Forcing https with wordpress on dreamhost

In order to be able to force the http to https redirection when using wordpress in dreamhost use the following (taken from https://help.dreamhost.com/hc/en-us/articles/215747758-Force-your-site-to-load-securely-with-an-htaccess-file) :

Using port number in Terraform output

Problem

You would like to output some additional information (ie port number) in addition to the variable provided by Terraform.

Solution

Use interpolation of the Terraform variable using ${var} together with the rest of the string you would like to output, like:

More information about the language https://learn.hashicorp.com/tutorials/terraform/outputs?in=terraform/configuration-language

Creating two types of IAM users in AWS using the CLI

To create a user in AWS IAM using the CLI (after you have configured it), use the following:

Create a user with programmatic access (access key ID and secret access key):

And for a user with console access:

Failed to start docker.service: Unit is masked

Problem

Trying to start the docker service after some upgrades fails with the following message:

Solution

It turns out that after upgrading or more specifically removing and then upgrading the docker installation in ubuntu (in this particular case in raspberry 4 with Ubuntu 20.04 installed), results in this error.

A search brings up the following:

https://forums.docker.com/t/failed-to-start-docker-service-unit-is-masked/67413

and from that the following bug post:

https://bugs.launchpad.net/ubuntu/+source/docker.io/+bug/1844894

So the solution is to run the following to be able to start the docker service (described in the first link above):

Find the current AMI image (i.e. Ubuntu 16.04) in AWS using command line

If you would like to programatically find the current image of a specific distribution in AWS for your region, with the use of the aws cli, use the following (in this example looking for Ubuntu 16.04).

Or for 18.04

This is from the examples in the documentation here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/finding-an-ami.html

Getting detailed information about your Linux distribution

To be able to get a more detailed information about your current linux distribution, including the code names use the following:

Using strace for analyzing performance

There is a very nice example on the O’reilly ‘Linux Under The Hood’ training about using strace to compare performance of two commands that provide the same output but with different calls. The two different commands were: ls and echo *, that they both provide the listing of the current directory.

First using the strace with ls:

And using the same with echo *

So the difference in time is 0.00000 for the echo and 0.000601 for the ls.

Similarly the number of calls for the echo is 33, but ls is using 100.