I am new to YAML and I would like to understand the following piece of a .yaml file:
version: "3.7"
services:
influxdb:
image: influxdb:alpine
environment:
INFLUXDB_DB: ft_services
INFLUXDB_ADMIN_USER: admin
INFLUXDB_ADMIN_PASSWORD: admin
volumes:
- datainfluxdb:/var/lib/influxdb
deploy:
restart_policy:
condition: on-failureAs far as I know, there are 3 types of data that can be used in a .yaml file: scalars, sequences and mappings. For example, version: "3.7" is a scalar. But I am not sure what the following are:
volumes:
- datainfluxdb:/var/lib/influxdbenvironment:
INFLUXDB_DB: ft_services
INFLUXDB_ADMIN_USER: admin
INFLUXDB_ADMIN_PASSWORD: adminI don't really understand what type of data are these and how do they work, can someone give me a hint?
example
volumes:
- data: /var/lib
other-field: "example"
- data: /etcEach indented line beginning with an - above is the beginning of a List Item. There is two items in the list in the example and the whole list is named volumes. The example is a List of Maps, but also List of Scalars is valid.
example
environment:
INFLUXDB_DB: ft_services
INFLUXDB_ADMIN_USER: admin
INFLUXDB_ADMIN_PASSWORD: adminas you wrote, this is a Map with Key-Value pairs and the whole Map is named environment.
As you wrote there is also scalars of various types. A value within quotes like "3.7" is a string.
But I am not sure what the following are:
List of maps:
volumes:
- datainfluxdb:/var/lib/influxdbEqual json:
{
"volumes": [
{"datainfluxdb": "/var/lib/influxdb"}
]
}
Map:
environment:
INFLUXDB_DB: ft_services
INFLUXDB_ADMIN_USER: admin
INFLUXDB_ADMIN_PASSWORD: adminEqual json:
{
"environment": {
"INFLUXDB_DB": "ft_services",
"INFLUXDB_ADMIN_USER": "admin",
"INFLUXDB_ADMIN_PASSWORD": "admin"
}
}
And not mentioned in your question, but a simple List of strings
```
accessModes:
- ReadWriteOnce
```
Equal json:
```
{
"accessModes": [
"ReadWriteOnce"
]
}
```
These 3 are the most frequently seen in Kubernetes.
In my opinion, in the beginning, YAML gets the most confusing when you have nested structures. For easier understanding, I suggest using smth like https://onlineyamltools.com/convert-yaml-to-json to convert to JSON, which has more explicit structures syntax.