Implement backups

* trigger backup importation via http route
* follow backup advancement with status route
* import backup via a command line
* let user choose batch size of documents to import (command lines)

closes #884
closes #840

meilisearch-http/src/helpers/compression.rs

@@ -0,0 +1,27 @@
+use flate2::Compression;
+use flate2::read::GzDecoder;
+use flate2::write::GzEncoder;
+use std::fs::{create_dir_all, File};
+use std::path::Path;
+use tar::{Builder, Archive};
+
+use crate::error::Error;
+
+pub fn to_tar_gz(src: &Path, dest: &Path) -> Result<(), Error> {
+    let f = File::create(dest)?;
+    let gz_encoder = GzEncoder::new(f, Compression::default());
+    let mut tar_encoder = Builder::new(gz_encoder);
+    tar_encoder.append_dir_all(".", src)?;
+    let gz_encoder = tar_encoder.into_inner()?;
+    gz_encoder.finish()?;
+    Ok(())
+}
+
+pub fn from_tar_gz(src: &Path, dest: &Path) -> Result<(), Error> {
+    let f = File::open(src)?;
+    let gz = GzDecoder::new(f);
+    let mut ar = Archive::new(gz);
+    create_dir_all(dest)?;
+    ar.unpack(dest)?;
+    Ok(())
+}

meilisearch-http/src/helpers/mod.rs

@@ -1,6 +1,7 @@
 pub mod authentication;
 pub mod meilisearch;
 pub mod normalize_path;
+pub mod compression;
 
 pub use authentication::Authentication;
 pub use normalize_path::NormalizePath;