Author: Jerry Wang

Installing Ruby from Source on Debian 8 Using SaltStack

Posted on by Jerry Wang
Photo by Castorly Stock on Pexels.com

The default Ruby shipped with Debian 8 is of version 2.1.5, which is very old. You can use the following SaltStack states to install Ruby 2.5.1 from source:

bison:
  pkg.installed

libgdbm-dev:
  pkg.installed

libreadline-dev:
  pkg.installed

libssl-dev:
  pkg.installed

openssl:
  pkg.installed

zlib1g-dev:
  pkg.installed

download_ruby_2.5.1_source:
  cmd.run:
    - name: curl -s -S --retry 5 https://cache.ruby-lang.org/pub/ruby/2.5/ruby-2.5.1.tar.gz | tar xz
    - runas: jenkins
    - cwd: /var/lib/jenkins
    - unless: command -v ruby && test '2.5.1p57' = $(ruby -v|awk '{print $2}')

install_ruby_2.5.1_from_source:
  cmd.run:
    - name: cd /var/lib/jenkins/ruby-2.5.1 && ./configure && make && make install
    - onchanges:
      - download_ruby_2.5.1_source

remove_ruby_2.5.1_source:
  file.absent:
    - name: /var/lib/jenkins/ruby-2.5.1
    - onchanges:
      - download_ruby_2.5.1_source

References

Adding Multiple Lines to a File using Ansible

Posted on by Jerry Wang
Photo by Pixabay on Pexels.com

The Ansible module lineinfile will search a file for a line and ensure that it is present or absent. It is useful when you want to change a single line in a file only. But how to add multiple lines to a file? You can use a loop to do this together with lineinfile like the following:

- name: ASE Deps | Configure sudoers
  lineinfile:
    dest: /etc/sudoers
    line: "{{ item }}"
  with_items:
    - "Defaults:sybase !requiretty"
    - "sybase ALL=(ALL) NOPASSWD: /bin/mount, /bin/umount, /bin/mkdir, /bin/rmdir, /bin/ps"

Want to buy me a coffee? Do it here: https://www.buymeacoffee.com/j3rrywan9

Configuring DNS when DHCP is Used on Ubuntu

Posted on by Jerry Wang
Photo by panumas nikhomkhai on Pexels.com

When eth0 is configured to use DHCP on Ubuntu (14.04 LTS), the contents of /etc/resolv.conf are overwritten by resolvconf (man 8 resolvconf), which in turn is called by dhclient. So you can neither set “dns-nameservers” and “dns-search” in /etc/resolv.conf nor /etc/network/interfaces.d/eth0.cfg.

The solution is to supersede the “domain-name-servers” and “domain-search” values in /etc/dhcp/dhclient.conf (man 5 dhclient.conf):

supersede domain-name-servers 172.16.101.11;
supersede domain-search "example.com";

And you may need to renew DHCP lease to make above change effective:

sudo dhclient -r eth0
sudo dhclient eth0

Passwordless SSH to Git Server

Posted on by Jerry Wang
Photo by Pixabay on Pexels.com

Generate RSA key for the user “git” on your Git server.

Add following lines to your ssh_config:

Host git git.example.com
  User git
  UserKnownHostsFile /dev/null
  StrictHostKeyChecking no
  IdentitiesOnly yes
  IdentityFile /etc/ssh/id_rsa_insecure

Where file id_rsa_insecure contains the private key of the user “git” on your Git server.

Changing Database ID of an Oracle Database

Posted on by Jerry Wang
Photo by Manuel Geissinger on Pexels.com

DBNEWID is a database utility that can change the internal database identifier (DBID) and the database name (DBNAME) for an Oracle database.

ora11202@bbdhcp:/home/ora11202-> sqlplus / as sysdba

SQL*Plus: Release 11.2.0.2.0 Production on Tue Jul 14 20:44:21 2015

Copyright (c) 1982, 2010, Oracle. All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area 634679296 bytes
Fixed Size 2229160 bytes
Variable Size 385879128 bytes
Database Buffers 243269632 bytes
Redo Buffers 3301376 bytes
Database mounted.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
ora11202@bbdhcp:/home/ora11202-> nid target=/

DBNEWID: Release 11.2.0.2.0 - Production on Tue Jul 14 20:45:30 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.

Connected to database DBDHCP3 (DBID=528973516)

Connected to server version 11.2.0

Control Files in database:
 /datafile/dbdhcp3/oradata/dbdhcp3/control01.ctl
 /datafile/dbdhcp3/oradata/dbdhcp3/control02.ctl

Change database ID of database DBDHCP3? (Y/[N]) => Y

Proceeding with operation
Changing database ID from 528973516 to 632686762
 Control File /datafile/dbdhcp3/oradata/dbdhcp3/control01.ctl - modified
 Control File /datafile/dbdhcp3/oradata/dbdhcp3/control02.ctl - modified
 Datafile /datafile/dbdhcp3/oradata/dbdhcp3/system01.db - dbid changed
 Datafile /datafile/dbdhcp3/oradata/dbdhcp3/sysaux01.db - dbid changed
 Datafile /datafile/dbdhcp3/oradata/dbdhcp3/undotbs01.db - dbid changed
 Datafile /datafile/dbdhcp3/oradata/dbdhcp3/users01.db - dbid changed
 Datafile /u03/app/ora11202/product/11.2.0/dbhome_1/dbs/dbv_R2V4.db - dbid changed
 Datafile /datafile/dbdhcp3/oradata/dbdhcp3/temp01.db - dbid changed
 Control File /datafile/dbdhcp3/oradata/dbdhcp3/control01.ctl - dbid changed
 Control File /datafile/dbdhcp3/oradata/dbdhcp3/control02.ctl - dbid changed
 Instance shut down

Database ID for database DBDHCP3 changed to 632686762.
All previous backups and archived redo logs for this database are unusable.
Database is not aware of previous backups and archived logs in Recovery Area.
Database has been shutdown, open database with RESETLOGS option.
Succesfully changed database ID.
DBNEWID - Completed succesfully.

Time Conversion in Go

Posted on by Jerry Wang
Photo by David Bartus on Pexels.com

Convert seconds (integer) to hour:minute:second formatted string:

package main

import (
    "fmt"
    "strconv"
    "time"
)

func convertElapsedSecondsToString(seconds int64) string {
    timeElapsedString := strconv.FormatInt(seconds, 10) + "s"
    duration, err := time.ParseDuration(timeElapsedString)
    if err != nil {
        panic(err)
    }
    hour := int64(duration/time.Hour)
    min := int64(duration/time.Minute) - hour * 60
    sec := seconds - hour * 60 * 60 - min * 60
    h := strconv.FormatInt(hour, 10)
    m := strconv.FormatInt(min, 10)
    s := strconv.FormatInt(sec, 10)
    return fmt.Sprintf("%s:%s:%s", h, m, s)
}

func main() {
    myTestRunDuration := convertElapsedSecondsToString(20555)
    fmt.Println(myTestRunDuration)
}