3 files changed, 34 insertions, 0 deletions
diff --git a/main.c b/main.c
index 0564879..efeba71 100644
--- a/main.c
+++ b/main.c
@@ -63,10 +63,12 @@ static const struct collector *collectors[] = {
 
 struct config {
   const char *port;
+  bool print;
 };
 
 const struct config default_config = {
   .port = "9100",
+  .print = false,
 };
 
 struct collector_ctx {
@@ -84,6 +86,11 @@ int main(int argc, char *argv[]) {
   if (!initialize(argc, argv, &cfg, &ctx))
     return 1;
 
+  if (cfg.print) {
+    scrape_print(ctx.enabled, ctx.coll, ctx.coll_ctx);
+    return 0;
+  }
+
   scrape_server *server = scrape_listen(cfg.port);
   if (!server)
     return 1;
@@ -143,6 +150,11 @@ static bool initialize(int argc, char *argv[], struct config *cfg, struct collec
       goto next_arg;
     }
 
+    if (strncmp(argv[arg], "--stdout", 8) == 0) {
+      cfg->print = true;
+      goto next_arg;
+    }
+
     fprintf(stderr, "unknown argument: %s\n", argv[arg]);
     return false;
  next_arg: ;
diff --git a/scrape.c b/scrape.c
index 68f8c80..f68f9b9 100644
--- a/scrape.c
+++ b/scrape.c
@@ -218,6 +218,25 @@ void scrape_close(scrape_server *srv) {
   free(srv);
 }
 
+void scrape_print(unsigned ncoll, const struct collector *coll[], void *coll_ctx[]) {
+  bbuf *buf = bbuf_alloc(BUF_INITIAL, BUF_MAX);
+  for (unsigned i = 0; i < ncoll; i++) {
+    bbuf_reset(buf);
+
+    struct scrape_req req = {
+      .state = req_state_write_metrics,
+      .buf = buf,
+    };
+    coll[i]->collect(&req, coll_ctx[i]);
+
+    size_t len;
+    char *data = bbuf_get(buf, &len);
+    write_all(1, data, len);
+  }
+
+  bbuf_free(buf);
+}
+
 // scrape write API implementation
 
 void scrape_write(scrape_req *req, const char *metric, const struct label *labels, double value) {
diff --git a/scrape.h b/scrape.h
index 0c93828..f163e52 100644
--- a/scrape.h
+++ b/scrape.h
@@ -43,6 +43,9 @@ void scrape_serve(scrape_server *server, unsigned ncoll, const struct collector
 /** Closes the scrape server sockets and frees any resources. */
 void scrape_close(scrape_server *server);
 
+/** Run all scrapers once and print to stdout. */
+void scrape_print(unsigned ncoll, const struct collector *coll[], void *coll_ctx[]);
+
 /** Container for label keys and values. */
 struct label {
   char *key;