Output errors on a single line if backtraces are disabled

[romac]

Closes: #1529

Description

This uses our fork of simple-eyre, called oneline-eyre.

---

Output with RUST_BACKTRACE = "full":

2021-10-27T22:00:13.861230Z ERROR ThreadId(27) [ibc-0] failed to collect events:
   0: WebSocket driver failed
   1:
   1:    0: web socket error: failed to read from WebSocket connection
   1:    1: WebSocket protocol error: Connection reset without closing handshake

   1: Location:
   1:    /Users/coromac/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/flex-error-0.4.4/src/tracer_impl/eyre.rs:10

   1:   ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   1:                                 ⋮ 10 frames hidden ⋮

...

Output without RUST_BACKTRACE unset or set to "0" or "":

2021-10-27T22:01:37.228355Z ERROR ThreadId(27) [ibc-0] failed to collect events: WebSocket driver failed: web socket error: failed to read from WebSocket connection: WebSocket protocol error: Connection reset without closing handshake

---

For contributor use:

• Added a changelog entry, using unclog.
• If applicable: Unit tests written, added test to CI.
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Updated relevant documentation (docs/) and code comments.
• Re-reviewed Files changed in the Github PR explorer.

[soareschen]

This feels a bit overly restrictive that it would be impossible to capture full back trace in log files if it is ever needed. Should we only use the one-line error reporter if RUST_BACKTRACE is "" or not set?

[soareschen]

I think in this case if RUST_BACKTRACE is not set, the error case Err(_) will return false when it should be true.

This should be clearer with comment explaining what should happen in different branches:

fn main() -> eyre::Result<()> {
    install_error_reporter()?;

    abscissa_core::boot(&APPLICATION);
}

fn install_error_reporter() -> eyre::Result<()> {
    if enable_ansi() {
        // If we are in a terminal supporting color, display
        // full error logs in color
        color_eyre::install()?;
    } else if !backtrace_enabled() {
        // Else if we are piping logs to file and backtrace is *not* enabled,
        // display errors in single line.
        oneline_eyre::install()?;
    } else {
        // Else backtrace is enabled and we are piping to logs, so use the
        // default error report handler, which displays multiline errors
        // without color.
    }

    Ok(())
}

fn backtrace_enabled() -> bool {
    match std::env::var("RUST_BACKTRACE").as_deref() {
        Ok("" | "0") | Err(_) => false,
        Ok(_) => true,
    }
}

[romac]

Good catch, thanks! Shouldn't we invert the first two branches? ie. if backtraces are not enabled, we use one-line logs, otherwise if there is a tty we use colors, else we use the default reporter.

fn install_error_reporter() -> eyre::Result<()> {
    if !backtrace_enabled() {
        // If backtraces are disabled, display errors in single line.
        oneline_eyre::install()
    } else if enable_ansi() {
        // Else, if backtraces are enabled and we are in a terminal
        // supporting color, display full error logs in color.
        color_eyre::install()
    } else {
        // Otherwise, backtraces are enabled and we are piping to logs, so use the
        // default error report handler, which displays multiline errors
        // without color.
        Ok(())
    }
}

[soareschen]

I think it depends on what we want the default behavior to be. Most of the time the relayer will run without RUST_BACKTRACE set, even for terminal cases. Do we want those to display one-line errors as well?

[mircea-c]

Most of the time the relayer will be piping to logs. So one line logs should be the default case.