Use a numeric User ID in the alpine-based examples

This fixes failure of the container to start when run on a system with a
PodSecurityPolicy specifying RunAsUser as "MustRunAsNonRoot".

Signed-off-by: Paul "Hampy" Hampson <p_hampson@wargaming.net>

examples/allocator-service/Dockerfile

@@ -27,13 +27,13 @@ RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o service .
 # Create the final image that will run the allocator service
 FROM alpine:3.8
 RUN apk add --update ca-certificates
-RUN adduser -D service
+RUN adduser -D -u 1000 service
 
 COPY --from=builder /go/src/agones.dev/agones/examples/allocator-service \
                     /home/service
 
 RUN chown -R service /home/service && \
     chmod o+x /home/service/service
 
-USER service
+USER 1000
 ENTRYPOINT /home/service/service

examples/autoscaler-webhook/Dockerfile

@@ -22,13 +22,13 @@ RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server .
 
 # Create the final image that will run the webhook server for FleetAutoscaler webhook policy
 FROM alpine:3.8
-RUN adduser -D server
+RUN adduser -D -u 1000 server
 
 COPY --from=builder /go/src/autoscaler-webhook \
                     /home/server
 
 RUN chown -R server /home/server && \
     chmod o+x /home/server/server
 
-USER server
+USER 1000
 ENTRYPOINT /home/server/server

examples/crd-client/Dockerfile

@@ -22,13 +22,13 @@ RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o client .
 
 # Create the final image that will run the webhook server for FleetAutoscaler webhook policy
 FROM alpine:3.8
-RUN adduser -D client
+RUN adduser -D -u 1000 client
 
 COPY --from=builder /go/src/crd-client \
                     /home/client
 
 RUN chown -R client /home/client && \
     chmod o+x /home/client/client
 
-USER client
+USER 1000
 ENTRYPOINT /home/client/client

examples/simple-tcp/Dockerfile

@@ -23,10 +23,10 @@ RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server .
 # final image
 FROM alpine:3.10
 
-RUN adduser -D server
+RUN adduser -D -u 1000 server
 COPY --from=builder /go/src/simple-tcp/server /home/server/server
 RUN chown -R server /home/server && \
     chmod o+x /home/server/server
 
-USER server
+USER 1000
 ENTRYPOINT ["/home/server/server"]

examples/simple-udp/Dockerfile

@@ -23,10 +23,10 @@ RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server .
 # final image
 FROM alpine:3.10
 
-RUN adduser -D server
+RUN adduser -D -u 1000 server
 COPY --from=builder /go/src/simple-udp/server /home/server/server
 RUN chown -R server /home/server && \
     chmod o+x /home/server/server
 
-USER server
+USER 1000
 ENTRYPOINT ["/home/server/server"]