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Simple multi cloud Docker cluster using Docker Swarm

This guide explains how to create a simple multi cloud Docker cluster using Docker Swarm, Docker Machine and the three top cloud providers nowadays - Google Compute Engine, Microsoft Azure and AWS.

Prerequisites

This guide assumes you have a Linux host with Docker CE installed. If you are using Docker for Mac or Docker for Windows you can avoid the Docker Machine set up since it comes included.

Install Docker Machine

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Configure SSH with multiple git accounts

Scenario: same git provider, for this example GitHub (this trick is provider agnostic, has been tested with GitLab as well), and we want to have SSH configured for two different users (or more): jesugmz and myseconduser.

Step 1

Configure SSH config in order to get an alias with different configuration as follow:

$ cat ~/.ssh/config

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Python docstring reStructuredText style

Python Signatures

Signatures of functions, methods and class constructors can be given like they would be written in Python.

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Deploy Next.js static to GitLab pages

Create a basic GitLab CI config:

$ cat .gitlab-ci.yml
image: node

before_script:
 - npm install

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Display raw images from Google Drive

https://drive.google.com/uc?export=view&id={fileId} where file ID is the unique hash Google Drive gives when the shared link is created.

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docker login will produce a base64 digest if the binaries pass and secretservice are not present on Linux platforms (source).

To generate a base64 auth token:

echo -n 'username:password' | base64

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Let’s Encrypt certificate for dockerized Nginx under Cloudflare

Real example about how to generate and add a Let's Encrypt SSL/TLS certificates to a dockerized Nginx under a running Docker Swarm using Cloudflare DNS to enable HTTPS.

https://certbot.eff.org/docs/using.html#dns-plugins

https://certbot-dns-cloudflare.readthedocs.io/en/stable/

1. Generate the certificate

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#
# Avoid the message 'External file changes sync may be slow: The current inotify(7) watch limit is too low.' from JetBrains products.
#
# 1. Create the file /etc/sysctl.d/60-jetbrains.conf and paste this code
# 2. Restart the sysctl service: sudo sysctl -p --system
# 3. Restart the IDE
#
# More info:
# https://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit

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Check host TLS version

Just check the output looking for the TLS versions. In this case v1.0, v1.1, v1.2 and v1.3:

$ nmap --script ssl-enum-ciphers -p 443 www.google.com
Starting Nmap 7.93 ( https://nmap.org ) at 2023-03-29 18:12 CEST
NSOCK ERROR [0.0620s] ssl_init_helper(): OpenSSL legacy provider failed to load.

Nmap scan report for www.google.com (142.250.185.4)

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GNU/Linux debbuging tools

ctop

top-like interface for container metrics.

dig

DNS lookup utility.