create docker image (#12)

* create initial dockerfile and supporting config

* add github workflow for build and push docker image

* update dockerfile to support writing SSL certs to tmp

* scripts/docker-entrypoint: improve certificate env var names

Author: albertrdixon

.dockerignore

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+flake.*
+**.md
+.github
+**.example

.github/workflows/build-push-image.yml

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+name: Build Push Image
+
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build-push-image:
+    name: github container registry
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup qemu
+        uses: docker/setup-qemu-action@v3
+
+      - name: Setup buildkit
+        uses: docker/setup-buildx-action@v3
+
+      - id: metadata
+        name: Set image metadata
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository }}
+          tags: |
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=ref,event=pr
+
+      - name: Login to ghcr.io
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push to ghcr.io/${{ github.repository }}
+        uses: docker/build-push-action@v5
+        with:
+          push: ${{ github.event_name != 'pull_request' }}
+          platforms: linux/amd64,linux/arm64
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          tags: ${{ steps.metadata.outputs.tags }}
+          labels: ${{ steps.metadata.outputs.labels }}

Dockerfile

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+FROM --platform=$BUILDPLATFORM golang:1.21 AS build
+
+WORKDIR /go/src/app
+ARG TARGETOS
+ARG TARGETARCH
+ENV CGO_ENABLED=0 \
+  GOOS=${TARGETOS} \
+  GOARCH=${TARGETARCH} \
+  GOCACHE=/cache/go \
+  GOMODCACHE=/cache/gomod
+
+RUN <<-EOF
+  go env -w GOCACHE=${GOCACHE}
+  go env -w GOMODCACHE=${GOMODCACHE}
+EOF
+
+RUN --mount=type=bind,source=go.mod,target=/go/src/app/go.mod,readonly \
+  --mount=type=bind,source=go.sum,target=/go/src/app/go.sum,readonly \
+  --mount=type=cache,target=${GOCACHE} \
+  --mount=type=cache,target=${GOMODCACHE} \
+  --mount=type=cache,target=/go/pkg \
+  go mod download -x
+
+RUN --mount=type=bind,source=.,target=/go/src/app,readonly \
+  --mount=type=cache,target=${GOCACHE} \
+  --mount=type=cache,target=${GOMODCACHE} \
+  --mount=type=cache,target=/go/pkg \
+  go build -x -a -ldflags="-w -s" -trimpath -o /go/bin/app ./cmd/migrate
+
+FROM alpine:3.18 AS main
+RUN apk add --no-cache ca-certificates
+USER nobody
+COPY scripts/docker-entrypoint.sh /docker-entrypoint.sh
+COPY --from=build /go/bin/app /migrate
+ENTRYPOINT ["/docker-entrypoint.sh"]

scripts/docker-entrypoint.sh

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+#!/bin/sh
+
+if test -n "$DATABASE_CLIENT_CERT_B64"; then
+  echo "$DATABASE_CLIENT_CERT_B64" | base64 -d >/tmp/client-cert.pem
+fi
+
+if test -n "$DATABASE_CLIENT_KEY_B64"; then
+  echo "$DATABASE_CLIENT_KEY_B64" | base64 -d >/tmp/client-key.pem
+fi
+
+if test -n "$DATABASE_SERVER_CA_B64"; then
+  echo "$DATABASE_SERVER_CA_B64" | base64 -d >/tmp/ca.pem
+fi
+
+exec /migrate "$@"