🐠 A demo of zero-downtime deploys with Docker Compose and Traefik

This is a demonstration of a method that uses Docker Compose and Traefik to achieve zero-downtime deployment. I use this same approach to automate deployments to a VPS for projects like remotejobs.org.

Checkout the companion article to read a detailed description of how this works and the benefits of such a workflow.

Note Ensure that a recent version of Docker is installed and available on your system.

Start the Traefik project:

$ docker compose --project-name=traefik --file docker-compose.traefik.yml up --detach

Now trigger a deployment with the blue-green-deploy.sh script:

$ ./blue-green-deploy.sh

Once this process completes, you can visit https://localhost:80 in your browser. From here, you can continue to make changes to your service and then use the script to deploy them.

Warning :80 is commonly already bound. If so, consider updating the Traefik configuration to use another port and connect to that instead.

For instance, update server.js as such:

diff --git a/server.js b/server.js
index a137c60..6afa5c7 100644
--- a/server.js
+++ b/server.js
@@ -8,7 +8,7 @@ const HOST = "0.0.0.0";
 const app = express();

 app.get("/", (_req, res) => {
-    res.send("Hello, zero-downtime deployment world");
+    res.send("Hello, blue-green world");
 });

 app.get("/health", (_req, res) => {

Now re-run blue-green-deploy.sh and this time when you visit the page you should see the new message.