{"id":4790,"date":"2026-05-16T21:33:08","date_gmt":"2026-05-16T16:03:08","guid":{"rendered":"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/"},"modified":"2026-05-16T21:33:08","modified_gmt":"2026-05-16T16:03:08","slug":"what-is-docker-a-complete-guide-to-containerization","status":"publish","type":"post","link":"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/","title":{"rendered":"What is Docker? A Complete Guide to Containerization"},"content":{"rendered":"<p>I\u2019m sitting here looking at a dashboard full of &#8220;microservices&#8221; consuming 64GB of RAM to serve a basic CRUD application that could have run on a 486 DX2 with 8MB of memory, and I\u2019m being asked to explain <strong>what is docker<\/strong> to a generation of developers who think a &#8220;server&#8221; is an abstract concept living in a cloud.<\/p>\n<p>Fine. You want to know what it is? It\u2019s not a revolution. It\u2019s not a &#8220;game-changer&#8221;\u2014god, I hate that phrase. It\u2019s a glorified wrapper around Linux kernel features we\u2019ve had since the early 2000s, packaged for people who can\u2019t be bothered to learn how a linker works. It\u2019s a way to ship your &#8220;it works on my machine&#8221; excuses in a neat little tarball so that when it breaks at 3:00 AM, it breaks in a predictable, isolated way that I still have to fix.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_80 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a099aa8b87b4\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6a099aa8b87b4\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#1_The_3_00_AM_Incident_Why_This_Mess_Exists\" >1. The 3:00 AM Incident: Why This Mess Exists<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#2_The_Kernel_Lie_Namespaces_and_the_Illusion_of_Isolation\" >2. The Kernel Lie: Namespaces and the Illusion of Isolation<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#3_The_Overlay2_Autopsy_A_File_System_Made_of_Lies\" >3. The Overlay2 Autopsy: A File System Made of Lies<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#4_The_Networking_Nightmare_Bridges_Veth_and_NAT\" >4. The Networking Nightmare: Bridges, Veth, and NAT<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#5_The_Security_Delusion_Why_%E2%80%9CIsolated%E2%80%9D_Doesnt_Mean_%E2%80%9CSecure%E2%80%9D\" >5. The Security Delusion: Why &#8220;Isolated&#8221; Doesn&#8217;t Mean &#8220;Secure&#8221;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#6_The_Verdict_When_to_Stop_Being_Lazy\" >6. The Verdict: When to Stop Being Lazy<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#Technical_Appendix_for_the_Uninitiated\" >Technical Appendix for the Uninitiated<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/#Related_Articles\" >Related Articles<\/a><\/li><\/ul><\/nav><\/div>\n<h3><span class=\"ez-toc-section\" id=\"1_The_3_00_AM_Incident_Why_This_Mess_Exists\"><\/span>1. The 3:00 AM Incident: Why This Mess Exists<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Before I dissect the guts of Docker Engine v24.0.7, you need to understand the trauma that birthed it. It\u2019s 2004. I\u2019m in a data center in Northern Virginia. The AC is failing, the floor tiles are vibrating, and a Sun Fire V240 is screaming because a &#8220;senior&#8221; dev pushed a binary compiled against a version of <code>glibc<\/code> that didn&#8217;t exist on the production cluster.<\/p>\n<p>Back then, we didn&#8217;t have &#8220;containers.&#8221; We had bare metal. If you wanted isolation, you bought another $10,000 rack-mounted heater. We spent six hours that night trying to manually symlink shared libraries, fighting dependency hell while the database sat locked because some &#8220;helpful&#8221; script had overwritten a global environment variable. We were basically performing open-heart surgery on a running OS with a rusty spoon.<\/p>\n<p>Docker exists because you lot kept breaking the global namespace. You couldn&#8217;t keep your binaries in your pants, so the industry had to build a playpen. When people ask &#8220;what is docker,&#8221; the honest answer is: it\u2019s a straitjacket for software.<\/p>\n<pre class=\"codehilite\"><code class=\"language-bash\"># This is what my nightmare looked like before you kids got your 'containers'\n# Just trying to see why the hell the linker is crying\nldd \/usr\/local\/bin\/legacy_app\n    linux-vdso.so.1 (0x00007ffcb95f3000)\n    libstdc++.so.6 =&gt; \/lib\/x86_64-linux-gnu\/libstdc++.so.6 (0x00007f8e1a200000)\n    libc.so.6 =&gt; \/lib\/x86_64-linux-gnu\/libc.so.6 (0x00007f8e19e00000)\n    \/lib64\/ld-linux-x86-64.so.2 (0x00007f8e1a5f5000)\n# Oh look, a version mismatch. Time to spend 4 hours rebuilding the world.\n<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"2_The_Kernel_Lie_Namespaces_and_the_Illusion_of_Isolation\"><\/span>2. The Kernel Lie: Namespaces and the Illusion of Isolation<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Let\u2019s get one thing straight: Docker is not a Virtual Machine. If I hear one more &#8220;DevOps Evangelist&#8221; compare a container to a VM, I\u2019m going to throw my Model M keyboard at them. <\/p>\n<p>A VM uses a hypervisor to emulate hardware. It\u2019s heavy, it\u2019s slow, but it\u2019s honest. Docker is a liar. It uses the same host kernel as everyone else. When you run a container, you\u2019re just running a process on the host, but the kernel is wearing a blindfold.<\/p>\n<p>Docker relies on two primary Linux primitives: <strong>Namespaces<\/strong> and <strong>Control Groups (cgroups)<\/strong>. <\/p>\n<p>When you run <code>docker run<\/code>, the engine calls <code>clone()<\/code> with a bunch of flags like <code>CLONE_NEWPID<\/code>, <code>CLONE_NEWNET<\/code>, <code>CLONE_NEWNS<\/code>, and <code>CLONE_NEWUTS<\/code>.<br \/>\n&#8211; <code>CLONE_NEWPID<\/code> tells the process: &#8220;You are PID 1. You are the king of the world.&#8221; In reality, on the host, it\u2019s just PID 45029.<br \/>\n&#8211; <code>CLONE_NEWNET<\/code> gives it a private network stack so it doesn&#8217;t see the host&#8217;s interfaces. <\/p>\n<p>It\u2019s a trick. It\u2019s <code>chroot<\/code> on steroids. You aren&#8217;t &#8220;inside&#8221; anything; you&#8217;re just being gaslit by the kernel.<\/p>\n<pre class=\"codehilite\"><code class=\"language-bash\"># Let's look at the reality of your 'isolated' world\n# Host kernel version - I'm running this on a dusty Ubuntu box\nuname -a\nLinux hardware-arch-01 5.15.0-76-generic #83-Ubuntu SMP Thu Jun 15 19:16:32 UTC 2023 x86_64 x86_64 x86_64 GNU\/Linux\n\n# Now look at a container's 'isolation'\ndocker inspect 7a2b3c4d5e6f\n[\n    {\n        &quot;Id&quot;: &quot;7a2b3c4d5e6f...&quot;,\n        &quot;State&quot;: {\n            &quot;Status&quot;: &quot;running&quot;,\n            &quot;Pid&quot;: 45029\n        },\n        &quot;GraphDriver&quot;: {\n            &quot;Data&quot;: {\n                &quot;LowerDir&quot;: &quot;\/var\/lib\/docker\/overlay2\/...&quot;,\n                &quot;MergedDir&quot;: &quot;\/var\/lib\/docker\/overlay2\/...&quot;,\n                &quot;UpperDir&quot;: &quot;\/var\/lib\/docker\/overlay2\/...&quot;\n            },\n            &quot;Name&quot;: &quot;overlay2&quot;\n        },\n        &quot;Config&quot;: {\n            &quot;Hostname&quot;: &quot;app-container&quot;,\n            &quot;Image&quot;: &quot;node:18-alpine&quot;\n        }\n    }\n]\n<\/code><\/pre>\n<p>See that <code>Pid: 45029<\/code>? That\u2019s the truth. Your &#8220;isolated&#8221; container is just a line item in the host\u2019s process table. If that process decides to eat 100% of the CPU because you wrote a recursive loop in JavaScript, the host feels it. That\u2019s where <strong>cgroups v2<\/strong> comes in\u2014the only thing keeping your sloppy code from crashing my entire rack. It limits memory, CPU, and I\/O. But don&#8217;t think for a second it&#8217;s a hard barrier. It\u2019s a suggestion enforced by a very tired kernel.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"3_The_Overlay2_Autopsy_A_File_System_Made_of_Lies\"><\/span>3. The Overlay2 Autopsy: A File System Made of Lies<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Now, let\u2019s talk about how Docker handles files. You think you have a &#8220;disk&#8221; in your container? Wrong. You have a stack of folders pretending to be a disk. <\/p>\n<p>Docker uses a Union File System, specifically <code>overlay2<\/code> these days. It\u2019s a &#8220;copy-on-write&#8221; mechanism. When you build an image, every line in your Dockerfile creates a new layer. These layers are read-only tarballs sitting in <code>\/var\/lib\/docker\/overlay2<\/code>.<\/p>\n<p>When you start the container, Docker throws a thin &#8220;read-write&#8221; layer on top. If you try to modify a file that exists in a lower layer, the kernel has to copy that file up to the top layer before you can write to it. This is why your database performance is garbage if you don&#8217;t use volumes. You\u2019re making the kernel do a frantic dance of copying files every time you write a log line.<\/p>\n<pre class=\"codehilite\"><code class=\"language-bash\"># This is where your 'images' actually live. It's just a mess of hex strings.\nls -l \/var\/lib\/docker\/overlay2\ntotal 0\ndrwx------ 4 root root 72 Oct 12 10:45 0123456789abcdef...\ndrwx------ 4 root root 72 Oct 12 10:45 123456789abcdef0...\ndrwx------ 4 root root 72 Oct 12 10:46 23456789abcdef01...\ndrwx------ 3 root root 48 Oct 12 10:46 l\n<\/code><\/pre>\n<p>The <code>l<\/code> directory there? Those are shortened symbolic links because the kernel has a limit on how long a mount argument can be. We\u2019ve reached a point in software engineering where we have to use aliases for our aliases because the abstraction is too long for the OS to read. Let that sink in.<\/p>\n<p>Every time you do an <code>apt-get update<\/code> in a Dockerfile, you\u2019re adding 300MB of metadata to a permanent layer that will haunt your disk space forever. And you wonder why the SSDs in the SAN are crying.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"4_The_Networking_Nightmare_Bridges_Veth_and_NAT\"><\/span>4. The Networking Nightmare: Bridges, Veth, and NAT<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>If the file system is a lie, the networking is a hallucination. <\/p>\n<p>When Docker starts, it creates a virtual bridge called <code>docker0<\/code>. Every container gets a <code>veth<\/code> (virtual ethernet) pair. One end of the pipe is inside the container\u2019s network namespace (the <code>CLONE_NEWNET<\/code> thing I mentioned), and the other end is plugged into the <code>docker0<\/code> bridge on the host.<\/p>\n<p>To get traffic from the outside world into your container, Docker uses <code>iptables<\/code>. It\u2019s a mess of Network Address Translation (NAT). Every packet entering your &#8220;high-performance&#8221; Go microservice has to be mangled by the host\u2019s kernel, rewritten, and shoved through a virtual pipe. <\/p>\n<p>Back in my day, a packet went from the wire to the NIC to the application. Now, it goes:<br \/>\n1. Physical NIC<br \/>\n2. Host Kernel (iptables PREROUTING)<br \/>\n3. Bridge Interface (<code>docker0<\/code>)<br \/>\n4. Virtual Ethernet Pair (<code>veth<\/code>)<br \/>\n5. Container Network Namespace<br \/>\n6. Application<\/p>\n<p>And you people have the audacity to ask why the latency is spiking. You\u2019ve built a Rube Goldberg machine for bits and called it &#8220;modern infrastructure.&#8221;<\/p>\n<h3><span class=\"ez-toc-section\" id=\"5_The_Security_Delusion_Why_%E2%80%9CIsolated%E2%80%9D_Doesnt_Mean_%E2%80%9CSecure%E2%80%9D\"><\/span>5. The Security Delusion: Why &#8220;Isolated&#8221; Doesn&#8217;t Mean &#8220;Secure&#8221;<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>This is the part that keeps me up at night. People treat Docker containers like they\u2019re impenetrable vaults. &#8220;Oh, it\u2019s in a container, it\u2019s fine.&#8221; <\/p>\n<p>No, it\u2019s not fine. <\/p>\n<p>Because you\u2019re sharing the same kernel, a vulnerability in a syscall\u2014like <code>copy_file_range<\/code> or some obscure <code>io_uring<\/code> bug\u2014can allow a process to break out of the container and get root on the host. In a VM, you have to break the guest kernel, then the hypervisor. In Docker, you just have to trick the host kernel into thinking you\u2019re allowed to talk to it.<\/p>\n<p>Most of you run your applications as <code>root<\/code> inside the container. You think, &#8220;It\u2019s okay, it\u2019s a container root.&#8221; But if I manage to exploit your shitty Node.js app and you haven&#8217;t configured your <code>seccomp<\/code> profiles or <code>AppArmor<\/code> correctly, I\u2019m one kernel exploit away from owning your entire cluster. <\/p>\n<p>Docker tries to help with &#8220;Capabilities.&#8221; It drops things like <code>CAP_SYS_ADMIN<\/code> by default. But then some developer gets a &#8220;Permission Denied&#8221; error, looks up a fix on StackOverflow, and adds <code>--privileged<\/code> to their run command. Congratulations, you just gave the container permission to do almost anything to the host hardware. You might as well just give me your SSH keys and go home.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"6_The_Verdict_When_to_Stop_Being_Lazy\"><\/span>6. The Verdict: When to Stop Being Lazy<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>So, <strong>what is docker<\/strong>? <\/p>\n<p>It\u2019s a tool for managing the complexity of your own making. It\u2019s a way to package an environment so that the &#8220;works on my machine&#8221; problem becomes &#8220;it works in this specific, resource-constrained, kernel-namespaced environment.&#8221;<\/p>\n<p>Is it useful? Yes. It\u2019s useful for CI\/CD pipelines where I need to spin up a clean build environment and tear it down ten seconds later. It\u2019s useful for ensuring that the version of Python you\u2019re using in dev is the same one I\u2019m running in production.<\/p>\n<p>But it is not a replacement for understanding how an operating system works. It is not a magic wand that makes your code &#8220;scalable.&#8221; If your app is a bloated, synchronous, memory-leaking pile of garbage, putting it in a container just makes it a portable, isolated pile of garbage.<\/p>\n<p>Stop using it because it\u2019s trendy. Stop using it to hide the fact that you don&#8217;t know how to write a proper Makefile or manage a library path. Use it because you need reproducible environments. Use it because you need to limit the blast radius of your dependencies. <\/p>\n<p>But for the love of all that is holy, stop acting like it\u2019s magic. It\u2019s just a bunch of <code>tar<\/code> files and kernel flags. Now, if you&#8217;ll excuse me, I have to go find out why a &#8220;simple&#8221; containerized update just triggered an OOM kill on a database node that has 256GB of RAM. <\/p>\n<p>I miss the days when we just had to worry about the hardware catching fire. At least the fire was honest.<\/p>\n<hr \/>\n<h3><span class=\"ez-toc-section\" id=\"Technical_Appendix_for_the_Uninitiated\"><\/span>Technical Appendix for the Uninitiated<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>If you\u2019ve read this far and still think I\u2019m just being a &#8220;hater,&#8221; let\u2019s look at the actual syscalls. When you run a container, the Docker daemon (or <code>containerd<\/code> these days, because we needed more layers of abstraction) isn&#8217;t doing anything you couldn&#8217;t do yourself with a bit of C code and some patience.<\/p>\n<p><strong>The Syscall Chain:<\/strong><br \/>\n1. <strong><code>unshare()<\/code><\/strong>: This is the heart of it. It allows a process to disassociate parts of its execution context that are currently being shared with other processes.<br \/>\n2. <strong><code>mount()<\/code><\/strong>: Docker uses this to set up the <code>rootfs<\/code>. It mounts the <code>merged<\/code> layer of the <code>overlay2<\/code> filesystem as the new root.<br \/>\n3. <strong><code>pivot_root()<\/code><\/strong>: This is the more secure version of <code>chroot<\/code>. It moves the root file system of the current process to a new directory and puts the old root in another directory.<br \/>\n4. <strong><code>sethostname()<\/code><\/strong>: Because why not let the container think its name is <code>f3a1b2c3d4e5<\/code>?<\/p>\n<p><strong>The Memory Allocation Reality:<\/strong><br \/>\nIn a VM, the memory is &#8220;pinned.&#8221; If you give a VM 8GB, that 8GB is gone from the host&#8217;s perspective. In Docker, because of the shared kernel, the memory management is handled by the host&#8217;s MMU (Memory Management Unit). If your container isn&#8217;t using its allocated 8GB, the host can give it to someone else. This sounds &#8220;efficient&#8221; until you realize it leads to &#8220;noisy neighbor&#8221; syndrome. One container starts thrashing the swap, and suddenly every other container on that physical CPU socket is waiting on I\/O.<\/p>\n<p><strong>The Docker Engine Versioning:<\/strong><br \/>\nWe are currently dealing with Docker Engine v24.0.7. Over the years, they\u2019ve moved from a monolithic daemon to a decoupled architecture: <code>docker<\/code> (the CLI) -&gt; <code>dockerd<\/code> (the daemon) -&gt; <code>containerd<\/code> (the supervisor) -&gt; <code>runC<\/code> (the actual executor). <\/p>\n<p>Every one of those arrows is a socket connection or a process fork. Every one of those is a potential point of failure. We\u2019ve replaced a single binary with a four-stage relay race just to start a process. <\/p>\n<p><strong>Final Advice:<\/strong><br \/>\nIf you want to actually understand &#8220;what is docker,&#8221; stop using the <code>docker<\/code> command for a day. Try to build a container manually using <code>ip netns<\/code>, <code>chroot<\/code>, and <code>cgroups<\/code>. Once you see how the sausage is made, you\u2019ll realize why I\u2019m so grumpy. It\u2019s not that the technology is bad\u2014it\u2019s that it\u2019s being used as a crutch for a lack of fundamental systems knowledge.<\/p>\n<p>Now get out of my office and go check your image layers. You&#8217;ve got <code>curl<\/code> and <code>vim<\/code> installed in a production image, and it\u2019s a security nightmare waiting to happen.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Related_Articles\"><\/span>Related Articles<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Explore more insights and best practices:<\/p>\n<ul>\n<li><a href=\"https:\/\/itsupportwale.com\/blog\/fixed-freepbx-dashboard-very-slow-to-load\/\">Fixed Freepbx Dashboard Very Slow To Load<\/a><\/li>\n<li><a href=\"https:\/\/itsupportwale.com\/blog\/javascript-best-practices-write-cleaner-faster-code-2\/\">Javascript Best Practices Write Cleaner Faster Code 2<\/a><\/li>\n<li><a href=\"https:\/\/itsupportwale.com\/blog\/how-to-handle-android-runtime-permissions\/\">How To Handle Android Runtime Permissions<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>I\u2019m sitting here looking at a dashboard full of &#8220;microservices&#8221; consuming 64GB of RAM to serve a basic CRUD application that could have run on a 486 DX2 with 8MB of memory, and I\u2019m being asked to explain what is docker to a generation of developers who think a &#8220;server&#8221; is an abstract concept living &#8230; <a title=\"What is Docker? A Complete Guide to Containerization\" class=\"read-more\" href=\"https:\/\/itsupportwale.com\/blog\/what-is-docker-a-complete-guide-to-containerization\/\" aria-label=\"Read more  on What is Docker? A Complete Guide to Containerization\">Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-4790","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>What is Docker? 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