diff --git a/README.md b/README.md
index 2679aa0..af63d35 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
:information_source: This repo contains questions and exercises on various technical topics, sometimes related to DevOps and SRE :)
-:bar_chart: There are currently **1962** questions
+:bar_chart: There are currently **1999** questions
:books: To learn more about DevOps and SRE, check the resources in [devops-resources](https://github.com/bregman-arie/devops-resources) repository
@@ -32,7 +32,7 @@
Programming |
Python |
Go |
- 
Shell Scripting |
+
Shell Scripting |
Kubernetes |
Prometheus |
@@ -5313,270 +5313,6 @@ If more pods are running than needed -> it deletes some of them
If not enough pods are running -> it creates more
-## Shell Scripting
-
-### Shell Scripting Exercises
-
-|Name|Topic|Objective & Instructions|Solution|Comments|
-|--------|--------|------|----|----|
-|Hello World|Variables|[Exercise](exercises/shell/hello_world.md)|[Solution](exercises/shell/solutions/hello_world.md) | Basic
-|Basic date|Variables|[Exercise](exercises/shell/basic_date.md)|[Solution](exercises/shell/solutions/basic_date.md) | Basic
-|Great Day|Variables|[Exercise](exercises/shell/great_day.md)|[Solution](exercises/shell/solutions/great_day.md) | Basic
-|Factors|Arithmetic|[Exercise](exercises/shell/factors.md)|[Solution](exercises/shell/solutions/factors.md) | Basic
-|Argument Check|Conditionals|[Exercise](exercises/shell/argument_check.md)|[Solution](exercises/shell/solutions/argument_check.md) | Basic
-|Files Size|For Loops|[Exercise](exercises/shell/files_size.md)|[Solution](exercises/shell/solutions/files_size.md) | Basic
-|Count Chars|Input + While Loops|[Exercise](exercises/shell/count_chars.md)|[Solution](exercises/shell/solutions/count_chars.md) | Basic
-|Sum|Functions|[Exercise](exercises/shell/sum.md)|[Solution](exercises/shell/solutions/sum.md) | Basic
-|Number of Arguments|Case Statement|[Exercise](exercises/shell/num_of_args.md)|[Solution](exercises/shell/solutions/num_of_args.md) | Basic
-|Empty Files|Misc|[Exercise](exercises/shell/empty_files.md)|[Solution](exercises/shell/solutions/empty_files.md) | Basic
-|Directories Comparison|Misc|[Exercise](exercises/shell/directories_comparison.md)| :( | Basic
-|It's alive!|Misc|[Exercise](exercises/shell/host_status.md)|[Solution](exercises/shell/solutions/host_status.md) | Intermediate
-
-## Shell Scripting - Self Assessment
-
-
-What does this line in shell scripts means?: #!/bin/bash
-
-
-`#!/bin/bash` is She-bang
-
-/bin/bash is the most common shell used as default shell for user login of the linux system. The shell’s name is an acronym for Bourne-again shell. Bash can execute the vast majority of scripts and thus is widely used because it has more features, is well developed and better syntax.
-
-
-
-
-True or False? When a certain command/line fails in a shell script, the shell script, by default, will exit and stop running
-
-Depends on the language and settings used.
-If the script is a bash script then this statement is true. When a script written in Bash fails to run a certain command it will keep running and will execute all other commands mentioned after the command which failed.
-
-Most of the time we might actually want the opposite to happen. In order to make Bash exist when a specific command fails, use 'set -e' in your script.
-
-
-
-What do you tend to include in every script you write?
-
-Few example:
-
- * Comments on how to run it and/or what it does
- * If a shell script, adding "set -e" since I want the script to exit if a certain command failed
-
-You can have an entirely different answer. It's based only on your experience and preferences.
-
-
-
-Today we have tools and technologies like Ansible, Puppet, Chef, ... Why would someone still use shell scripting?
-
- * Speed
- * Flexibility
- * The module we need doesn't exist (perhaps a weak point because most CM technologies allow to use what is known as "shell" module)
- * We are delivering the scripts to customers who don't have access to the public network and don't necessarily have Ansible installed on their systems.
-
-
-#### Shell Scripting - Variables
-
-
-How to define a variable with the value "Hello World"?
-
-`HW="Hello World`
-
-
-
-How to define a variable with the value of the current date?
-
-`DATE=$(date)`
-
-
-
-How to print the first argument passed to a script?
-
-`echo $1`
-
-
-
-Write a script to print "yay" unless an argument was passed and then print that argument
-
-```
-echo "${1:-yay}"
-```
-
-
-
-What would be the output of the following script?
-
-```
-#!/usr/bin/env bash
-NINJA_TURTLE=Donatello
-function the_best_ninja_turtle {
- local NINJA_TURTLE=Michelangelo
- echo $NINJA_TURTLE
-}
-NINJA_TURTLE=Raphael
-the_best_ninja_turtle
-```
-
-Michelangelo
-
-
-
-Explain what would be the result of each command:
-
- * echo $0
- * echo $?
- * echo $$
- * echo $#
-
-
-
-What is $@?
-
-
-
-What is difference between $@ and $*?
-
-`$@` is an array of all the arguments passed to the script
-`$*` is a single string of all the arguments passed to the script
-
-
-
-How do you get input from the user in shell scripts?
-
-Using the keyword read so for example read x will wait for user input and will store it in the variable x.
-
-
-
-How to compare variables length?
-
-```
-if [ ${#1} -ne ${#2} ]; then
- ...
-```
-
-
-#### Shell Scripting - Conditionals
-
-
-Explain conditionals and demonstrate how to use them
-
-
-
-In shell scripting, how to negate a conditional?
-
-
-
-In shell scripting, how to check if a given argument is a number?
-
-```
-regex='^[0-9]+$'
-if [[ ${var//*.} =~ $regex ]]; then
-...
-```
-
-
-#### Shell Scripting - Arithmetic Operations
-
-
-How to perform arithmetic operations on numbers?
-
-One way: `$(( 1 + 2 ))`
-Another way: `expr 1 + 2`
-
-
-
-How to perform arithmetic operations on numbers?
-
-
-
-How to check if a given number has 4 as a factor?
-
-`if [ $(($1 % 4)) -eq 0 ]; then`
-
-
-#### Shell Scripting - Loops
-
-
-What is a loop? What types of loops are you familiar with?
-
-
-
-Demonstrate how to use loops
-
-
-#### Shell Scripting - Troubleshooting
-
-
-How do you debug shell scripts?
-
-Answer depends on the language you are using for writing your scripts. If Bash is used for example then:
-
- * Adding -x to the script I'm running in Bash
- * Old good way of adding echo statements
-
-If Python, then using pdb is very useful.
-
-
-
-Running the following bash script, we don't get 2 as a result, why?
-
-```
-x = 2
-echo $x
-```
-
-
-Should be `x=2`
-
-
-#### Shell Scripting - Substring
-
-
-How to extract everything after the last dot in a string?
-
-`${var//*.}`
-
-
-
-How to extract everything before the last dot in a string?
-
-${var%.*}
-
-
-#### Shell Scripting - Misc
-
-
-Generate 8 digit random number
-
-shuf -i 9999999-99999999 -n 1
-
-
-
-Can you give an example to some Bash best practices?
-
-
-
-What is the ternary operator? How do you use it in bash?
-
-A short way of using if/else. An example:
-
-[[ $a = 1 ]] && b="yes, equal" || b="nope"
-
-
-
-What does the following code do and when would you use it?
-
-diff <(ls /tmp) <(ls /var/tmp)
-
-
-It is called 'process substitution'. It provides a way to pass the output of a command to another command when using a pipe | is not possible. It can be used when a command does not support STDIN or you need the output of multiple commands.
-https://superuser.com/a/1060002/167769
-
-
-
-What are you using for testing shell scripts?
-
-bats
-
-
## SQL
### SQL Exercises
diff --git a/exercises/aws/README.md b/exercises/aws/README.md
index 8cb646b..70836a9 100644
--- a/exercises/aws/README.md
+++ b/exercises/aws/README.md
@@ -19,6 +19,7 @@
| Launch EC2 web instance | EC2 | [Exercise](launch_ec2_web_instance.md) | [Solution](solutions/launch_ec2_web_instance.md) | Easy |
| Security Groups | EC2 | [Exercise](security_groups.md) | [Solution](solutions/security_groups.md) | Easy |
| IAM Roles | EC2 + IAM | [Exercise](ec2_iam_roles.md) | [Solution](solutions/ec2_iam_roles.md) | Easy |
+| Spot Instances | EC2 | [Exercise](create_spot_instances.md) | [Solution](solutions/create_spot_instances.md) | Easy |
#### AWS - Lambda
@@ -352,6 +353,12 @@ On Demand is good for short-term non-interrupted workloads (but it also has the
Reserved instances: they are cheaper than on-demand and the instance is yours for the chosen period of time.
+
+Which pricing model has potentially the biggest discount and what its advantage
+
+Spot instances provide the biggest discount but has the disadvantage of risking losing them due bigger bid price.
+
+
You need an instance for two years, but only between 10:00-15:00 every day. Which pricing model would you use?
@@ -434,7 +441,7 @@ EBS
-What EC2 RI types are there?
+What EC2 reserved instance types are there?
Standard RI - most significant discount + suited for steady-state usage
Convertible RI - discount + change attribute of RI + suited for steady-state usage
@@ -443,6 +450,18 @@ Scheduled RI - launch within time windows you reserve
Learn more about EC2 RI [here](https://aws.amazon.com/ec2/pricing/reserved-instances)
+
+For how long can reserved instances be reserved?
+
+1 or 3 years.
+
+
+
+What allows you to control inbound and outbound instance traffic?
+
+Security Groups
+
+
What bootstrapping means and how to use it in AWS EC2?
@@ -482,6 +501,14 @@ To terminate such instances, you must cancel the Spot instance request first.
Set of Spot instance and if you want, also on-demand instances.
+
+What strategies are there to allocate Spot instances?
+
+* lowestPrice: launch instances from the pool that has the lowest price
+* diversified: distributed across all pools
+* capacityOptimized: optimized based on the number of instances
+
+
#### AWS - Lambda
diff --git a/exercises/aws/create_spot_instances.md b/exercises/aws/create_spot_instances.md
new file mode 100644
index 0000000..7a178e7
--- /dev/null
+++ b/exercises/aws/create_spot_instances.md
@@ -0,0 +1,9 @@
+## AWS EC2 - Spot Instances
+### Objectives
+
+A. Create two Spot instances using a Spot Request with the following properties:
+
+* Amazon Linux 2 AMI
+* 2 instances as target capacity (at any given point of time) while each one has 2 vCPUs and 3 GiB RAM
+
+B. Create a single Spot instance using Amazon Linux 2 and t2.micro
diff --git a/exercises/aws/solutions/create_spot_instances.md b/exercises/aws/solutions/create_spot_instances.md
new file mode 100644
index 0000000..0459b5c
--- /dev/null
+++ b/exercises/aws/solutions/create_spot_instances.md
@@ -0,0 +1,35 @@
+## AWS EC2 - Spot Instances
+### Objectives
+
+A. Create two Spot instances using a Spot Request with the following properties:
+
+* Amazon Linux 2 AMI
+* 2 instances as target capacity (at any given point of time) while each one has 2 vCPUs and 3 GiB RAM
+
+B. Create a single Spot instance using Amazon Linux 2 and t2.micro
+
+### Solution
+
+A. Create Spot Fleets:
+
+1. Go to EC2 service
+2. Click on "Spot Requests"
+3. Click on "Request Spot Instances" button
+4. Set the following values for parameters:
+ * Amazon Linux 2 AMI
+ * Total target capacity -> 2
+ * Check "Maintain target capacity"
+ * vCPUs: 2
+ * Memory: 3 GiB RAM
+5. Click on Launch
+
+B. Create a single Spot instance:
+
+1. Go to EC2 service
+2. Click on "Instances"
+3. Click on "Launch Instances"
+4. Choose "Amazon Linux 2 AMI" and click on "Next"
+5. Choose t2.micro and click on "Next: Configure Instance Details"
+6. Select "Request Spot instances"
+7. Set Maximum price above current price
+8. Click on "Review and Launch"
diff --git a/exercises/shell/README.md b/exercises/shell/README.md
new file mode 100644
index 0000000..be96da8
--- /dev/null
+++ b/exercises/shell/README.md
@@ -0,0 +1,264 @@
+## Shell Scripting
+
+### Shell Scripting Exercises
+
+|Name|Topic|Objective & Instructions|Solution|Comments|
+|--------|--------|------|----|----|
+|Hello World|Variables|[Exercise](hello_world.md)|[Solution](solutions/hello_world.md) | Basic
+|Basic date|Variables|[Exercise](basic_date.md)|[Solution](solutions/basic_date.md) | Basic
+|Great Day|Variables|[Exercise](great_day.md)|[Solution](solutions/great_day.md) | Basic
+|Factors|Arithmetic|[Exercise](factors.md)|[Solution](solutions/factors.md) | Basic
+|Argument Check|Conditionals|[Exercise](argument_check.md)|[Solution](solutions/argument_check.md) | Basic
+|Files Size|For Loops|[Exercise](files_size.md)|[Solution](solutions/files_size.md) | Basic
+|Count Chars|Input + While Loops|[Exercise](count_chars.md)|[Solution](solutions/count_chars.md) | Basic
+|Sum|Functions|[Exercise](sum.md)|[Solution](solutions/sum.md) | Basic
+|Number of Arguments|Case Statement|[Exercise](num_of_args.md)|[Solution](solutions/num_of_args.md) | Basic
+|Empty Files|Misc|[Exercise](empty_files.md)|[Solution](solutions/empty_files.md) | Basic
+|Directories Comparison|Misc|[Exercise](directories_comparison.md)| :( | Basic
+|It's alive!|Misc|[Exercise](host_status.md)|[Solution](solutions/host_status.md) | Intermediate
+
+## Shell Scripting - Self Assessment
+
+
+What does this line in shell scripts means?: #!/bin/bash
+
+
+`#!/bin/bash` is She-bang
+
+/bin/bash is the most common shell used as default shell for user login of the linux system. The shell’s name is an acronym for Bourne-again shell. Bash can execute the vast majority of scripts and thus is widely used because it has more features, is well developed and better syntax.
+
+
+
+
+True or False? When a certain command/line fails in a shell script, the shell script, by default, will exit and stop running
+
+Depends on the language and settings used.
+If the script is a bash script then this statement is true. When a script written in Bash fails to run a certain command it will keep running and will execute all other commands mentioned after the command which failed.
+
+Most of the time we might actually want the opposite to happen. In order to make Bash exist when a specific command fails, use 'set -e' in your script.
+
+
+
+What do you tend to include in every script you write?
+
+Few example:
+
+ * Comments on how to run it and/or what it does
+ * If a shell script, adding "set -e" since I want the script to exit if a certain command failed
+
+You can have an entirely different answer. It's based only on your experience and preferences.
+
+
+
+Today we have tools and technologies like Ansible, Puppet, Chef, ... Why would someone still use shell scripting?
+
+ * Speed
+ * Flexibility
+ * The module we need doesn't exist (perhaps a weak point because most CM technologies allow to use what is known as "shell" module)
+ * We are delivering the scripts to customers who don't have access to the public network and don't necessarily have Ansible installed on their systems.
+
+
+#### Shell Scripting - Variables
+
+
+How to define a variable with the value "Hello World"?
+
+`HW="Hello World`
+
+
+
+How to define a variable with the value of the current date?
+
+`DATE=$(date)`
+
+
+
+How to print the first argument passed to a script?
+
+`echo $1`
+
+
+
+Write a script to print "yay" unless an argument was passed and then print that argument
+
+```
+echo "${1:-yay}"
+```
+
+
+
+What would be the output of the following script?
+
+```
+#!/usr/bin/env bash
+NINJA_TURTLE=Donatello
+function the_best_ninja_turtle {
+ local NINJA_TURTLE=Michelangelo
+ echo $NINJA_TURTLE
+}
+NINJA_TURTLE=Raphael
+the_best_ninja_turtle
+```
+
+Michelangelo
+
+
+
+Explain what would be the result of each command:
+
+ * echo $0
+ * echo $?
+ * echo $$
+ * echo $#
+
+
+
+What is $@?
+
+
+
+What is difference between $@ and $*?
+
+`$@` is an array of all the arguments passed to the script
+`$*` is a single string of all the arguments passed to the script
+
+
+
+How do you get input from the user in shell scripts?
+
+Using the keyword read so for example read x will wait for user input and will store it in the variable x.
+
+
+
+How to compare variables length?
+
+```
+if [ ${#1} -ne ${#2} ]; then
+ ...
+```
+
+
+#### Shell Scripting - Conditionals
+
+
+Explain conditionals and demonstrate how to use them
+
+
+
+In shell scripting, how to negate a conditional?
+
+
+
+In shell scripting, how to check if a given argument is a number?
+
+```
+regex='^[0-9]+$'
+if [[ ${var//*.} =~ $regex ]]; then
+...
+```
+
+
+#### Shell Scripting - Arithmetic Operations
+
+
+How to perform arithmetic operations on numbers?
+
+One way: `$(( 1 + 2 ))`
+Another way: `expr 1 + 2`
+
+
+
+How to perform arithmetic operations on numbers?
+
+
+
+How to check if a given number has 4 as a factor?
+
+`if [ $(($1 % 4)) -eq 0 ]; then`
+
+
+#### Shell Scripting - Loops
+
+
+What is a loop? What types of loops are you familiar with?
+
+
+
+Demonstrate how to use loops
+
+
+#### Shell Scripting - Troubleshooting
+
+
+How do you debug shell scripts?
+
+Answer depends on the language you are using for writing your scripts. If Bash is used for example then:
+
+ * Adding -x to the script I'm running in Bash
+ * Old good way of adding echo statements
+
+If Python, then using pdb is very useful.
+
+
+
+Running the following bash script, we don't get 2 as a result, why?
+
+```
+x = 2
+echo $x
+```
+
+
+Should be `x=2`
+
+
+#### Shell Scripting - Substring
+
+
+How to extract everything after the last dot in a string?
+
+`${var//*.}`
+
+
+
+How to extract everything before the last dot in a string?
+
+${var%.*}
+
+
+#### Shell Scripting - Misc
+
+
+Generate 8 digit random number
+
+shuf -i 9999999-99999999 -n 1
+
+
+
+Can you give an example to some Bash best practices?
+
+
+
+What is the ternary operator? How do you use it in bash?
+
+A short way of using if/else. An example:
+
+[[ $a = 1 ]] && b="yes, equal" || b="nope"
+
+
+
+What does the following code do and when would you use it?
+
+diff <(ls /tmp) <(ls /var/tmp)
+
+
+It is called 'process substitution'. It provides a way to pass the output of a command to another command when using a pipe | is not possible. It can be used when a command does not support STDIN or you need the output of multiple commands.
+https://superuser.com/a/1060002/167769
+
+
+
+What are you using for testing shell scripts?
+
+bats
+
+