Reduce docker layers

Dockerfile

@@ -7,18 +7,18 @@ RUN gradle --debug --no-daemon shadowJar
 # -- run
 FROM gcr.io/distroless/java:8
 
-ENV BIND_PORT "80"
-ENV CLIENT_ID "REPLACE_ME"
-ENV CLIENT_SECRET "REPLACE_ME"
-ENV CLOUD_IAM_AUTH_ENABLED "true"
-ENV NEXUS_HTTP_HOST "nexus.example.com"
-ENV REDIRECT_URL "<oauth-callback>"
-ENV SESSION_TTL "1440000"
-ENV UPSTREAM_HOST "localhost"
-ENV UPSTREAM_HTTP_PORT "8081"
-ENV JWK_URL "<openid-certs>"
-ENV TOKEN_ENDPOINT "<openid-token-endpoint>"
-ENV AUTHORIZE_ENDPOINT "<openid-authorize-url>"
+ENV BIND_PORT="80" \
+    CLIENT_ID="REPLACE_ME" \
+    CLIENT_SECRET="REPLACE_ME" \
+    CLOUD_IAM_AUTH_ENABLED="true" \
+    NEXUS_HTTP_HOST="nexus.example.com" \
+    REDIRECT_URL="<oauth-callback>" \
+    SESSION_TTL="1440000" \
+    UPSTREAM_HOST="localhost" \
+    UPSTREAM_HTTP_PORT="8081" \
+    JWK_URL="<openid-certs>" \
+    TOKEN_ENDPOINT="<openid-token-endpoint>" \
+    AUTHORIZE_ENDPOINT="<openid-authorize-url>"
 
 COPY --from=builder /src/build/libs/nexus-proxy-2.3.0.jar /nexus-proxy.jar