Docker has become a popular tool in recent years for building and deploying applications in a portable and scalable way. However, the build process can sometimes be slow, especially for large applications with many dependencies. In this article, we’ll explore how we can optimize our Dockerfile to speed it up.

When building a rails app for production we would need to do the following steps in the docker file

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COPY . .
bundle install
yarn install
bundle exec rails assets:precompile

Docker after building each step it will cache that step. If the instructions/context of that steps or steps before haven’t change then docker will use the cache.

So we need to make docker understand that there is no change, hence we can use the cache instead of rebuilding it.

Docker engine has inbuild API service that allows you to control & modify your docker engine and docker instance using HTTP.

NFS - Network File System is a distributed file system protocol developed by Sun Systems. It facilitates a client computer to have access to file/folder over network like a local folder. This is a easy/simple way to provide persistant storage for your docker-swarm or kubernetes cluster. In both these cases, the container (or pod) run on one of the available nodes (servers), and when we have replicas it will be running on more than one node. So local storage on the server is out of the question.

With NFS we can directly mount the folder in the container. We can control everything from the configuration file. And thanks to the NFS storage we can increase and reduce node without worries as well.

PiHole is a DNS server that will block ads and website on a DNS level. This is an integral part of my homelab as it blocks a lot of ads on my phones and system, and also easily allows us to manage domains for local application.

For homelab I have a docker-swarm which is managed using portainer. I have a nginx proxy manager to map the ports to a proper domain, even provide https using lets encrypt.But PiHole doesn’t have a wildcard domain setting, hence after i set or before i set a domain my nginx proxy I need to add it to PiHole.

YAML stands for “YAML Ain’t Markup Language”. YAML is a data serialization language that is often used for writing configuration files.

In simple terms YAML is like XML or JSON, but for human beings rather than computers. I feel this is getting overlooked a lot, programmers need to understand that. Another human like configuration language I like is TOML (Tom’s Obvious Minimal Language).

In a static language (like crystal) you need to define the structure of a YAML or JSON file. Defining the structure also act as validation of its schema. Validating the schema is a good idea because it ensure’s that all the required data is present. Its better to know data is missing when your program starts rather than while it is running.

For dynamic language like ruby you can load a yaml file, and ruby will dynamically initialize it. It does make your life easier as a programmer. You don’t need to define the schema, and remember to update the schema when you add a new variable to your file.

But defining the schema has its benefits -

1. For the User: It reminds then to have the configuration filled before running their program
2. For the Developer: It helps us to eliminate the configuration file as a possible reason for the program not running.