<?xml version="1.0" encoding="utf-8"?><feedxmlns="http://www.w3.org/2005/Atom"><generatoruri="https://jekyllrb.com/"version="4.2.1">Jekyll</generator><linkhref="https://sahinakkaya.dev/feed.xml"rel="self"type="application/atom+xml"/><linkhref="https://sahinakkaya.dev/"rel="alternate"type="text/html"/><updated>2022-02-27T05:08:20+00:00</updated><id>https://sahinakkaya.dev/feed.xml</id><titletype="html">Şahin Akkaya’s Personal Page</title><subtitle>Şahin Akkaya's personal blog - a perfectionist who likes to tinker everything until it is just right. Get ready to find some sweet tips that will boost your productivity and make you fall in love with your computer.</subtitle><author><name>Şahin Akkaya</name></author><entry><titletype="html">SSH into Machine That Is Behind a Private Network</title><linkhref="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html"rel="alternate"type="text/html"title="SSH into Machine That Is Behind a Private Network"/><published>2022-02-26T21:40:00+00:00</published><updated>2022-02-26T21:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network</id><contenttype="html"xml:base="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html"><h2 id="story">Story</h2>
<p>I believe there is always a “tech support person” in every home. Everyone knows that when there is a problem with any electronic device, they should ask this person. I am the tech support in our house. Today, I had to fix a problem in our desktop. Since I was not at home, I had to fix the problem remotely.</p>
<p>Just tell the non-tech people at home to configure the router to forward ssh traffic to desktop, right? Well, this is not an option for me, not because people are non-tech, but there is no router! The desktop is connected to internet via hotspot from mobile phone. There is no root access in the phone and even if there was, it is a really big pain to forward the packets manually. Trust me. Been there, done that!</p>
</li>
<li>
<p>There are tools like <a href="https://www.ngrok.com">ngrok</a>, <a href="localtunnel.me">localtunnel</a> which exposes your localhost to the internet and gives you a URL to access it but I did not want to use them.</p>
<ul>
<li>I did not want to use <code class="language-plaintext highlighter-rouge">ngrok</code> because it is not open source and it might have security issues. They are also charging you.</li>
<li><code class="language-plaintext highlighter-rouge">localtunnel</code> seemed perfect. The code of both client and server is open. That is great news! But it did not last long because it is just forwarding http/https traffic :(</li>
<p>I was thinking of extending the functionality of <code class="language-plaintext highlighter-rouge">localtunnel</code>, but I learned a very simple way. You don’t need any external program to overcome this issue. The good old <code class="language-plaintext highlighter-rouge">ssh</code> can do that! All you need is another machine (a remote server) that both computers can access via ssh.</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c"># local machine (my home computer)</span>
<p>This command forwards all the incoming connections to port 7777 of remote machine to port 22 of our current machine. In order for this to work, you need to make sure <code class="language-plaintext highlighter-rouge">GatewayPorts</code> is set to <code class="language-plaintext highlighter-rouge">yes</code> in the remote server ssh configuration. It also assumes our current machine accepts ssh connections via port 22.</p>
<hr />
<p>Now, go to any machine and connect to the remote server first. When we are connected, we will create another ssh connection to port 7777 to connect our home computer.</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c"># another local machine (my laptop)</span>
<p>As a result, it only took us 2 simple ssh commands to do this. This is just unbelievable! Now, I need to find a way to make non-tech people at home run this command when there is a problem. Too bad Linux can’t help me there :D</p></content><author><name>Şahin Akkaya</name></author><categoryterm="ssh"/><categoryterm="private-network"/><categoryterm="remote-port-forwarding"/><summarytype="html">Story I believe there is always a “tech support person” in every home. Everyone knows that when there is a problem with any electronic device, they should ask this person. I am the tech support in our house. Today, I had to fix a problem in our desktop. Since I was not at home, I had to fix the problem remotely.</summary></entry><entry><titletype="html">Using ffmpeg for Simple Video Editing</title><linkhref="https://sahinakkaya.dev/2022/01/21/ffmpeg-to-rescue.html"rel="alternate"type="text/html"title="Using ffmpeg for Simple Video Editing"/><published>2022-01-21T20:40:00+00:00</published><updated>2022-01-21T20:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/01/21/ffmpeg-to-rescue</id><contenttype="html"xml:base="https://sahinakkaya.dev/2022/01/21/ffmpeg-to-rescue.html"><h2 id="story">Story</h2>
<p>Today, I have recorded a video for one of my classes and I was required to upload it till midnight. The video was perfect except for a few seconds where I misspelled some words and started again. I had to remove that part from the video before uploading it. Since I was low on time, I thought that I better use a GUI program to do this job. I opened up <a href="https://kdenlive.org/en/">Kdenlive</a> and jumped into editing my video. It was my first time using it so I spent some time to cut and delete the parts that I want to get rid of. When I was ready, I clicked Render button to render my video. It was waaay too slow than I expected. Since I have nothing to do while waiting for render to finish, I thought I could give <code class="language-plaintext highlighter-rouge">ffmpeg</code> a shot.</p>
<h2 id="let-the-show-begin">Let the show begin</h2>
<p>Like Kdenlive, I have never used <code class="language-plaintext highlighter-rouge">ffmpeg</code> before. Like every normal Linux user do, I opened up a terminal and typed <code class="language-plaintext highlighter-rouge">man ffmpeg</code> to learn how to use it… Just kidding :D I opened a browser and typed <em>“ffmpeg cut video by time”</em>. Not the best search query, but it was good enough to find what I am looking for as the <a href="https://stackoverflow.com/questions/18444194/cutting-the-videos-based-on-start-and-end-time-using-ffmpeg">first result</a>.</p>
<h3 id="cutting-the-videos-based-on-start-and-end-time">Cutting the videos based on start and end time</h3>
<p>According to answers on the page I mentioned, I run the following commands to cut my video into two parts:</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code>ffmpeg <span class="nt">-ss</span> 00:00:00 <span class="nt">-to</span> 00:01:55 <span class="nt">-i</span> input.mov <span class="nt">-c</span> copy part1.mp4 <span class="c"># take from 00:00 to 01:55</span>
ffmpeg <span class="nt">-ss</span> 00:02:03 <span class="nt">-to</span> 00:05:17 <span class="nt">-i</span> input.mov <span class="nt">-c</span> copy part2.mp4 <span class="c"># take from 02:03 to 05:17</span>
</code></pre></div></div>
<p>These two commands run <strong>instantly</strong>! Kdenlive was still rendering… The progress was 46%. Meh… I said “Duck it, I am gonna use ffmpeg only” and cancelled the rendering.</p>
<h3 id="concatenating-the-video-files">Concatenating the video files</h3>
<p>Now we have two videos that we want to join. Guess what will be our next search query? <em>“ffmpeg join videos”</em>. And <a href="https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg">here</a> is the first result:</p>
<p>And we are DONE! How easy was that? Whole process took about 10 minutes including my search on the internet. If I continued waiting for Kdenlive to finish rendering, I would probably be still waiting at that time. I love the power of command line!</p></content><author><name>Şahin Akkaya</name></author><categoryterm="cli"/><categoryterm="ffmpeg"/><summarytype="html">Story Today, I have recorded a video for one of my classes and I was required to upload it till midnight. The video was perfect except for a few seconds where I misspelled some words and started again. I had to remove that part from the video before uploading it. Since I was low on time, I thought that I better use a GUI program to do this job. I opened up Kdenlive and jumped into editing my video. It was my first time using it so I spent some time to cut and delete the parts that I want to get rid of. When I was ready, I clicked Render button to render my video. It was waaay too slow than I expected. Since I have nothing to do while waiting for render to finish, I thought I could give ffmpeg a shot.</summary></entry><entry><titletype="html">Automatically Build and Deploy Your Site using GitHub Actions and Webhooks</title><linkhref="https://sahinakkaya.dev/2022/01/04/build-and-deploy-automatically.html"rel="alternate"type="text/html"title="Automatically Build and Deploy Your Site using GitHub Actions and Webhooks"/><published>2022-01-04T17:40:00+00:00</published><updated>2022-01-04T17:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/01/04/build-and-deploy-automatically</id><contenttype="html"xml:base="https://sahinakkaya.dev/2022/01/04/build-and-deploy-automatically.html"><p>In this post I will explain how you can use GitHub to automate the build and deployment processes that you have. I am going to automate the deployment of this site but you can do whatever you want. Just understanding the basics will be enough.</p>
<h2 id="introduction-to-github-actions-and-webhooks">Introduction to GitHub Actions and Webhooks</h2>
<p>Let me start by explaining what are GitHub Actions and GitHub Webhooks.</p>
<blockquote>
<p><strong>Github Actions</strong> is a continuous integration and continuous delivery (CI/CD) platform that allows you to automate your build, test, and deployment pipeline. You can create workflows that build and test every pull request to your repository, or deploy merged pull requests to production.</p>
</blockquote>
<blockquote>
<p><strong>Webhooks</strong> provide a way for notifications to be delivered to an external web server whenever certain actions occur on a repository or organization. … For example, you can configure a webhook to execute whenever:</p>
<ul>
<li>A repository is pushed to</li>
<li>A pull request is opened</li>
<li>A GitHub Pages site is built</li>
<li>A new member is added to a team</li>
</ul>
</blockquote>
<h2 id="defining-the-problem-and-solution">Defining the problem and solution</h2>
<p>As I said, my example will be automating the deployment of this site. Here is the normal workflow of me doing it manually:
<p>As you can see, the only place where my work is really required is writing the post. Other two steps can be automated. We will use GitHub Actions to generate the site content and Webhooks to let our server know about the new content so it can pull the changes. Let’s get started.</p>
<h3 id="setting-up-github-actions">Setting up GitHub Actions</h3>
<p>Setting up a GitHub Action is as easy as creating a <code class="language-plaintext highlighter-rouge">.yml</code> file in <code class="language-plaintext highlighter-rouge">.github/workflows/</code> directory in your repository. Let us create a new action to build our site. Fortunately, there is already a <a href="https://github.com/marketplace/actions/jekyll-actions">GitHub action</a> to do it for us. Create a file called <code class="language-plaintext highlighter-rouge">.github/workflows/jekyll.yml</code> in your root directory of your repository and put the following contents:</p>
<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="na">name</span><span class="pi">:</span><span class="s">Jekyll site CI</span>
<p>That’s it! We have created our first Action. When we push this change, GitHub will start building our site and push the result to <code class="language-plaintext highlighter-rouge">gh-pages</code> branch. Currently, it will take a while to build because we don’t use caching. So let’s include it to build faster. Add the following piece as a second step:</p>
<div class="language-yaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c1"># Use GitHub Actions' cache to shorten build times and decrease load on servers</span>
<p>We are done with the Actions part. You can see the final code <a href="https://github.com/Asocia/sahinakkayadotdev/blob/main/.github/workflows/jekyll.yml">here</a>. When you are also done with the code, just push it to trigger the action.</p>
<h3 id="setting-up-the-webhook-and-related-endpoint">Setting up the Webhook and related endpoint</h3>
<h4 id="creating-a-webhook-from-github">Creating a Webhook from GitHub</h4>
<p>To add a Webhook, open your repository in browser and navigate to <em>‘Settings &gt; Webhooks’</em> and click <em>‘Add Webhook’</em>. Fill in the form with appropriate values. Here is an example:
<img src="/assets/images/gh-actions-and-webhooks/add-webhook.png" alt="Webhook form example" /></p>
<p>This is all you have to do from GitHub. Now, whenever there is a <em><code class="language-plaintext highlighter-rouge">push</code></em> event to your repository, GitHub will send a POST request to your <em>payload url</em> with the details.</p>
<p class="notice--info"><strong>Note:</strong> Our Action is configured to push to a branch in our repository, so it will also trigger this hook and we will catch it.</p>
<h4 id="creating-an-endpoint-to-handle-the-requests">Creating an endpoint to handle the requests</h4>
<p>I will use <a href="https://flask.palletsprojects.com/en/2.0.x/">Flask</a> framework to handle the post requests coming to our endpoint. You can use whatever programming language or framework you want. It will be very simple code with just one job: Validate the secret keys and run a specific code.</p>
<span class="n">APP_KEY</span><span class="o">=</span><span class="s">"your-secret-key"</span><span class="c1"># same key that is used in github while creating the webhook
</span><span class="n">PROJECT_PATH</span><span class="o">=</span><span class="s">"/path/to/your/project/"</span><span class="c1"># you will want to cd into this path and perform commands such as git pull etc.
<p>I will not go into details explaining what each line does. Basically, we are checking if the request is a POST request and if so we are comparing the secret keys to make sure that the request is coming from GitHub. In our case, this is not too important because when the keys match we are running simple git commands in our repository but you might need it if you are doing something more complicated. And here is the contents of <code class="language-plaintext highlighter-rouge">perform-git-pull.sh</code> file:</p>
<p>We are almost done! All we need to do is create a service to automatically run our code and let nginx handle our endpoint correctly.</p>
<p>Create a new file <code class="language-plaintext highlighter-rouge">post_receiver.service</code> in <code class="language-plaintext highlighter-rouge">/etc/systemd/system/</code>:</p>
<p>That’s it! <code class="language-plaintext highlighter-rouge">curl https://yourdomain.com/postreceive/</code> should return <code class="language-plaintext highlighter-rouge">"OK"</code> and we are ready to accept POST requests from GitHub.</p>
<h3 id="notes-for-debugging">Notes for debugging</h3>
<p>In case anything goes wrong, here are a few tips to debug:</p>
<ul>
<li>Every GitHub Action produces a log that you can examine. Check them to see if anything is odd.</li>
<li>In the <em>Webhooks</em> tab, there is a sub-tab called <em>Recent Deliveries</em>. You can take a look at there to see the results of the requests from your hooks.</li>
<li>You can always test your code locally with <code class="language-plaintext highlighter-rouge">curl</code>:
<p>Happy hacking!</p></content><author><name>Şahin Akkaya</name></author><categoryterm="github-actions"/><categoryterm="github-webhooks"/><categoryterm="ci-cd"/><summarytype="html">In this post I will explain how you can use GitHub to automate the build and deployment processes that you have. I am going to automate the deployment of this site but you can do whatever you want. Just understanding the basics will be enough.</summary></entry><entry><titletype="html">Stop cat-pipe’ing, You Are Doing It Wrong!</title><linkhref="https://sahinakkaya.dev/2022/01/01/stop-cat-pipeing.html"rel="alternate"type="text/html"title="Stop cat-pipe’ing, You Are Doing It Wrong!"/><published>2022-01-01T15:00:00+00:00</published><updated>2022-01-01T15:00:00+00:00</updated><id>https://sahinakkaya.dev/2022/01/01/stop-cat-pipeing</id><contenttype="html"xml:base="https://sahinakkaya.dev/2022/01/01/stop-cat-pipeing.html"><div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="nb">cat </span>some_file | <span class="nb">grep </span>some_pattern
<p>I’m sure that you run a command something like above at least once if you are using terminal. You know how <code class="language-plaintext highlighter-rouge">cat</code> and <code class="language-plaintext highlighter-rouge">grep</code> works and you also know what pipe (<code class="language-plaintext highlighter-rouge">|</code>) does. So you naturally combine all of these to make the job done. I was also doing it this way. What I didn’t know is that <code class="language-plaintext highlighter-rouge">grep</code> already accepts file as an argument. So the above command could be rewritten as:</p>
<p>… which can make you save a few keystrokes and a few nanoseconds of CPU cycles. Phew! Not a big deal if you are not working files that contains GBs of data, right? I agree but you should still use the latter command because it will help you solve some other problems better. Here is a real life scenario: You want to search for some specific pattern in all the files in a directory.</p>
<ul>
<li>If you use the first approach, you may end up running commands like this:</li>
❯<span class="c"># You still have a lot to do :/</span>
</code></pre></div></div>
<ul>
<li>If you use the second approach, you will immediately realize that you can send all the files with <code class="language-plaintext highlighter-rouge">*</code> operator and you will finish the job with just one command (2 if you include mandatory <code class="language-plaintext highlighter-rouge">ls</code> :D):</li>
<p>Isn’t this neat? You might say that <em>“This is cheating! You are using a wild card, of course it will be easier.”</em> Well, yes. Technically I could use the same wild card in the first command like <code class="language-plaintext highlighter-rouge">cat * | grep light</code> but:</p>
<ul>
<li>I figured that out only after using wild card in the second command. So I think it is does not feel natural.</li>
<li>It is still not giving the same output. Try and see the difference! <a href="##" title="You will not be able to see which file contains which line. 'cat' will just concatenate all the input.">*</a></li>
</ul></content><author><name>Şahin Akkaya</name></author><categoryterm="cat"/><categoryterm="grep"/><categoryterm="linux"/><categoryterm="command-line"/><summarytype="html">cat some_file | grep some_pattern I’m sure that you run a command something like above at least once if you are using terminal. You know how cat and grep works and you also know what pipe (|) does. So you naturally combine all of these to make the job done. I was also doing it this way. What I didn’t know is that grep already accepts file as an argument. So the above command could be rewritten as: grep some_pattern some_file</summary></entry><entry><titletype="html">First blog post</title><linkhref="https://sahinakkaya.dev/2021/12/24/first-blog-post.html"rel="alternate"type="text/html"title="First blog post"/><published>2021-12-24T23:54:08+00:00</published><updated>2021-12-24T23:54:08+00:00</updated><id>https://sahinakkaya.dev/2021/12/24/first-blog-post</id><contenttype="html"xml:base="https://sahinakkaya.dev/2021/12/24/first-blog-post.html"><style>
<p><em><code class="language-plaintext highlighter-rouge">Hello, World!</code></em><a href="##" title="I think I just wrote the best first sentence I could write as a programmer :D" class="cd"><sup class="ab">*</sup></a>
So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it finally have come true. You might think that I could sign-up for a social media platform and my profile would be a personal space for me but no. I just don’t feel comfortable with that way. This has been the case since my childhood and also the reason why I don’t use Facebook, Instagram or any other social media. If you think you found me on these platforms, I would say it is not me. I might write another post about why I don’t like social media but I will cut this one here.</p>
<h2 id="why-i-wanted-to-start-blogging">Why I wanted to start blogging?</h2>
<p>There are several reasons for starting my own site and blogging, but I can list the most important ones as follows:</p>
<h3 id="giving-back-to-community">Giving back to community</h3>
<p>I use the software developed and brought by the community every day. The moment I power on my computer I start using Free Software. It really amazes me to see the work produced by people who do not know each other at all. For example, I did not even write a single line of code for this site. If Free Software didn’t exist, I’d either have to spend money and use a platform that I have limited control over, or waste my time and build a site with a possibly worse design than this one<a href="##" title="swh" class="cd"><sup class="ab">*</sup></a>. In return for this, I want to give back to the community. For me, the way to give back to the community so far has been to share the projects I’ve done and archive the things I learn every day in a repository called <a href="https://github.com/Asocia/til">TIL</a><a href="##" title="Today I Learned" class="cd"><sup class="ab">*</sup></a>. But some of the til’s I’ve written recently are getting lengthy and I think they deserve their own posts. So instead of writing long til’s, I will blog what I learned here.</p>
<h3 id="archiving-the-memories">Archiving the memories</h3>
<p>I like to go over what I have done in the past once in a while. Blogging is perfect way to do this. I still read my diaries that I wrote in the past and they are fun. But I promise I will keep these posts more formal than my diaries<a href="##" title="swh" class="cd"><sup class="ab">*</sup></a>.</p>
<h3 id="pushing-myself-to-do-something-useful">Pushing myself to do something useful</h3>
<p>At the end of every year, I sit on my desk and think about what I did in that year. I generally don’t like the result because I fail to keep some of my resolutions for that year. Setting up a personal website was one of my resolutions for 2021 and it looks like I manage to keep it<a href="##" title="hooray!" class="cd"><sup class="ab">*</sup></a><a href="##" title="swh" class="cd"><sup class="ab">*</sup></a>. Unfortunately, I can’t always keep my spirits up. Sometimes I just do nothing and all the time passes. Hopefully, the feeling that I have to write something will help me get out of bad mood at such times.</p>
<h3 id="improving-my-writing-skills">Improving my writing skills</h3>
<p>Last but not least, I want to improve my writing. Even though I don’t use a formal language while writing here, I think it will help me improve my writing skills.</p>
<p>While writing this post I already come up with some new topics to write but I think they need their own posts.</p>
<p>Subscribe to my <a href="/feed.xml"><i class="fas fa-fw fa-rss-square" aria-hidden="true"></i>RSS Feed</a> to not miss them. You know RSS, right? I recently started using it and it is the best way to consume content. Do yourself a favor and search it if you don’t know. I will probably write something about it in the following blog posts. That’s all from me and thank you for reading. See you next time!</p></content><author><name>Şahin Akkaya</name></author><summarytype="html">Hello, World!* So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it fi...</summary></entry></feed>
