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مدرس و برنامه نویس پایتون و لینوکس @alirezastack
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DO NOT USE UWSGI multi-threaded mode with alpine image!

I've been stuck on this issue for a couple of days as our service returned 503 Gateway timeout while our server load was totally ok around 1.0 (1m load average). So our load test got failed at the be beginning of the test! We found out it is related to docker base image of python alpine. Use python slim image instead. Or in case you have many changes you can stick with alpine and change thread to 1 in uswgi configuration file.


#docker #alpine #uwsgi #python #slim #respawn
For prometheus you can use an alert manager, it has a docker file in the link below:
- https://hub.docker.com/r/prom/alertmanager

Awesome Prometheus alerts:
- https://github.com/samber/awesome-prometheus-alerts

alertmanager has rules, you can see sample rules here in the following link:
- https://awesome-prometheus-alerts.grep.to/rules

So to add alertmanager service:

alertmanager:
image: prom/alertmanager:latest
restart: always
command: --config.file=/etc/alertmanager/alertmanager.yml
volumes:
- ./alert/config/alertmanager.yml:/etc/alertmanager/alertmanager.yml
dns:
- 8.8.8.8


You alert manager configuration may look something like below:

global:
resolve_timeout: 5m

route:
# When a new group of alerts is created by an incoming alert, wait at
# least 'group_wait' to send the initial notification.
# This way ensures that you get multiple alerts for the same group that start
# firing shortly after another are batched together on the first
# notification.
group_wait: 10s

# When the first notification was sent, wait 'group_interval' to send a betch
# of new alerts that started firing for that group.
group_interval: 5m

# If an alert has successfully been sent, wait 'repeat_interval' to
# resend them.
repeat_interval: 30m

# A default receiver
receiver: "slack"

# All the above attributes are inherited by all child routes and can
# overwritten on each.
routes:
- receiver: "slack"
group_wait: 10s
match_re:
severity: error|warning
continue: true

# - receiver: "sms"
# group_wait: 10s
# match_re:
# severity: error
# continue: true

receivers:
- name: "slack"
slack_configs:
- api_url: 'YOUR-WEBHOOK-URL'
send_resolved: true
channel: 'monitoring'
text: "{{ range .Alerts }}<!channel> {{ .Annotations.summary }}\n{{ .Annotations.description }}\n{{ end }}"

# - name: "sms"
# webhook_config:
# - url: http://a.b.c:8080/send/sms
# send_resolved: true


You should be up & running with this sample configurations.
Spread your love for M2SH :)

#prometheus #prom #alert #alert_manager #docker #dockerfile #slack
How tom remove dangling volumes in docker?

docker volume rm $(docker volume ls -qf dangling=true)


#docker #linux #dangling
In Dockerfile`s some people in the community use `alpine base image in order to reduce docker image size. apk is its package management tool that can be used to install OS packages. So for example if
you want to install network tools (like ping) you need to install netcat-openbsd:

apk add netcat-openbsd


You can squash your image size even further by some tips. When you install a package, linux distros first download the package and put it in a cache folder. In Alpine it is located in /var/cache/apk.
To tell the OS to delete the cache after installation you can provide --no-cache option to it:

apk add --no-cache netcat-openbsd


There are some package like g++ or git that is needed on installation of some other packages. After installation those packages is useless and just increase image size. You can remove those packages b
y using --virtual command:

apk add --no-cache --virtual .build-deps g++ \
&& # do you stuff here \
&& apk del .build-deps


Great job guys! You have reduced your alpine docker images so much :)

#docker #linux #alpine #apk #virtual #no_cache #apk_del #apk_add