Kubernetes + Minikube - How to see all stdout output? - ruby

Question

I'm running a Ruby app on Kubernetes with Minikube.
However, whenever I look at the logs I don't see the output I would have seen in my terminal when running the app locally.
I presume it's because it only shows stderr?
What can I do to see all types of console logs (e.g. from puts or raise)?
On looking around is this something to do with it being in detached mode - see the Python related issue: Logs in Kubernetes Pod not showing up
Thanks.
=
As requested - here is the deployment.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: sample
spec:
replicas: 1
template:
metadata:
labels:
app: sample
spec:
containers:
- name: sample
image: someregistry
imagePullPolicy: Always
command: ["/bin/sh","-c"]
args: ["bundle exec rake sample:default --trace"]
envFrom:
- configMapRef:
name: sample
- secretRef:
name: sample
ports:
- containerPort: 3000
imagePullSecrets:
- name: regsecret

Answer 1

As shown in this article, kubectl logs pod apod should show you stdout and stderr for a pod deployed in a minikube.
By default in Kubernetes, Docker is configured to write a container's stdout and stderr to a file under /var/log/containers on the host system
Kubernetes adds:
There are two types of system components: those that run in a container and those that do not run in a container.
For example:
The Kubernetes scheduler and kube-proxy run in a container.
The kubelet and container runtime, for example Docker, do not run in containers.
And:
On machines with systemd, the kubelet and container runtime write to journald.
If systemd is not present, they write to .log files in the /var/log directory.
Similarly to the container logs, system component logs in the /var/log directory should be rotated.
In Kubernetes clusters brought up by the kube-up.sh script, those logs are configured to be rotated by the logrotate tool daily or once the size exceeds 100MB.

Answer 2

I presume it's because it only shows stderr?
Not really, unless something specific is disabled in your container or pod spec. I assume you are using Docker so then the default it's to output stdout and stderr and that's what you see when you do a kubectl logs <pod-name>
What can I do to see all types of console logs (e.g. from puts or raise)?
You should see them in the container logs. It would help to post your pod or deployment definition.