Linting for yaml files (#872)

* Add YAML file linting

* Add cmake-linux.yml lint and address its concerns

.circleci/config.yml

@@ -1,3 +1,4 @@
+---
 version: 2.1
 
 orbs:

.github/workflows/cmake-linux.yml

@@ -1,3 +1,4 @@
+---
 name: CMake
 
 on: [push]
@@ -8,9 +9,9 @@ env:
 
 jobs:
   build:
-    # The CMake configure and build commands are platform agnostic and should work equally
-    # well on Windows or Mac.  You can convert this to a matrix build if you need
-    # cross-platform coverage.
+    # The CMake configure and build commands are platform agnostic and should
+    # work equally well on Windows or Mac.  You can convert this to a matrix
+    # build if you need cross-platform coverage.
     # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
     runs-on: ${{ matrix.os }}
     strategy:
@@ -24,29 +25,33 @@ jobs:
       - uses: actions/checkout@v2
 
       - name: Create Build Environment
-      # Some projects don't allow in-source building, so create a separate build directory
-      # We'll use this as our working directory for all subsequent commands
+        # Some projects don't allow in-source building, so create a separate
+        # build directory. We'll use this as our working directory for all
+        # subsequent commands
         run: cmake -E make_directory ${{github.workspace}}/build
 
       - name: Configure CMake
-      # Use a bash shell so we can use the same syntax for environment variable
-      # access regardless of the host operating system
+        # Use a bash shell so we can use the same syntax for environment
+        # variable access regardless of the host operating system
         shell: bash
         working-directory: ${{github.workspace}}/build
-      # Note the current convention is to use the -S and -B options here to specify source 
-      # and build directories, but this is only available with CMake 3.13 and higher.  
-      # The CMake binaries on the Github Actions machines are (as of this writing) 3.12
+        # Note the current convention is to use the -S and -B options here to
+        # specify source and build directories, but this is only available
+        # with CMake 3.13 and higher. The CMake binaries on the Github Actions
+        # machines are (as of this writing) 3.12
         run: cmake $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=$BUILD_TYPE
 
       - name: Build
         working-directory: ${{github.workspace}}/build
         shell: bash
-      # Execute the build.  You can specify a specific target with "--target <NAME>"
+        # Execute the build.  You can specify a specific target
+        # with "--target <NAME>"
         run: cmake --build . --config $BUILD_TYPE
 
       - name: Test
         working-directory: ${{github.workspace}}/build
         shell: bash
         # Execute tests defined by the CMake configuration.
-      # See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
+        # See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more
+        # detail
         run: ctest -C $BUILD_TYPE

.travis.yml

@@ -1,3 +1,4 @@
+---
 language: c++
 dist: xenial
 

.yamllint.yml

@@ -0,0 +1,8 @@
+---
+extends: default
+
+rules:
+  # 80 chars should be enough, but don't fail if a line is longer
+  line-length:
+    max: 80
+    level: warning

Makefile.in

@@ -140,6 +140,7 @@ BUILD_DEP:=\
 	libzstd-dev \
 	shellcheck \
 	uncrustify \
+	yamllint \
 
 SUBDIRS+=tools
 
@@ -147,7 +148,7 @@ COVERAGEDIR?=coverage
 
 .PHONY: $(SUBDIRS)
 .PHONY: steps build push all clean distclean install test cover gcov build-dep
-.PHONY: lint lint.python lint.ccode lint.shell
+.PHONY: lint lint.python lint.ccode lint.shell lint.yaml
 
 all: $(APPS) $(DOCS) $(SUBDIRS)
 
@@ -184,7 +185,7 @@ win32/n2n_win32.a: win32
 test: tools
 	scripts/test_harness.sh
 
-lint: lint.python lint.ccode lint.shell
+lint: lint.python lint.ccode lint.shell lint.yaml
 
 lint.python:
 	flake8 scripts/n2n-ctl scripts/n2n-httpd
@@ -195,6 +196,10 @@ lint.ccode:
 lint.shell:
 	shellcheck scripts/*.sh
 
+lint.yaml:
+	yamllint .circleci/config.yml .travis.yml .yamllint.yml \
+		.github/workflows/cmake-linux.yml
+
 # To generate coverage information, run configure with
 # CFLAGS="-fprofile-arcs -ftest-coverage" LDFLAGS="--coverage"
 # and run the desired tests.  Ensure that package gcovr is installed