commit 9b743b3108f7ca3084604add712f7f901da38677
parent 99e0402bf836d03944de758c2fa526c5e8231602
Author: Paco Esteban <paco@e1e0.net>
Date: Tue, 11 Aug 2020 12:53:17 +0200
new article about kubectl plugins
Diffstat:
2 files changed, 100 insertions(+), 1 deletion(-)
diff --git a/src/gophermap b/src/gophermap
@@ -12,6 +12,7 @@ Sometimes I write things so I do not forget ...
o--o-- Random (usually tech) stuff
+0kubectl plugins /kubectl-plugins.md e1e0.net 70
0Aliases and helper functions for the shell /aliases-helper-functions-shell.md e1e0.net 70
0Easy DNS zone management across providers /easy-dns-zone-management-accross-providers.md e1e0.net 70
0Manage Kubernetes clusters from OpenBSD /manage-k8s-from-openbsd.md e1e0.net 70
@@ -51,5 +52,5 @@ Have any comments ?
Send an email to <comments@e1e0.net>
o- o -- -------------------------------------------------------- -- o --
-Last updated: Fri, 03 Jul 2020 08:38:16 +0000
+Last updated: Tue, 11 Aug 2020 10:52:35 +0000
o- o -- -------------------------------------------------------- -- o --
diff --git a/src/kubectl-plugins.md b/src/kubectl-plugins.md
@@ -0,0 +1,98 @@
+Title: kubectl plugins
+Author: paco
+Date: 2020-08-11
+Type: article
+
+Following the `kubernetes` management theme, there's something that may be of
+interest for `kubectl` users.
+
+That management tool accepts what they call _plugins_. Those are simply
+executables that reside in `$PATH`, and they follow a naming convention, that is
+`kubectl-name`. Where `name` is a subcommand you want to create.
+Sub-sub-commands can nested by creating executables with the form
+`kubectl-sub-sub-command` (so dash separated words for them).
+
+They can be compiled binaries written in your language of choice, or scripts
+made in your preferred interpreted programming language.
+
+I use this to simplify or wrap around existing subcommands, for tasks that I do
+regularly and annoy me, but can be used to develop new functionalities.
+
+For reference, [this is the official documentation][1]
+I'll show a couple of examples here.
+
+## Restart a deployment
+
+This one is as simple as it gets. Actually there's no way of restarting
+a deployment on kubernetes. Pods are (or should be) stateless and expendable,
+so you really kill them and the scheduler re-creates them when the deployment
+definition requirements are not met.
+
+A simple way of _"emulating"_ a restart, is modifying the deployment so the
+scheduler re-creates all the pods in it. For that, just changing the value of
+an environment variable in the deployment definition will suffice. For that
+I created this plugin:
+
+```
+#!/bin/sh
+
+set -eu
+
+usage() {
+ echo "kubectl restart <deployment>"
+ exit 1
+}
+
+deployment=${1:-x}
+
+test $deployment != "x" || usage
+
+kubectl set env \
+ "deployment/$deployment" \
+ LAST_MANUAL_RESTART="$(date +%Y%m%d.%H%M%S)"
+```
+
+## Custom log output
+
+Even with all the log aggregation and the cloudy stuff doing cloudy things, one
+sometimes needs to take a peek at the logs of an specific container. That can
+be done with the `kubectl logs` command, which will dump all the things to your
+terminal.
+
+Some of the apps at work spit out some sort of structured JSON as logs, which is
+hard to read when they come in one line and without any time stamp on them.
+For that I created this:
+
+```
+#!/bin/sh
+
+set -eu
+
+if ! command -v jq > /dev/null; then
+ echo 'You need to have jq installed to run this plugin.'
+ exit 1
+fi
+
+usage() {
+ echo "kubectl pslog <pod> [container] [options]"
+ echo "(options can be any option passed to kubectl logs)"
+ exit 1
+}
+
+pod=${1:-x}
+
+test $pod != "x" || usage
+
+kubectl logs $* |\
+ grep -E '^{' |\
+ jq -r '"\(.timestamp.seconds | strftime("%Y-%m-%d %H:%M:%S %Z")) | \(.message)"'
+```
+
+`kubectl pslog` uses the power of `jq` to print the time stamp in a human
+readable manner in front of each log entry, and then _prettifies_ it in the
+process, which is way more readable.
+
+Not much more to say, hope this gives you some ideas to make your life easier
+when using `kubectl`.
+
+[1]: https://kubernetes.io/docs/tasks/extend-kubectl/kubectl-plugins/
