Category Archives: Administration

Using tcpdump for k8s pods

You need wireshark to be installed on your local machine — download (more on this below). If you don’t have tcpdump installed inside the pod, you can install it with

# get pod name
kubectl get po -Lversion,cfg,infra-cfg -lapp=<pod-tag>
kubectl exec -it <pod-name> sh
# inside the pod, alpine
apk add tcpdump

# get pod name

kubectl get po -Lversion,cfg,infra-cfg -lapp=<pod-tag>

kubectl exec -it <pod-name> sh

# inside the pod, alpine

apk add tcpdump

Then, on your local machine:

kubectl exec <pod-name> -- tcpdump -i eth0 -w - | wireshark -k -i -

1	kubectl exec <pod-name> -- tcpdump -i eth0 -w - \| wireshark -k -i -

If you want to see packets in grpc/http2, you can add a rule in Wireshark. For this, click …

Forward multiple kubernetes pods for local development

kubefwd is a great tool that can forward a lot of pods at once to your local machine. The only downside for me is that it touches your local /etc/hosts. That’s how I use it:

sudo KUBECONFIG=<path to your k8s config> kubefwd svc -l "app in (first-api, second-api, third-service)"

1	sudo KUBECONFIG=<path to your k8s config> kubefwd svc -l "app in (first-api, second-api, third-service)"

It does not have huge documentation, but it is written in golang, and you can check how the source …

DD_AGENT_MAJOR_VERSION=7 DD_API_KEY=<your-key> DD_SITE="datadoghq.eu" bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script.sh)"

sudo nano /etc/datadog-agent/datadog.yaml
# uncomment logs_enabled: true
sudo systemctl restart datadog-agent
sudo mkdir /etc/datadog-agent/conf.d/go.d
sudo nano /etc/datadog-agent/conf.d/go.d/conf.yaml
# and add contents from the url below

DD_AGENT_MAJOR_VERSION=7 DD_API_KEY=<your-key> DD_SITE="datadoghq.eu" bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script.sh)"

sudo nano /etc/datadog-agent/datadog.yaml

# uncomment logs_enabled: true

sudo systemctl restart datadog-agent

sudo mkdir /etc/datadog-agent/conf.d/go.d

sudo nano /etc/datadog-agent/conf.d/go.d/conf.yaml

# and add contents from the url below

https://app.datadoghq.eu/logs/onboarding/server https://docs.datadoghq.com/agent/faq/error-restarting-agent-already-listening-on-a-configured-port/ Or, if you want a dockerized version of DataDog agent, and you want to listen to docker logs, you can do this:

docker run -d --name datadog-agent \
           -e DD_API_KEY=<DATADOG_API_KEY> \
           -e DD_LOGS_ENABLED=true \
           -e DD_LOGS_CONFIG_CONTAINER_COLLECT_ALL=true \
           -e DD_CONTAINER_EXCLUDE_LOGS="name:datadog-agent" \
           -e DD_SITE="datadoghq.eu"  \
           -v /var/run/docker.sock:/var/run/docker.sock:ro \
           -v /proc/:/host/proc/:ro \
           -v /opt/datadog-agent/run:/opt/datadog-agent/run:rw \
           -v /sys/fs/cgroup/:/host/sys/fs/cgroup:ro \
           datadog/agent:latest

docker run -d --name datadog-agent \

-e DD_API_KEY=<DATADOG_API_KEY> \

-e DD_LOGS_ENABLED=true \

-e DD_LOGS_CONFIG_CONTAINER_COLLECT_ALL=true \

-e DD_CONTAINER_EXCLUDE_LOGS="name:datadog-agent" \

-e DD_SITE="datadoghq.eu" \

-v /var/run/docker.sock:/var/run/docker.sock:ro \

-v /proc/:/host/proc/:ro \

-v /opt/datadog-agent/run:/opt/datadog-agent/run:rw \

-v /sys/fs/cgroup/:/host/sys/fs/cgroup:ro \

datadog/agent:latest

More info here — https://docs.datadoghq.com/agent/docker/log/?tab=containerinstallation Then you will see your logs here — https://app.datadoghq.eu/logs

Add all lines from a .env file to environment

zsh:

zsh ./configs/dev/dev.env|sed 's/#1.*$//g'|grep '^[^#]'|grep -v '^$'|sed 's/^/export /g'

1	zsh ./configs/dev/dev.env\|sed 's/#1.*$//g'\|grep '^[^#]'\|grep -v '^$'\|sed 's/^/export /g'

bash:

bash ./configs/dev/dev.env|sed 's/#1.*$//g'|grep '^[^#]'|grep -v '^$'|sed 's/^/export /g'

1	bash ./configs/dev/dev.env\|sed 's/#1.*$//g'\|grep '^[^#]'\|grep -v '^$'\|sed 's/^/export /g'

to output to stdout

cat ./configs/dev/dev.env|sed 's/#1.*$//g'|grep '^[^#]'|grep -v '^$'|sed 's/^/export /g'

1	cat ./configs/dev/dev.env\|sed 's/#1.*$//g'\|grep '^[^#]'\|grep -v '^$'\|sed 's/^/export /g'

prepend running a command (did not try it, but something similar):

env $(cat ./configs/dev/dev.env|sed 's/#.*$//g'|grep '^[^#]'|grep -v '^$'|xargs)

1	env $(cat ./configs/dev/dev.env\|sed 's/#.*$//g'\|grep '^[^#]'\|grep -v '^$'\|xargs)

Integration tests with testcontainers-go

Here is the go library that simplifies integration tests with docker containers — https://github.com/testcontainers/testcontainers-go. That’s how you can use it to test sql — https://github.com/testcontainers/testcontainers-go/blob/master/docs/examples/cockroachdb.md. Project documentation — https://golang.testcontainers.org/features/docker_compose/ The idea is to prepare the environment, build your app, then make requests and check the DB state.

How to update your k8s pod limits

kubectl edit deployment ←name-of-your-app→

1	kubectl edit deployment ←name-of-your-app→

Then search for memory (for instance) and update request/limit for it. When you quit, it will be saved automatically for you.

Load testing tools

Read logs from docker container

tail -f `docker inspect --format='{{.LogPath}}' [containername]`

1	tail -f `docker inspect --format='{{.LogPath}}' [containername]`

Interesting alternative to grpc_cli

https://github.com/ktr0731/evans It has REPL mode and CLI mode for e2e tests I think, it could be a good alternative to grpc_cli.

How to install linux mint on hp

I’ve run into a problem — had a lot of error logging saying «PCIe Bus Error: severity=Corrected, type=Physical Layer», «AER Corrected error received», and similar. The problem is that it fills all the log space and the installation process cannot finish. You can run into it on HP laptops on monoblocks. What you can do.