Make the project capable of handling multiple runtimes

[sea212]

Closes #493

This PR splits the previous runtime crate into three different crates: runtime/common, runtime/battery-station and runtime/zeitgeist. runtime/common contains common types, tests, API implementations and the common runtime. The runtime/battery-station and runtime/zeitgeist crate utilize those through wrapping macros. Those macros copy the common parts over and in some cases also allow to extend those, for example to add new pallets to the runtime, extend the configuration or add new APIs. This might not be the cleanest approach, but the other approach to use one common create for everything, which will spare us copying from common to another runtime, does not work because it introduces circular dependencies and requires the node to build the same crate with different features, which is prohibited.

In addition to that, this PR adjusts the node crate to be able to handle multiple runtimes. A new abstract client implementation is offered, which abstracts the client over the generic RuntimeAPI and Executor (which is used to dispatch calls). The node can be built with with-battery-station-runtime and/or with-zeitgeist-runtime features to include the respective runtimes. By default, both runtimes are used. When creating a new chainspec (staging network), the respective runtime used to generate the chainspec must be included in the build. Currently the dev chain option uses the battery station runtime with a development staging chainspec. The rationale behind this is that battery station should always be the most advanced network, hence be used for development work. However, this can be extended to zeitgeist-dev and battery-station-dev if required.

[maltekliemann]

Looks good to me! 👍

Some comments (in addition to the remars in the code):

• I think the README.md should be updated to reflect these changes. We should also update the documentation repository regarding compiling for Battery Station.
• When I run cargo build --release --features=with-zeitgeist-runtime, both Zeitgeist and Battery Station get compiled. Is this as expected?
• The standalone node seems to default to Battery Station, so even after building specifically with with-zeitgeist-runtime, running target/release/zeitgeist starts a Battery Station client. Is this as expected?

Edit. What worries me about the macro usage is that we cannot auto-format the code, and, that error messages may be become cryptic.

[sea212]

The standalone node seems to default to Battery Station, so even after building specifically with with-zeitgeist-runtime, running target/release/zeitgeist starts a Battery Station client. Is this as expected?

This is expected behavior. When we enter no chain or "dev", the node has to select which runtime it will execute the development (staging) configuration on. I assumed that Battery Station is the more advanced network (and it has sudo, which is useful in the development network), so it defaults to Battery Station.

[sea212]

When I run cargo build --release --features=with-zeitgeist-runtime, both Zeitgeist and Battery Station get compiled. Is this as expected?

Yes. By default, both runtimes are built (default feature in Cargo.toml). If you want to build the node with only one runtime, you have to execute this command: cargo build --no-default-features --features=with-zeitgeist-runtime from within the node crate. If you execute that command from the top level directory, it will build both runtimes anyways because they are members of the complete workspace.
With regard to that fact (auto build both runtimes), do you still think a readme and docs update is necessary? All the docs are still up to date and lead to fully functional clients.

[maltekliemann]

With regard to that fact (auto build both runtimes), do you still think a readme and docs update is necessary? All the docs are still up to date and lead to fully functional clients.

Ok, somehow I assumed that setting one of the features was necessary. Yeah, didn't think this through. We can leave the docs the way they are. 👍

[maltekliemann]

👍

[sea212]

Thanks for reviewing this monster of a PR guys!