Michael Suchacz 183bd57061
fix: log external mux server exits in launcher (#796)
## Summary
Keep the Mux module's launcher around after startup so it can append
useful diagnostics when `mux server` is killed outside the Node runtime.

## Background
The module previously forked `mux server` and returned immediately,
which meant external kills (for example `SIGKILL` or an OOM kill) could
leave users with only a stopped app and no launcher-side clue about what
happened.

## Implementation
- keep the existing module inputs and startup shape intact
- launch `mux server` under a detached Bash watcher that waits for the
child process to exit
- append signal/exit-code diagnostics to `log_path` when the server dies
unexpectedly
- include a best-effort kernel OOM/SIGKILL hint in the log when the host
exposes it
- add Terraform and Bun tests that cover the new launcher diagnostics
- bump the module examples from `1.3.1` to `1.4.0`

## Validation
- `bun x prettier --check registry/coder/modules/mux/README.md
registry/coder/modules/mux/main.test.ts
registry/coder/modules/mux/mux.tftest.hcl
registry/coder/modules/mux/run.sh`
- `terraform fmt -check -recursive registry/coder/modules/mux`
- `cd registry/coder/modules/mux && terraform validate`
- `cd registry/coder/modules/mux && terraform test -verbose`
- `cd registry/coder/modules/mux && bun test main.test.ts`
- `bun run shellcheck -- registry/coder/modules/mux/run.sh`

---

Generated with mux (exec mode) using openai:gpt-5.4.
2026-03-10 14:32:58 +01:00

173 lines
4.7 KiB
TypeScript

import { describe, expect, it } from "bun:test";
import {
executeScriptInContainer,
execContainer,
findResourceInstance,
readFileContainer,
removeContainer,
runContainer,
runTerraformApply,
runTerraformInit,
testRequiredVariables,
} from "~test";
describe("mux", async () => {
await runTerraformInit(import.meta.dir);
testRequiredVariables(import.meta.dir, {
agent_id: "foo",
});
it("runs with default", async () => {
const state = await runTerraformApply(import.meta.dir, {
agent_id: "foo",
});
const output = await executeScriptInContainer(
state,
"alpine/curl",
"sh",
"apk add --no-cache bash tar gzip ca-certificates findutils nodejs && update-ca-certificates",
);
if (output.exitCode !== 0) {
console.log("STDOUT:\n" + output.stdout.join("\n"));
console.log("STDERR:\n" + output.stderr.join("\n"));
}
expect(output.exitCode).toBe(0);
const expectedLines = [
"📥 No package manager found; downloading tarball from registry...",
"🥳 mux has been installed in /tmp/mux",
"🚀 Starting mux server on port 4000...",
"Check logs at /tmp/mux.log!",
];
for (const line of expectedLines) {
expect(output.stdout).toContain(line);
}
}, 60000);
it("parses custom additional_arguments", async () => {
const state = await runTerraformApply(import.meta.dir, {
agent_id: "foo",
install: false,
log_path: "/tmp/mux.log",
additional_arguments:
"--open-mode pinned --add-project '/workspaces/my repo'",
});
const instance = findResourceInstance(state, "coder_script");
const id = await runContainer("alpine/curl");
try {
const setup = await execContainer(id, [
"sh",
"-c",
`apk add --no-cache bash >/dev/null
mkdir -p /tmp/mux
cat <<'EOF' > /tmp/mux/mux
#!/usr/bin/env sh
i=1
for arg in "$@"; do
echo "arg$i=$arg"
i=$((i + 1))
done
EOF
chmod +x /tmp/mux/mux`,
]);
expect(setup.exitCode).toBe(0);
const output = await execContainer(id, ["sh", "-c", instance.script]);
if (output.exitCode !== 0) {
console.log("STDOUT:\n" + output.stdout);
console.log("STDERR:\n" + output.stderr);
}
expect(output.exitCode).toBe(0);
await execContainer(id, ["sh", "-c", "sleep 1"]);
const log = await readFileContainer(id, "/tmp/mux.log");
expect(log).toContain("arg1=server");
expect(log).toContain("arg2=--port");
expect(log).toContain("arg3=4000");
expect(log).toContain("arg4=--open-mode");
expect(log).toContain("arg5=pinned");
expect(log).toContain("arg6=--add-project");
expect(log).toContain("arg7=/workspaces/my repo");
} finally {
await removeContainer(id);
}
}, 60000);
it("logs signal-based exits after startup", async () => {
const state = await runTerraformApply(import.meta.dir, {
agent_id: "foo",
install: false,
log_path: "/tmp/mux.log",
});
const instance = findResourceInstance(state, "coder_script");
const id = await runContainer("alpine/curl");
try {
const setup = await execContainer(id, [
"sh",
"-c",
`apk add --no-cache bash >/dev/null
mkdir -p /tmp/mux
cat <<'EOF' > /tmp/mux/mux
#!/usr/bin/env sh
target_pid="$$"
(
sleep 1
kill -9 "$target_pid"
) &
while true; do
sleep 1
done
EOF
chmod +x /tmp/mux/mux`,
]);
expect(setup.exitCode).toBe(0);
const output = await execContainer(id, ["sh", "-c", instance.script]);
if (output.exitCode !== 0) {
console.log("STDOUT:\n" + output.stdout);
console.log("STDERR:\n" + output.stderr);
}
expect(output.exitCode).toBe(0);
await execContainer(id, ["sh", "-c", "sleep 2"]);
const log = await readFileContainer(id, "/tmp/mux.log");
expect(log).toContain("shell exit code 137");
expect(log).toContain(
"SIGKILL usually means the process was killed externally or by the OOM killer.",
);
} finally {
await removeContainer(id);
}
}, 60000);
it("runs with npm present", async () => {
const state = await runTerraformApply(import.meta.dir, {
agent_id: "foo",
});
const output = await executeScriptInContainer(
state,
"node:20-alpine",
"sh",
"apk add bash",
);
expect(output.exitCode).toBe(0);
const expectedLines = [
"📦 Installing mux via npm into /tmp/mux...",
"⏭️ Skipping lifecycle scripts with --ignore-scripts",
"🥳 mux has been installed in /tmp/mux",
"🚀 Starting mux server on port 4000...",
"Check logs at /tmp/mux.log!",
];
for (const line of expectedLines) {
expect(output.stdout).toContain(line);
}
}, 180000);
});