feat: add download command to retrieve PEM bundle from Key Vault

README.md

@@ -44,6 +44,7 @@ Commands:
   scan    List all domains tagged for ACME management
   status  Show certificate expiry status for all managed domains
   renew    Force-renew a certificate for a specific domain
+  download Download the PEM bundle for a domain from Key Vault
 
 Common options:
   --keyvault-url <url>        Azure KeyVault URL
@@ -77,6 +78,18 @@ azure-acme-provisioner run --http 8080
 
 > **Note:** Binding port 80 requires root privileges or `CAP_NET_BIND_SERVICE`. When running in Docker, map the host port to the container: `-p 80:8080` and pass `--http 8080`.
 
+### Downloading certificates
+
+The `download` command fetches the PEM bundle (private key + certificate + chain) from Key Vault and writes it to stdout or a file:
+
+```sh
+# Print to stdout
+azure-acme-provisioner download api.example.com
+
+# Write to a file
+azure-acme-provisioner download api.example.com --output api.example.com.pem
+```
+
 ## Configuration
 
 All configuration is via environment variables. CLI flags override env vars when both are provided.

src/cli.ts

@@ -1,4 +1,5 @@
 #!/usr/bin/env node
+import { writeFileSync } from 'node:fs';
 import { Command } from 'commander';
 import { loadConfig } from './lib/config.js';
 import { domainToCertName, Provisioner } from './lib/provisioner.js';
@@ -119,6 +120,24 @@ sharedOptions(
   if (result.errors.length > 0) process.exit(1);
 });
 
+sharedOptions(
+  program
+    .command('download <domain>')
+    .description('Download the PEM bundle (private key + certificate + chain) for a domain')
+    .option('--output <file>', 'Write to file instead of stdout')
+).action(async (domain: string, options: Record<string, unknown>) => {
+  applyOverrides(options);
+  const config = loadConfig();
+  const provisioner = new Provisioner(config);
+  const pem = await provisioner.download(domain);
+  if (options['output']) {
+    writeFileSync(String(options['output']), pem, 'utf8');
+    console.log(`Certificate written to ${options['output']}`);
+  } else {
+    process.stdout.write(pem);
+  }
+});
+
 program.parseAsync(process.argv).catch((err: unknown) => {
   console.error(err instanceof Error ? err.message : String(err));
   process.exit(1);

src/lib/provisioner.ts

@@ -131,6 +131,13 @@ export class Provisioner {
     return result;
   }
 
+  async download(domain: string): Promise<string> {
+    const certName = domainToCertName(domain);
+    const pem = await this.store.getSecret(certName);
+    if (!pem) throw new Error(`Certificate not found in KeyVault: ${certName}`);
+    return pem;
+  }
+
   async scan(): Promise<DomainRecord[]> {
     return scanDnsZones(this.credential, this.config);
   }