Merge pull request #2266 from itowlson/trigger-metadata-protocol

Multi-trigger: ask triggers which flags they can accept

Author: itowlson

crates/plugins/src/manifest.rs

@@ -1,3 +1,5 @@
+use std::io::IsTerminal;
+
 use anyhow::{anyhow, Context, Result};
 use semver::{Version, VersionReq};
 use serde::{Deserialize, Serialize};
@@ -181,7 +183,9 @@ fn inner_warn_unsupported_version(
     if !is_version_fully_compatible(supported_on, spin_version)? {
         let version = Version::parse(spin_version)?;
         if !version.pre.is_empty() {
-            terminal::warn!("You're using a pre-release version of Spin ({spin_version}). This plugin might not be compatible (supported: {supported_on}). Continuing anyway.");
+            if std::io::stderr().is_terminal() {
+                terminal::warn!("You're using a pre-release version of Spin ({spin_version}). This plugin might not be compatible (supported: {supported_on}). Continuing anyway.");
+            }
         } else if override_compatibility_check {
             terminal::warn!("Plugin is not compatible with this version of Spin (supported: {supported_on}, actual: {spin_version}). Check overridden ... continuing to install or execute plugin.");
         } else {

crates/trigger/src/cli.rs

@@ -17,6 +17,9 @@ use crate::{
 };
 use crate::{TriggerExecutor, TriggerExecutorBuilder};
 
+mod launch_metadata;
+pub use launch_metadata::LaunchMetadata;
+
 pub const APP_LOG_DIR: &str = "APP_LOG_DIR";
 pub const DISABLE_WASMTIME_CACHE: &str = "DISABLE_WASMTIME_CACHE";
 pub const FOLLOW_LOG_OPT: &str = "FOLLOW_ID";
@@ -125,6 +128,9 @@ where
 
     #[clap(long = "help-args-only", hide = true)]
     pub help_args_only: bool,
+
+    #[clap(long = "launch-metadata-only", hide = true)]
+    pub launch_metadata_only: bool,
 }
 
 /// An empty implementation of clap::Args to be used as TriggerExecutor::RunConfig
@@ -147,6 +153,13 @@ where
             return Ok(());
         }
 
+        if self.launch_metadata_only {
+            let lm = LaunchMetadata::infer::<Executor>();
+            let json = serde_json::to_string_pretty(&lm)?;
+            eprintln!("{json}");
+            return Ok(());
+        }
+
         // Required env vars
         let working_dir = std::env::var(SPIN_WORKING_DIR).context(SPIN_WORKING_DIR)?;
         let locked_url = std::env::var(SPIN_LOCKED_URL).context(SPIN_LOCKED_URL)?;

crates/trigger/src/cli/launch_metadata.rs

@@ -0,0 +1,86 @@
+use clap::{Args, CommandFactory};
+use serde::{Deserialize, Serialize};
+use std::ffi::OsString;
+
+use crate::{cli::TriggerExecutorCommand, TriggerExecutor};
+
+/// Contains information about the trigger flags (and potentially
+/// in future configuration) that a consumer (such as `spin up`)
+/// can query using `--launch-metadata-only`.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct LaunchMetadata {
+    all_flags: Vec<LaunchFlag>,
+}
+
+// This assumes no triggers that want to participate in multi-trigger
+// use positional arguments. This is a restriction we'll have to make
+// anyway: suppose triggers A and B both take one positional arg, and
+// the user writes `spin up 123 456` - which value would go to which trigger?
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+struct LaunchFlag {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(default)]
+    short: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(default)]
+    long: Option<String>,
+}
+
+impl LaunchMetadata {
+    pub fn infer<Executor: TriggerExecutor>() -> Self
+    where
+        Executor::RunConfig: Args,
+    {
+        let all_flags: Vec<_> = TriggerExecutorCommand::<Executor>::command()
+            .get_arguments()
+            .map(LaunchFlag::infer)
+            .collect();
+
+        LaunchMetadata { all_flags }
+    }
+
+    pub fn matches<'a>(&self, groups: &[Vec<&'a OsString>]) -> Vec<&'a OsString> {
+        let mut matches = vec![];
+
+        for group in groups {
+            if group.is_empty() {
+                continue;
+            }
+            if self.is_match(group[0]) {
+                matches.extend(group);
+            }
+        }
+
+        matches
+    }
+
+    fn is_match(&self, arg: &OsString) -> bool {
+        self.all_flags.iter().any(|f| f.is_match(arg))
+    }
+
+    pub fn is_group_match(&self, group: &[&OsString]) -> bool {
+        if group.is_empty() {
+            false
+        } else {
+            self.all_flags.iter().any(|f| f.is_match(group[0]))
+        }
+    }
+}
+
+impl LaunchFlag {
+    fn infer(arg: &clap::Arg) -> Self {
+        Self {
+            long: arg.get_long().map(|s| format!("--{s}")),
+            short: arg.get_short().map(|ch| format!("-{ch}")),
+        }
+    }
+
+    fn is_match(&self, candidate: &OsString) -> bool {
+        let Some(s) = candidate.to_str() else {
+            return false;
+        };
+        let candidate = Some(s.to_owned());
+
+        candidate == self.long || candidate == self.short
+    }
+}