I stumbled upon a great tool called Dasel which enables you to query and modify data structures using selector strings.
I was working on a Rust project and wanted a way to query Toml files, similar to how you would use jq for json data.
Dasel was exactly what I was looking for.
Installation
If you are on Mac you can use homebrew to install:
brew install dasel
If you are on Linux you can install Dasel using:
wget https://github.com/TomWright/dasel/releases/download/v2.1.2/dasel_linux_amd64
install -o root -g root -m 0755 dasel_linux_amd64 /usr/bin/dasel
YAML
For the first demonstration we will use the following deployment.yaml file:
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- image: nginx:1.15.0
name: nginx
ports:
- containerPort: 80
Let's say we wanted to query the number of replicas:
$ dasel -f deployment.yaml -r yaml '.spec.replicas'
2
If we wanted to view the image:
$ dasel -f deployment.yaml -r yaml '.spec.template.spec.containers.[0].image'
nginx:1.14.2
We can use put to query and write information back to the yaml file. In this example we will update the container image:
dasel put -t string -v nginx:1.15.0 -f deployment.yaml -r yaml '.spec.template.spec.containers.[0].image'
To view if the image was updated:
dasel -f deployment.yaml -r yaml '.spec.template.spec.containers.[0].image'
nginx:1.15.0
TOML
For toml configuration, lets say the file we are working with is Cargo.toml:
[package]
name = "helloworld"
version = "0.1.0"
edition = "2021"
To view the name:
$ dasel -f Cargo.toml -r toml '.package.name'
helloworld
JSON
For JSON data, we can query it like this:
$ echo '{"names": [{"name":{"first":"Tom","last":"Wright"}}]}' | dasel -r json 'names.[0].name.first'
Tom
We can also use the filter function:
$ echo '{"names": [{"name":"Tom","last":"Wright"},{"name":"John","last":"Wrong"}]}' | dasel -r json 'names.all().filter(name)'
Thank You
Thanks for reading.
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