Switch from alpine to ubuntu as a base for the docker image

The PFC components depend on glibc.  I'm building the web service as a
static binary so we don't need to install musl libc.

More info on golang static builds:
golang/go#26492

build/package/Dockerfile

@@ -1,20 +1,27 @@
 FROM golang:alpine as builder
 
-# build the web service
+ENV GOOS=linux
+
 WORKDIR /usr/src/egw-ws
 COPY . ./
-RUN go build -o /usr/local/bin/ ./cmd/egw-ws
+
+# build the web service (static)
+RUN go build  -tags 'osusergo netgo' -o /usr/local/bin/ ./cmd/egw-ws
 
 # download golang-migrate
 RUN apk add curl
 RUN curl -sL https://github.com/golang-migrate/migrate/releases/download/v4.11.0/migrate.linux-amd64.tar.gz | tar -C /usr/local/bin -xzf -
 
 
 # start fresh
-FROM alpine
+FROM ubuntu:20.04
+
+# install dependencies
+RUN apt-get update \
+    && apt-get install -y postgresql-client libelf-dev \
+    && rm -rf /var/lib/apt/lists/*
 
-# install executables
-RUN apk add postgresql-client busybox-extras
+# copy executables from the builder image
 WORKDIR /usr/local/bin
 COPY --from=builder /usr/local/bin/migrate.linux-amd64 ./migrate
 COPY --from=builder /usr/local/bin/egw-ws ./