Setup your own gitlab runner

To add your own gitlab runner, follow the steps below

  • Create your runner, in EC2, Google, or any other cloud provider and have ssh access to it.
  • Login to your runner from the previous step and install the gitlab-runner (there are various methods described here: https://docs.gitlab.com/runner/install/. We install using Gitlab’s repositories)
  • Register the gitlab-runner by following the instructions here: https://docs.gitlab.com/runner/register/index.html . You would need to get the token for each project you want to register your runner with (Gitlab -> Settings -> CI/CD -> Runners -> Expand). You can use different executors for your running during the registration such as docker, shell etc.
  • Go to your Gitlab project and find the runner you register above and enable it for the project. You should also add the tags: name_of_your_runner in your .gitlab-ci.yml file.

Cannot login to MariaDB server with root account

Problem

You are trying to login to MariaDB with the root user, but even after resetting the password, it is still not possible to login.

Solution

It seems that certain MariaDB packages that come with Linux distributions use the unix_socket as the authentication method.

MariaDB [mysql]> SELECT user, host, plugin FROM user WHERE user='root';
+------+-----------+-------------+
| user | host      | plugin      |
+------+-----------+-------------+
| root | localhost | unix_socket |
+------+-----------+-------------+
1 row in set (0.00 sec)

Change the plugin as described here (https://stackoverflow.com/a/43424234) with the following:

MariaDB [mysql]> UPDATE mysql.user SET plugin = '' WHERE user = 'root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Get a list of directories with user permissions

Problem

You want to run a command in a hosted server but you don’t have su permissions. There are directories that have different owners/permissions, so you would like to see them.

Solution

Use the tree command and save the output in a file if you have many directories:

tree -pufid /home/directory_to_check > /home/user/permissions.txt

taken from the answer here: https://unix.stackexchange.com/a/82374

kubectl error: “The connection to the server localhost:8080 was refused – did you specify the right host or port?”

Problem

You want to use the kubectl to get your cluster information but you are getting the following error message

$ kubectl cluster-info
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
The connection to the server localhost:8080 was refused - did you specify the right host or port?

Solution

That could happen if you have already setup kubectl before or have used a different environment.

So you will need to first unset the environment variable KUBECONFIG with:

$ unset KUBECONFIG

and then use the gcloud client to set your environment again:


$ gcloud container clusters get-credentials your_cluster_name --zone europe-west2-a --project your_project_name

So after this you should be able to use kubectl to get the cluster information

kubeconfig entry generated for your_cluster_name.

$ kubectl cluster-info
Kubernetes master is running at https://xxx.xxx.xxx.xxx
GLBCDefaultBackend is running at https://xxx.xxx.xxx.xxx/api/v1/namespaces/kube-system/services/default-http-backend:http/proxy
Heapster is running at https://xxx.xxx.xxx.xxx/api/v1/namespaces/kube-system/services/heapster/proxy
KubeDNS is running at https://xxx.xxx.xxx.xxx/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
Metrics-server is running at https://xxx.xxx.xxx.xxx/api/v1/namespaces/kube-system/services/https:metrics-server:/proxy

Change PDF orientation in linux command line

Problem

You would like to change the orientation of a PDF file (portrait to landscape) in the linux command line

Solution

Use the pdftk program as following (taken from the answer https://unix.stackexchange.com/a/394068)

pdftk portrait.pdfcat 1-endwest output landscape_anti_clockwise.pdf

pdftk portrait.pdf cat 1-endeast output landscape_clockwise.pdf