Class: K8s::Stack

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/k8s/stack.rb

Overview

Usage: customize the LABEL and CHECKSUM_ANNOTATION

Constant Summary collapse

LABEL = 
'k8s.kontena.io/stack'
CHECKSUM_ANNOTATION = 
'k8s.kontena.io/stack-checksum'
PRUNE_IGNORE = 
[
  'v1:ComponentStatus', # apiserver ignores GET /v1/componentstatuses?labelSelector=... and returns all resources
  'v1:Endpoints', # inherits stack label from service, but not checksum annotation
]

Constants included from Logging

Logging::LOG_LEVEL, Logging::LOG_TARGET

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Logging

included, #logger, #logger!

Methods included from Logging::ModuleMethods

#debug!, #log_level, #log_level=, #quiet!, #verbose!

Constructor Details

#initialize(name, resources = [], debug: false, label: LABEL, checksum_annotation: CHECKSUM_ANNOTATION) ⇒ Stack

Returns a new instance of Stack.



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# File 'lib/k8s/stack.rb', line 41

def initialize(name, resources = [], debug: false, label: LABEL, checksum_annotation: CHECKSUM_ANNOTATION)
  @name = name
  @resources = resources
  @keep_resources = {}
  @label = label
  @checksum_annotation = checksum_annotation

  logger! progname: name, debug: debug
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/k8s/stack.rb', line 39

def name
  @name
end

#resources ⇒ Object (readonly)

Returns the value of attribute resources.



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# File 'lib/k8s/stack.rb', line 39

def resources
  @resources
end

Class Method Details

.apply(name, path, client, prune: true, **options) ⇒ Object

Parameters:

  • name (String) —

    unique name for stack

  • path (String) —

    load resources from YAML files

  • client (K8s::Client) —

    apply using client

  • prune (Boolean) (defaults to: true) —

    delete old resources



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# File 'lib/k8s/stack.rb', line 27

def self.apply(name, path, client, prune: true, **options)
  load(name, path, **options).apply(client, prune: prune)
end

.delete(name, client, **options) ⇒ Object

Remove any installed stack resources.

Parameters:

  • name (String) —

    unique name for stack

  • client (K8s::Client) —

    apply using client



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# File 'lib/k8s/stack.rb', line 35

def self.delete(name, client, **options)
  new(name, **options).delete(client)
end

.load(name, path, **options) ⇒ K8s::Stack

Parameters:

  • name (String) —

    unique name for stack

  • path (String) —

    load resources from YAML files

Returns:



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# File 'lib/k8s/stack.rb', line 18

def self.load(name, path, **options)
  resources = K8s::Resource.from_files(path)
  new(name, resources, **options)
end

Instance Method Details

#apply(client, prune: true) ⇒ Array<K8s::Resource>

Returns:



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# File 'lib/k8s/stack.rb', line 71

def apply(client, prune: true)
  server_resources = client.get_resources(resources)

  resources.zip(server_resources).map do |resource, server_resource|
    if server_resource
      # keep server checksum for comparison
      # NOTE: this will not compare equal for resources with arrays containing hashes with default values applied by the server
      #       however, that will just cause extra PUTs, so it doesn't have any functional effects
      compare_resource = server_resource.merge(resource).merge(metadata: {
        labels: { @label => name },
      })
    end

    if !server_resource
      logger.info "Create resource #{resource.apiVersion}:#{resource.kind}/#{resource.metadata.name} in namespace #{resource.metadata.namespace} with checksum=#{checksum}"
      keep_resource! client.create_resource(prepare_resource(resource))
    elsif server_resource != compare_resource
      logger.info "Update resource #{resource.apiVersion}:#{resource.kind}/#{resource.metadata.name} in namespace #{resource.metadata.namespace} with checksum=#{checksum}"
      keep_resource! client.update_resource(prepare_resource(resource, base_resource: server_resource))
    else
      logger.info "Keep resource #{resource.apiVersion}:#{resource.kind}/#{resource.metadata.name} in namespace #{resource.metadata.namespace} with checksum=#{compare_resource.metadata.annotations[@checksum_annotation]}"
      keep_resource! compare_resource
    end
  end

  prune(client, keep_resources: true) if prune
end

#checksum ⇒ Object 



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# File 'lib/k8s/stack.rb', line 51

def checksum
  @checksum ||= SecureRandom.hex(16)
end

#delete(client) ⇒ Object

Delete all stack resources



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# File 'lib/k8s/stack.rb', line 134

def delete(client)
  prune(client, keep_resources: false)
end

#keep_resource!(resource) ⇒ Object

key MUST NOT include resource.apiVersion: the same kind can be aliased in different APIs



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# File 'lib/k8s/stack.rb', line 100

def keep_resource!(resource)
  @keep_resources["#{resource.kind}:#{resource.metadata.name}@#{resource.metadata.namespace}"] = resource.metadata.annotations[@checksum_annotation]
end

#keep_resource?(resource) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/k8s/stack.rb', line 103

def keep_resource?(resource)
  @keep_resources["#{resource.kind}:#{resource.metadata.name}@#{resource.metadata.namespace}"] == resource.metadata.annotations[@checksum_annotation]
end

#prepare_resource(resource, base_resource: nil) ⇒ K8s::Resource

Parameters:

  • resource (K8s::Resource) —

    to apply

  • base_resource (K8s::Resource) (defaults to: nil) —

    preserve existing attributes from base resource

Returns:



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# File 'lib/k8s/stack.rb', line 58

def prepare_resource(resource, base_resource: nil)
  if base_resource
    resource = base_resource.merge(resource)
  end

  # add stack metadata
  resource.merge(metadata: {
    labels: { @label => name },
    annotations: { @checksum_annotation => checksum },
  })
end

#prune(client, keep_resources:) ⇒ Object

Delete all stack resources that were not applied



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# File 'lib/k8s/stack.rb', line 108

def prune(client, keep_resources: )
  client.list_resources(labelSelector: {@label => name}).each do |resource|
    next if PRUNE_IGNORE.include? "#{resource.apiVersion}:#{resource.kind}"

    resource_label = resource.metadata.labels ? resource.metadata.labels[@label] : nil
    resource_checksum = resource.metadata.annotations ? resource.metadata.annotations[@checksum_annotation] : nil

    logger.debug { "List resource #{resource.apiVersion}:#{resource.kind}/#{resource.metadata.name} in namespace #{resource.metadata.namespace} with checksum=#{resource_checksum}" }

    if resource_label != name
      # apiserver did not respect labelSelector
    elsif keep_resources && keep_resource?(resource)
      # resource is up-to-date
    else
      logger.info "Delete resource #{resource.apiVersion}:#{resource.kind}/#{resource.metadata.name} in namespace #{resource.metadata.namespace}"
      begin
        client.delete_resource(resource)
      rescue K8s::Error::NotFound
        # assume aliased objects in multiple API groups, like for Deployments
        # alternatively, a custom resource whose definition was already deleted earlier
      end
    end
  end
end