Process API

The experimental WIT interface obelisk:activity/process@1.0.0 allows activities to spawn, wait for, kill etc. a local process.

Disk IO must be explicitly enabled globally in the configuration using directories.enabled = true setting. The Process Spawn API must be enabled for the specific activity using directories.process_provider = "native" setting.

The native process provider executes spawned processes in a process group. Server attempts to kill the whole process group when the activity is terminated.

Example of running touch somefile:

// Idempotently create a file.
let process = process_support::spawn(
    "touch",
    &process_support::SpawnOptions {
        args: vec!["somefile".to_string()],
        environment: vec![],
        current_working_directory: None,
        stdin: process_support::Stdio::Discard,
        stdout: process_support::Stdio::Discard,
        stderr: process_support::Stdio::Discard,
    },
)?;
println!("Waiting for {}", process.id());
let exit_status = process.wait()?;
ensure!(exit_status == Some(0));

Idempotency of each file IO operation is needed only when reuse_on_retry is enabled in the configuration, i.e. when the same temporary folder is used for retries.

More examples can be found in the process example activity.