add observability infrastructure for cli subcmds

src/cli.rs

@@ -7,7 +7,10 @@ use std::path::PathBuf;
 
 use clap::{Parser, Subcommand};
 
-use crate::error;
+use crate::{
+    config::{default_tracing_filter, EnvFilterClone, LogFormat},
+    error, observability,
+};
 
 mod serve;
 
@@ -51,6 +54,21 @@ pub(crate) struct ConfigArg {
     pub(crate) config: Option<PathBuf>,
 }
 
+/// Observability arguments for CLI subcommands
+#[derive(clap::Args)]
+struct ObservabilityArgs {
+    /// Log format
+    #[clap(long, default_value_t = LogFormat::Full)]
+    log_format: LogFormat,
+
+    /// Log filter
+    ///
+    /// For information about the syntax, see here:
+    /// <https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives>
+    #[clap(long, default_value_t = default_tracing_filter())]
+    log_filter: EnvFilterClone,
+}
+
 #[derive(clap::Args)]
 pub(crate) struct ServeArgs {
     #[clap(flatten)]
@@ -59,9 +77,23 @@ pub(crate) struct ServeArgs {
 
 impl Args {
     pub(crate) async fn run(self) -> Result<(), error::Main> {
+        if let Some((format, filter)) = self.command.cli_observability_args() {
+            observability::init_for_cli(format, filter.into())?;
+        }
+
         match self.command {
             Command::Serve(args) => serve::run(args).await?,
         }
         Ok(())
     }
 }
+
+impl Command {
+    fn cli_observability_args(&self) -> Option<(LogFormat, EnvFilterClone)> {
+        // All subcommands other than `serve` should return `Some`. Keep these
+        // match arms sorted by the enum variant name.
+        match self {
+            Command::Serve(_) => None,
+        }
+    }
+}