diff --git a/Dockerfile b/Dockerfile
index d3b0160..2ade5db 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,16 +1,14 @@
-FROM golang:1
-
-LABEL "com.github.actions.name"="Auto Closer"
-LABEL "com.github.actions.description"="Auto Closer"
-LABEL "com.github.actions.icon"="check-circle"
-LABEL "com.github.actions.color"="red"
-LABEL "repository"="https://github.com/lowply/auto-closer"
-LABEL "homepage"="https://github.com/lowply/auto-closer"
-LABEL "maintainer"="Sho Mizutani <lowply@github.com>"
+FROM golang:1 as builder
 
+ENV CGO_ENABLED=0
+ENV GOOS=linux
+ENV GOARCH=amd64
 WORKDIR /go/src
 COPY src .
 RUN GO111MODULE=on go build -o /go/bin/main
 
-ADD entrypoint.sh /entrypoint.sh
-ENTRYPOINT ["/entrypoint.sh"]
+FROM alpine
+RUN apk add --no-cache ca-certificates
+RUN update-ca-certificates
+COPY --from=builder /go/bin/main /bin/main
+ENTRYPOINT main
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..62ab315
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,9 @@
+name: 'Auto Closer'
+author: 'Sho Mizutani <lowply@github.com>'
+description: 'A GitHub Action that closes all issues with a specific label while keeping the latest one(s) open.'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+branding:
+  icon: 'check-circle'
+  color: 'red'
diff --git a/entrypoint.sh b/entrypoint.sh
deleted file mode 100755
index 9e5a120..0000000
--- a/entrypoint.sh
+++ /dev/null
@@ -1,8 +0,0 @@
-#!/bin/sh
-
-if [ -z "$GITHUB_TOKEN" ]; then
-    echo "GITHUB_TOKEN is missing"
-    exit 1
-fi
-
-/go/bin/main