Adding linting to Chart and values yaml files (#2429)

This does not lint yaml templates as they are templates rather
than valid yaml files. They cannot be linted with a normal linter

yamllint is used for linting. This is an existing Python project
https://github.com/adrienverge/yamllint

The rules are not the default rules and are stored in their
entirity so they can be controlled over time

The existance of a Chart.yaml file and values.yaml file is checked
and an error is thrown if one is missing. Helm lint will not
detect a chart if Chart.yaml is missing and if a values.yaml file
is missing it is noted as info.

The run function is introduced to enable running all the linters,
capturing non-zero exit codes, and exiting with a non-zdero code
if any of them fail. This is used instead of exiting when the
first failure happens to provide more feedback to chart developers.

.circleci/config.yml

@@ -10,5 +10,5 @@ jobs:
            name: install tools
            command: test/circle/install.sh
        - run: 
-           name: helm lint
+           name: lint
            command: test/circle/lint.sh

test/circle/install.sh

@@ -1,4 +1,4 @@
-#!/bin/bash -xe
+#!/bin/bash -e
 # Copyright 2017 The Kubernetes Authors All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -20,4 +20,8 @@ wget http://storage.googleapis.com/kubernetes-helm/helm-${HELM_LATEST_VERSION}-l
 tar -xvf helm-${HELM_LATEST_VERSION}-linux-amd64.tar.gz
 sudo mv linux-amd64/helm /usr/local/bin
 rm -f helm-${HELM_LATEST_VERSION}-linux-amd64.tar.gz
-rm -rf linux-amd64
+rm -rf linux-amd64
+
+# Install A YAML Linter
+# Pinning to a version for consistency
+sudo pip install yamllint==1.8.1

test/circle/lint.sh

@@ -1,4 +1,4 @@
-#!/bin/bash -xe
+#!/bin/bash
 # Copyright 2017 The Kubernetes Authors All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -16,6 +16,20 @@
 # Compare to the merge-base rather than master to limit scanning to changes
 # this PR/changeset is introducing. Making sure the comparison is to the
 # upstream charts repo rather than a fork.
+
+exitCode=0
+
+# Run is a wrapper around the execution of functions. It captures non-zero exit
+# codes and remembers an error happened. This enables running all the linters
+# and capturing if any of them failed.
+run() {
+  $@
+  local ret=$?
+  if [ $ret -ne 0 ]; then
+    exitCode=1
+  fi
+}
+
 git remote add k8s https://github.com/kubernetes/charts
 git fetch k8s master
 CHANGED_FOLDERS=`git diff --find-renames --name-only $(git merge-base k8s/master HEAD) stable/ incubator/ | awk -F/ '{print $1"/"$2}' | uniq`
@@ -30,6 +44,26 @@ for directory in ${CHANGED_FOLDERS}; do
   if [ "$directory" == "incubator/common" ]; then
     continue
   elif [ -d $directory ]; then
-    helm lint ${directory}
+    run helm lint ${directory}
+
+    # If a Chart.yaml file is present lint it. Otherwise report an error
+    # because one should exist
+    if [ -e ${directory}/Chart.yaml ]; then
+      run yamllint -c test/circle/lintconf.yml ${directory}/Chart.yaml
+    else
+      echo "Error ${directory}/Chart.yaml file is missing"
+      exitCode=1
+    fi
+
+    # If a values.yaml file is present lint it. Otherwise report an error
+    # because one should exist
+    if [ -e ${directory}/values.yaml ]; then
+      run yamllint -c test/circle/lintconf.yml ${directory}/values.yaml
+    else
+      echo "Error ${directory}/values.yaml file is missing"
+      exitCode=1
+    fi
   fi
-done
+done
+
+exit $exitCode

test/circle/lintconf.yml

@@ -0,0 +1,43 @@
+---
+rules:
+  braces:
+    min-spaces-inside: 0
+    max-spaces-inside: 0
+    min-spaces-inside-empty: -1
+    max-spaces-inside-empty: -1
+  brackets:
+    min-spaces-inside: 0
+    max-spaces-inside: 0
+    min-spaces-inside-empty: -1
+    max-spaces-inside-empty: -1
+  colons:
+    max-spaces-before: 0
+    max-spaces-after: 1
+  commas:
+    max-spaces-before: 0
+    min-spaces-after: 1
+    max-spaces-after: 1
+  comments:
+    require-starting-space: true
+    min-spaces-from-content: 2
+  comments-indentation: enable
+  document-end: disable
+  document-start: disable           # No --- to start a file
+  empty-lines:
+    max: 2
+    max-start: 0
+    max-end: 0
+  hyphens:
+    max-spaces-after: 1
+  indentation:
+    spaces: consistent
+    indent-sequences: whatever      # - list indentation will handle both indentation and without
+    check-multi-line-strings: false
+  key-duplicates: enable
+  line-length: disable              # Lines can be any length
+  new-line-at-end-of-file: enable
+  new-lines:
+    type: unix
+  trailing-spaces: enable
+  truthy:
+    level: warning