diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index b268b411..4381ccc6 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -2,27 +2,27 @@
 // https://github.com/microsoft/vscode-dev-containers/tree/v0.241.1/containers/ruby-rails-postgres
 // Update the VARIANT arg in docker-compose.yml to pick a Ruby version
 {
-	"name": "Black Candy",
-	"dockerComposeFile": "docker-compose.yml",
-	"service": "app",
-	"workspaceFolder": "/workspace",
-	// Configure tool-specific properties.
-	"customizations": {
-		// Configure properties specific to VS Code.
-		"vscode": {
-			// Add the IDs of extensions you want installed when the container is created.
-			"extensions": [
-				"rebornix.Ruby"
-			]
-		}
-	},
-	// Use 'forwardPorts' to make a list of ports inside the container available locally.
-	// This can be used to network with other containers or the host.
-	"forwardPorts": [
-		3000
-	],
-	// Use 'postCreateCommand' to run commands after the container is created.
-	"postCreateCommand": "bundle install && yarn install && rake db:prepare",
-	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
-	"remoteUser": "vscode"
+  "name": "Black Candy",
+  "dockerComposeFile": "docker-compose.yml",
+  "service": "app",
+  "workspaceFolder": "/workspace",
+  // Configure tool-specific properties.
+  "customizations": {
+    // Configure properties specific to VS Code.
+    "vscode": {
+      // Add the IDs of extensions you want installed when the container is created.
+      "extensions": [
+        "rebornix.Ruby"
+      ]
+    }
+  },
+  // Use 'forwardPorts' to make a list of ports inside the container available locally.
+  // This can be used to network with other containers or the host.
+  "forwardPorts": [
+    3000
+  ],
+  // Use 'postCreateCommand' to run commands after the container is created.
+  "postCreateCommand": "bundle install && yarn install && rake db:prepare",
+  // Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+  "remoteUser": "vscode"
 }
\ No newline at end of file
diff --git a/.devcontainer/docker-compose.yml b/.devcontainer/docker-compose.yml
index 6ac2c5fd..8df530f1 100644
--- a/.devcontainer/docker-compose.yml
+++ b/.devcontainer/docker-compose.yml
@@ -49,7 +49,7 @@ services:
     # (Adding the "ports" property to this file will not forward from a Codespace.)
 
   redis:
-    image: redis:4.0-alpine
+    image: redis:6.0-alpine
     volumes:
       - redis-data:/data
     networks:
diff --git a/README.md b/README.md
index 6e9337bf..caff8006 100644
--- a/README.md
+++ b/README.md
@@ -86,37 +86,15 @@ $ docker-compose restart
 - Postgres 11
 - Redis 6.0 
 - Nodejs 12
-- Yarn 1.22
-- Imagemagick 7
-- ffmpeg 4.3
+- Yarn
+- Imagemagick
+- ffmpeg
 
-You can use [nix](https://nixos.org) to setup dev environment easily. 
+You can use VS Code Remote Containers or GitHub Codespaces to setup dev environment easily.
+For more infomations about dev container, please visit this link <https://code.visualstudio.com/docs/remote/create-dev-container>.
 
-```shell
-# First, install nix. You can check out the nix doc for more details.
-$ curl -L https://nixos.org/nix/install | sh
-
-# Then clone the repo.
-$ git clone https://github.com/aidewoode/black_candy.git
-
-# Change to the directory.
-$ cd black_candy
-
-# Go into nix shell, the nix shell will auto setup all dev requirements you need.
-$ nix-shell 
-
-# Install requirement gems.
-$ bundle
-
-# Install npm packages.
-$ yarn
-
-# Setup database.
-$ rails db:setup
-
-# Finally, start all services.
-$ ./bin/dev 
-```
+After the dev container has been built. You can run `./bin/dev` in terminal to start all services. 
+Then visit <http://localhost:3000> use initial admin user to login (email: admin@admin.com, password: foobar).
 
 ## Test