How to change pids_limit value in OpenShift 4.x

 

Ref: https://computingforgeeks.com/change-pids-limit-value-in-openshift/

In OpenShift 4.x environment, each container running will be limited to the default maximum PID value of 1024. If there is a need to run applications with more than 1024 processes within one single container, the OpenShift Container Platform Cluster operator is required to adjust the default maximum PID value to a higher number.

pids_limit is the maximum number of processes allowed in a container, and it can be viewed by running the command below in an OpenShift node:

$ sudo crio-status config | grep pid
pids_limit = 1024

In OpenShift, it is NOT recommended to change the value directly by editing crio.conf file:

$ grep  pids_limit /etc/crio/crio.conf
pids_limit = 1024

It is recommended to follow the correct way that depends on the OCP version in use. I’m running OpenShift 4.4 and in this version, ContainerRuntimeConfig custom resource was introduced. You can check KCS Article 5133191.

Create ContainerRuntimeConfig custom resource for configuring cri-o pidsLimit

cat <<EOF > custom-pidslimit.yaml
apiVersion: machineconfiguration.openshift.io/v1
kind: ContainerRuntimeConfig
metadata:
 name: custom-pidslimit
spec:
 machineConfigPoolSelector:
   matchLabels:
     custom-crio: custom-pidslimit
 containerRuntimeConfig:
   pidsLimit: 4096
EOF

You can update the configuration file before applying:

vim custom-pidslimit.yaml

Apply configuration:

$ oc create -f custom-pidslimit.yaml
containerruntimeconfig.machineconfiguration.openshift.io/custom-pidslimit created

Verify the resource has been created

$ oc get ctrcfg
NAME               AGE
custom-pidslimit   44s

Once the custom resource is created, we need to roll out the pidslimit changes to all the worker nodes in the cluster.

Let’s add custom-crio: custom-pidslimit under labels in the machineConfigPool config

$ oc edit machineconfigpool worker
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  creationTimestamp: "2020-07-15T08:29:58Z"
  generation: 7
  labels:
    custom-crio: custom-pidslimit      #add this line

Check to ensure that a new 99-worker-XXX-containerruntime is created and that a new rendered worker is created:

$ oc get machineconfigs | grep containerruntime
99-worker-261cdd8d-c387-4f61-b1ce-b9ab2d025f09-containerruntime   601c2285f497bf7c73d84737b9977a0e697cb86a   2.2.0             93s

The changes should now be rolled out to each node in the worker pool via that new rendered-worker machine config.

You can verify by checking that the latest rendered-worker machine-config has been rolled out to the pools successfully:

$ oc get mcp
NAME     CONFIG                                             UPDATED   UPDATING   DEGRADED   MACHINECOUNT   READYMACHINECOUNT   UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
master   rendered-master-238bb9ffd94d526621cba8ee876c3ac8   True      False      False      5              5                   5                     0                      216d
worker   rendered-worker-6c236aa19af4d88fa0acdbc8f6ff53f3   False     True       True       10             0                   0                     7                      216d

Once a worker node is rebooted you can login and confirm the current setting:

$ oc debug node/<workernode>
sh-4.4# chroot /host
sh-4.4# grep pids_limit /etc/crio/crio.conf

I hope this short guide was helpful in changing the default value of pids_limit in your OpenShift 4.x cluster.

How to Upgrade Ubuntu 16.04 to Ubuntu 18.04

 

 

sudo apt-get update -y
sudo apt-get upgrade -y
sudo apt-get dist-upgrade -y

sudo apt install update-manager-core -y

sudo do-release-upgrade

 

SQL test query or validation query

 

Ref: https://stackoverflow.com/questions/3668506/efficient-sql-test-query-or-validation-query-that-will-work-across-all-or-most

Many database connection pooling libraries provide the ability to test their SQL connections for idleness. For example, the JDBC pooling library c3p0 has a property called preferredTestQuery, which gets executed on the connection at configured intervals. Similarly, Apache Commons DBCP has validationQuery.

-- Access

SELECT 1 FROM (SELECT count(*) dual FROM MSysResources) AS dual

-- BigQuery, CockroachDB, Exasol, H2, Ignite, MariaDB, MySQL, PostgreSQL, 

-- Redshift, Snowflake, SQLite, SQL Server, Sybase ASE, Vertica

SELECT 1

-- MemSQL, Oracle

SELECT 1 FROM DUAL

-- CUBRID

SELECT 1 FROM db_root

-- Db2

SELECT 1 FROM SYSIBM.DUAL

-- Derby

SELECT 1 FROM SYSIBM.SYSDUMMY1

-- Firebird

SELECT 1 FROM RDB$DATABASE

-- HANA, Sybase SQL Anywhere

SELECT 1 FROM SYS.DUMMY

-- HSQLDB

SELECT 1 FROM (VALUES(1)) AS dual(dual)

-- Informix

SELECT 1 FROM (SELECT 1 AS dual FROM systables WHERE (tabid = 1)) AS dual

-- Ingres, Teradata

SELECT 1 FROM (SELECT 1 AS "dual") AS "dual"

[Gitlab] HOW TO USE SPECIFIC RUNNERS IN GITLAB CI/CD PIPELINE

What are Gitlab Runners?

GitLab Runner is an application that works with GitLab CI/CD to run jobs in a pipeline. They can also run

inside a Docker container or be deployed into a Kubernetes cluster.

Types of Runners:

• Shared Runner: These types of runners are available globally and can automatically be allocated based on their availability.
• Specific Runner: For this, you have to register a runner and you can only use it in a specific project or can also use it in a specific stage of your pipeline. Will discuss this more in detail.
• Group Runner: These runners are shared across projects in the group.

How to register a specific runner?

sudo gitlab-runner register

This command will start the process of registering a runner. Then go to the Gitlab Project -Settings->CI/CD->Runners and copy the URL of specific runners.

How to use this specific runner in a pipeline?

Just add the tags field in your pipeline and name the tag which you added during the registration of a runner.

Here is the sample pipeline for your reference.

stage: test

script:

- echo "Testing"

- test -f "build/info.txt"

tags:

- testing

npm:

image: node:latest

stage: npm

How to use this specific runner in a pipeline?

script:

- echo "image pulled"

[Gitlab] gitlab runner doesn`t work on a specific project

Ref: gitlab runner doesn`t work on a specific project

Error:

Fetching changes with git depth set to 50...
fatal: remote origin already exists.
fatal: git fetch-pack: expected shallow list
ERROR: Job failed: exit status 1

Solution:

Centos 7 ships with git version 1.8.3.1 . This version doesn't support commands like git fetch-pack . To fix this problem, you could update git on your server from the IUS repository. update git on Centos 7 to version 2 from third-party IUS repo

$ git --version
git version 1.8.3.1

sudo yum -y install https://packages.endpointdev.com/rhel/7/os/x86_64/endpoint-repo.x86_64.rpm
sudo yum install git

[Gitlab] Install gitlab runner

 

Ref:https://docs.gitlab.com/runner/install/linux-manually.html

Download

To download the appropriate package for your system:

1. Find the latest file name and options at https://gitlab-runner-downloads.s3.amazonaws.com/latest/index.html.
2. Choose a version and download a binary, as described in the documentation for downloading any other tagged releases for bleeding edge GitLab Runner releases.

For example, for Debian or Ubuntu:

curl -LJO "https://gitlab-runner-downloads.s3.amazonaws.com/latest/deb/gitlab-runner_${arch}.deb"

For example, for CentOS or Red Hat Enterprise Linux:

curl -LJO "https://gitlab-runner-downloads.s3.amazonaws.com/latest/rpm/gitlab-runner_${arch}.rpm"

For example, for FIPS compliant GitLab Runner on RHEL:

curl -LJO "https://gitlab-runner-downloads.s3.amazonaws.com/latest/rpm/gitlab-runner_amd64-fips.rpm"

Install

1. Install the package for your system as follows.

   For example, for Debian or Ubuntu:
   dpkg -i gitlab-runner_<arch>.deb For example, for CentOS or Red Hat Enterprise Linux:
   rpm -i gitlab-runner_<arch>.rpm

2. Register a runner

Update

Download the latest package for your system then upgrade as follows:

For example, for Debian or Ubuntu:

dpkg -i gitlab-runner_<arch>.deb

For example, for CentOS or Red Hat Enterprise Linux:
rpm -Uvh gitlab-runner_<arch>.rpm

[Report Server] fully share files

Ref: https://reportserver.net/en/guides/admin/chapters/File-System/

 To fully share files you may place them in a folder where a tick is set at Share folder for web access.