diff --git a/Cargo.lock b/Cargo.lock
index be3c8eb..1874af3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -461,6 +461,9 @@ dependencies = [
  "cave",
  "futures",
  "http",
+ "metrics",
+ "metrics-exporter-prometheus",
+ "metrics-util",
  "redis",
  "reqwest",
  "serde",
diff --git a/sieve/Cargo.toml b/sieve/Cargo.toml
index ba4ad6b..d7c92da 100644
--- a/sieve/Cargo.toml
+++ b/sieve/Cargo.toml
@@ -16,3 +16,6 @@ redis = { version = "0.23", features = ["tokio-comp", "connection-manager"] }
 reqwest = { version = "0.11" }
 http = "*"
 sigh = "*"
+metrics = "0.20"
+metrics-util = "0.14"
+metrics-exporter-prometheus = "0.11"
diff --git a/sieve/config.yaml b/sieve/config.yaml
index 0e8efba..801d2bc 100644
--- a/sieve/config.yaml
+++ b/sieve/config.yaml
@@ -2,3 +2,4 @@ redis: "redis://fedi.buzz:6379/"
 redis_password_file: "redis_password.txt"
 in_topic: "relay-in"
 priv_key_file: private-key.pem
+prometheus_port: 9102
diff --git a/sieve/src/config.rs b/sieve/src/config.rs
index 157641b..5caa25e 100644
--- a/sieve/src/config.rs
+++ b/sieve/src/config.rs
@@ -8,6 +8,7 @@ pub struct Config {
     pub redis_password_file: String,
     pub in_topic: String,
     priv_key_file: String,
+    pub prometheus_port: u16,
 }
 
 impl Config {
diff --git a/sieve/src/main.rs b/sieve/src/main.rs
index 5c09246..8a4829e 100644
--- a/sieve/src/main.rs
+++ b/sieve/src/main.rs
@@ -13,6 +13,8 @@ use cave::{
     config::LoadConfig,
     feed,
 };
+use metrics_util::MetricKindMask;
+use metrics_exporter_prometheus::PrometheusBuilder;
 
 mod config;
 
@@ -41,6 +43,14 @@ async fn main() {
     cave::init::init_logger(5557);
 
     let config = config::Config::load();
+
+    PrometheusBuilder::new()
+        .with_http_listener(([0; 8], config.prometheus_port))
+        .add_global_label("application", env!("CARGO_PKG_NAME"))
+        .idle_timeout(MetricKindMask::ALL, Some(Duration::from_secs(600)))
+        .install()
+        .unwrap();
+
     let priv_key = Arc::new(config.priv_key());
     let relay_in = connect_relay_in(config.redis_url(), &config.in_topic)
         .await
@@ -71,6 +81,7 @@ async fn main() {
     relay_in.for_each(|action| async {
         // Filter by action type
         if ! allowed_action_types.contains(&action.action_type) {
+            metrics::counter!("sieve_activity", 1, "type" => "type_ignored");
             return;
         }
 
@@ -100,10 +111,13 @@ async fn main() {
                 // fetch info for id
                 tracing::debug!("GET {id}");
                 match authorized_fetch(&client, id, KEY_ID, &priv_key).await {
-                    Ok(res) =>
-                        res,
+                    Ok(res) => {
+                        metrics::counter!("sieve_activity", 1, "type" => "fetch_object_ok");
+                        res
+                    }
                     Err(e) => {
                         tracing::error!("{id} HTTP: {e:?}");
+                        metrics::counter!("sieve_activity", 1, "type" => "fetch_object_error");
                         return;
                     }
                 }
@@ -117,21 +131,26 @@ async fn main() {
                     post,
                 Err(e) => {
                     tracing::error!("JSON of {id}: {e:?}");
+                    metrics::counter!("sieve_activity", 1, "type" => "json_error");
                     return;
                 }
             };
 
             let author: activitypub::Actor = if let Some(author_url) = &post.attributed_to {
                 match authorized_fetch(&client, author_url, KEY_ID, &priv_key).await {
-                    Ok(author) =>
-                        author,
+                    Ok(author) => {
+                        metrics::counter!("sieve_activity", 1, "type" => "fetch_author_ok");
+                        author
+                    }
                     Err(e) => {
                         tracing::error!("{author_url} HTTP: {e:?}");
+                        metrics::counter!("sieve_activity", 1, "type" => "fetch_author_error");
                         return;
                     }
                 }
             } else {
                 tracing::error!("No attributedTo in {id}");
+                metrics::counter!("sieve_activity", 1, "type" => "no_author");
                 return;
             };
             // Translate ActivityPub post to Mastodon client API post format
@@ -146,16 +165,23 @@ async fn main() {
                 post
             } else {
                 tracing::error!("Cannot serialize post {id}");
+                metrics::counter!("sieve_activity", 1, "type" => "serialize_error");
                 return;
             };
 
             match store.save_post(encodable_post).await {
-                Ok(true) =>
-                    tracing::info!("Post was new: {id}"),
-                Ok(false) =>
-                    tracing::info!("Post was already known: {id}"),
-                Err(e) =>
-                    tracing::error!("Error forwarding post {id}: {e:?}"),
+                Ok(true) => {
+                    tracing::info!("Post was new: {id}");
+                    metrics::counter!("sieve_activity", 1, "type" => "post_new");
+                }
+                Ok(false) => {
+                    tracing::info!("Post was already known: {id}");
+                    metrics::counter!("sieve_activity", 1, "type" => "post_known");
+                }
+                Err(e) => {
+                    tracing::error!("Error forwarding post {id}: {e:?}");
+                    metrics::counter!("sieve_activity", 1, "type" => "post_error");
+                }
             }
         });
     }).await;