// Copyright 2019 The Kubernetes Authors. // SPDX-License-Identifier: Apache-2.0 // Code generated by "mdtogo"; DO NOT EDIT. package api var ConfigFnLong = `# Configuration Functions API Semantics Configuration Functions are functions packaged as executables in containers which enable **shift-left practices**. They configure applications and infrastructure through Kubernetes style Resource Configuration, but run locally pre-commit. Configuration functions enable shift-left practices (client-side) through: - Pre-commit / delivery validation and linting of configuration - e.g. Fail if any containers don't have PodSecurityPolicy or CPU / Memory limits - Implementation of abstractions as client actuated APIs (e.g. templating) - e.g. Create a client-side *"CRD"* for generating configuration checked into git - Aspect Orient configuration / Injection of cross-cutting configuration - e.g. T-Shirt size containers by annotating Resources with ` + "`" + `small` + "`" + `, ` + "`" + `medium` + "`" + `, ` + "`" + `large` + "`" + ` and inject the cpu and memory resources into containers accordingly. - e.g. Inject ` + "`" + `init` + "`" + ` and ` + "`" + `side-car` + "`" + ` containers into Resources based off of Resource Type, annotations, etc. Performing these on the client rather than the server enables: - Configuration to be reviewed prior to being sent to the API server - Configuration to be validated as part of the CD pipeline - Configuration for Resources to validated holistically rather than individually per-Resource -- e.g. ensure the ` + "`" + `Service.selector` + "`" + ` and ` + "`" + `Deployment.spec.template` + "`" + ` labels match. - MutatingWebHooks are scoped to a single Resource instance at a time. - Low-level tweaks to the output of high-level abstractions -- e.g. add an ` + "`" + `init container` + "`" + ` to a client *"CRD"* Resource after it was generated. - Composition and layering of multiple functions together - Compose generation, injection, validation together Configuration Functions are implemented as executable programs published in containers which: - Accept as input (stdin): - A list of Resource Configuration - A Function Configuration (to configure the function itself) - Emit as output (stdout + exit): - A list of Resource Configuration - An exit code for success / failure ### Function Specification - Functions **SHOULD** be published as container images containing a ` + "`" + `CMD` + "`" + ` invoking an executable. - Functions **MUST** accept input on STDIN a ` + "`" + `ResourceList` + "`" + ` containing the Resources and ` + "`" + `functionConfig` + "`" + `. - Functions **MUST** emit output on STDOUT a ` + "`" + `ResourceList` + "`" + ` containing the modified Resources. - Functions **MUST** exit non-0 on failure, and exit 0 on success. - Functions **MAY** emit output on STDERR with error messaging. - Functions performing validation **SHOULD** exit failure and emit error messaging on a validation failure. - Functions generating Resources **SHOULD** retain non-conflicting changes on the generated Resources -- e.g. 1. the function generates a Deployment, but doesn't specify ` + "`" + `cpu` + "`" + `, 2. the user sets the ` + "`" + `cpu` + "`" + ` on the generated Resource, 3. the function should keep the ` + "`" + `cpu` + "`" + ` when regenerating the Resource a second time. - Functions **SHOULD** be usable outside ` + "`" + `kustomize config run` + "`" + ` -- e.g. though pipeline mechanisms such as Tekton. #### Input Format Functions must accept on STDIN: ` + "`" + `ResourceList` + "`" + `: - contains ` + "`" + `items` + "`" + ` field, same as ` + "`" + `List.items` + "`" + ` - contains ` + "`" + `functionConfig` + "`" + ` field -- a single item with the configuration for the function itself Example ` + "`" + `ResourceList` + "`" + ` Input: apiVersion: config.kubernetes.io/v1alpha1 kind: ResourceList functionConfig: apiVersion: example.com/v1beta1 kind: Nginx metadata: name: my-instance annotations: config.kubernetes.io/local-config: "true" spec: replicas: 5 items: - apiVersion: apps/v1 kind: Deployment metadata: name: my-instance spec: replicas: 3 ... - apiVersion: v1 kind: Service metadata: name: my-instance spec: ... #### Output Format Functions must emit on STDOUT: ` + "`" + `ResourceList` + "`" + `: - contains ` + "`" + `items` + "`" + ` field, same as ` + "`" + `List.items` + "`" + ` Example ` + "`" + `ResourceList` + "`" + ` Output: apiVersion: config.kubernetes.io/v1alpha1 kind: ResourceList items: - apiVersion: apps/v1 kind: Deployment metadata: name: my-instance spec: replicas: 5 ... - apiVersion: v1 kind: Service metadata: name: my-instance spec: ... #### Container Environment When run by ` + "`" + `kustomize config run` + "`" + `, functions are run in containers with the following environment: - Network: ` + "`" + `none` + "`" + ` - User: ` + "`" + `nobody` + "`" + ` - Security Options: ` + "`" + `no-new-privileges` + "`" + ` - Volumes: the volume containing the ` + "`" + `functionConfig` + "`" + ` yaml is mounted under ` + "`" + `/local` + "`" + ` as ` + "`" + `ro` + "`" + ` ### Example Function Implementation Following is an example for implementing an nginx abstraction using a config function. #### ` + "`" + `nginx-template.sh` + "`" + ` ` + "`" + `nginx-template.sh` + "`" + ` is a simple bash script which uses a *heredoc* as a templating solution for generating Resources from the functionConfig input fields. The script wraps itself using ` + "`" + `config run wrap -- $0` + "`" + ` which will: 1. Parse the ` + "`" + `ResourceList.functionConfig` + "`" + ` (provided to the container stdin) into env vars 2. Merge the stdout into the original list of Resources 3. Defaults filenames for newly generated Resources (if they are not set as annotations) to ` + "`" + `config/NAME_KIND.yaml` + "`" + ` 4. Format the output #!/bin/bash # script must run wrapped by ` + "`" + `kustomize config run wrap` + "`" + ` # for parsing input the functionConfig into env vars if [ -z ${WRAPPED} ]; then export WRAPPED=true config run wrap -- $0 exit $? fi cat < result: ` + "`" + `5` + "`" + ` - non-associative lists -- lists without a merge key - if present only in the dest, it keeps its value - if present in the src and is non-null, take the src value -- if ` + "`" + `null` + "`" + `, clear it - example src: ` + "`" + `[1, 2, 3]` + "`" + `, dest: ` + "`" + `[a, b, c]` + "`" + ` => result: ` + "`" + `[1, 2, 3]` + "`" + ` - map keys and fields -- paired by the map-key / field-name - if present only in the dest, it keeps its value - if present only in the src, it is added to the dest - if the field is present in both the src and dest, and the src value is ` + "`" + `null` + "`" + `, the field is removed from the dest - if the field is present in both the src and dest, the value is recursively merged - example src: ` + "`" + `{'key1': 'value1', 'key2': 'value2'}` + "`" + `, dest: ` + "`" + `{'key2': 'value0', 'key3': 'value3'}` + "`" + ` => result: ` + "`" + `{'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}` + "`" + ` - associative list elements -- paired by the associative key - if present only in the dest, it keeps its value in the list - if present only in the src, it is added to the dest list - if the field is present in both the src and dest, the value is recursively merged ### Associative Keys Associative keys are used to identify "same" elements within 2 different lists, and merge them. The following fields are recognized as associative keys: [` + "`" + `mountPath` + "`" + `, ` + "`" + `devicePath` + "`" + `, ` + "`" + `ip` + "`" + `, ` + "`" + `type` + "`" + `, ` + "`" + `topologyKey` + "`" + `, ` + "`" + `name` + "`" + `, ` + "`" + `containerPort` + "`" + `] Any lists where all of the elements contain associative keys will be merged as associative lists. ### Example > Source apiVersion: apps/v1 kind: Deployment spec: replicas: 3 # scalar template: spec: containers: # associative list -- (name) - name: nginx image: nginx:1.7 command: ['new_run.sh', 'arg1'] # non-associative list - name: sidecar2 image: sidecar2:v1 > Destination apiVersion: apps/v1 kind: Deployment spec: replicas: 1 template: spec: containers: - name: nginx image: nginx:1.6 command: ['old_run.sh', 'arg0'] - name: sidecar1 image: sidecar1:v1 > Result apiVersion: apps/v1 kind: Deployment spec: replicas: 3 # scalar template: spec: containers: # associative list -- (name) - name: nginx image: nginx:1.7 command: ['new_run.sh', 'arg1'] # non-associative list - name: sidecar1 image: sidecar1:v1 - name: sidecar2 image: sidecar2:v1` var Merge3Long = `# Merge (3-way) 3-way merge identifies changes between an original source + updated source and merges the result into a destination, overriding the destination fields where they have changed between original and updated. ### Resource MergeRules - Resources present in the original and deleted from the update are deleted. - Resources missing from the original and added in the update are added. - Resources present only in the dest are kept without changes. - Resources present in both the update and the dest have their fields merged with the destination. ### Field Merge Rules Fields are recursively merged using the following rules: - scalars - if present in either dest or updated and ` + "`" + `null` + "`" + `, clear the value - if unchanged between original and updated, keep dest value - if changed between original and updated (added, deleted, changed), take the updated value - non-associative lists -- lists without a merge key - if present in either dest or updated and ` + "`" + `null` + "`" + `, clear the value - if unchanged between original and updated, keep dest value - if changed between original and updated (added, deleted, changed), take the updated value - map keys and fields -- paired by the map-key / field-name - if present in either dest or updated and ` + "`" + `null` + "`" + `, clear the value - if present only in the dest, it keeps its value - if not-present in the dest, add the delta between original-updated as a field - otherwise recursively merge the value between original, updated, dest - associative list elements -- paired by the associative key - if present only in the dest, it keeps its value - if not-present in the dest, add the delta between original-updated as a field - otherwise recursively merge the value between original, updated, dest ### Associative Keys Associative keys are used to identify "same" elements within 2 different lists, and merge them. The following fields are recognized as associative keys: [` + "`" + `mountPath` + "`" + `, ` + "`" + `devicePath` + "`" + `, ` + "`" + `ip` + "`" + `, ` + "`" + `type` + "`" + `, ` + "`" + `topologyKey` + "`" + `, ` + "`" + `name` + "`" + `, ` + "`" + `containerPort` + "`" + `] Any lists where all of the elements contain associative keys will be merged as associative lists.`