new post: docker image size

content/posts/2024-12-05-docker-image-size.md

@@ -0,0 +1,41 @@
+---
+title: "Docker image size"
+date: 2024-12-05T13:05:44+01:00
+tags:
+  - dev
+  - devops
+---
+
+When trying to optimize docker images in terms of size, the workflow is as
+follows:
+
+<!--more-->
+
+## Terminal 1
+
+```shell
+% docker build -f Dockerfile . -t argocd-download-tools
+```
+
+...possibly paired up with `entr` or `fswatch` depending on your eagerness for
+automatic builds.
+
+## Terminal 2
+
+```shell
+% docker image inspect argocd-download-tools | jq -r '.[0].Size' | numfmt --to=iec
+134M
+```
+
+...possibly prepended with `watch`.
+
+I wasn't aware of [`numfmt`](https://man.archlinux.org/man/numfmt.1):
+
+> numfmt - Convert numbers from/to human-readable strings
+
+...instead of displaying plain bytes, it converts numbers to human-readable
+strings (à la `df -h` or `free -h`).
+
+Regarding the [units](https://en.wikipedia.org/wiki/Binary_prefix): they don't
+matter much, because we are only interested in an approximation, no need to
+shave bytes off here. `SI` has 1k = 1000, whereas `IEC` has 1Ki = 1024.