yamlak

yamlak is a command line tool for accessing and manipulating yaml files. It consists of 3 commands that are used to get, set and delete nodes in yaml files.

Usage

yamlak get

Use yamlak get to find what value a node has:

foo@bar:~$ yamlak get spec.template.spec.containers[0].image file.yaml
nginx

yamlak set

You can use yamlak set to set a node to given value.

foo@bar:~$ yamlak get spec.template.spec.containers[0].image "nginx" file.yaml
apiVersion: apps/v1
kind: Deployment
...

Creating paths with yamlak set

Command yamlak set only works if the given node exists, otherwise it returns an error. If you want to create a path to node you should use flag --force or -f:

foo@bar:~$ yamlak get spec.template.spec.containers[0].image "nginx" file.yaml --force
apiVersion: apps/v1
kind: Deployment
...

Flag -f creates the whole path to a node if it doesn't exist, but it does not work when trying to create more than one new array element. So if in spec.template.spec.containers you have just one container defined, then this command will be ok

foo@bar:~$ yamlak get spec.template.spec.containers[1].image "nginx" file.yaml --force
...

but this one will fail

foo@bar:~$ yamlak get spec.template.spec.containers[2].image "nginx" file.yaml --force
...

Updating the file

By default yamlak set will output result of its operation to standard output. If instead you want to overwrite the current file you should use --in-place flag or its shorthand -i:

foo@bar:~$ yamlak get spec.template.spec.containers[1].image "nginx" file.yaml --in-place

Deleting nodes

You can delete nodes in yaml files using yamlak delete or yamlak del:

foo@bar:~$ yamlak del spec.template.spec.containers[1].image file.yaml
apiVersion: apps/v1
kind: Deployment
...

yamlak delete by default prints output to standard output but it supports the --in-force flag when you want to overwrite the file itself

Multi-object files

When working with mult-object (separated with "---") you can make use of --condition flag or its shorthand -c which can help you apply your command to only some of declared objects:

foo@bar:~$ yamlak del spec.template.spec.containers[0].image file.yaml
busybox
nginx

foo@bar:~$ yamlak get spec.template.spec.containers[0].image file.yaml --condition="kind==Deployment"
nginx

foo@bar:~$ yamlak get spec.template.spec.containers[0].image file.yaml --condition="spec.replicas>1"
nginx

The condition flag supports operators ">", "<", "<=", ">=", "!=" oraz "==". When the --condition flag is used with yamlak set or yamlak del it will only modify objects that fulfill condition but the output will consist of all of objects in file.

Using docker image

You can use yamlak by using its docker image but you have to remember to mount the file you want to parse as docker volume:

foo@bar:~$ docker run -v file.yaml:/var/file.yaml slimo300/yamlak get spec.template.spec.containers[0].image /var/file.yaml