diff --git a/.github/actions/release/action.yaml b/.github/actions/release/action.yaml
new file mode 100644
index 0000000..c3f3b23
--- /dev/null
+++ b/.github/actions/release/action.yaml
@@ -0,0 +1,38 @@
+name: release
+description: release executables
+
+inputs:
+  tag:
+    description: check out the tag if not empty
+    default: ''
+  token:
+    description: GitHub token
+    required: true
+
+runs:
+  using: composite
+
+  steps:
+  - uses: actions/checkout@v3
+    name: "checkout tag ${{ inputs.tag }}"
+    if: "inputs.tag != ''"
+    with:
+      ref: refs/tags/${{ inputs.tag }}
+    env:
+      GITHUB_TOKEN: ${{ inputs.token }}
+  - name: Set up Go
+    uses: actions/setup-go@v3
+    with:
+      go-version: ~1.16
+  - name: Login to GitHub Container Registry
+    uses: docker/login-action@v2
+    with:
+      registry: ghcr.io
+      username: pfnet-research
+      password: ${{ inputs.token }}
+  - name: Run GoReleaser
+    uses: goreleaser/goreleaser-action@v3
+    with:
+      args: release --rm-dist
+    env:
+      GITHUB_TOKEN: ${{ inputs.token }}
diff --git a/.github/release-drafter.yml b/.github/release-drafter.yml
deleted file mode 100644
index 2c9d4fb..0000000
--- a/.github/release-drafter.yml
+++ /dev/null
@@ -1,20 +0,0 @@
-name-template: 'v$NEXT_PATCH_VERSION'
-tag-template: 'v$NEXT_PATCH_VERSION'
-categories:
-- title: '💣 Breaking Changes'
-  label: 'release-note/breaking-change'
-- title: '🚀 Features'
-  label: 'release-note/feature'
-- title: '🐛 Bug Fixes'
-  label: 'release-note/bugfix'
-- title: '📜 Documentation'
-  label: 'release-note/document'
-- title: '🧰 Maintenance'
-  label: 'release-note/chore'
-exclude-labels:
-- 'release-note/skip'
-template: |
-  ## What’s Changed from $PREVIOUS_TAG
-  $CHANGES
-
-  Thanks to $CONTRIBUTORS
diff --git a/.github/release.yml b/.github/release.yml
new file mode 100644
index 0000000..9d9a77b
--- /dev/null
+++ b/.github/release.yml
@@ -0,0 +1,24 @@
+changelog:
+  exclude:
+    labels:
+    - release-note/skip
+    - tagpr
+  categories:
+  - title: "💣 Breaking Changes"
+    labels:
+    - release-note/breaking-change
+  - title: "🚀 Features"
+    labels:
+    - release-note/feature
+  - title: "🐛 Bug Fixes"
+    labels:
+    - release-note/bugfix
+  - title: "📜 Documentation"
+    labels:
+    - release-note/document
+  - title: "🧰 Maintenance"
+    labels:
+    - release-note/chore
+  - title: "🔬 Other Changes"
+    labels:
+    - "*"
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index f8b1309..7f2751e 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -11,57 +11,57 @@ on:
 
 jobs:
 
-  test:
-    name: Test
+  lint:
+    name: Lint
     runs-on: ubuntu-latest
     steps:
+    - name: Check out
+      uses: actions/checkout@v3
     - name: Set up Go 1.x
-      uses: actions/setup-go@v2
+      uses: actions/setup-go@v3
       with:
-        go-version: ^1.16
+        go-version: ~1.16
       id: go
-    - name: Check out code into the Go module directory
-      uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
     - name: Get dependencies
       run: go mod download
     - name: Get Devtools
       run: make setup
     - name: Lint
       run : make lint
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out
+      uses: actions/checkout@v3
+    - name: Set up Go 1.x
+      uses: actions/setup-go@v3
+      with:
+        go-version: ~1.16
+      id: go
+    - name: Get dependencies
+      run: go mod download
+    - name: Get Devtools
+      run: make setup
     - name: Build
-      run: make
+      run: make build-only
     - name: Test
       run: make test
-    - name: Validate .goreleaser.yml
-      uses: goreleaser/goreleaser-action@v2
-      with:
-        version: latest
-        args: release --snapshot --skip-publish --rm-dist --debug
 
-  image_build:
-    name: Image Build
+  validate-goreleaser:
+    name: Validate .goreleaser.yml
     runs-on: ubuntu-latest
-    env:
-      DOCKER_BUILDKIT: 1
-      IMAGE_PREFIX: docker.pkg.github.com/${{ github.repository }}/
     steps:
-      - name: Set up Go 1.x
-        uses: actions/setup-go@v2
-        with:
-          go-version: ^1.16
-        id: go
-      - name: Check out
-        uses: actions/checkout@v2
-        with:
-          fetch-depth: 0
-      - name: Get Devtools
-        run: make setup
-      - name: Login GitHub Registry
-        run: docker login docker.pkg.github.com -u owner -p ${{ secrets.GITHUB_TOKEN }}
-      - name: Build Docker image
-        run: make build-image
-      - name: Push Docker image
-        if: github.ref == 'refs/heads/master' && github.event_name == 'push'
-        run: make push-image
+    - name: Check out
+      uses: actions/checkout@v3
+    - name: Set up Go 1.x
+      uses: actions/setup-go@v3
+      with:
+        go-version: ~1.16
+      id: go
+    - name: Validate GoReleaser
+      uses: goreleaser/goreleaser-action@v3
+      with:
+        version: latest
+        args: release --snapshot --skip-publish --rm-dist --debug
diff --git a/.github/workflows/manual_release.yaml b/.github/workflows/manual_release.yaml
new file mode 100644
index 0000000..adacef2
--- /dev/null
+++ b/.github/workflows/manual_release.yaml
@@ -0,0 +1,17 @@
+name: Release By Tagged Manually
+on:
+  push:
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+"
+
+jobs:
+  goreleaser:
+    name: Release
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/')
+    steps:
+      - name: Check out
+        uses: actions/checkout@v3
+      - uses: ./.github/actions/release
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/publish_dev_image.yaml b/.github/workflows/publish_dev_image.yaml
new file mode 100644
index 0000000..d562d4b
--- /dev/null
+++ b/.github/workflows/publish_dev_image.yaml
@@ -0,0 +1,47 @@
+name: Publish Dev Image
+
+on:
+  push:
+    branches: [ master ]
+    tags-ignore: [ "**" ]
+    paths-ignore: [ "**.md" ]
+
+jobs:
+  publish_dev_image:
+    name: Publish Dev Image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v3
+      - name: Set up Go 1.x
+        uses: actions/setup-go@v3
+        with:
+          go-version: ~1.16
+        id: go
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: pfnet-research
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build Snapshots
+        uses: goreleaser/goreleaser-action@v3
+        with:
+          version: latest
+          args: release --snapshot --rm-dist --debug
+        # Mimic docker, docker_manifests artifacts in goreleaser here.
+        # because "goreleaser release --snapshot" does NOT publish any artifact
+      - name: Publish Snapshot Images
+        shell: bash
+        run: |
+          set -euo pipefail
+          IMAGES=($(jq -r '.[] | select(.type=="Docker Image") | .name' dist/artifacts.json))
+          for i in ${IMAGES[@]}; do
+            docker push $i
+          done
+          MANIFEST=$(jq '.[] | select(.type=="Docker Image") | .name' dist/artifacts.json | jq -sr '.[0]' | sed -e "s|-[a-z0-9]\+$||g")
+          docker manifest create ${MANIFEST} ${IMAGES[@]}
+          docker manifest push ${MANIFEST}
+          MANIFEST_LATEST=$(jq '.[] | select(.type=="Docker Image") | .name' dist/artifacts.json | jq -sr '.[0]' | sed -e "s|:.*$||g"):latest
+          docker manifest create ${MANIFEST_LATEST} ${IMAGES[@]}
+          docker manifest push ${MANIFEST_LATEST}
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
deleted file mode 100644
index 2082906..0000000
--- a/.github/workflows/release.yaml
+++ /dev/null
@@ -1,72 +0,0 @@
-name: Release
-on:
-  push:
-    tags:
-      - "v[0-9]+.[0-9]+.[0-9]+"
-
-jobs:
-  image_build:
-    name: Release Docker Image
-    runs-on: ubuntu-latest
-    if: startsWith(github.ref, 'refs/tags/')
-    env:
-      RELEASE: "true"
-      DOCKER_BUILDKIT: 1
-      IMAGE_PREFIX: docker.pkg.github.com/${{ github.repository }}/
-    steps:
-      - name: Set up Go 1.x
-        uses: actions/setup-go@v2
-        with:
-          go-version: ^1.16
-        id: go
-      - name: Check out
-        uses: actions/checkout@v2
-        with:
-          fetch-depth: 0
-      - name: Get Devtools
-        run: make setup
-      - name: Login GitHub Registry
-        run: docker login docker.pkg.github.com -u owner -p ${{ secrets.GITHUB_TOKEN }}
-      - name: Build Docker image
-        run: make build-image
-      - name: Push Docker image
-        run: make push-image
-
-  goreleaser:
-    name: Release Binaries
-    runs-on: ubuntu-latest
-    if: startsWith(github.ref, 'refs/tags/')
-    env:
-      RELEASE: "true"
-    steps:
-      - name: Set up Go 1.x
-        uses: actions/setup-go@v2
-        with:
-          go-version: ^1.16
-        id: go
-      - name: Check out
-        uses: actions/checkout@v2
-        with:
-          fetch-depth: 0
-      - name: Get Devtools
-        run: make setup
-      - name: Get dependencies
-        run: go mod download
-      - name: Run GoReleaser
-        uses: goreleaser/goreleaser-action@v2
-        with:
-          version: latest
-          args: release --rm-dist
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-  update_release_draft:
-    name: Draft Release Note
-    runs-on: ubuntu-latest
-    if: startsWith(github.ref, 'refs/tags/')
-    env:
-      RELEASE: "true"
-    steps:
-      - uses: release-drafter/release-drafter@v5
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/tagpr.yaml b/.github/workflows/tagpr.yaml
new file mode 100644
index 0000000..e5fb31f
--- /dev/null
+++ b/.github/workflows/tagpr.yaml
@@ -0,0 +1,32 @@
+#
+# tagpr workflow
+#
+name: tagpr
+on:
+  push:
+    branches: ["master"]
+
+jobs:
+  tagpr:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - id: tagpr
+      name: Tagpr
+      uses: Songmu/tagpr@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      # If tagpr pushed tags, invoke release custom action manually.
+      # It is because:
+      # > When you use the repository's GITHUB_TOKEN to perform tasks, 
+      # > events triggered by the GITHUB_TOKEN, with the exception of 
+      # > workflow_dispatch and repository_dispatch, will not create 
+      # > a new workflow run.
+      # ref: https://docs.github.com/en/actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow
+    - name: "Release (only when tagged)"
+      uses: ./.github/actions/release
+      if: "steps.tagpr.outputs.tag != ''"
+      with:
+        tag: ${{ steps.tagpr.outputs.tag }}
+        token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.goreleaser.yaml b/.goreleaser.yaml
index 0e14cc1..787d614 100644
--- a/.goreleaser.yaml
+++ b/.goreleaser.yaml
@@ -22,7 +22,47 @@ builds:
   - netgo
   ldflags:
   - -s -w -X github.com/pfnet-research/pftaskqueue/cmd.Version={{.Version}} -X github.com/pfnet-research/pftaskqueue/cmd.Revision={{.ShortCommit}} -extldflags "-static"
-# changelog will be generated by release drafter
-# see .github/release-drafter.yml
+
+dockers:
+- image_templates: ["ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-amd64"]
+  dockerfile: Dockerfile
+  goarch: amd64
+  use: buildx
+  build_flag_templates:
+  - --platform=linux/amd64
+  - --label=org.opencontainers.image.title={{ .ProjectName }}
+  - --label=org.opencontainers.image.description={{ .ProjectName }}
+  - --label=org.opencontainers.image.url=https://github.com/pfnet-research/{{ .ProjectName }}
+  - --label=org.opencontainers.image.source=https://github.com/pfnet-research/{{ .ProjectName }}
+  - --label=org.opencontainers.image.version={{ .Version }}
+  - --label=org.opencontainers.image.revision={{ .ShortCommit }}
+  - --label=org.opencontainers.image.licenses=Apache-2.0
+- image_templates: ["ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-arm64v8"]
+  dockerfile: Dockerfile
+  goarch: arm64
+  use: buildx
+  build_flag_templates:
+  - --platform=linux/arm64/v8
+  - --label=org.opencontainers.image.title={{ .ProjectName }}
+  - --label=org.opencontainers.image.description={{ .ProjectName }}
+  - --label=org.opencontainers.image.url=https://github.com/pfnet-research/{{ .ProjectName }}
+  - --label=org.opencontainers.image.source=https://github.com/pfnet-research/{{ .ProjectName }}
+  - --label=org.opencontainers.image.version={{ .Version }}
+  - --label=org.opencontainers.image.revision={{ .ShortCommit }}
+  - --label=org.opencontainers.image.licenses=Apache-2.0
+
+docker_manifests:
+- name_template: ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}
+  image_templates:
+  - ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-amd64
+  - ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-arm64v8
+- name_template: ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev{{else}}release{{end}}:latest
+  image_templates:
+  - ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-amd64
+  - ghcr.io/pfnet-research/{{ .ProjectName }}/{{ if .IsSnapshot }}dev:{{ incpatch .Version }}-alpha-{{ .ShortCommit }}{{else}}release:{{ .Version }}{{end}}-arm64v8
+
+snapshot:
+  name_template: '{{ incpatch .Version }}-alpha-{{ .ShortCommit }}'
+
 changelog:
   skip: true
diff --git a/.tagpr b/.tagpr
new file mode 100644
index 0000000..065e8a3
--- /dev/null
+++ b/.tagpr
@@ -0,0 +1,36 @@
+# config file for the tagpr in git config format
+# The tagpr generates the initial configuration, which you can rewrite to suit your environment.
+# CONFIGURATIONS:
+#   tagpr.releaseBranch
+#       Generally, it is "main." It is the branch for releases. The pcpr tracks this branch,
+#       creates or updates a pull request as a release candidate, or tags when they are merged.
+#
+#   tagpr.versionFile
+#       Versioning file containing the semantic version needed to be updated at release.
+#       It will be synchronized with the "git tag".
+#       Often this is a meta-information file such as gemspec, setup.cfg, package.json, etc.
+#       Sometimes the source code file, such as version.go or Bar.pm, is used.
+#       If you do not want to use versioning files but only git tags, specify the "-" string here.
+#       You can specify multiple version files by comma separated strings.
+#
+#   tagpr.vPrefix
+#       Flag whether or not v-prefix is added to semver when git tagging. (e.g. v1.2.3 if true)
+#       This is only a tagging convention, not how it is described in the version file.
+#
+#   tagpr.changelog (Optional)
+#       Flag whether or not changelog is added or changed during the release.
+#
+#   tagpr.command (Optional)
+#       Command to change files just before release.
+#
+#   tagpr.tmplate (Optional)
+#       Pull request template in go template format
+#
+#   tagpr.release (Optional)
+#       GitHub Release creation behavior after tagging [true, draft, false]
+#       If this value is not set, the release is to be created.
+[tagpr]
+	vPrefix = true
+	releaseBranch = master
+	versionFile = -
+	changelog = false
diff --git a/Dockerfile b/Dockerfile
index df45f0a..81fa7b0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,16 +1,4 @@
-FROM golang:1.16 as builder
-ARG RELEASE
-ARG VERSION
-WORKDIR /workspace
-COPY go.mod go.mod
-COPY go.sum go.sum
-RUN go mod download
-
-COPY . /workspace
-RUN make build-only
-
-FROM ubuntu:18.04 as runtime
-RUN apt-get update && apt-get install -y ca-certificates && apt-get clean && rm -rf /var/lib/apt/lists/*
+FROM gcr.io/distroless/base-debian11
 WORKDIR /
-COPY --from=builder /workspace/dist/pftaskqueue /usr/local/bin/pftaskqueue
+COPY pftaskqueue /usr/local/bin/pftaskqueue
 ENTRYPOINT ["/usr/local/bin/pftaskqueue"]
diff --git a/Makefile b/Makefile
index 601b6e8..094c97b 100644
--- a/Makefile
+++ b/Makefile
@@ -4,12 +4,9 @@ export CGO_ENABLED=0
 
 # project metadta
 NAME         := pftaskqueue
-VERSION      ?= $(if $(RELEASE),$(shell git semv now),$(shell git semv patch -p))
 REVISION     := $(shell git rev-parse --short HEAD)
 IMAGE_PREFIX ?= pftaskqueue/
-IMAGE_NAME   := $(if $(RELEASE),release,dev)
-IMAGE_TAG    ?= $(if $(RELEASE),$(VERSION),$(VERSION)-$(REVISION))
-LDFLAGS      := -ldflags="-s -w -X \"github.com/pfnet-research/pftaskqueue/cmd.Version=$(VERSION)\" -X \"github.com/pfnet-research/pftaskqueue/cmd.Revision=$(REVISION)\" -extldflags \"-static\""
+LDFLAGS      := -ldflags="-s -w -X github.com/pfnet-research/pftaskqueue/cmd.Version=dev -X github.com/pfnet-research/pftaskqueue/cmd.Revision=$(REVISION) -extldflags \"-static\""
 OUTDIR       ?= ./dist
 
 .DEFAULT_GOAL := build
@@ -17,69 +14,38 @@ OUTDIR       ?= ./dist
 .PHONY: setup
 setup:
 	npm install --prefix=.dev markdown-toc && \
-	npm install --prefix=.dev github-release-notes && \
 	cd $(shell go env GOPATH) && \
 	go get -u golang.org/x/tools/cmd/goimports && \
 	curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(shell go env GOPATH)/bin v1.27.0 && \
-	go get -u github.com/elastic/go-licenser && \
-	go get -u github.com/tcnksm/ghr && \
-	go get -u github.com/linyows/git-semv/cmd/git-semv
+	go get -u github.com/elastic/go-licenser
+
 
 .PHONY: fmt
-fmt:
+fmt: build-readme-toc
 	$(shell go env GOPATH)/bin/goimports -w cmd/ pkg/
 	$(shell go env GOPATH)/bin/go-licenser --licensor "Preferred Networks, Inc."
 
 .PHONY: lint
 lint: fmt
 	$(shell go env GOPATH)/bin/golangci-lint run --config .golangci.yml --deadline 30m
+	git diff --exit-code README.md
 
 .PHONY: build-readme-toc
 build-readme-toc:
 	.dev/node_modules/markdown-toc/cli.js -i README.md
 
 .PHONY: build
-build: fmt lint build-readme-toc
+build: fmt lint 
 	go build -tags netgo -installsuffix netgo $(LDFLAGS) -o $(OUTDIR)/$(NAME) .
 
 .PHONY: build-only
-build-only: 
+build-only:
 	go build -tags netgo -installsuffix netgo $(LDFLAGS) -o $(OUTDIR)/$(NAME) .
 
 .PHONY: test
-test: fmt lint
+test:
 	go test  ./...
 
 .PHONY: clean
 clean:
 	rm -rf "$(OUTDIR)"
-
-.PHONY: build-image
-build-image:
-	docker build -t $(shell make -e docker-tag) --build-arg RELEASE=$(RELEASE) --build-arg VERSION=$(VERSION) --target runtime .
-	docker tag $(shell make -e docker-tag) $(IMAGE_PREFIX)$(IMAGE_NAME):$(VERSION)  # without revision
-	docker tag $(shell make -e docker-tag) $(IMAGE_PREFIX)$(IMAGE_NAME):latest      # latest
-
-.PHONY: push-image
-push-image:
-	docker push $(shell make -e docker-tag)
-	docker push $(IMAGE_PREFIX)$(IMAGE_NAME):$(VERSION) # without revision
-	docker push $(IMAGE_PREFIX)$(IMAGE_NAME):latest     # latest
-
-.PHONY: docker-tag
-docker-tag:
-	@echo $(IMAGE_PREFIX)$(IMAGE_NAME):$(IMAGE_TAG)
-
-#
-# Release
-#
-guard-%:
-	@ if [ "${${*}}" = "" ]; then \
-    echo "Environment variable $* is not set"; \
-		exit 1; \
-	fi
-.PHONY: release
-release: guard-RELEASE guard-RELEASE_TAG
-	git diff --quiet HEAD || (echo "your current branch is dirty" && exit 1)
-	git tag $(RELEASE_TAG) $(REVISION)
-	git push origin $(RELEASE_TAG)
diff --git a/README.md b/README.md
index 5b4915e..afc5a6d 100644
--- a/README.md
+++ b/README.md
@@ -94,10 +94,10 @@ Just download a tar ball for your platform from [releases](./../../releases) pag
 
 `pftaskqueue` publishes two kind of docker iamges in [GitHub Packages](https://github.com/pfnet-research/pftaskqueue/packages)
 
-- `docker.pkg.github.com/pfnet-research/pftaskqueue/dev:latest`: built on the latest master branch
-  - `docker.pkg.github.com/pfnet-research/pftaskqueue/dev:vx.y.z-alppha.n` is also available for old dev images
-- `docker.pkg.github.com/pfnet-research/pftaskqueue/release:latest`: the latest release image
-  -  `docker.pkg.github.com/pfnet-research/pftaskqueue/release:vx.y.z` is also available for previous/specific release images
+- `ghcr.io/pfnet-research/pftaskqueue/dev:latest`: built on the latest master branch
+  - `ghcr.io/pfnet-research/pftaskqueue/dev:vx.y.z-alpha-{{revision}}` is also available for old dev images
+- `ghcr.io/pfnet-research/pftaskqueue/release:latest`: the latest release image
+  -  `ghcr.io/pfnet-research/pftaskqueue/release:vx.y.z` is also available for previous/specific release images
 
 To pull those images, you would need `docker login docker.pkg.github.com` first.  Please see [Configuring Docker for use with GitHub Packages](https://help.github.com/en/packages/using-github-packages-with-your-projects-ecosystem/configuring-docker-for-use-with-github-packages) if you are not familiar wit it.
 
@@ -825,12 +825,7 @@ make test
 
 ### How to make release
 
-`release` target tags a commit and push the tag to `origin`.  Release process will run in GitHub Action.
-
-```bash
-$ RELEASE_TAG=$(git semv patch) # next patch version.  bump major/minor version if necessary
-$ make release RELEASE=true RELEASE_TAG=${RELEASE_TAG}
-```
+The release process is fully automated by [tagpr](https://github.com/Songmu/tagpr). To release, just merge [the latest release PR](https://github.com/pfnet-research/pftaskqueue/pulls?q=is:pr+is:open+label:tagpr).
 
 ## License
 
diff --git a/cmd/print_config.go b/cmd/print_config.go
index 27d6cb5..e71ea1b 100644
--- a/cmd/print_config.go
+++ b/cmd/print_config.go
@@ -22,7 +22,7 @@ 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
+	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,
diff --git a/pkg/worker/worker.go b/pkg/worker/worker.go
index cbac54c..c2594fc 100644
--- a/pkg/worker/worker.go
+++ b/pkg/worker/worker.go
@@ -402,21 +402,21 @@ func (w *Worker) workspacePath(t *task.Task) string {
 	return filepath.Join(w.thisWorkerWorkDir(), t.Status.CurrentRecord.ProcessUID)
 }
 
-//  {task workspace path}/
-//    input/
-//      # taskspec info
-//      payload             # also exported as PFTQ_TASK_HANDLER_INPUT_PAYLOAD
-//      retryLimit          # also exported as PFTQ_TASK_HANDLER_INPUT_RETRY_LIMIT
-//      timeoutSeconds      # also exported as PFTQ_TASK_HANDLER_INPUT_TIMEOUT_SECONDS
-//      meta/
-//		  taskUID           # also exported as PFTQ_TASK_HANDLER_INPUT_TASK_UID
-//        task.json         # also exported as PFTQ_TASK_HANDLER_INPUT_TASK_JSON
-//        processUID        # also exported as PFTQ_TASK_HANDLER_INPUT_PROCESS_UID
-//        # worker info
-//        workerName        # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_NAME
-//        workerUID         # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_UID
-//        workerConfig.json # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_CONFIG_JSON
-//    output/
+//	 {task workspace path}/
+//	   input/
+//	     # taskspec info
+//	     payload             # also exported as PFTQ_TASK_HANDLER_INPUT_PAYLOAD
+//	     retryLimit          # also exported as PFTQ_TASK_HANDLER_INPUT_RETRY_LIMIT
+//	     timeoutSeconds      # also exported as PFTQ_TASK_HANDLER_INPUT_TIMEOUT_SECONDS
+//	     meta/
+//			  taskUID           # also exported as PFTQ_TASK_HANDLER_INPUT_TASK_UID
+//	       task.json         # also exported as PFTQ_TASK_HANDLER_INPUT_TASK_JSON
+//	       processUID        # also exported as PFTQ_TASK_HANDLER_INPUT_PROCESS_UID
+//	       # worker info
+//	       workerName        # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_NAME
+//	       workerUID         # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_UID
+//	       workerConfig.json # also exported as PFTQ_TASK_HANDLER_INPUT_WORKER_CONFIG_JSON
+//	   output/
 func (w *Worker) prepareTaskHandlerDirAndEnvvars(t *task.Task) (string, []string, error) {
 	inputOutputDirPermission := os.FileMode(0750)
 	inputFilePermission := os.FileMode(0440)
@@ -501,11 +501,12 @@ func (w *Worker) prepareTaskHandlerDirAndEnvvars(t *task.Task) (string, []string
 	return workspacePath, envvars, nil
 }
 
-//  {task workspace path}/
-//    output/
-//      message
-//      payload
-//      postHooks.json
+// {task workspace path}/
+//
+//	output/
+//	  message
+//	  payload
+//	  postHooks.json
 func (w *Worker) fetchResultContents(logger zerolog.Logger, t *task.Task) (*string, *string, []task.TaskSpec, error) {
 	workspaceDir := w.workspacePath(t)
 	postHooksPath := filepath.Join(workspaceDir, "output", "postHooks.json")