A Crossplane Composition Function for calculating Classless Inter-Domain Routing (CIDR) numbers. A CIDR is an IP address allocation method that is used to improve data routing efficiency on the internet.
This composition function offers 4 HashiCorp compatible IP Network Functions plus one custom wrapper. Follow the function links for detailed explanations of the function semantics.
- cidrhost
- cidrnetmask
- cidrsubnet
- cidrsubnets
- cidrsubnetloop wraps cidrsubnet
To use this function, apply the following functions.yaml to your Crossplane management cluster.
cat <<EOF|kubectl apply -f -
apiVersion: pkg.crossplane.io/v1beta1
kind: Function
metadata:
name: function-cidr
annotations:
render.crossplane.io/runtime: Docker
spec:
package: xpkg.upbound.io/upbound/function-cidr:v0.1.0
EOF
Call the function from a Crossplane composition as described below.
The cidrfunc IP Network Functions have various input parameters.
Below are brief descriptions for context.
prefixmust be given in CIDR notation, as defined in RFC 4632 section 3.1.hostnumis a whole number that can be represented as a binary integer with no more than the number of digits remaining in the address after the given prefix.newbitsis the number of additional bits with which to extend the prefix. For example, if given a prefix ending in /16 and a newbits value of 4, the resulting subnet address will have length /20.netnumis a whole number that can be represented as a binary integer with no more than newbits binary digits, which will be used to populate the additional bits added to the prefix.
Specify the cidrfunc calculation type in the composition function input.
Valid values are as follows:
- cidrhost
- cidrnetmask
- cidrsubnet
- cidrsubnets
- cidrsubnetloop
Specify a custom outputfield in the function input parameters
when the output should appear at a different path
than the respective status.atFunction.cidr sub field default path.
All cidrfunc IP Network Functions require a CIDR prefix as input.
Provide the prefix directly in the
function input or specify a prefixfield in the XR where
the function shall pick up the prefix value.
Function input field names ending in field indicate that
the function shall read the field path value from the specified
field path in the XR.
The cidrhost cidrfunc requires a hostnum or hostnumfield as
function input. hostnum is an integer.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: vpc
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrhost
prefix: "10.0.0.0/20"
hostNum: 111
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: vpc
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrhost
prefixField: spec.forFunction.cidr
hostNumField: spec.forFunction.hostNum
outputField: "status.atFunction.cidr.hostAddress"
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
forFunction:
cidr: 10.0.0.0/20
hostNum: 111
The function writes its output into the specified outputfield.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
status:
atFunction:
cidr:
hostAddress: 10.0.0.111
The cidrnetmask cidrfunc does not require additional parameters
beyond the prefix. The prefix can be read from an XR field
when the prefixField path is specified in the function input
instead of a prefix value.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: cidr-example
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrnetmask
prefix: 172.16.0.0/12
The cidrnetmask function does not rely on any fields in the XR.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
The function writes its output to the default status.cidr
field unless the function input outputfield has been specified.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
status:
atFunction:
cidr:
netmask: 255.240.0.0
The cidrhost cidrsubnet reauires a netnum or netnumfield,
and a newbits or newbitsfield as function input.
netNum is an integer.
newBits is one integer in an array of integers.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: cidr-example
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrsubnet
prefixField: spec.forFunction.cidr
newBitsField: spec.forFunction.newBits
netNumField: spec.forFunction.netNum
outputField: status.atFunction.cidr.subnet-1
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
forFunction:
cidr: 10.0.0.0/20
newBits:
- 8
netNum: 3
The function writes its output into the specified outputfield.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
status:
atFunction:
cidr:
subnet-1: 10.0.0.48/28
The cidrhost cidrsubnets reauires a newBits
or newBitsField as function input.
newBits is an array of integers.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: cidr-example
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrsubnets
prefix: 10.0.0.0/20
newBitsField: spec.forFunction.newBits
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
forFunction:
newBits:
- 8
- 4
- 2
The function writes its output into the default outputfield.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
status:
atFunction:
cidr:
subnets:
- 10.0.0.0/28
- 10.0.1.0/24
- 10.0.4.0/22
The cidrhost cidrsubnetloop reauires the following input fields.
newBits(integer array) ornewBitsFieldnetNumCount(integer) ornetNumCountFieldnetNumItems(string array) ornetNumItemsFieldoffsetoroffsetfield** netNumCount and netNumItems are mutually exclusive **
The cidrsubnetloop wrapper calculates cidrsubnet CIDRs using
the prefix and newBits parameters as input. It performs the
calculations in a loop. The netnum is calculated during each
iteration from iteration+offset. The iterations are either from
0 to netNumCount -1 or from 0 to number of items in netNumItemsCount
or their respective values from their XR field references.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: cidr-example
spec:
compositeTypeRef:
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
mode: Pipeline
pipeline:
- step: cidr
functionRef:
name: function-cidr
input:
apiVersion: cidr.fn.crossplane.io/v1beta1
kind: Parameters
cidrFunc: cidrsubnetloop
prefixField: spec.forFunction.cidrBlock
newBitsField: spec.forFunction.newBits
netNumItemsField: spec.forFunction.azs
offsetField: spec.forFunction.offset
outputfield: spec.atFunction.cidr.subnets
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
forFunction:
cidr: 10.0.0.0/20
newBits:
- 8
netNum: 3
The function writes its output into the specified outputField.
apiVersion: platform.upbound.io/v1alpha1
kind: XVPC
metadata:
name: cidr-example
spec:
atFunction:
cidr:
subnets:
- 10.0.0.48/32
- 10.0.0.49/32
- 10.0.0.50/32
- 10.0.0.51/32
- 10.0.0.52/32
Clone the repo. Run make debug and in a second terminal run make render
and examine the output. Corresponding compositions and XR yaml can be
found in the examples folder.