neon_local init: add --force mode that allows an empty dir (#6328)

Need this in https://github.com/neondatabase/neon/pull/6214
refs https://github.com/neondatabase/neon/issues/5771

control_plane/src/bin/neon_local.rs

@@ -6,11 +6,11 @@
 //! rely on `neon_local` to set up the environment for each test.
 //!
 use anyhow::{anyhow, bail, Context, Result};
-use clap::{value_parser, Arg, ArgAction, ArgMatches, Command};
+use clap::{value_parser, Arg, ArgAction, ArgMatches, Command, ValueEnum};
 use compute_api::spec::ComputeMode;
 use control_plane::attachment_service::AttachmentService;
 use control_plane::endpoint::ComputeControlPlane;
-use control_plane::local_env::LocalEnv;
+use control_plane::local_env::{InitForceMode, LocalEnv};
 use control_plane::pageserver::{PageServerNode, PAGESERVER_REMOTE_STORAGE_DIR};
 use control_plane::safekeeper::SafekeeperNode;
 use control_plane::tenant_migration::migrate_tenant;
@@ -338,7 +338,7 @@ fn handle_init(init_match: &ArgMatches) -> anyhow::Result<LocalEnv> {
 
     let mut env =
         LocalEnv::parse_config(&toml_file).context("Failed to create neon configuration")?;
-    let force = init_match.get_flag("force");
+    let force = init_match.get_one("force").expect("we set a default value");
     env.init(pg_version, force)
         .context("Failed to initialize neon repository")?;
 
@@ -1266,9 +1266,15 @@ fn cli() -> Command {
         .required(false);
 
     let force_arg = Arg::new("force")
-        .value_parser(value_parser!(bool))
+        .value_parser(value_parser!(InitForceMode))
         .long("force")
-        .action(ArgAction::SetTrue)
+        .default_value(
+            InitForceMode::MustNotExist
+                .to_possible_value()
+                .unwrap()
+                .get_name()
+                .to_owned(),
+        )
         .help("Force initialization even if the repository is not empty")
         .required(false);
 

control_plane/src/local_env.rs

@@ -5,6 +5,7 @@
 
 use anyhow::{bail, ensure, Context};
 
+use clap::ValueEnum;
 use postgres_backend::AuthType;
 use reqwest::Url;
 use serde::{Deserialize, Serialize};
@@ -162,6 +163,31 @@ impl Default for SafekeeperConf {
     }
 }
 
+#[derive(Clone, Copy)]
+pub enum InitForceMode {
+    MustNotExist,
+    EmptyDirOk,
+    RemoveAllContents,
+}
+
+impl ValueEnum for InitForceMode {
+    fn value_variants<'a>() -> &'a [Self] {
+        &[
+            Self::MustNotExist,
+            Self::EmptyDirOk,
+            Self::RemoveAllContents,
+        ]
+    }
+
+    fn to_possible_value(&self) -> Option<clap::builder::PossibleValue> {
+        Some(clap::builder::PossibleValue::new(match self {
+            InitForceMode::MustNotExist => "must-not-exist",
+            InitForceMode::EmptyDirOk => "empty-dir-ok",
+            InitForceMode::RemoveAllContents => "remove-all-contents",
+        }))
+    }
+}
+
 impl SafekeeperConf {
     /// Compute is served by port on which only tenant scoped tokens allowed, if
     /// it is configured.
@@ -384,7 +410,7 @@ impl LocalEnv {
     //
     // Initialize a new Neon repository
     //
-    pub fn init(&mut self, pg_version: u32, force: bool) -> anyhow::Result<()> {
+    pub fn init(&mut self, pg_version: u32, force: &InitForceMode) -> anyhow::Result<()> {
         // check if config already exists
         let base_path = &self.base_data_dir;
         ensure!(
@@ -393,25 +419,34 @@ impl LocalEnv {
         );
 
         if base_path.exists() {
-            if force {
-                println!("removing all contents of '{}'", base_path.display());
-                // instead of directly calling `remove_dir_all`, we keep the original dir but removing
-                // all contents inside. This helps if the developer symbol links another directory (i.e.,
-                // S3 local SSD) to the `.neon` base directory.
-                for entry in std::fs::read_dir(base_path)? {
-                    let entry = entry?;
-                    let path = entry.path();
-                    if path.is_dir() {
-                        fs::remove_dir_all(&path)?;
-                    } else {
-                        fs::remove_file(&path)?;
+            match force {
+                InitForceMode::MustNotExist => {
+                    bail!(
+                        "directory '{}' already exists. Perhaps already initialized?",
+                        base_path.display()
+                    );
+                }
+                InitForceMode::EmptyDirOk => {
+                    if let Some(res) = std::fs::read_dir(base_path)?.next() {
+                        res.context("check if directory is empty")?;
+                        anyhow::bail!("directory not empty: {base_path:?}");
+                    }
+                }
+                InitForceMode::RemoveAllContents => {
+                    println!("removing all contents of '{}'", base_path.display());
+                    // instead of directly calling `remove_dir_all`, we keep the original dir but removing
+                    // all contents inside. This helps if the developer symbol links another directory (i.e.,
+                    // S3 local SSD) to the `.neon` base directory.
+                    for entry in std::fs::read_dir(base_path)? {
+                        let entry = entry?;
+                        let path = entry.path();
+                        if path.is_dir() {
+                            fs::remove_dir_all(&path)?;
+                        } else {
+                            fs::remove_file(&path)?;
+                        }
                     }
                 }
-            } else {
-                bail!(
-                    "directory '{}' already exists. Perhaps already initialized? (Hint: use --force to remove all contents)",
-                    base_path.display()
-                );
             }
         }
 

test_runner/fixtures/neon_fixtures.py

@@ -472,6 +472,7 @@ class NeonEnvBuilder:
         self.test_output_dir = test_output_dir
         self.test_overlay_dir = test_overlay_dir
         self.overlay_mounts_created_by_us: List[Tuple[str, Path]] = []
+        self.config_init_force: Optional[str] = None
 
         assert test_name.startswith(
             "test_"
@@ -935,7 +936,7 @@ class NeonEnv:
             cfg["safekeepers"].append(sk_cfg)
 
         log.info(f"Config: {cfg}")
-        self.neon_cli.init(cfg)
+        self.neon_cli.init(cfg, force=config.config_init_force)
 
     def start(self):
         # Start up broker, pageserver and all safekeepers
@@ -1423,6 +1424,7 @@ class NeonCli(AbstractNeonCli):
     def init(
         self,
         config: Dict[str, Any],
+        force: Optional[str] = None,
     ) -> "subprocess.CompletedProcess[str]":
         with tempfile.NamedTemporaryFile(mode="w+") as tmp:
             tmp.write(toml.dumps(config))
@@ -1430,6 +1432,9 @@ class NeonCli(AbstractNeonCli):
 
             cmd = ["init", f"--config={tmp.name}", "--pg-version", self.env.pg_version]
 
+            if force is not None:
+                cmd.extend(["--force", force])
+
             storage = self.env.pageserver_remote_storage
 
             append_pageserver_param_overrides(