• Linux kernel version: uname -r
• Ubuntu version: lsb_release -a

Working with Files

• Less: view file one page at a time
  • Open file and view first page: less [filePath]
  • Navigate by page: Keybrd[PageUp] | Keybrd[PageDwn]
  • Exit less: Keybrd[q]
• Vim: view and edit files
  • enter mode select visually by character: v
  • enter mode select visually by line: V
  • copy selection: y
  • paste at cursor: p

Users

• list all users: less /etc/passwd
• switch to different user: su [usernameToSwitchTo]

• Get ghost version/location/port etc: ghost ls

Restart Ghost

• Grab file from another branch: git checkout [branch-name] -- [file-name]

Tracking

• Track existing remote branch: git checkout --track origin/dev
• Push new branch with tracking: git push -u origin dev

Undo commits

• Undo last commit and put in staging git reset --soft HEAD~1

Branch Activity

• Branch activity by date for k in `git branch | sed s/^..//`; do echo -e `git log -1 --pretty=format:"%Cgreen%ci %Cblue%cr%Creset" $k --`\\t"$k";done | sort

Git tagging

Note: if the tag is part of a build process for versioning, tag locally...push tag to remote...then push branch

• Create annotated tag git tag -a v1.0.0 -m "version 1.0.0"
• Delete a tag git tag -d v1.0.0
• Push tag to remote git push upstream v1.0.0

Delete Container docker rm [containerId]
Stop all containers docker stop $(docker ps -a -q)
Delete all containers docker rm $(docker ps -a -q)

In my spare time I have been developing an application with a free MongoDb instance at MLab. After getting some more Linux skills in my repetoire I decided I would go for installing on a $5/mo Digital Ocean Droplet. My goal is to spin up the vps, install Mongo and get a simple script in place to backup the db once per day and ship the backup to a remote location.

First Decisions

My first thought was to install the One Click feature on the Create New Droplet page, however Digital Ocean was offering 3.2 at the time and I wanted to get out in front as far as possible with 3.4. That made me decide to install a new plain new vps on Xenial (Ubuntu 16.04.1 x32). I chose the 32 bit version because of my small vps (512 MP/ 1CPU; 20 GB ssd) and a 64 bit version would require more processing power.

But...guess what...I was wrong! Mongo required x64 version of Linux. So I destroyed my droplet and started over with the same specifications as above but selected the x64 Xenial version.

Following the interactive setup on the Digital Ocean site was very easy and took about 2 minutes. The only thing to note was creating the ssh key...just do the following:

ssh-keygen -t rsa

# and then copy the output of:

cat ~/.ssh/id_rsa.pub  

Add the cat'ed ssh key to the set up page back on Digital Ocean. After the vps is installed you can ssh to your machine:

ssh root@your_ip_address  

Installing MongoDb

I followed the instructions here and below are the commands I used.

First get the key for apt-get

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 0C49F3730359A14518585931BC711F9BA15703C6  

Add the key to the sources.list

echo "deb [ arch=amd64,arm64 ] http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.4.list  

Update apt-get

sudo apt-get update  

Install mongo

sudo apt-get install -y mongodb-org  

Start the daemon service

sudo service mongod start  

Add root user for mongo and setup security for remote access

Now that mongo is installed on our vps, we need to allow our application that is hosted elsewhere access to the database(s). We will modify the default mongo config and add an admin user as well as a database specific user.

Setting Up Root User

First we will set up a root superuser before we lock down the server. This user will have access to all databases with all privileges. We will create the user on the admin database and when logging in will authenticate against this database.

Log into mongo:

mongo  

Run the following commands in the mongo shell:

use admin

db.createUser(  
{
    user: "root",
    pwd: "password",
    roles: [ "root" ]
})

Setting up security

Got help here for modifying the mongo config.

sudo vim /etc/mongod.conf  

We will remove the bindIp from the config to allow access from other IP addresses. However, when you do this be sure to add the security in the next step.

# network interfaces
net:  
  port: 27017
#  bindIp: 127.0.0.1  <- comment out this line

Now enable security by uncommenting the security line and adding the authorization enabled line.

security:  
  authorization: 'enabled'

Save the changes to the config.

Let's Test

First lets restart the mongo service:

sudo service mongod restart  

Now try logging in to the mongo client

mongo admin -u root -p  

This command says login to the admin database with the username of root and prompt me for a password.

Assuming success let's add a new database and a user with much less privileges:

use testDatabase;

db.createUser({user: "dbUsername", pwd: "password", roles: [{role: "readWrite", db: "testDatabase"}]})  

Logout of mongo and re-login as the newly created user using the password you just created:

mongo testDatabase -u dbUsername -p  

Setting up Backup Script

Create the Backup

mongodump -d databaseName -o outputDir  

Restore a Backup

mongorestore pathToBackup  

Script to Automate Backups

Here is my thought...let's automate the create backup script by executing a cron job once per day. In this script we can have it keep the last three days of backups. Here it is:

vim backupMongo  

Add these commands to the script:

#!/usr/bin/env bash
cp -rf ~/backups/ninjaAPIBackup-1/* ~/backups/ninjaAPIBackup-2  
cp -rf ~/backups/ninjaAPIBackup/* ~/backups/ninjaAPIBackup-1  
rm -rf ~/backups/ninjaAPIBackup  
mongodump -d ninjaAPI -o ~/backups/ninjaAPIBackup -u username -p password  

We need to make the script executable:

chmod +x backupMongo  

And let's symlink the file into cron.daily

ln backupMongo /etc/cron.daily/