First time when installing manta, it fails due to the missing config.toml file

[annaloro]

Here is the error just after finishing the installation :

(base) $USER@$HOSTNAME:~/GIT$ manta --version thread 'main' panicked at src/common/config_ops.rs:31:10: called Result::unwrap() on an Err value: configuration file "/home/$USER.config/manta/config.toml" not found note: run with RUST_BACKTRACE=1 environment variable to display a backtrace (base) $USER@$HOSTNAME:~/GIT$

Could you provide a default config.toml file ?

Thanks, Kind Regards, Vincenzo

[miguelgila]

An addition to this issue: I think it would be useful if Manta would have a pre-check phase at startup time where all the required files and components are checked. This could be useful to print better error messages when the certificates or the CA are not present, or if the socks proxy is unreachable.

It'd be nice if it would also provide some defaults to be used as examples, printing the actual location of the files on the different platforms used (Linux or Mac, so far).

[Masber]

Hi @annaloro ,

the configuration file could be found here https://github.com/eth-cscs/manta?tab=readme-ov-file#configuration

thanks

[Masber]

this is a typical example of Result/Error management (https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html)

The error is here https://github.com/eth-cscs/manta/blob/main/src/common/config_ops.rs#L31

The build function (https://docs.rs/config/latest/config/builder/struct.ConfigBuilder.html#method.build) is returning a Result<Config, ConfigError>.

The problem is, if manta can't find the config file, then, the build function will return a Result containing a ConfigError, therefore unwrap will fail because unwrap assumes build was successful and expects a Config therefore the code panics.

The best way to solve this is by using pattern matching to evaluate what Result contains, if it is a successful value, then process as usual, otherwise (eg config file is missing) exit the program with status code 1 and show an error message. An example can be done as follows:

    let config_rslt = ::config::Config::builder()
        .add_source(::config::File::from(config_path))
        .add_source(
            ::config::Environment::with_prefix("MANTA")
                .try_parsing(true)
                .prefix_separator("_"),
        )
        .build();

    match config_rslt {
        Ok(config) => config,
        Err(error) => {
            eprintln!("Error processing config.toml file. Reason:\n{}", error);
            std::process::exit(1);
        }
    }

In this example, we save the Result from build function in a variable called config_rslt and inspect its content using pattern matching, if the Result is successful (Ok) then we just return the value, if it is an error, then, the error is sent to stderr and exit code 1