Add backport CLI (#490)

* Add backport CLI

* Reformat nix files

* Attempt 2 without node2nix

* Remove backport node2nix task and format files

* Add comment about how to regen the package-lock.json if necessary

* Add CONTRIBUTING.md backport section

Author: andrewstucki

.backportrc.json

@@ -0,0 +1,9 @@
+{
+  "repoOwner": "redpanda-data",
+  "repoName": "redpanda-operator",
+  "targetBranchChoices": ["release/v2.3.x"],
+  "targetPRLabels": ["backport"],
+  "branchLabelMapping": {
+    "^v(\\d+).(\\d+).\\d+$": "release/v$1.$2.x"
+  }
+}

CONTRIBUTING.md

@@ -31,6 +31,16 @@ It is recommend to use [direnv](https://direnv.net/) to automatically enter the
 development shell when `cd`'ing into the repository. The [.envrc](./.envrc) is
 already configured.
 
+## Backporting
+
+We are currently experimenting with workflows for backporting leveraging the
+[backport CLI](https://github.com/sorenlouv/backport). To do a manual backport, once a PR
+has merged, ensure that you have a Github personal access token in
+`~/.backport/config.json` as documented [here](https://github.com/sorenlouv/backport/blob/v9.6.6/docs/config-file-options.md#global-config-backportconfigjson),
+and then run `backport --pr ###` with the PR number.
+
+We will eventually try and set up an automated Github action for backports based on PR labels.
+
 ## CHANGELOG Management
 
 Our CHANGELOG.mds are managed with [Changie](https://github.com/miniscruff/changie).
@@ -49,4 +59,4 @@ To release any project in this repository:
 4. Commit the resultant diff with the commit message `<project>: cut release <version>` and rebase it into master via a Pull Request.
 5. Tag the above commit with as `<project>/v<version>` with `git tag $(changie latest -j <project>) <commit-sha>`.
     - If the operator is being released, also tag the same commit as `v<version>`.
-6. Push the tag(s).
+6. Push the tag(s).

ci/backport.nix

@@ -0,0 +1,44 @@
+{ buildNpmPackage
+, fetchFromGitHub
+, lib
+, pkgs
+}:
+
+buildNpmPackage rec {
+  pname = "backport";
+  version = "9.6.6";
+
+  src = fetchFromGitHub {
+    owner = "sorenlouv";
+    repo = "backport";
+    rev = "v${version}";
+    hash = "sha256-VgEOUqbsgZ0EP9dN9iRmh+V05gEUaNhKASivt0pUKIw=";
+  };
+
+  dontNpmBuild = true;
+
+  # the compiled typescript files don't come in the release tags and neither does a package-lock.json
+  # due to this project using yarn, so just copy over the checked in package-lock.json and generate
+  # the typescript files prior to installation so the binary can be run.
+  #   
+  # to generate a new package-lock.json if say the version of backport installed needs to be changed
+  # download the version of the backport release you want to install unzip it into your system, run "npm install"
+  # and copy the package-lock.json to "ci/files/backport-package-lock.json"
+  preInstall = ''
+    npx tsc
+  '';
+  packageLock = pkgs.writeText "package-lock.json" (builtins.readFile ./files/backport-package-lock.json);
+  postPatch = ''
+    cp ${packageLock} package-lock.json
+  '';
+
+  npmDepsHash = "sha256-ZjmP/kCDEYHHJLFyITIPlM93TFMYDSLbrRS9MGHAEvE=";
+
+  meta = with lib; {
+    description = "Backport CLI tool";
+    mainProgram = "backport";
+    homepage = "https://github.com/sorenlouv/backport";
+    changelog = "https://github.com/sorenlouv/backport/releases/tag/v${version}";
+    license = licenses.asl20;
+  };
+}