The following variables are usually set in the Dockerfile
OW_COMPILER points to the compiler script to use to compile actions.
OW_SAVE_JAR enables checking that an uploaded file is a jar (that is itself a zip file) and it will not expand it if there is a subdirectory named "META-INF" (so it is a jar file). Used to support uploading of Java jars.
OW_WAIT_FOR_ACK enables waiting for an acknowledgment in the action loop protocol. It should be enabled in all the newer runtimes. Do not enable in existing runtimes as it would break existing actions built for that runtime.
OW_EXECUTION_ENV enables detection and verification of the compilation environment. The compiler is expected to create a file named exec.env in the same folder as the exec file to be run. If this variable is set, before starting an action, the initialization will check that the content of the exec.env, trimmed of spaces and new lines, is the same, to ensure an action is executed in the right execution environment.
OW_LOG_INIT_ERROR enables logging of compilation error; the default behavior is to return errors in the result from initialization.
The proxy itself sets the following environment variables:
__OW_EXECUTION_ENV is the same value that the proxy receives as OW_EXECUTION_ENV
__OW_WAIT_FOR_ACK is set if the proxy has the variable OW_WAIT_FOR_ACK set.
Any other environment variables set in the Dockerfile that start with __OW_ are propagated to the proxy and can override the values set by the proxy.
Furthermore, actions receive their own environment variables and such values override the variables set from the proxy and in the environment.