diff --git a/.github/workflows/dockerimage.yml b/.github/workflows/dockerimage.yml
new file mode 100644
index 0000000..a9822c5
--- /dev/null
+++ b/.github/workflows/dockerimage.yml
@@ -0,0 +1,13 @@
+name: Docker Image CI
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag ${{ github.repository }}:$(date +%s)
diff --git a/.github/workflows/reviewdog.yml b/.github/workflows/reviewdog.yml
new file mode 100644
index 0000000..7e683dd
--- /dev/null
+++ b/.github/workflows/reviewdog.yml
@@ -0,0 +1,40 @@
+name: reviewdog
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  shellcheck:
+    name: runner / shellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: haya14busa/action-cond@v1
+        id: reporter
+        with:
+          cond: ${{ github.event_name == 'pull_request' }}
+          if_true: "github-pr-review"
+          if_false: "github-check"
+      - uses: reviewdog/action-shellcheck@v1
+        with:
+          github_token: ${{ secrets.github_token }}
+          reporter: ${{ steps.reporter.outputs.value }}
+          level: warning
+
+  hadolint:
+    name: runner / hadolint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: haya14busa/action-cond@v1
+        id: reporter
+        with:
+          cond: ${{ github.event_name == 'pull_request' }}
+          if_true: "github-pr-review"
+          if_false: "github-check"
+      - uses: reviewdog/action-hadolint@v1
+        with:
+          github_token: ${{ secrets.github_token }}
+          reporter: ${{ steps.reporter.outputs.value }}
+          level: warning
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..9f69c41
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,20 @@
+name: Test
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ./
+        id: autobump
+        with:
+          file: testdata/testfile
+          version_name: REVIEWDOG_VERSION
+          repo: reviewdog/reviewdog
+
+      - name: Check diff
+        run: git diff
diff --git a/.github/workflows/update_semver.yml b/.github/workflows/update_semver.yml
new file mode 100644
index 0000000..8e832ec
--- /dev/null
+++ b/.github/workflows/update_semver.yml
@@ -0,0 +1,15 @@
+name: Update Semver
+on:
+  push:
+    branches-ignore:
+      - '**'
+    tags:
+      - 'v*.*.*'
+jobs:
+  update-semver:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: haya14busa/action-update-semver@v1
+        with:
+          github_token: ${{ secrets.github_token }}
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..0d29f94
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,7 @@
+FROM alpine:3.10
+
+RUN apk --no-cache add git jq curl grep coreutils
+
+COPY entrypoint.sh /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..4fecb82
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 haya14busa
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..e1dcdd6
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,23 @@
+name: 'Bump version in code to latest semantic ver release'
+description: 'Bump version in code to latest semantic ver release. (e.g. REVIEWDOG=0.9.17 in Dockerfile)'
+author: 'haya14busa'
+inputs:
+  github_token:
+    description: 'GITHUB_TOKEN to get latest version with GitHub Release API'
+    default: '${{ github.token }}'
+  file:
+    description: 'target file'
+    required: true
+  version_name:
+    description: 'target version name. e.g. REVIEWDOG_VERSION'
+    required: true
+  repo:
+    description: 'target GitHub repository. e.g. reviewdog/reviewdog'
+    required: true
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+# Ref: https://haya14busa.github.io/github-action-brandings/
+branding:
+  icon: 'refresh-cw'
+  color: 'orange'
diff --git a/entrypoint.sh b/entrypoint.sh
new file mode 100755
index 0000000..b0b8295
--- /dev/null
+++ b/entrypoint.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+set -e
+
+if [ -n "${GITHUB_WORKSPACE}" ]; then
+  cd "${GITHUB_WORKSPACE}" || exit
+fi
+
+FILE="${INPUT_FILE:-Dockerfile}"
+REPO="${INPUT_REPO:-reviewdog/reviewdog}"
+VERSION_NAME="${INPUT_VERSION_NAME:-REVIEWDOG_VERSION}"
+
+# Get current version.
+CURRENT_VERSION=$(grep -oP "${VERSION_NAME}=\K\d+\.\d+\.\d+" "${FILE}")
+if [ -z "${CURRENT_VERSION}" ]; then
+  echo "cannot parse ${VERSION_NAME}"
+  exit 1
+fi
+echo "Current ${VERSION_NAME}=${CURRENT_VERSION}"
+
+# Get latest semantic version release tag name from GitHub Release API.
+list_releases() {
+  if [ -n "${INPUT_GITHUB_TOKEN}" ]; then
+    echo "Use INPUT_GITHUB_TOKEN to get release data." >&2
+    curl -s -H "Authorization: token ${INPUT_GITHUB_TOKEN}" "https://api.github.com/repos/${REPO}/releases"
+  else
+    echo "INPUT_GITHUB_TOKEN is not available. Subscequent GitHub API call can fail due to API limit." >&2
+    curl -s "https://api.github.com/repos/${REPO}/releases"
+  fi
+}
+LATEST_VERSION=$(\
+  list_releases | \
+  jq -r '.[] | .tag_name' | \
+  sed 's/^v//' | \
+  grep -P '\d+\.\d+\.\d+' | \
+  sort --version-sort --reverse | \
+  head -n1
+)
+if [ -z "${LATEST_VERSION}" ]; then
+  echo "cannot get latest ${REPO} version"
+  exit 1
+fi
+echo "Latest ${VERSION_NAME}=${LATEST_VERSION}"
+
+if [ "${CURRENT_VERSION}" = "${LATEST_VERSION}" ]; then
+  echo "${VERSION_NAME} is latest. Nothing to do."
+  exit 0
+fi
+
+echo "Updating ${VERSION_NAME} to ${LATEST_VERSION} in ${FILE}"
+sed -i "s/\(${VERSION_NAME}=\)\([0-9]\+\.[0-9]\+\.\?[0-9]\+\)/\1${LATEST_VERSION}/" "${FILE}"
+
+echo "Updated. Commit and create Pull-Request as you need."
+echo "::set-output name=current::${CURRENT_VERSION}"
+echo "::set-output name=latest::${LATEST_VERSION}"
diff --git a/testdata/testfile b/testdata/testfile
new file mode 100644
index 0000000..501c049
--- /dev/null
+++ b/testdata/testfile
@@ -0,0 +1,6 @@
+This is test file.
+
+REVIEWDOG_VERSION=0.1.0
+
+The above version should be updated to the latest version with this action.
+