[chore] add automation for codeowner tooling

.github/workflows/add-codeowners-to-pr.yml

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+name: 'Add code owners to a PR'
+on:
+  pull_request_target:
+    types:
+      - opened
+      - synchronize
+
+jobs:
+  add-owners-to-pr:
+    runs-on: ubuntu-24.04
+    if: ${{ github.actor != 'dependabot[bot]' && github.actor != 'renovate[bot]' && github.repository_owner == 'open-telemetry' }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run add-codeowners-to-pr.sh
+        run: ./.github/workflows/scripts/add-codeowners-to-pr.sh
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          PR: ${{ github.event.number }}

.github/workflows/add-labels.yml

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+name: 'Add Labels'
+on:
+  issue_comment:
+    types: [created]
+
+jobs:
+  add-labels:
+    if: ${{ !github.event.issue.pull_request && startsWith(github.event.comment.body, '/label') && github.repository_owner == 'open-telemetry' }}
+
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run add-labels.sh
+        run: ./.github/workflows/scripts/add-labels.sh
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ISSUE: ${{ github.event.issue.number }}
+          COMMENT: ${{ github.event.comment.body }}
+          SENDER: ${{ github.event.sender.login }}

.github/workflows/ping-codeowners-issues.yml

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+name: 'Ping code owners on issues'
+on:
+  issues:
+    types: [labeled]
+
+jobs:
+  ping-owners:
+    runs-on: ubuntu-24.04
+    if: ${{ github.repository_owner == 'open-telemetry' }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run ping-codeowners-issues.sh
+        run: ./.github/workflows/scripts/ping-codeowners-issues.sh
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ISSUE: ${{ github.event.issue.number }}
+          COMPONENT: ${{ github.event.label.name }}

.github/workflows/ping-codeowners-on-new-issue.yml

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+name: 'Ping code owners on a new issue'
+on:
+  issues:
+    types: [opened]
+
+jobs:
+  ping-owners-on-new-issue:
+    runs-on: ubuntu-24.04
+    if: ${{ github.repository_owner == 'open-telemetry' }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run ping-codeowners-on-new-issue.sh
+        run: ./.github/workflows/scripts/ping-codeowners-on-new-issue.sh
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ISSUE: ${{ github.event.issue.number }}
+          TITLE: ${{ github.event.issue.title }}
+          BODY: ${{ github.event.issue.body }}
+          OPENER: ${{ github.event.issue.user.login }}

.github/workflows/ping-codeowners-prs.yml

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+name: 'Ping code owners on PRs'
+on:
+  pull_request_target:
+    types: [labeled]
+
+jobs:
+  ping-owners:
+    runs-on: ubuntu-24.04
+    if: ${{ github.actor != 'dependabot[bot]' && github.actor != 'renovate[bot]' && github.repository_owner == 'open-telemetry' }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run ping-codeowners-prs.sh
+        run: ./.github/workflows/scripts/ping-codeowners-prs.sh
+        env:
+          REPO: ${{ github.repository }}
+          AUTHOR: ${{ github.event.pull_request.user.login }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR: ${{ github.event.number }}
+          COMPONENT: ${{ github.event.label.name }}

.github/workflows/scripts/add-codeowners-to-pr.sh

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+#!/usr/bin/env bash
+#
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+#
+# Adds code owners without write access as reviewers on a PR. Note that
+# the code owners must still be a member of the `open-telemetry`
+# organization.
+#
+# Note that since this script is considered a requirement for PRs,
+# it should never fail.
+
+set -euo pipefail
+
+if [[ -z "${REPO:-}" || -z "${PR:-}" ]]; then
+    echo "One or more of REPO and PR have not been set, please ensure each is set."
+    exit 0
+fi
+
+main () {
+    CUR_DIRECTORY=$(dirname "$0")
+    # Reviews may have comments that need to be cleaned up for jq,
+    # so restrict output to only printable characters and ensure escape
+    # sequences are removed.
+    # The latestReviews key only returns the latest review for each reviewer,
+    # cutting out any other reviews. We use that instead of requestedReviews
+    # since we need to get the list of users eligible for requesting another
+    # review. The GitHub CLI does not offer a list of all reviewers, which
+    # is only available through the API. To cut down on API calls to GitHub,
+    # we use the latest reviews to determine which users to filter out.
+    JSON=$(gh pr view "${PR}" --json "files,author,latestReviews" | tr -dc '[:print:]' | sed -E 's/\\[a-z]//g')
+    AUTHOR=$(echo -n "${JSON}"| jq -r '.author.login')
+    FILES=$(echo -n "${JSON}"| jq -r '.files[].path')
+    REVIEW_LOGINS=$(echo -n "${JSON}"| jq -r '.latestReviews[].author.login')
+    COMPONENTS=$(bash "${CUR_DIRECTORY}/get-components.sh")
+    REVIEWERS=""
+    LABELS=""
+    declare -A PROCESSED_COMPONENTS
+    declare -A REVIEWED
+
+    for REVIEWER in ${REVIEW_LOGINS}; do
+        # GitHub adds "app/" in front of user logins. The API docs don't make
+        # it clear what this means or whether it will always be present. The
+        # '/' character isn't a valid character for usernames, so this won't
+        # replace characters within a username.
+        REVIEWED["@${REVIEWER//app\//}"]=true
+    done
+
+    if [[ -v REVIEWED[@] ]]; then
+        echo "Users that have already reviewed this PR and will not have another review requested:" "${!REVIEWED[@]}"
+    else
+        echo "This PR has not yet been reviewed, all code owners are eligible for a review request"
+    fi
+
+    for COMPONENT in ${COMPONENTS}; do
+        # Files will be in alphabetical order and there are many files to
+        # a component, so loop through files in an inner loop. This allows
+        # us to remove all files for a component from the list so they
+        # won't be checked against the remaining components in the components
+        # list. This provides a meaningful speedup in practice.
+        for FILE in ${FILES}; do
+            MATCH=$(echo -n "${FILE}" | grep -E "^${COMPONENT}" || true)
+
+            if [[ -z "${MATCH}" ]]; then
+                continue
+            fi
+
+            # If we match a file with a component we don't need to process the file again.
+            FILES=$(echo -n "${FILES}" | grep -v "${FILE}")
+
+            if [[ -v PROCESSED_COMPONENTS["${COMPONENT}"] ]]; then
+                continue
+            fi
+
+            PROCESSED_COMPONENTS["${COMPONENT}"]=true
+
+            OWNERS=$(COMPONENT="${COMPONENT}" bash "${CUR_DIRECTORY}/get-codeowners.sh")
+
+            for OWNER in ${OWNERS}; do
+                # Users that leave reviews are removed from the "requested reviewers"
+                # list and are eligible to have another review requested. We only want
+                # to request a review once, so remove them from the list.
+                if [[ -v REVIEWED["${OWNER}"] || "${OWNER}" = "@${AUTHOR}" ]]; then
+                    continue
+                fi
+
+                if [[ -n "${REVIEWERS}" ]]; then
+                    REVIEWERS+=","
+                fi
+                REVIEWERS+=$(echo -n "${OWNER}" | sed -E 's/@(.+)/"\1"/')
+            done
+
+            # Convert the CODEOWNERS entry to a label
+            COMPONENT_NAME=$(echo -n "${COMPONENT}" | sed -E 's%^(.+)/(.+)\1%\1/\2%')
+
+            if (( "${#COMPONENT_NAME}" > 50 )); then
+                echo "'${COMPONENT_NAME}' exceeds GitHub's 50-character limit on labels, skipping adding label"
+                continue
+            fi
+
+            if [[ -n "${LABELS}" ]]; then
+                LABELS+=","
+            fi
+            LABELS+="${COMPONENT_NAME}"
+        done
+    done
+
+    if [[ -n "${LABELS}" ]]; then
+        echo "Adding labels: ${LABELS}"
+        gh pr edit "${PR}" --add-label "${LABELS}" || echo "Failed to add labels"
+    else
+        echo "No labels found"
+    fi
+
+    # Note that adding the labels above will not trigger any other workflows to
+    # add code owners, so we have to do it here.
+    #
+    # We have to use the GitHub API directly due to an issue with how the CLI
+    # handles PR updates that causes it require access to organization teams,
+    # and the GitHub token doesn't provide that permission.
+    # For more: https://github.com/cli/cli/issues/4844
+    #
+    # The GitHub API validates that authors are not requested to review, but
+    # accepts duplicate logins and logins that are already reviewers.
+    if [[ -n "${REVIEWERS}" ]]; then
+        echo "Requesting review from ${REVIEWERS}"
+        curl \
+            -X POST \
+            -H "Accept: application/vnd.github+json" \
+            -H "Authorization: Bearer ${GITHUB_TOKEN}" \
+            "https://api.github.com/repos/${REPO}/pulls/${PR}/requested_reviewers" \
+            -d "{\"reviewers\":[${REVIEWERS}]}" \
+            | jq ".message" \
+            || echo "jq was unable to parse GitHub's response"
+    else
+        echo "No code owners found"
+    fi
+}
+
+# We don't want this workflow to ever fail and block a PR,
+# so ensure all errors are caught.
+main || echo "Failed to run $0"

.github/workflows/scripts/add-labels.sh

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+#!/usr/bin/env bash
+#
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+#
+#
+
+set -euo pipefail
+
+if [[ -z "${ISSUE:-}" || -z "${COMMENT:-}" || -z "${SENDER:-}" ]]; then
+    echo "At least one of ISSUE, COMMENT, or SENDER has not been set, please ensure each is set."
+    exit 0
+fi
+
+CUR_DIRECTORY=$(dirname "$0")
+
+if [[ ${COMMENT:0:6} != "/label" ]]; then
+    echo "Comment is not a label comment, exiting."
+    exit 0
+fi
+
+# key: label in comment
+# value: actual label
+declare -A COMMON_LABELS
+COMMON_LABELS["arm64"]="arm64"
+COMMON_LABELS["good-first-issue"]="good first issue"
+COMMON_LABELS["help-wanted"]="help wanted"
+COMMON_LABELS["discussion-needed"]="discussion-needed"
+COMMON_LABELS["os:macos"]="os:macos"
+COMMON_LABELS["os:windows"]="os:windows"
+COMMON_LABELS["waiting-for-author"]="waiting-for-author"
+COMMON_LABELS["waiting-for-codeowners"]="waiting-for-codeowners"
+COMMON_LABELS["bug"]="bug"
+COMMON_LABELS["priority:p0"]="priority:p0"
+COMMON_LABELS["priority:p1"]="priority:p1"
+COMMON_LABELS["priority:p2"]="priority:p2"
+COMMON_LABELS["priority:p3"]="priority:p3"
+COMMON_LABELS["stale"]="Stale"
+
+LABELS=$(echo "${COMMENT}" | sed -E 's%^/label%%')
+
+for LABEL_REQ in ${LABELS}; do
+    LABEL=$(echo "${LABEL_REQ}" | sed -E s/^[+-]?//)
+    # Trim newlines from label that would cause matching to fail
+    LABEL=$(echo "${LABEL}" | tr -d '\n')
+
+    SHOULD_ADD=true
+    if [[ "${LABEL_REQ:0:1}" = "-" ]]; then
+        SHOULD_ADD=false
+    fi
+
+    if [[ -v COMMON_LABELS["${LABEL}"] ]]; then
+        if [[ ${SHOULD_ADD} = true ]]; then
+            gh issue edit "${ISSUE}" --add-label "${COMMON_LABELS["${LABEL}"]}"
+        else
+            gh issue edit "${ISSUE}" --remove-label "${COMMON_LABELS["${LABEL}"]}"
+        fi
+        continue
+    fi
+
+    # Grep exits with status code 1 if there are no matches,
+    # so we manually set RESULT to 0 if nothing is found.
+    RESULT=$(grep -c "${LABEL}" .github/CODEOWNERS || true)
+
+    if [[ ${RESULT} = 0 ]]; then
+        echo "\"${LABEL}\" doesn't correspond to a component, skipping."
+        continue
+    fi
+
+    if [[ ${SHOULD_ADD} = true ]]; then
+        gh issue edit "${ISSUE}" --add-label "${LABEL}"
+
+        # Labels added by a GitHub Actions workflow don't trigger other workflows
+        # by design, so we have to manually ping code owners here.
+        COMPONENT="${LABEL}" ISSUE=${ISSUE} SENDER="${SENDER}" bash "${CUR_DIRECTORY}/ping-codeowners-issues.sh"
+    else
+        gh issue edit "${ISSUE}" --remove-label "${LABEL}"
+    fi
+done
+
+

.github/workflows/scripts/get-codeowners.sh

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+#!/usr/bin/env bash
+#
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+#
+# This script checks the GitHub CODEOWNERS file for any code owners
+# of contrib components and returns a string of the code owners if it
+# finds them.
+
+set -euo pipefail
+
+get_component_type() {
+  echo "${COMPONENT}" | cut -f 1 -d '/'
+}
+
+get_codeowners() {
+  # grep arguments explained:
+  #   -m 1: Match the first occurrence
+  #   ^: Match from the beginning of the line
+  #   ${1}: Insert first argument given to this function
+  #   [\/]\?: Match 0 or 1 instances of a forward slash
+  #   \s: Match any whitespace character
+(grep -m 1 "^${1}[\/]\?\s" .github/CODEOWNERS || true) | \
+        sed 's/   */ /g' | \
+        cut -f3- -d ' '
+}
+
+if [[ -z "${COMPONENT:-}" ]]; then
+    echo "COMPONENT has not been set, please ensure it is set."
+    exit 1
+fi
+
+OWNERS="$(get_codeowners "${COMPONENT}")"
+
+if [[ -z "${OWNERS:-}" ]]; then
+    COMPONENT_TYPE=$(get_component_type "${COMPONENT}")
+    OWNERS="$(get_codeowners "${COMPONENT}${COMPONENT_TYPE}")"
+fi
+
+echo "${OWNERS}"

.github/workflows/scripts/get-components.sh

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+#!/usr/bin/env sh
+#
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+#
+# Get a list of components within the repository that have some form of ownership
+# ascribed to them.
+
+grep -E '^[A-Za-z0-9/]' .github/CODEOWNERS | \
+    awk '{ print $1 }' | \
+    sed -E 's%(.+)/$%\1%'