRIVATE_KEY env vars, and I get an error:

  Please add PUBLIC_KEY and PRIVATE_KEY to the configuration.

  It turned out that yes, in JSON configuration I could provide them as top-level fields with these names, but when it comes to ENV, I should specify them as IROHA_PUBLIC_KEY and IROHA_PRIVATE_KEY.

  By the way: yes, it prints exactly "PUBLIC_KEY AND PRIVATE_KEY", not "PUBLIC_KEY and PRIVATE_KEY".

  The descriptive error would be:

  Please add PUBLIC_KEY (env: IROHA_PUBLIC_KEY) and PRIVATE_KEY (env: IROHA_PRIVATE_KEY) fields to the configuration.

• I forgot to specify the P2P addr:

  Please add p2p_addr to the configuration.

  The descriptive error would be:

  Please add TORII.P2P_ADDR (env: TORII_P2P_ADDR) to the configuration.

Thoughts on implementation

Introduce a data structure for configuration parameter location:

struct Location {
  env_var: &'static str,
  serde: &'static str
}

Then refactor the configuration proc macros so they can generate all of the locations in order to use them statically.

Sample macro usage:

#[derive(Proxy)]
#[proxy(locations = "config_locations_private", env_prefix = "IROHA_")]
struct Iroha {
  public_key: PublicKey,
  sumeragi: Sumeragi
}

#[derive(Proxy)]
#[proxy(env_prefix = "SUMERAGI_")]
struct Sumeragi {
  p2p_addr: String
}

Generated modules

// by proc macro
mod config_locations_private {
  use crate::Location;

  pub const public_key: Location = Location {
    env_var: "IROHA_PUBLIC_KEY",
    serde: "PUBLIC_KEY"
  }

  pub mod sumeragi {
    pub const p2p_addr: Location = Location {
      env_var: "SUMERAGI.P2P_ADDR",
      serde: "SUMERAGI_P2P_ADDR"
    }
  }
}

// visibility control, if needed
pub mod config_locations {
  pub use super::config_locations_private;
}

Then, this code could be used in other parts to throw descriptive errors, like that:

if let (Some(public_key), Some(private_key)) = (&self.public_key, &self.private_key) {
  // ...
} else {
  return Err(ConfigError::MissingParameters {
    locations: vec![config_locations::public_key, config_locations::private_key]
  });
}

Motivation

Iroha will be even more useful if it throws descriptive and helpful errors when misconfiguration happens.

Also, it will be useful for #2373 - the tool will be able to define ENV variables in a docker-compose configuration with static check.

Who can help?

No response