fix: readd custom-email-sender

Author: sgtoj

assets/custom-email-sender/Dockerfile

@@ -0,0 +1,30 @@
+# --------------------------------------------------------------------- base ---
+
+FROM golang:1.19 as base
+
+ARG APP_VERSION=latest
+
+ENV GOOS=linux
+ENV GOARCH=amd64
+ENV CGO_ENABLED=0
+
+RUN mkdir -p /opt/app
+WORKDIR /opt/app
+
+RUN git clone https://github.com/cruxstack/cognito-custom-message-sender-go.git .
+RUN if [ "$APP_VERSION" != "latest" ] ; then git checkout $APP_VERSION ; fi
+RUN go mod download
+RUN go build -o bootstrap
+
+RUN echo "$SERVICE_OPA_POLICY_ENCODED" | base64 -d > /opt/app/policy.rego
+
+# ------------------------------------------------------------------ package ---
+
+FROM alpine:latest as package
+
+COPY --from=base /opt/app/bootstrap /opt/app/dist/bootstrap
+COPY --from=base /opt/app/policy.rego /opt/app/dist/policy.rego
+
+RUN apk add zip \
+    && cd /opt/app/dist \
+    && zip -r /tmp/package.zip .