---
title: "Atomic deploys"
description: "To minimize a deployment's downtime, we use atomic deployments for a couple of clients."
canonical_url: "https://codex.republic.se/development/atomic-deploys"
section: "Pages"
---

# ⚛️ Atomic deploys

To minimize a deployment's downtime, we use [atomic deployments](https://buddy.works/blog/introducing-atomic-deployments) for a couple of clients.

---

## Concept

This concept uses a directory structure like:

```bash
~
├── deploy-cache
├── releases
│   ├── 7fd8ff39e3935dc865b2e498681b162127313550
│   ├── 93162127313555dc865b2e498681b7fd8ff39e30
│   ├── …
│	  └── 5dc865b2e498681b7fd8ff39e393162127313550
└── shared
    ├── cache
    ├── content
    └── storage

```

And two `symlink`s to tell the web server which release is the current one, where **current** always points to the latest release and **htdocs** points to the htdocs folder of the current release.

```bash
~
├── current -> releases/7fd8ff39e3935dc865b2e498681b162127313550
├── htdocs -> current/htdocs

```

When deploying files to the server, they all get `rsync`ed into `/deploy-cache` and then copied to a new folder in `/releases`. When done, the current symlink is changed to the new release folder and the site is updated.

## Setup

- Create a `deploy-cache` folder on the server
- Use an Atomic deploy setup in Buddy
- Symlink the current release’s web root to the `htdocs` used by the web server `ln -nfs current/htdocs htdocs`

## **How it works (from [Buddy’s guide](https://buddy.works/blog/introducing-atomic-deployments))**

> The whole process is handled entirely by two actions — **SFTP** and **SSH** — and involves creating a couple of directories on the server:
> 
> - `/current` - the directory to which your web server points. It containing a symbolic link to the current website version in the `/releases` directory.
> - `/releases` - contains the history of uploaded releases. For each version a directory with the name of the release tag is created. This allows for a quick rollback of changes.
> - `/deploy-cache` - used for storing new files during the deployment. Once the upload has finished, its contents are copied to a new directory in the `/releases` directory.
> 
> In short, when the deployment is triggered, Buddy will first deploy the files to the cache directory on the server, copy the files to a newly created release directory, and switch the symlink of the web server to the new version.

## Database backup with `mysqldump`

If all tables are in the form of **InnoDB** we can use the `--single-transaction` flag to keep the database available while taking a DB dump. Without that the tables will be locked while using `mysqldump` and the site will respond with a 503 status.

### Example from Oderland

```bash
mysqldump --single-transaction --skip-lock-tables -u username_craft -p password_craft > prod_craft.sql

```