clone-shim/README.md
Jake Hillion 5e7eba5f61
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2022-04-28 17:08:36 +01:00

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clone-shim

Running the examples

examples/basic

The basic example instructs the shim to spawn two processes, each of which writes "hello from main{1,2}!" to stdout.

To run this example:

cargo build
cargo build --example basic
target/debug/clone-shim -s examples/basic/spec.json target/debug/examples/basic

examples/pipes

The pipes example shows some of the power of the shim by using pipes. The process "pipe_sender" sends two messages down a pipe that it's given by the shim. These two messages each spawn a completely isolated process, "pipe_receiver", that receives that message.

To run this example:

cargo build
cargo build --example pipes
target/debug/clone-shim -s examples/pipes/spec.json target/debug/examples/pipes

Debugging the shim

The shim can be debugged as with most processes, but it is exceptionally forky. Breaking before a clone in rust-gdb then running set follow-fork-mode child is often necessary. The best approach is to go in with a plan of attack.

Debugging the child

Debugging the child processes is vastly more difficult than in other more Linux-like containerisation solutions.

The --debug flag on the shim attempts to stop application spawned processes as soon as they are voided. This gives you a chance to attach with a debugger.

The debugger must be run from the ambient namespace and not within the void, as none of the prerequisites will exist within the void.

Good luck!