| <!-- |
| # |
| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You under the Apache License, Version 2.0 |
| # (the "License"); you may not use this file except in compliance with |
| # the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| # |
| --> |
| # Scala component configuration |
| |
| Our Scala components are in the process of switching from our own `WhiskConfig` to the TypesafeConfig based `pureconfig`. That will give us a more sane way of parsing environment values, overriding them and defining sensible defaults for them. |
| |
| TypesafeConfig is able to override its values via JVM system properties. Unfortunately, docker only supports passing environment variables in a comfortable way. |
| |
| To solve that mismatch, we use a script to transform environment variables into JVM system properties to spare the developer of manually overriding all the values via explicit environment -> TypesafeConfig value mapping. That script applies the following transformations to all environment variables starting with a defined prefix ("CONFIG_" in our case): |
| |
| - `_` becomes `.` (TypesafeConfig hierarchies are built using `.`) |
| - `camelCased` becomes `camel-cased` (Kebabcase is usually used for TypesafeConfig keys) |
| - `PascalCased` stays `PascalCased` (Defining classnames for overriding SPIs is crucial) |
| |
| ### Examples: |
| |
| - `CONFIG_whisk_loadbalancer_invokerBusyThreshold` becomes `-Dwhisk.loadbalancer.invoker-busy-threshold` |
| - `CONFIG_akka_remote_netty_tcp_bindPort` becomes `-Dakka.remote.netty.tcp.bind-port` |
| - `CONFIG_whisk_spi_LogStoreProvider` becomes `-Dwhisk.spi.LogStoreProvider` |
