diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..97f6577
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,12 @@
+FROM ubuntu:20.04
+
+LABEL maintainer="Antrea <projectantrea-dev@googlegroups.com>"
+LABEL description="A Docker-based Github action to determine if changes were made outside of a provided path exclusion list."
+
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends git jq && \
+    rm -rf /var/lib/apt/lists/*
+
+COPY entrypoint.sh /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]
diff --git a/README.md b/README.md
index b0da520..49aed7a 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,26 @@
-# has-changes
-A GitHub action to detect if the diff for a push or pull_request event has changes outside of a list of paths
+# "Has Changes" Docker Action
+
+This action sets a boolean output (`has_changes`) if the diff (`push` or
+`pull_request` event) includes changes outside of a provided list of paths.
+
+## Inputs
+
+The list of paths to exclude. The action will use Bash pattern matching, so
+wildcards (`*`) are supported.
+
+## Outputs
+
+### `has_changes`
+
+Whether ('yes' or 'no') the diff includes changes outside of the provided list
+of paths.
+
+## Example usage
+
+```yaml
+uses: antrea-io/antrea/ci/gh-actions/has-changes@main
+with:
+  args: docs *.md ci
+```
+
+Make sure to checkout the repo first.
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..9cea910
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,9 @@
+# action.yml
+name: 'Has Changes'
+description: 'Checks if diff includes changes outside of a provided path exclusion list'
+outputs:
+  has_changes:
+    description: 'Whether (yes/no) the diff includes changes'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
diff --git a/entrypoint.sh b/entrypoint.sh
new file mode 100755
index 0000000..fc4840b
--- /dev/null
+++ b/entrypoint.sh
@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+# Copyright 2022 Antrea Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+set -eo pipefail
+
+read -r -a PATTERNS <<< "$*"
+
+cat "$GITHUB_EVENT_PATH"
+
+PR_BASE_SHA=$(jq -r '.pull_request.base.sha' "$GITHUB_EVENT_PATH")
+BEFORE=$(jq -r '.before' "$GITHUB_EVENT_PATH")
+if [[ $PR_BASE_SHA != "" && $PR_BASE_SHA != "null" ]]; then # PR events
+    SHA=$PR_BASE_SHA
+elif [[ $BEFORE != "" && $BEFORE != "null" ]]; then # push events
+    SHA=$BEFORE
+else
+    echo "This does not appear to be a PR or a push event"
+    echo "Setting 'has_changes' to 'yes'"
+    echo "::set-output name=has_changes::yes"
+    exit 0
+fi
+echo "BASE SHA: $SHA"
+
+CHANGED_FILES=$(git diff --name-only "$SHA" HEAD) || rc=$?
+
+if [[ $rc -ne 0 ]]; then
+    echo "Error when running 'git diff'"
+    echo "This is expected when the repo was not checked-out properly, or after a force push"
+    echo "Setting 'has_changes' to 'yes'"
+    echo "::set-output name=has_changes::yes"
+    exit 0
+fi
+
+echo "CHANGED_FILES are:"
+echo "$CHANGED_FILES"
+
+has_changes=false
+for changed_file in $CHANGED_FILES; do
+    matched=false
+    for pattern in "${PATTERNS[@]}"; do
+        if [[ "$changed_file" == $pattern ]]; then
+            matched=true
+            break
+        fi
+    done
+    if ! $matched; then
+        has_changes=true
+        break
+    fi
+done
+
+if $has_changes; then
+    echo "Setting 'has_changes' to 'yes'"
+    echo "::set-output name=has_changes::yes"
+else
+    echo "Setting 'has_changes' to 'no'"
+    echo "::set-output name=has_changes::no"
+fi