feat: add verbose and dry run

README.md

@@ -10,10 +10,14 @@ You will need rust installed. Clone repo and run:
 cargo install --path .
 ```
 
-To print the underlying docker commands as they run, build with debug
-assertions:
+## seeing what it runs
+
+`-v` prints each docker command as it runs, and `--dry-run` prints the ones it
+would run without running them. Both work before or after the subcommand.
+
 ```bash
-cargo install --path . --debug
+ahab -v django test
+ahab --dry-run postgres import ./dump
 ```
 
 ## shell completion

src/cli/ahab.rs

@@ -8,8 +8,15 @@ use clap_complete::Shell;
 pub struct Ahab {
     #[command(subcommand)]
     pub command: Commands,
-}
 
+    /// Print each docker command as it runs
+    #[arg(short, long, global = true)]
+    pub verbose: bool,
+
+    /// Print the docker commands that would run, without running them
+    #[arg(long, global = true)]
+    pub dry_run: bool,
+}
 #[derive(Debug, Subcommand)]
 pub enum Commands {
     /// Django related subcommands

src/command_builder.rs

@@ -2,10 +2,9 @@ use anyhow::{Context, Result, bail};
 use std::{
     fmt::Display,
     process::{Child, Command, ExitStatus, Stdio},
+    sync::OnceLock,
 };
 
-use crate::debug_eprintln;
-
 pub struct Args(Vec<String>);
 
 impl From<&str> for Args {
@@ -54,8 +53,9 @@ impl CommandBuilder {
     }
 
     pub fn build(self) -> Result<Command> {
-        debug_eprintln!("running `{self}`");
-
+        if options().verbose {
+            eprintln!("running `{self}`");
+        }
         let (first, rest) = self.args.split_first().context("empty args")?;
         let mut command = Command::new(first);
         command.args(rest);
@@ -72,6 +72,11 @@ impl CommandBuilder {
     }
 
     pub fn exec(self) -> Result<()> {
+        if options().dry_run {
+            eprintln!("would run `{self}`");
+            return Ok(());
+        }
+
         let shown = self.to_string();
         let status = self.build()?.spawn()?.wait()?;
 
@@ -83,6 +88,11 @@ impl CommandBuilder {
     }
 
     pub fn exec_redirect_stdout(self, stdio: Stdio) -> Result<()> {
+        if options().dry_run {
+            eprintln!("would run `{self}`");
+            return Ok(());
+        }
+
         let shown = self.to_string();
         let status = self.build()?.stdout(stdio).spawn()?.wait()?;
 
@@ -100,3 +110,23 @@ fn check(command: &str, status: ExitStatus) -> Result<()> {
         None => bail!("`{command}` was killed by a signal"),
     }
 }
+
+#[derive(Default, Clone, Copy)]
+pub struct Options {
+    pub verbose: bool,
+    pub dry_run: bool,
+}
+
+static OPTIONS: OnceLock<Options> = OnceLock::new();
+
+pub fn set_options(options: Options) {
+    let _ = OPTIONS.set(options);
+}
+
+fn options() -> Options {
+    OPTIONS.get().copied().unwrap_or_default()
+}
+
+pub fn is_dry_run() -> bool {
+    options().dry_run
+}

src/main.rs

@@ -1,4 +1,4 @@
-use ahab::{cli, scripts};
+use ahab::{cli, command_builder, scripts};
 
 use anyhow::Result;
 use clap::Parser;
@@ -6,6 +6,11 @@ use clap::Parser;
 fn main() -> Result<()> {
     let args = cli::Ahab::parse();
 
+    command_builder::set_options(command_builder::Options {
+        verbose: args.verbose,
+        dry_run: args.dry_run,
+    });
+
     match args.command {
         cli::Commands::Django { command } => match command {
             cli::Django::Bash => scripts::django::bash(),

src/scripts/postgres.rs

@@ -10,7 +10,8 @@ use std::{
 
 use super::docker_compose;
 use crate::cli::Format;
-use crate::{command_builder::CommandBuilder, compose::Compose, debug_eprintln};
+use crate::command_builder;
+use crate::{command_builder::CommandBuilder, compose::Compose};
 
 const CUSTOM_MAGIC: &[u8] = b"PGDMP";
 const TAR_MAGIC: &[u8] = b"toc.dat";
@@ -193,7 +194,10 @@ fn piped(db: &Database, script: &str, input: &Path) -> Result<std::process::Comm
 }
 
 fn wait_until_ready(db: &Database) -> Result<()> {
-    debug_eprintln!("waiting until pg_isready");
+    if command_builder::is_dry_run() {
+        return Ok(());
+    }
+
     let deadline = Instant::now() + READY_TIMEOUT;
 
     loop {
@@ -319,6 +323,9 @@ pub fn import(file: &Path) -> Result<()> {
     }
 
     wait_until_ready(&db)?;
+    if command_builder::is_dry_run() {
+        eprintln!("would restore with {tool}");
+    } else {
         match (kind, restore.as_deref()) {
             // psql's output is read rather than streamed here, to keep the expected
             // role errors out of the way
@@ -341,6 +348,7 @@ pub fn import(file: &Path) -> Result<()> {
                 }
             }
         }
+    }
 
     if matches!(dump, Dump::Directory) {
         let _ = in_container(&db).args("rm -rf").arg(&remote).exec();