/**
* Container runtime detection module.
* Detects Docker or Podman and their compose variants, caching the result per process.
*/
import { spawnSync } from "child_process";
import { ContainerRuntime, ContainerRuntimeInfo } from "./types";
/** Module-level cached runtime info */
let cachedRuntime: ContainerRuntimeInfo | null = null;
/**
* Try running a command and return true if it exits 0.
*/
function commandSucceeds(cmd: string, args: string[]): boolean {
try {
const result = spawnSync(cmd, args, {
stdio: "pipe",
encoding: "utf8",
});
return result.status === 0;
} catch {
return false;
}
}
/**
* Try running a command and return its stdout if it exits 0, otherwise undefined.
*/
function commandOutput(cmd: string, args: string[]): string | undefined {
try {
const result = spawnSync(cmd, args, {
stdio: "pipe",
encoding: "utf8",
});
if (result.status === 0 && result.stdout) {
return result.stdout.trim();
}
return undefined;
} catch {
return undefined;
}
}
/**
* Extract version string from runtime --version output.
* e.g. "Docker version 24.0.7, build afdd53b" → "24.0.7"
* "podman version 4.9.3" → "4.9.3"
*/
function parseVersion(output: string): string | undefined {
const match = output.match(/(\d+\.\d+\.\d+)/);
return match?.[1];
}
/**
* Detect the compose command for a given runtime.
* Priority for docker: docker compose → docker-compose
* Priority for podman: podman compose → podman-compose → docker-compose (fallback)
*/
function detectComposeCmd(runtime: ContainerRuntime): string[] | null {
const runtimeCmd = runtime;
// Try "<runtime> compose version" (compose v2 plugin)
if (commandSucceeds(runtimeCmd, ["compose", "version"])) {
return [runtimeCmd, "compose"];
}
// Try "<runtime>-compose --version" (standalone compose)
const standaloneCompose = `${runtimeCmd}-compose`;
if (commandSucceeds(standaloneCompose, ["--version"])) {
return [standaloneCompose];
}
// Cross-runtime fallback: try docker-compose as last resort
if (commandSucceeds("docker-compose", ["--version"])) {
return ["docker-compose"];
}
return null;
}
/**
* Perform full container runtime detection.
* Priority: docker > podman.
* Checks runtime availability, daemon status, and compose command.
*/
export function detectContainerRuntime(): ContainerRuntimeInfo {
const runtimes: ContainerRuntime[] = ["docker", "podman"];
for (const runtime of runtimes) {
const versionOutput = commandOutput(runtime, ["--version"]);
if (versionOutput) {
// Runtime binary exists, check if daemon is accessible
const runtimeAvailable = commandSucceeds(runtime, ["info"]);
const composeCmd = detectComposeCmd(runtime);
const runtimeVersion = parseVersion(versionOutput);
return {
runtime,
runtimeCmd: runtime,
runtimeAvailable,
composeCmd,
runtimeVersion,
};
}
}
// No runtime found at all
return {
runtime: "docker",
runtimeCmd: "docker",
runtimeAvailable: false,
composeCmd: null,
runtimeVersion: undefined,
};
}
/**
* Get cached container runtime info.
* Detects once per process and caches the result.
*/
export function getContainerRuntime(): ContainerRuntimeInfo {
cachedRuntime ??= detectContainerRuntime();
return cachedRuntime;
}
/**
* Reset the runtime cache. Used in tests to allow re-detection.
*/
export function resetRuntimeCache(): void {
cachedRuntime = null;
}
