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Hi let us understand about yaml file, within kubernetes we will be defining

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every object using this yaml that's a declarative way of defining how that

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particular object should behave and what are all its properties. Of course we

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do have other formats as well like XML or Json and comparatively yaml is much

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easier to understand for the human as well as for the computer systems

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understanding of the basics of yaml is much important because we are going to

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define every object for our demo using this yaml file. Yaml it's very simple where

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I am going to have collection of key-value pairs. When I say collection of key-value

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pairs it's like a map where a key is going to be a string and value could be

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anything right from a string or integer or it could be another complex object like a

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collection or in fact another map as well. Let's go over a few samples that's going

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to give us some clarity. In this particular example I do have a collection of map

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that is a key value pair with API version as key and V1 as value. The same way I do

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have another key value pair where kind is a key and value pod. Now instead of this

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particular value I can have another collection as well, the entire yaml file

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works based on the alignment of the text where I am going to have a regular

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interval between the text intent within the yaml file. Say for example within this

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particular file I do have two spaces and that particular aligned collection is going

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to be a child element for this particular element. Let's go over another sample

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here I do have a key value pair api version V1 kind as a key and pod as

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value. The next key is going to be metadata which is going to have another

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map as value and map is going to have a collection of key value pair, where name is

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the key my-site is value, if you look at only this particular block entire map is

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going to be a value for this particular key metadata and within this particular key

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value pair the first element that is name and my-site is one record within the map

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and name is the key my sight is value and within the labels key I'm going to

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have another map as value. So app a web and I may have some more

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additional elements or may not. So this is an example of having another map as the

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value within a key like this I can have any combinations where I can have map of

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maps, maps of list, list of lists and lists of maps. Now let us understand how a list

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going to be. For any key I may want to represent a collection of values, say for

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example when I want to expose a collection of ports, I may give collection

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saying these are all the ports I want to expose or I may want to pass a

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collection of arguments. These are all the arguments I want to pass it as a

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collection. So for a key args I'm going to pass four values that will be marked with

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a dash and all the dash will be arranged in the same intent. Now let us go over this particular

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yaml file where I do have a key value pair api version and v1 this is one key value

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pair and next to that we have another key value pair kind as pod and the next we

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have the key metadata and the value is this, what this particular value going to

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have, that's going to have name as the key my-site as value and the next key is

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labels that's going to have a child key and value pair. Now let's look into this

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specific key, the fourth key that is specs of the entire yaml file, that's going to

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have a key containers. That's having a collection the first element is a map

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and the second element is another map, within the map I do have a key value pair

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name as the key front-end as value. Then I do have images key and I do have value

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then I have ports within that I do have a collection, within the collection I have

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mentioned what is the container port and the other details will follow with a dash.

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So we have seen four major parts that is key that's going to be a string always and

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I'm going to have a value. Value could be any type and it could be a simple string

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or an integer or it could be another complex object like a map or a collection

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and every element within that particular map can have another inner complex

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object. So if you look at yaml file as just key and a value, value could be any

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complex object then the things going to be very simple. If you consider any yaml

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file that's going to have key-value pairs. If you look at this particular example I do

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have a yaml file and I do have a collection of representation of the

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objects, every object will be represented using these four important keys

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api version kind metadata and its specification. Here I do have a kind called

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service and the version is v1, so I do have a key value pair, api version and

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values is v1 the kind is the key and value is service then I do have a key as

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metadata within that I do have a map and how many keys are there, name as one

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key, labels as another key. Name it is having a text and labels is having another

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map, that map is having three key value pairs and the keys are app, tier and role.

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So if you look at any yaml file this is how the structure going to be, let's have an

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understanding on this specific structure, I do have a key value pair api version as

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the key apps/v1 as value and the comment within the yaml file will be

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represented using a hash symbol and the next key value pair is kind as the key

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deployment as value, metadata is the key and that is having a key value pair as a

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value which is having one key value pair name and front end. Then I do have spec

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spec is having selector as one key, replicas as other key, template as another

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key. So everything is represented using this same intent, within template I do

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have a key called metadata and spec, within metadata I do have a key called

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labels that is going to have two key value pairs, app as the key and tier as the

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another key. The same way I can decode any yaml file and we will be representing

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every object within the kubernetes session as the yaml file and the entire

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yaml file will also be uploaded as a part of the session, so that you don't need to

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code the yaml file but always it is a good idea to have a thorough understanding on

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the yaml file, so that any changes to the yaml file we can do it over the text file

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as well and there are n number of online yaml validator, where you can validate

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whether it is following the right syntax or not. So in a quick summary we had seen

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what is the yaml file and how the syntax is being followed within the yaml file and

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we saw a few samples as well how the keys and values

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will be represented within the yaml file.