Add workflow to update go mod version.

actions/update-go-mod-version/Dockerfile

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+FROM alpine
+
+RUN apk add \
+    bash \
+    && rm -rf /var/cache/apk/*
+
+COPY entrypoint /entrypoint
+ENTRYPOINT ["/entrypoint"]

actions/update-go-mod-version/action.yml

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+name: "Update Go Mod Version"
+description: |
+  Updates the versions of go and the go toolchain in a go.mod file
+
+inputs:
+  toolchain-version:
+    description: 'Version of the toolchain to write'
+    required: true
+
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+  - "--toolchain-version"
+  - "${{ inputs.toolchain-version }}"

actions/update-go-mod-version/entrypoint

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+#! /usr/bin/env bash
+
+set -euo pipefail
+shopt -s inherit_errexit
+
+function main() {
+  local min_go_version toolchain_version
+  min_go_version="1.21" # 1.21 is the minimum to use the toolchain directive in go.mod
+  toolchain_version=""
+
+  while [[ "${#}" != 0 ]]; do
+    case "${1}" in
+      --toolchain-version)
+        toolchain_version="${2}"
+        shift 2
+        ;;
+
+      "")
+        # skip if the argument is empty
+        shift 1
+        ;;
+
+      *)
+        echo "Unknown argument" "$@"
+        exit 1
+    esac
+  done
+
+  if [[ -z "${toolchain_version}" ]]; then
+    echo "Must provide toolchain version"
+    exit 1
+  fi
+
+  found_go_version="$(grep -E 'go ([0-9]+\.[0-9]+)' < go.mod | sed 's/go //g')"
+
+  if lt "${found_go_version}" "${min_go_version}"; then
+    echo "Updating go version to the minimum required version '${min_go_version}' (was '${found_go_version}')"
+    sed -i "s/go ${found_go_version}/go ${min_go_version}/g" go.mod
+    found_go_version="${min_go_version}"
+  else
+    echo "not updating go version as current version (${found_go_version}) is >= minimum required version (${min_go_version})"
+  fi
+
+  echo "setting toolchain to: '${toolchain_version}'"
+  if grep -qE 'toolchain go(.*)' < go.mod; then 
+    sed -i "s/toolchain go.*/toolchain go${toolchain_version}/g" go.mod    
+  else
+    # Write the toolchain directive two lines below the go version
+    sed -i "/go ${found_go_version}/r"<(printf "\ntoolchain go%s\n" "${toolchain_version}") go.mod
+  fi
+}
+
+# returns $1 <= $2
+function lte() {
+    printf '%s\n' "$1" "$2" | sort -CV
+}
+
+# returns $1 < $2
+function lt() {
+  ! lte "$2" "$1"
+}
+
+main "${@:-}"
+

builder/.github/workflows/update-go-mod-version.yml

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+name: Update Go version
+
+on:
+  schedule:
+    - cron: '53 5 * * MON'  # every monday at 5:53 UTC
+  workflow_dispatch:
+
+concurrency: update-go
+
+jobs:
+  update-go:
+    name: Update go toolchain in go.mod
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Checkout PR Branch
+        uses: paketo-buildpacks/github-config/actions/pull-request/checkout-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+      - name: Setup Go
+        id: setup-go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 'stable'
+      - name: Get current go toolchain version
+        id: current-go-version
+        uses: pivotal-cf/tanzu-cnb-github-config/actions/update-go-mod-version@main
+        with:
+          toolchain-version: ${{ steps.setup-go.outputs.go-version }}
+      - name: Show changes
+        run: |
+          echo "head -n10 go.mod "
+          head -n10 go.mod
+
+          echo "git diff"
+          git diff
+      - name: Commit
+        id: commit
+        uses: paketo-buildpacks/github-config/actions/pull-request/create-commit@main
+        with:
+          message: "Updating go mod version"
+          pathspec: "."
+          keyid: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY_ID }}
+          key: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY }}
+
+      - name: Push Branch
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/push-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+
+      - name: Open Pull Request
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/open@main
+        with:
+          token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+          title: "Updates go mod version"
+          branch: automation/go-mod-update/update-main
+
+  failure:
+    name: Alert on Failure
+    runs-on: ubuntu-22.04
+    needs: [update-go]
+    if: ${{ always() && needs.update-go.result == 'failure' }}
+    steps:
+      - name: File Failure Alert Issue
+        uses: paketo-buildpacks/github-config/actions/issue/file@main
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          repo: ${{ github.repository }}
+          label: "failure:update-go-version"
+          comment_if_exists: true
+          issue_title: "Failure: Update Go Mod Version workflow"
+          issue_body: |
+            Update GitHub config workflow [failed](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}).
+          comment_body: |
+            Another failure occurred: https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}

implementation/.github/workflows/update-go-mod-version.yml

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+name: Update Go version
+
+on:
+  schedule:
+    - cron: '48 4 * * MON'  # every monday at 4:48 UTC
+  workflow_dispatch:
+
+concurrency: update-go
+
+jobs:
+  update-go:
+    name: Update go toolchain in go.mod
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Checkout PR Branch
+        uses: paketo-buildpacks/github-config/actions/pull-request/checkout-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+      - name: Setup Go
+        id: setup-go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 'stable'
+      - name: Get current go toolchain version
+        id: current-go-version
+        uses: pivotal-cf/tanzu-cnb-github-config/actions/update-go-mod-version@main
+        with:
+          toolchain-version: ${{ steps.setup-go.outputs.go-version }}
+      - name: Show changes
+        run: |
+          echo "head -n10 go.mod "
+          head -n10 go.mod
+
+          echo "git diff"
+          git diff
+      - name: Commit
+        id: commit
+        uses: paketo-buildpacks/github-config/actions/pull-request/create-commit@main
+        with:
+          message: "Updating go mod version"
+          pathspec: "."
+          keyid: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY_ID }}
+          key: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY }}
+
+      - name: Push Branch
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/push-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+
+      - name: Open Pull Request
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/open@main
+        with:
+          token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+          title: "Updates go mod version"
+          branch: automation/go-mod-update/update-main
+
+  failure:
+    name: Alert on Failure
+    runs-on: ubuntu-22.04
+    needs: [update-go]
+    if: ${{ always() && needs.update-go.result == 'failure' }}
+    steps:
+      - name: File Failure Alert Issue
+        uses: paketo-buildpacks/github-config/actions/issue/file@main
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          repo: ${{ github.repository }}
+          label: "failure:update-go-version"
+          comment_if_exists: true
+          issue_title: "Failure: Update Go Mod Version workflow"
+          issue_body: |
+            Update GitHub config workflow [failed](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}).
+          comment_body: |
+            Another failure occurred: https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}

language-family/.github/workflows/update-go-mod-version.yml

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+name: Update Go version
+
+on:
+  schedule:
+    - cron: '13 4 * * MON'  # every monday at 4:13 UTC
+  workflow_dispatch:
+
+concurrency: update-go
+
+jobs:
+  update-go:
+    name: Update go toolchain in go.mod
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Checkout PR Branch
+        uses: paketo-buildpacks/github-config/actions/pull-request/checkout-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+      - name: Setup Go
+        id: setup-go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 'stable'
+      - name: Get current go toolchain version
+        id: current-go-version
+        uses: pivotal-cf/tanzu-cnb-github-config/actions/update-go-mod-version@main
+        with:
+          toolchain-version: ${{ steps.setup-go.outputs.go-version }}
+      - name: Show changes
+        run: |
+          echo "head -n10 go.mod "
+          head -n10 go.mod
+
+          echo "git diff"
+          git diff
+      - name: Commit
+        id: commit
+        uses: paketo-buildpacks/github-config/actions/pull-request/create-commit@main
+        with:
+          message: "Updating go mod version"
+          pathspec: "."
+          keyid: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY_ID }}
+          key: ${{ secrets.PAKETO_BOT_GPG_SIGNING_KEY }}
+
+      - name: Push Branch
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/push-branch@main
+        with:
+          branch: automation/go-mod-update/update-main
+
+      - name: Open Pull Request
+        if: ${{ steps.commit.outputs.commit_sha != '' }}
+        uses: paketo-buildpacks/github-config/actions/pull-request/open@main
+        with:
+          token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+          title: "Updates go mod version"
+          branch: automation/go-mod-update/update-main
+
+  failure:
+    name: Alert on Failure
+    runs-on: ubuntu-22.04
+    needs: [update-go]
+    if: ${{ always() && needs.update-go.result == 'failure' }}
+    steps:
+      - name: File Failure Alert Issue
+        uses: paketo-buildpacks/github-config/actions/issue/file@main
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          repo: ${{ github.repository }}
+          label: "failure:update-go-version"
+          comment_if_exists: true
+          issue_title: "Failure: Update Go Mod Version workflow"
+          issue_body: |
+            Update GitHub config workflow [failed](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}).
+          comment_body: |
+            Another failure occurred: https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}