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‫For your first cluster, maybe even possibly your first few

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‫clusters, you won't have to worry too much about this

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‫concept of namespaces and contexts.

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‫But, it is something you need to be aware of that it exists

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‫in case you need to use it.

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‫Namespaces is essentially virtual clusters,

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‫or virtual views, inside a single cluster.

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‫It filters not just the view of the command so

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‫that you only see certain things when you type commands,

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‫but it also, with the right network policy plugins,

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‫can control the networking.

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‫This is a little bit different than Swarm where Swarm,

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‫out-of-the-box, you would create different overlay networks

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‫and everything was essentially private.

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‫In Kubernetes, networking and control of

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‫apps and their privacy, and what they can see and access,

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‫and what's physically controlled there is really dependent

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‫on your network plugin.

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‫Namespaces itself is not related

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‫to Docker namespaces, which you may have heard of, which is

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‫really a part of the Linux subsystem, and that's kind of

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‫how containers work. This isn't anything to do with that.

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‫This is simply Kubernetes saying, hey you might

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‫have a whole lot of stuff going on in your cluster, and I'm

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‫giving you the opportunity to make little mini clusters

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‫where you'd set the namespace with a context and that's

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‫your view is by changing your context.

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‫You can change what you see.

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‫Then the namespace is different segments

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‫for filtering the commands, as well as potentially

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‫the networking. On my system here on my desktop,

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‫I simply see kubectl get namespaces and

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‫that command shows me 4. That's kind of, out-of-the-box,

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‫the standard you're going to see.

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‫Default is what you've been working with so far.

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‫That's made for the default namespace

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‫of your apps. The only thing it really shows you when you

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‫did a kubectl get all is the

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‫Kubernetes API endpoint itself, right.

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‫Until we start adding apps, we didn't really see anything

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‫there. There's technically all this stuff running in the

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‫background, right. That's what the kubectl get all

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‫--all namespaces.

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‫You can see all the API containers

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‫and whatnot running inside Kubernetes itself

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‫with that command. If I look at all the namespaces at once,

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‫I get everything including system stuff.

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‫This is a view of what it would look like on minikube

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‫which puts everything into their own pods for running the

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‫cluster itself.

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‫There's a lot going on there.

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‫The realization is that when you're normally

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‫using Kubernetes, the command line focuses on the default

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‫namespace, by default.

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‫You're only going to see your apps there really, other

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‫than the API endpoint.

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‫That's a good thing, right. It hides the complexity of

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‫what's going on in the background from your everyday

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‫command, because you don't really need to see that stuff

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‫unless you need to upgrade it, or change it, or if you have

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‫a problem. Context comes into play for setting

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‫your view for when you're running commands.

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‫The kubectl does lots of things, right.

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‫It can connect to different clusters.

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‫It can change the authentication, or the user, that

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‫you're using to talk to the cluster, which we haven't

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‫talked about, or the namespace.

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‫So, there's these three parts, really, of a context.

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‫That is cluster, the authentication, or the user,

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‫and then the namespace that you want to see.

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‫All that's defined, by default,

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‫in a file inside the .kube directory

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‫of your home directory.

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‫There's a file in there called config, and it will

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‫basically be a YAML file of all, three of those parts.

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‫You can have multiple entries in there, and you can

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‫edit it however you'd like.

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‫You could have a bunch of different clusters and as long as

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‫you have the certificates to talk to them, the right

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‫authentication, you can put all that stuff in that file,

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‫and it's something you want to keep secret. It's not

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‫something you really want to share because it typically has

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‫your authentication keys for talking

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‫to a cluster. If you use the kubectl config

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‫command with the sub command of get contexts,

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‫that's plural, you can see basically the

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‫output of that file. Instead of dumping it raw, you

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‫can actually see a little nice list of

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‫what it's got inside it.

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00:04:02,750 --> 00:04:05,641
‫In my case, I've got my standard Docker Desktop on my local

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00:04:05,810 --> 00:04:08,456
‫machine. That entry is in there twice for the last few

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00:04:08,780 --> 00:04:11,671
‫editions of Docker Desktop because they've changed the name

93
00:04:11,810 --> 00:04:14,089
‫so they're kind of keeping both in there for compatibility.

94
00:04:14,660 --> 00:04:17,660
‫Then I have a local minikube and

95
00:04:17,690 --> 00:04:20,749
‫a remote instance of micro K8s running

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00:04:20,779 --> 00:04:22,219
‫on an Ubuntu server.

97
00:04:22,490 --> 00:04:24,919
‫So, you can imagine that if I was managing a lot of other

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00:04:24,920 --> 00:04:27,949
‫servers, I don't necessarily always want to ssh into those

99
00:04:27,950 --> 00:04:30,740
‫machines. I really just want to sit on my local machine

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‫and talk to that remote API.

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00:04:33,050 --> 00:04:36,019
‫You can use the kubectl config command with

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‫any of the set options. You definitely want to check out

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00:04:38,690 --> 00:04:42,110
‫the help there. But, there's set options for setting

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‫the defaults for each one of these, so you could

105
00:04:44,840 --> 00:04:47,143
‫potentially change the user to have a different

106
00:04:47,720 --> 00:04:50,464
‫authentication. So, maybe you have God rights instead of

107
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‫just a subset of the commands that Kubernetes is

108
00:04:53,600 --> 00:04:55,699
‫could run. Or, maybe you're going to change the cluster

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‫you're talking to.

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00:04:57,020 --> 00:04:59,715
‫There's even command line plugins if you look around on

111
00:04:59,900 --> 00:05:01,762
‫Google for allowing you to see in your

112
00:05:02,910 --> 00:05:05,790
‫shell which of the context you're using.

113
00:05:06,060 --> 00:05:08,490
‫That's kind of handy when you end up managing a whole bunch

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00:05:08,520 --> 00:05:10,589
‫different clusters. You want to know, hey which one am I

115
00:05:10,590 --> 00:05:13,469
‫talking to right now? You can actually set that up, kind of

116
00:05:13,470 --> 00:05:16,229
‫like how the get prompts will tell you what branch you're

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00:05:16,230 --> 00:05:18,542
‫in. These will tell you, in your prompt, what

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‫context you have.