astro first commit

src/content/blog/speed-up-your-docker-builds-with-dockerignore.md

@@ -0,0 +1,74 @@
+---
+title: 'Speed up your docker builds with .dockerignore'
+date: '2019-12-23'
+categories:
+  - 'coding'
+tags:
+  - 'docker'
+coverImage: './images/thomas-kelley-t20pc32VbrU-unsplash-scaled-1.jpg'
+---
+
+So you ever wondered why your docker build takes so long to startup when all you do is adding a few files to your image and setting which command to run?
+
+Fear no more! `.dockerignore` to the rescue ⚓️.
+
+<figure>
+
+![](images/thomas-kelley-t20pc32VbrU-unsplash-scaled-1.jpg)
+
+<figcaption>
+
+Photo by [Thomas Kelley](https://unsplash.com/@thkelley?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText) on [Unsplash](https://unsplash.com/s/photos/whale?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText)
+
+</figcaption>
+
+</figure>
+
+Whenever you build a docker image the first thing you will always see is the following:
+
+```bash
+docker build -t my-image .
+Sending build context to Docker daemon  203.2MB
+Step 1/6 : FROM ...
+```
+
+The important thing to note is the context with a size of `203.2MB` in this case. What does it mean?
+
+Every time a docker image gets built, it requires the context. By default it's simply the directory of your `Dockerfile`. Basically it's the folder from which you can add files to the image you are building.
+
+This means that for each build, the docker client sends the whole directory to the docker engine to build.  
+If you are unlucky this includes either the whole node_modules folder, maybe a virtual env folder for your python or simply everything in your dist folder. In my case it was a venv with 200+MB of data.
+
+This slows down the process significantly and if you are iterating on a dockerfile making only a few tweak this can be very tearing.
+
+> Waiting is the most boring (duh) and painful thing ever.
+>
+> Every person on this planet
+
+## Solution: `.dockerignore`
+
+Simply create a `.dockerignore` file inside of your context (basically in the same directory as your `Dockerfile`) and specify what to include, what to ignore. It works just like our trusted `.gitignore`.
+
+Im my case I only wanted to have my `requirements.txt` and the `.py` files inside of my `src` folder.
+
+###### .dockerignore
+
+```
+# Ignore everything
+**
+
+!/requirements.txt
+!/src
+
+**/__pycache__
+```
+
+If I run `docker build` again watch what happens:
+
+```bash
+docker build -t my-image .
+Sending build context to Docker daemon  37.38kB
+Step 1/6 : FROM ...
+```
+
+Awesome! The context shrunk from 200MB to under 50kB and the startup time of docker build was greatly reduced. This will help substantially if you have a lot of files, like e.g. a node_modules folder.