Recently I was watching this video and got to know about `mail` attribute in ansible and we can send emails through it and I gave it a try and finally after some hacks I sent an email from my one account to another.
Here below code I have written to send the email –
---
- hosts: webservers
tasks:
- name: Sending an e-mail using Gmail SMTP servers
mail:
host: smtp.gmail.com
port: 587
username: your@email.com
password: yourPassword
to: Aniruddha Basak <some@email.com>
subject: Ansible check email
body: I am using {{ ansible_facts['os_family'] }}.
delegate_to: localhost
Above we are using gmail SMTP server. In case you are using 2FA of google then you have to add a device password for that and write the password in the password field.
If you are working on a project then you have to maintain it properly and that’s why we use git as our VCS(version control system) and github or gitlab as our cloud service where we store all our code remotely. Below there will be some basic git command and their description.
When you first start a project using git you have to initialize the git in side your project directory.
$ cd my_folder
$ git init
Initialized empty git repository in my_folder/.git/
Cloning repository
Suppose if you want to work on a project that is already on github so in order to contribute to that project first you have to clone that repo to your local machine. Here git clone comes to help you in that.
If you want to check the status of a repository like which files have added and deleted and modified then you have to execute the below commands. It will also show the tracked and untracked files of the repository.
$ git status
On branch master
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout –– <file>..." to discard changes in working directory)
modified: tasks.txt
no changes added to commit (use "git add" and/or "git commit –a")
Adding files to staging area
If you add a new file to your repository or you have modified some files then before committing you have to move those files to staging area. Here you have certain cases like you want to add files to staging area by one by on or you want to add all files to staging or you want to add all tracked files to staging area except untracked files. Below commands for all cases.
$ #Add specific file to staging area
$ git add [file_name]
$
$ #Add all new and changed file to staging area
$ git add -A
$
$ #Add all tracked files to staging area
$ git add -u
Committing changes
After adding files to staging area you have to commit those changes. Basically you are saving those changes as commits. Every commits has it’s commit message and unique commit ID.
$ git commit -m [commit message]
Removing files or folders
Suppose you have to delete some files from index which is not needed then you have to tell git to remove those and here git rm comes to help you.
$ git rm -r [file-name]
Branching
It is recommended that you should not change directly in the master branch. When you are experimenting something or adding any feature then always you should create a new branch and make changes there. So bellow command is showing you how to create a new branch.
$ git checkout -b <your_branch>
Switched to a new branch "your_branch"
Now type git branch to see all local branches. And if you want to see all the branches include local and remote then you have to type git branch -a. Now if you again want to come back to your master branch then you have to type below command.
$ git checkout master
Switched to branch 'master'
If you want to switch to the last checkout branch then type git checkout -. Now sometimes you have to delete a specific branch so in this case you have two branches one is in your local machine and one is in your server.
$ #delete your local branch
$ git branch -d <your_local_branch>
Deleted branch <your_local_branch> (was 4335a0a).
$
$ #delete your remote branch
$ git push origin --delete <your_remote_branch>
Merging
When you have finished your all features and changes in your branch it is now ok to merge with master branch. In order to merge any branch with master branch there we execute the below command.
`Basically in merging there is two branches one is source branch and another is target branch and in the above scenario the master branch is target branch and other is source branch. If you want to do the above operation in one line then you can do –
git merge [target branch]
Stashing
Use git stash when you want to record the current state of the working directory and the index, but want to go back to a clean working directory. The command saves your local modifications away and reverts the working directory to match the HEAD commit. And use git stash clear to remove all stashed entries.
Sharing & updating project
After all committing stuff it is the time to push the changed to the remote server or otherwise if your local computer get disturbed you will loose all changes. Use the below command –
$ git push origin <your_branch>
Sometimes you are just working on a specific branch for a long time and it is possible that git will remember the branch name for you. Use git push -u origin <your_branch> to make git remember your branch name. After this you just have to execute the command git push and it will automatically push the commits in the remembered branch.
Now suppose you have two laptops and from both you are maintaining the project so it is very necessary for you that you keep updated the project in the both laptops. So git pull will update the local repository to the latest commits.
So git has local repository and remote repository so when ever we push something it will go to the remote repository. So it is very important to tell git that what is our remote repository. In order to add the remote repository we execute the bellow commands –
Sometimes we clone the repository in the https format url or we have set the remote url in https format but we are planning to switch to ssh. Then we will execute the below command and everything is changed . Below we are switching to ssh remote url.
If you wand to see commit history then I already published a blog about git log you should checkout. Now if you want to see what you have changed after the last commit then do git diff. It is good to see the changes you have made in the feature branch before merging to the target branch. Execute the below command for that –
The purpose of any version control system is to record changes to your code. This gives you the power to go back into your project history and see who contributed what and when and figure out where bugs were introduced. But, having all of this history available is useless if you don’t know how to navigate it. That’s where the git log command comes in. Below various git log options that will be very helpful while maintaining a big project:
The --oneline option will give you a output of commits to a single line. By default it will show you the commit ID and first line of the commit message.
aniruddha ~/Desktop/foobar master
$ git log --oneline
505a2c6 (HEAD -> master) Add the file hellomars.txt and update helloworld.txt
fb8c32d First commit
By amount
The most basic filter that git gives us the limit the number of commits. You can pass -<n> after the git log.
$ git log -3
By author
When you are looking for commits created by a specific person then --author="name" will be the option you have to use. This will return all commits matches with the author name you have given.
$ git log --author="Aniruddha"
You can use regular expressions to search for commits. In the below example the following commands searches for commits by either Aniruddha or Sayan.
$ git log --author="Aniruddha\|Sayan"
By commit message
To filter the commits by their commit message, use the --grep flag. This works like the --author flag discussed in the above but it matches against the commit message instead of the author.
$ git log --grep="First"
By file
Some times you are only interested in changes that happened to a particular file. To see the history related to a file you just have to to pass the file path. Below we want to see the commits related to foo.py.
$ git log -- foo.py
See changed file names
If you want to see the files you have changed according to your git commit then execute the below git command.
SSH is a tool by which we can create a secure connection between the client and server. Basically it is an asymmetric type encryption that creates two key one is public and one is private. Public key can be distributed publicly and it is used for encrypt the data and the private key have to be kept secret for decrypting the data. Below commands will create the ssh keys:
$ ssh-keygen -t rsa -C "your_email@example.com"
Generating public/private rsa key pair.
Enter file in which to save the key (/home/ani/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/ani/.ssh/id_rsa.
Your public key has been saved in /home/ani/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:Up6KjbnEV4Hgfo75YM393QdQsK3Z0aTNBz0DoirrW+c ylo@klar
The key's randomart image is:
+---[RSA 2048]----+
| . ..oo..|
| . . . . .o.X.|
| . . o. ..+ B|
| . o.o .+ ..|
| ..o.S o.. |
| . %o= . |
| @.B... . |
| o.=. o. . . .|
| .oo E. . .. |
+----[SHA256]-----+
Now you have created a pair of keys and you have to add the public key in the github. Follow below instructions after doing the above the task –
Go to your github page and open settings.
Now click the SSH and GPG keys.
Now click New SSH key.
In the title field add a relevant title fr your key. Like if you are using Linux on your PC the give a title like “Linux PC”.
Then paste your public key in the box.
Then click Add SSH key.
If it ask for your password then confirm your password.
I usually check and reply all my blog comments on friday night and approve the spam comments. Last friday I was checking my spam comments and saw that there was almost more than 70 comments and I thought approving all comments will be a hectic process and I was thinking of a process that I can do it with one click. Then I came up with the solution of writing a JavaScript script to approve all comments.
Here below the script –
var x = document.getElementsByClassName('comment__action comment__action-approve');
for (var i = 0; i < x.length; i++) {
x[i].click();
}
The above code actually select the approve button and gives me an array then x[i].click(); this will click each approve button one by one.
In ansible we generally execute instruction written in playbook one after another. In some cases we have to collect some data from the user that can be a sensitive data or not. In this scenario we use prompts to collect the data from the user. We write all our prompts inside vars_prompt section. By default the data we write as input is private and we can change it by private: no . Below there is a basic example of ansible prompt.
---
- hosts: webservers
vars_prompt:
- name: username
prompt: "What is your username?"
private: no
- name: password_1
prompt: "What is your password?"
Here is the result –
$ ansible-playbook prompt.yml
What is your username?: ani
What is your password?:
PLAY [webservers] ***************************************************************************************************************************
TASK [Gathering Facts] **********************************************************************************************************************
ok: [localhost]
PLAY RECAP **********************************************************************************************************************************
localhost : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
We can even set a default value for any prompt and by default: 'value' and if there is a need of verifying any value like password then we can do this by confirm: yes . Below there is a example –
$ ansible-playbook prompt.yml
What is product release version? [1.0]: 2.0
Enter password_2:
confirm Enter password_2:
***** VALUES ENTERED DO NOT MATCH ****
Enter password_2:
confirm Enter password_2:
PLAY [webservers] ***************************************************************************************************************************
TASK [Gathering Facts] **********************************************************************************************************************
ok: [localhost]
PLAY RECAP **********************************************************************************************************************************
localhost : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
In the above you can see that the default value in the square bracket what we have mention in the playbook and if we skip that part then ansible will take the default value. You can see that we have entered the confirmed password wrong so it is showing a warning like this **** VALUES ENTERED DO NOT MATCH **** and second time we have entered the right value that’s why everything is ok.
Aniruddha Basak 