build: add Dockerfile

Dockerfile

+# Start from the official Golang image
+FROM golang:1.22-alpine as builder
+
+# Set the working directory inside the container
+WORKDIR /app
+
+# Install necessary packages
+RUN apk add --no-cache git
+
+# Copy go.mod and go.sum files to install dependencies
+COPY go.mod go.sum ./
+
+# Download and cache dependencies
+RUN go mod download
+
+# Copy the rest of the application source code
+COPY . .
+
+# Build the application
+RUN go build -o waitlist .
+
+# Start a new minimal image for the application
+FROM alpine:latest
+
+# Set the working directory inside the new container
+WORKDIR /app
+
+# Install necessary packages in the minimal image
+RUN apk add --no-cache ca-certificates
+
+# Copy the built binary from the previous stage
+COPY --from=builder /app/waitlist .
+
+# Expose the port the app runs on
+EXPOSE 3000
+
+# Run the application
+CMD ["./waitlist"]
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