new post about docker volumes

content/posts/digging-through-docker-volumes/index.md

@@ -0,0 +1,73 @@
+---
+draft: false
+title: "How to find that one volume you're pretty sure you didn't lose"
+date: "2024-06-25"
+series: []
+author: "Nick Dumas"
+cover: ""
+tags: ["bash", "docker"]
+summary: "Docker volumes can be opaque, so I wrote a small bash script to help you troubleshoot."
+showFullContent: false
+---
+
+## What I expect you to know
+This article is only relevant if you know about and user docker volumes and have some fluency in bash. I'll explain the code as I go, if it helps.
+
+## The Problem
+Over the lifetime of a Docker host machine, it's like that orphaned volumes ( and other detritus ) will accumulate over time. You might also find yourself fumbling a configuration and orphaning a volume yourself.
+
+However we got here, we have a bunch of volumes and we need to know if any of them are important. In a perfect world, they'll have decent names. We don't live in a perfect world.
+## Make a list
+Luckily, we have tools at our disposal to handle this. My thought process almost always starts with "Can I turn a list of the things I care about into a newline separated list?" If I can do that, I can start automating my troubleshooting.
+
+Let's start with `docker volume ls`. This is how we list volumes, but the default output isn't quite what I'm looking for:
+```
+docker volume ls
+DRIVER    VOLUME NAME
+local     d35fce052fbce42b94b2f9b2957be0f77090fa006b1a192030eff07db3675af2
+local     grafana-storage
+local     plausible_db-data
+local     plausible_event-data
+```
+This is human readable, and we could even do some slicing with `cut` or `awk`, but Docker gives us a flag that will take us exactly where we need to go: `--format`. Generally, Docker uses Go's `text/template` library to back this feature, and more specifically, individual flags (usually) [document](https://docs.docker.com/reference/cli/docker/volume/ls/#format) the template verbs available. Here, we want `Name`.
+```
+docker volume ls --format "{{.Name}}"
+d35fce052fbce42b94b2f9b2957be0f77090fa006b1a192030eff07db3675af2
+grafana-storage
+plausible_db-data
+plausible_event-data
+```
+
+And now we have a newline separated list of volume names. 
+## Process of elimination
+The next part is fairly straightforward. We loop over this list and ask Docker to create a temporary container based on alpine, with a single volume mounted at `/test/`.
+```
+#! /bin/bash
+
+# Newline separated list of volume names
+volumes=$(docker volume ls --format="{{.Name}}")
+for volume in $volumes; do
+	# Help the user keep track of which volume they're exploring
+	echo "Mounting $volume in a temporary image."
+    docker run --rm -v $volume:/test/ -it alpine /bin/sh
+done
+```
+Running this script should do something like this:
+```
+./cycle-volumes.sh
+Mounting d35fce052fbce42b94b2f9b2957be0f77090fa006b1a192030eff07db3675af2 in a temporary image.
+/ # ls /test/
+clickhouse-server.err.log   clickhouse-server.log.1.gz  clickhouse-server.log.4.gz  clickhouse-server.log.7.gz
+clickhouse-server.log       clickhouse-server.log.2.gz  clickhouse-server.log.5.gz  clickhouse-server.log.8.gz
+clickhouse-server.log.0.gz  clickhouse-server.log.3.gz  clickhouse-server.log.6.gz
+/ #
+Mounting grafana-storage in a temporary image.
+/ # ls /test
+alerting          csv               file-collections  grafana.db        plugins           png
+/ # exit
+Mounting plausible_db-data in a temporary image.
+/ # exit
+Mounting plausible_event-data in a temporary image.
+/ # exit
+```
+You can use bash to explore the volume and identify its contents, make note of which ones are which, and proceed accordingly.

content/posts/notes-as-tools/index.md

@@ -7,7 +7,7 @@ date: "2024-04-24"
 author: "Nick Dumas"
 cover: ""
 keywords: ["", ""]
-summary: "Note-taking and the tools we use to do it can present an overwhelming abundance of possibility. Explicitly modelling your notes as tools can grant clarity when creating and organizing your knowledge."
+summary: "Note-taking can present an overwhelming abundance of possibility. Explicitly modelling your notes as tools can grant clarity when creating and organizing your knowledge."
 showFullContent: false
 tags:
 - obsidian