Cogini Blog Articles in the DevOps category

Jake Morrison

Benchmarking Phoenix on Digital Ocean

Just for fun, I decided to benchmark the performance of the elixir deploy template running on a $5/month Digital Ocean Droplet. Read more…

Jake Morrison

Database migrations in the cloud

Database migrations are used to automatically keep the database in sync with the code that uses it. Elixir apps should be deployed as releases, supervised by systemd. Here is an example of how to run migrations when deploying Elixir releases. It's tempting to automatically run database migrations when the app … Read more…

Jake Morrison

Deploying Elixir apps without sudo

We normally deploy Elixir apps as releases, supervised by systemd. After we have deployed the new release, we restart the app to make it live: sudo /bin/systemctl restart foo The user account needs sufficient permissions to restart the app, though. Instead of giving the deploy account full sudo permissions … Read more…

Jake Morrison

Getting the client public IP address in Phoenix

When your app is running behind a proxy like Nginx or a CDN, then the requests will all look like they are coming from the proxy. Use the X-Forwarded-For header to set the remote_ip correctly. Read more…

Jake Morrison

Port forwarding with iptables

In order to listen on a TCP port less than 1024, an app traditionally needs to be started as root. Over the years this has resulted in many security problems. A better solution is to run the application on a normal port such as 4000, and redirect traffic in the … Read more…

Jake Morrison

Rate limiting Nginx requests

Any popular service may be the unfortunate recipient of a DDOS attack. We find that DDOS load ends up driving capacity planning, as it can easily be 10x the normal load. You can rate limit at multiple levels. You might use a service such as CloudFlare, filtering provided by your … Read more…

Jake Morrison

Serving your Phoenix app with Nginx

It's common to run web apps behind a proxy such as Nginx or HAProxy. Nginx listens on port 80, then forwards traffic to the app on another port, e.g. 4000. Following is an example nginx.conf config: user nginx; worker_processes auto; error_log /var/log/nginx/error.log … Read more…

Jake Morrison

Serving Phoenix static assets from a CDN

Phoenix is fast, but you can improve performance by serving requests for static files like images, CSS and JS from Nginx or a content delivery network (CDN). This allows your app to focus on dynamic content. Serving static assets from Nginx If you are running your app behind Nginx, configure … Read more…

Jake Morrison

Setting Ansible variables based on the environment

When deploying applications, we we usually have the same basic architecture in different environments (dev, test, prod), but settings differ. Some settings are common to all the machines in the environment, e.g. the db server connection string. We need to vary the size of instances depending on the environment … Read more…

Jake Morrison

Is it time for Lisp in DevOps?

We have been working on a project migrating a big Rails app from physical hardware to AWS, and I have been doing a lot of automation work. It strikes me how we are doing the same thing over and over with different tools: reading variables, templating files and running semi-declarative … Read more…


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