dkl apply-config --dry-run

src/apply.rs

@@ -5,25 +5,59 @@ use tokio::fs;
 
 use crate::base64_decode;
 
-pub async fn files(files: &[crate::File], root: &str) -> Result<()> {
+pub async fn files(files: &[crate::File], root: &str, dry_run: bool) -> Result<()> {
     for file in files {
         let path = chroot(root, &file.path);
         let path = Path::new(&path);
 
-        if let Some(parent) = path.parent() {
+        if !dry_run && let Some(parent) = path.parent() {
             fs::create_dir_all(parent).await?;
         }
 
         use crate::FileKind as K;
         match &file.kind {
-            K::Content(content) => fs::write(path, content.as_bytes()).await?,
+            K::Content(content) => {
+                if dry_run {
+                    info!(
+                        "would create {} ({} bytes from content)",
+                        file.path,
+                        content.len()
+                    );
+                } else {
+                    fs::write(path, content.as_bytes()).await?;
+                }
+            }
             K::Content64(content) => {
                 let content = base64_decode(content)?;
+                if dry_run {
+                    info!(
+                        "would create {} ({} bytes from content64)",
+                        file.path,
+                        content.len()
+                    );
+                } else {
                     fs::write(path, content).await?
                 }
-            K::Dir(true) => fs::create_dir(path).await?,
+            }
+            K::Dir(true) => {
+                if dry_run {
+                    info!("would create {} (directory)", file.path);
+                } else {
+                    fs::create_dir(path).await?;
+                }
+            }
             K::Dir(false) => {} // shouldn't happen, but semantic is to ignore
-            K::Symlink(tgt) => fs::symlink(tgt, path).await?,
+            K::Symlink(tgt) => {
+                if dry_run {
+                    info!("would create {} (symlink to {})", file.path, tgt);
+                } else {
+                    fs::symlink(tgt, path).await?;
+                }
+            }
+        }
+
+        if dry_run {
+            continue;
         }
 
         match file.kind {

src/bin/dkl.rs

@@ -24,6 +24,9 @@ enum Command {
         /// path prefix (aka chroot)
         #[arg(short = 'P', long, default_value = "/")]
         prefix: String,
+        /// don't really write files
+        #[arg(long)]
+        dry_run: bool,
     },
     Logger {
         /// Path where the logs are stored
@@ -97,9 +100,10 @@ async fn main() -> Result<()> {
             config,
             filters,
             prefix,
+            dry_run,
         } => {
             let filters = parse_globs(&filters)?;
-            apply_config(&config, &filters, &prefix).await
+            apply_config(&config, &filters, &prefix, dry_run).await
         }
         C::Logger {
             ref log_path,
@@ -156,7 +160,12 @@ async fn main() -> Result<()> {
     }
 }
 
-async fn apply_config(config_file: &str, filters: &[glob::Pattern], chroot: &str) -> Result<()> {
+async fn apply_config(
+    config_file: &str,
+    filters: &[glob::Pattern],
+    chroot: &str,
+    dry_run: bool,
+) -> Result<()> {
     let config = fs::read_to_string(config_file).await?;
     let config: dkl::Config = serde_yaml::from_str(&config)?;
 
@@ -168,7 +177,7 @@ async fn apply_config(config_file: &str, filters: &[glob::Pattern], chroot: &str
             .collect()
     };
 
-    dkl::apply::files(&files, chroot).await
+    dkl::apply::files(&files, chroot, dry_run).await
 }
 
 #[derive(Subcommand)]

src/dynlay.rs

@@ -1,4 +1,4 @@
-use eyre::{format_err, Result};
+use eyre::{Result, format_err};
 use log::{debug, error, info, warn};
 use std::path::PathBuf;
 use tokio::{fs, io::AsyncWriteExt, process::Command};

src/lib.rs

@@ -83,6 +83,6 @@ impl Config {
 }
 
 pub fn base64_decode(s: &str) -> Result<Vec<u8>, base64::DecodeError> {
-    use base64::{prelude::BASE64_STANDARD_NO_PAD as B64, Engine};
+    use base64::{Engine, prelude::BASE64_STANDARD_NO_PAD as B64};
     B64.decode(s.trim_end_matches('='))
 }

src/logger.rs

@@ -1,6 +1,6 @@
 use async_compression::tokio::write::{ZstdDecoder, ZstdEncoder};
 use chrono::{DurationRound, TimeDelta, Utc};
-use eyre::{format_err, Result};
+use eyre::{Result, format_err};
 use log::{debug, error, warn};
 use std::path::{Path, PathBuf};
 use std::process::Stdio;
@@ -9,7 +9,7 @@ use tokio::{
     io::{self, AsyncBufReadExt, AsyncRead, AsyncWrite, AsyncWriteExt, BufReader, BufWriter},
     process,
     sync::mpsc,
-    time::{sleep, Duration},
+    time::{Duration, sleep},
 };
 
 pub type Timestamp = chrono::DateTime<Utc>;