Deploy only from release branch (#410)

* Deploy only from release branch

* Adapt version.json for deploy from release branch

* Update CONTRIBUTING.md

* Update CONTRIBUTING.md

* Update appveyor.yml

* Add link to create release PR

CONTRIBUTING.md

@@ -4,15 +4,19 @@
 
 This library uses [Nerdbank.GitVersioning](https://github.com/AArnott/Nerdbank.GitVersioning) for generating stable and reproducible version numbers.
 
-The so-called base version is manually maintained in [the version config](version.json). Every build calculates its final version number based on the base version and the number of changes that occured since the last change to the version config.
+The base version is manually maintained in [the version config](version.json). Every build calculates its final version number based on the base version and the number of changes that occured since the last change to the version config.
 
-The base version represents the _next_ version that we will released. During development it contains a prerelease suffix, like `-beta` which is appended to the generated NuGet packages.
+The base version represents the MAJOR and MINOR parts of [SemVer](https://semver.org). If a PR contains breaking changes or new features the base version has to be changed accordingly. If a PR solely contains minor changes (bug fixes, code improvements) nothing needs to be done as the PATCH number will automatically increment with each commit.
 
-Every successful commit on `master` deploys packages to `nuget.org` and a creates GitHub release. As long as we have the prelease suffix both will be marked as such.
+## Branches / tags
+
+* `master` contains the latest sources - this is where we develop.
+* `release` contains the sources for the latest version on `nuget.org` - this is where we deploy from.
+* All versions on `nuget.org` have a matching GitHub release/tag
 
 ### Release workflow
 
-1. Remove prelease suffix from `version.json`.
-1. Wait for the completion of the deployment.
-1. Remove the prerelease flag from the newly created GitHub release.
-1. Increment the version number in `version.json` and again add the prelease suffix (usually `beta` is fine).
+1. Create a [PR from `master` to `release`](https://github.com/System-IO-Abstractions/System.IO.Abstractions/compare/release...master?expand=1) and wait for CI to finish. 
+1. Inspect CI run (test results, version number)
+1. Merge PR and wait for deployment
+1. Inspect newly created package versions on NuGet.org and newly created GitHub release

appveyor.yml

@@ -4,13 +4,17 @@ image:
 
 configuration: Release
 
+# Don't start CI for branches that already have a PR
 skip_branch_with_pr: true
 
+# Don't start CI when tags are pushed
 skip_tags: true
 
+# Limit CI to master/release branches (and PRs targeting them)
 branches:
   only:
     - master
+    - release
 
 environment:
   INHERITDOC_VERSION: 1.2.2.1
@@ -31,6 +35,7 @@ before_package:
 # This step replaces the inheritdoc tags in the xml documentation with documentation from mscorlib.xml
 - ps: '& $env:TEMP_DIR\InheritDoc.$env:INHERITDOC_VERSION\tools\InheritDoc.exe -b $env:APPVEYOR_BUILD_FOLDER -g "c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.X\mscorlib.xml" -o'
 
+# Perform deployments only for Windows job
 for:
 -
   matrix:
@@ -43,13 +48,13 @@ for:
     skip_symbols: false
     artifact: /.*\.nupkg/
     on:
-      branch: master
+      branch: release
 
   - provider: GitHub
     tag: v$(appveyor_build_version)
-    prerelease: true
+    prerelease: false
     artifact: /.*\.nupkg/
     auth_token:
       secure: Rrk1zp93EpCyxec/GXKnRnJjX7vU+ClNZEBnxbM+1j6l+C56qSV7B/fUrVsJuZYV
     on: 
-      branch: master
+      branch: release

version.json

@@ -5,12 +5,12 @@
       "precision": "major"
     },
     "publicReleaseRefSpec": [
-      "^refs/heads/master$"
+      "^refs/heads/release$"
     ],
     "cloudBuild": {
       "buildNumber": {
         "enabled": true,
         "setVersionVariables": true
       }
     }
-}
+}