How Do You Troubleshoot the Error “Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock”?

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Problem scenario
You try to run a Docker command, but you get this error: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.29/containers/json?all=1: dial unix /var/run/docker.sock: connect: permission denied

What should you do?

Solution
Have you added the user who was trying to execute the command to the “docker” group?

This command would add the user jdoe to the “docker” group:
sudo usermod -aG docker jdoe

If you ran the above command as the jdoe user,

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What Is a docker-compose.yml File?

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Question
What is a docker-compose.yml file?

Answer
It is a file used by the docker-compose utility which orchestrates the creation of multiple containers. For microservices, SOA and various stacks of applications (e.g., the LAMP stack), container orchestration is useful. Here are some quotes which help elucidate what docker-compose does:

“Compose is a tool for defining and running multi-container Docker applications.” (Taken from Docker’s website.)

“In order to do something useful with containers,

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How Do You Troubleshoot the Ansible Message “Syntax Error while loading YAML. expected , but found ””?

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Problem scenario
You run an Ansible playbook with a variable. But you get this message: “ERROR! Syntax Error while loading YAML. expected , but found ”” (Ansible found blank single quotes or a double quote mark.)

How do you get the playbook to run?

Solution
Notice the “offending line” in the message. Remove the braces and possibly the quotes around the braces.

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What Do You Do when an Ansible Playbook is Not Getting a Variable Assigned Properly?

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Problem scenario
 Ansible variables are not being picked up when the playbook runs. You may get no errors, or you may get errors like these:

“ERROR! Syntax Error while loading YAML…did not find expected key”

“ERROR! no action detected in task. This often indicates a misspelled module name, or incorrect module path”

What should you do?

Possible Solution #1
Are you using the -i flag when you are running the command to execute the playbook?

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What is a ReplicationController in Kubernetes?

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Question
What is a ReplicationController in Kubernetes?

Answer
It is a component that ensures the pods are constantly running (page 90 and 91 of Kubernetes in Action by Luksa). They were designed to create and manage redundant pods (page 91 of Kubernetes in Action by Luksa). They do just that — they do not transfer pods but create new ones on different nodes (page 93 of Kubernetes in Action by Luksa).

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How Do You Get an Ansible Variable to Not Add Single Quotes or Brackets when the Variable Is Substituted?

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Problem scenario
You are using an Ansible-supported method of a variable in a playbook. This variable will substitute a string or line number that the playbook is run on with the IP address of the host. You notice that this substitution includes an opening-and-closing single quote mark “‘” and a pair of opening-and-closing brackets “[]”. That is, single quotes and brackets are being introduced into the string you want to build with the Ansible playbook.

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How Do You Troubleshoot This Error “error executing access token command /google/google-cloud-sdk/bin/gcloud”?

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Problem scenario
You run a command like this to view your Google Kubernetes Engine (GKE) clusters:

kubectl get pods

You see this:
‘Unable to connect to the server: error executing access token command “/google/google-cloud-sdk/bin/gcloud config config-helper –format=json”: err=fork/exec /google/google-cloud-sdk/bin/gcloud: no such file or directory output= stderr=’

What should you do?

Solution
Check your config file in the .kube directory.

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How Do You Write an Ansible Playbook to Retrieve Files from a Directory Relative to where the .YAML File Is?

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Problem scenario
You want to refer to files in a subdirectory of the parent directory that houses your Ansible playbook. You have Git repositories with .yaml files and subdirectories. You want the Git repo to be transferred to a variety of different servers. The absolute path to the directory where the files are will vary. How do you have a variable or relative path reference in the playbook so as long as the directory structure is in place,

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How Do You Install Helm on Any Type of Linux?

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Problem scenario
You want to use Helm to manage Kubernetes applications. Helm helps you with packages for changes to Kubernetes (in ways that are similar to yum or apt). Helm uses what are called Charts (.yaml files) that enable you to do more with Kubernetes with less trouble. Helm consists of these two things: a CLI tool and a server component that runs as a pod in a Kubernetes cluster (page 531 of Kubernetes in Action by Luksa).

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