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If you are a DevOps Engineer, YAML parsing is something you will come across in different situations while writing automation scripts or in code.
YQ is a lightweight command-line utility to parse YAML. But wait, there’s more!
Not just YAML, yq also works with JSON, XML, LUA, Shell output, and properties files.
Also written in Go
Project: github.com/mikefarah/yq
It handles almost all file types you’ll encounter in CI/CD pipelines. Perfect for those times when you need to tweak files on the fly.
Here is one use case.
You can pair yq with kustomize to patch values directly into your YAML files.
For instance, read an image name from an environment variable and add it to the YAML.
Practical Examples
Let’s take an example of pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: my-nginx-pod
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80To get the apiVersion,
yq eval '.apiVersion' pod.yamlTo change the image name
yq eval -i '.spec.containers[0].image = "nginx:1.18"' pod.yamlLets say you want to extract a specific value from Helm values.yaml
yq eval '.app.image.tag' values.yamlYAML Formating
Another feature I really like about yq is --prettyPrint. It ensures the YAML configuration files are correctly formatted before deploying.
Using exit codes, you can use this as a YAML validator in CI/CD pipelines.
$ yq eval --prettyPrint secret.yaml
Error: bad file 'test.yaml': yaml: line 11: mapping values are not allowed in this context
$ echo $?
1