feat(xanthous/server): Add simple prometheus metrics r/3020

Add a prometheus exporter and some simple prometheus metrics, so that I
can look at dashboards and get alerts for things like lots of
connections

Change-Id: Ic1e0568200299dc852b74da647a6354267ee7576
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3811
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

4 files changed, 589 insertions, 11 deletions

diff --git a/users/grfn/xanthous/server/Cargo.lock b/users/grfn/xanthous/server/Cargo.lock
index 3fdcc7a65f8f..4bc9719911c8 100644
--- a/users/grfn/xanthous/server/Cargo.lock
+++ b/users/grfn/xanthous/server/Cargo.lock
@@ -23,7 +23,7 @@ version = "0.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9e8b47f52ea9bae42228d07ec09eb676433d7c4ed1ebdf0f1d1c29ed446f1ab8"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
  "cipher",
  "cpufeatures",
  "ctr",
@@ -31,6 +31,26 @@ dependencies = [
 ]
 
 [[package]]
+name = "ahash"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcb51a0695d8f838b1ee009b3fbf66bda078cd64590202a864a8f3e8c4315c47"
+dependencies = [
+ "getrandom",
+ "once_cell",
+ "version_check",
+]
+
+[[package]]
+name = "aho-corasick"
+version = "0.7.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e37cfd5e7657ada45f742d6e99ca5788580b5c529dc78faf11ece6dc702656f"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
 name = "ansi_term"
 version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -40,6 +60,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "atomic-shim"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d20fdac7156779a1a30d970e838195558b4810dd06aa69e7c7461bdc518edf9b"
+dependencies = [
+ "crossbeam",
+]
+
+[[package]]
 name = "atty"
 version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -64,7 +93,7 @@ checksum = "321629d8ba6513061f26707241fa9bc89524ff1cd7a915a97ef0c62c666ce1b6"
 dependencies = [
  "addr2line",
  "cc",
- "cfg-if",
+ "cfg-if 1.0.0",
  "libc",
  "miniz_oxide",
  "object",
@@ -139,6 +168,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "bumpalo"
+version = "3.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1e260c3a9040a7c19a12468758f4c16f31a81a1fe087482be9570ec864bb6c"
+
+[[package]]
 name = "byteorder"
 version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -158,6 +193,12 @@ checksum = "79c2681d6594606957bbb8631c4b90a7fcaaa72cdb714743a437b156d6a7eedd"
 
 [[package]]
 name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
+[[package]]
+name = "cfg-if"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
@@ -256,7 +297,102 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "81156fece84ab6a9f2afdb109ce3ae577e42b1228441eded99bd77f627953b1a"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
+]
+
+[[package]]
+name = "crossbeam"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69323bff1fb41c635347b8ead484a5ca6c3f11914d784170b158d8449ab07f8e"
+dependencies = [
+ "cfg-if 0.1.10",
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-epoch 0.8.2",
+ "crossbeam-queue",
+ "crossbeam-utils 0.7.2",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b153fe7cbef478c567df0f972e02e6d736db11affe43dfc9c56a9374d1adfb87"
+dependencies = [
+ "crossbeam-utils 0.7.2",
+ "maybe-uninit",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c20ff29ded3204c5106278a81a38f4b482636ed4fa1e6cfbeef193291beb29ed"
+dependencies = [
+ "crossbeam-epoch 0.8.2",
+ "crossbeam-utils 0.7.2",
+ "maybe-uninit",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "058ed274caafc1f60c4997b5fc07bf7dc7cca454af7c6e81edffe5f33f70dace"
+dependencies = [
+ "autocfg",
+ "cfg-if 0.1.10",
+ "crossbeam-utils 0.7.2",
+ "lazy_static",
+ "maybe-uninit",
+ "memoffset 0.5.6",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ec02e091aa634e2c3ada4a392989e7c3116673ef0ac5b72232439094d73b7fd"
+dependencies = [
+ "cfg-if 1.0.0",
+ "crossbeam-utils 0.8.5",
+ "lazy_static",
+ "memoffset 0.6.4",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-queue"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "774ba60a54c213d409d5353bda12d49cd68d14e45036a285234c8d6f91f92570"
+dependencies = [
+ "cfg-if 0.1.10",
+ "crossbeam-utils 0.7.2",
+ "maybe-uninit",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
+dependencies = [
+ "autocfg",
+ "cfg-if 0.1.10",
+ "lazy_static",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d82cfc11ce7f2c3faef78d8a684447b40d503d9681acebed6cb728d45940c4db"
+dependencies = [
+ "cfg-if 1.0.0",
+ "lazy_static",
 ]
 
 [[package]]
@@ -289,6 +425,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "dashmap"
+version = "4.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e77a43b28d0668df09411cb0bc9a8c2adc40f9a048afe863e05fd43251e8e39c"
+dependencies = [
+ "cfg-if 1.0.0",
+ "num_cpus",
+]
+
+[[package]]
 name = "data-encoding"
 version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -324,6 +470,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "endian-type"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c34f04666d835ff5d62e058c3995147c06f42fe86ff053337632bca83e42702d"
+
+[[package]]
 name = "eyre"
 version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -339,13 +491,19 @@ version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e6988e897c1c9c485f43b47a529cef42fde0547f9d8d41a7062518f1d8fc53f"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
  "crc32fast",
  "libc",
  "miniz_oxide",
 ]
 
 [[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
+[[package]]
 name = "futures"
 version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -455,7 +613,7 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
  "libc",
  "wasi",
 ]
@@ -471,6 +629,9 @@ name = "hashbrown"
 version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
+dependencies = [
+ "ahash",
+]
 
 [[package]]
 name = "heck"
@@ -501,6 +662,63 @@ dependencies = [
 ]
 
 [[package]]
+name = "http"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1323096b05d41827dadeaee54c9981958c0f94e670bc94ed80037d1a7b8b186b"
+dependencies = [
+ "bytes",
+ "fnv",
+ "itoa",
+]
+
+[[package]]
+name = "http-body"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ff4f84919677303da5f147645dbea6b1881f368d03ac84e1dc09031ebd7b2c6"
+dependencies = [
+ "bytes",
+ "http",
+ "pin-project-lite",
+]
+
+[[package]]
+name = "httparse"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acd94fdbe1d4ff688b67b04eee2e17bd50995534a61539e45adfefb45e5e5503"
+
+[[package]]
+name = "httpdate"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6456b8a6c8f33fee7d958fcd1b60d55b11940a79e63ae87013e6d22e26034440"
+
+[[package]]
+name = "hyper"
+version = "0.14.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b91bb1f221b6ea1f1e4371216b70f40748774c2fb5971b450c07773fb92d26b"
+dependencies = [
+ "bytes",
+ "futures-channel",
+ "futures-core",
+ "futures-util",
+ "http",
+ "http-body",
+ "httparse",
+ "httpdate",
+ "itoa",
+ "pin-project-lite",
+ "socket2",
+ "tokio",
+ "tower-service",
+ "tracing",
+ "want",
+]
+
+[[package]]
 name = "indenter"
 version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -517,12 +735,36 @@ dependencies = [
 ]
 
 [[package]]
+name = "instant"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a5bbe824c507c5da5956355e86a746d82e0e1464f65d862cc5e71da70e94b2c"
+dependencies = [
+ "cfg-if 1.0.0",
+]
+
+[[package]]
+name = "ipnet"
+version = "2.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68f2d64f2edebec4ce84ad108148e67e1064789bee435edc5b60ad398714a3a9"
+
+[[package]]
 name = "itoa"
 version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b71991ff56294aa922b450139ee08b3bfc70982c6b2c7562771375cf73542dd4"
 
 [[package]]
+name = "js-sys"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cc9ffccd38c451a86bf13657df244e9c3f37493cce8e5e21e940963777acc84"
+dependencies = [
+ "wasm-bindgen",
+]
+
+[[package]]
 name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -547,12 +789,30 @@ dependencies = [
 ]
 
 [[package]]
+name = "lock_api"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712a4d093c9976e24e7dbca41db895dabcbac38eb5f4045393d17a95bdfb1109"
+dependencies = [
+ "scopeguard",
+]
+
+[[package]]
 name = "log"
 version = "0.4.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
+]
+
+[[package]]
+name = "mach"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b823e83b2affd8f40a9ee8c29dbc56404c1e34cd2710921f2801e2cf29527afa"
+dependencies = [
+ "libc",
 ]
 
 [[package]]
@@ -565,6 +825,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "maybe-uninit"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60302e4db3a61da70c0cb7991976248362f30319e88850c487b9b95bbf059e00"
+
+[[package]]
 name = "md5"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -578,6 +844,15 @@ checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
 
 [[package]]
 name = "memoffset"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "043175f069eda7b85febe4a74abbaeff828d9f8b448515d3151a14a3542811aa"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "memoffset"
 version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59accc507f1338036a0477ef61afdae33cde60840f4dfe481319ce3ad116ddf9"
@@ -586,6 +861,70 @@ dependencies = [
 ]
 
 [[package]]
+name = "metrics"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a00f42f354a2ed4894db863b3a4db47aef2d2e4435b937221749bd37a8a7aaa8"
+dependencies = [
+ "ahash",
+ "metrics-macros",
+ "proc-macro-hack",
+]
+
+[[package]]
+name = "metrics-exporter-prometheus"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "343a5ceb38235928e7a5687412590f07e6d281522dcd9ff51246f8856eef5fe5"
+dependencies = [
+ "hyper",
+ "ipnet",
+ "metrics",
+ "metrics-util",
+ "parking_lot",
+ "quanta",
+ "thiserror",
+ "tokio",
+]
+
+[[package]]
+name = "metrics-macros"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "caa72e4a3d157986dd2565c82ecbddcc23941513669a3766b938f6b72eb87f3f"
+dependencies = [
+ "lazy_static",
+ "proc-macro-hack",
+ "proc-macro2",
+ "quote",
+ "regex",
+ "syn",
+]
+
+[[package]]
+name = "metrics-util"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74c9b6aee519e1461b678952d3671652bb341d0664b1188f895a436a4e2e6ffa"
+dependencies = [
+ "ahash",
+ "aho-corasick",
+ "atomic-shim",
+ "crossbeam-epoch 0.9.5",
+ "crossbeam-utils 0.8.5",
+ "dashmap",
+ "hashbrown",
+ "indexmap",
+ "metrics",
+ "num_cpus",
+ "ordered-float",
+ "parking_lot",
+ "quanta",
+ "radix_trie",
+ "sketches-ddsketch",
+]
+
+[[package]]
 name = "miniz_oxide"
 version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -618,6 +957,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "nibble_vec"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a5d83df9f36fe23f0c3648c6bbb8b0298bb5f1939c8f2704431371f4b84d43"
+dependencies = [
+ "smallvec",
+]
+
+[[package]]
 name = "nix"
 version = "0.23.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -625,9 +973,9 @@ checksum = "f305c2c2e4c39a82f7bf0bf65fb557f9070ce06781d4f2454295cc34b1c43188"
 dependencies = [
  "bitflags",
  "cc",
- "cfg-if",
+ "cfg-if 1.0.0",
  "libc",
- "memoffset",
+ "memoffset 0.6.4",
 ]
 
 [[package]]
@@ -701,6 +1049,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 
 [[package]]
+name = "ordered-float"
+version = "2.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97c9d06878b3a851e8026ef94bf7fef9ba93062cd412601da4d9cf369b1cc62d"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
 name = "os_str_bytes"
 version = "4.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -716,6 +1073,31 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2386b4ebe91c2f7f51082d4cefa145d030e33a1842a96b12e4885cc3c01f7a55"
 
 [[package]]
+name = "parking_lot"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d17b78036a60663b797adeaee46f5c9dfebb86948d1255007a1d6be0271ff99"
+dependencies = [
+ "instant",
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d76e8e1493bcac0d2766c42737f34458f1c8c50c0d23bcb24ea953affb273216"
+dependencies = [
+ "cfg-if 1.0.0",
+ "instant",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "winapi",
+]
+
+[[package]]
 name = "password-hash"
 version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -809,6 +1191,22 @@ dependencies = [
 ]
 
 [[package]]
+name = "quanta"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20afe714292d5e879d8b12740aa223c6a88f118af41870e8b6196e39a02238a8"
+dependencies = [
+ "crossbeam-utils 0.8.5",
+ "libc",
+ "mach",
+ "once_cell",
+ "raw-cpuid",
+ "wasi",
+ "web-sys",
+ "winapi",
+]
+
+[[package]]
 name = "quote"
 version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -818,6 +1216,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "radix_trie"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c069c179fcdc6a2fe24d8d18305cf085fdbd4f922c041943e203685d6a1c58fd"
+dependencies = [
+ "endian-type",
+ "nibble_vec",
+]
+
+[[package]]
 name = "rand"
 version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -858,6 +1266,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "raw-cpuid"
+version = "10.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "929f54e29691d4e6a9cc558479de70db7aa3d98cd6fe7ab86d7507aa2886b9d2"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
 name = "redox_syscall"
 version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -882,6 +1299,8 @@ version = "1.5.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d07a8629359eb56f1e2fb1652bb04212c072a87ba68546a04065d525673ac461"
 dependencies = [
+ "aho-corasick",
+ "memchr",
  "regex-syntax",
 ]
 
@@ -922,6 +1341,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
+[[package]]
 name = "serde"
 version = "1.0.130"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -956,7 +1381,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b69f9a4c9740d74c5baa3fd2e547f9525fa8088a8a958e0ca2409a514e33f5fa"
 dependencies = [
  "block-buffer",
- "cfg-if",
+ "cfg-if 1.0.0",
  "cpufeatures",
  "digest",
  "opaque-debug",
@@ -981,6 +1406,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "sketches-ddsketch"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76a77a8fd93886010f05e7ea0720e569d6d16c65329dbe3ec033bbbccccb017b"
+
+[[package]]
 name = "slab"
 version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -993,6 +1424,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ecab6c735a6bb4139c0caafd0cc3635748bbb3acf4550e8138122099251f309"
 
 [[package]]
+name = "socket2"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5dc90fe6c7be1a323296982db1836d1ea9e47b6839496dde9a541bc496df3516"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
+[[package]]
 name = "strsim"
 version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1171,12 +1612,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "tower-service"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "360dfd1d6d30e05fda32ace2c8c70e9c0a9da713275777f5a4dbb8a1893930c6"
+
+[[package]]
 name = "tracing"
 version = "0.1.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "375a639232caf30edfc78e8d89b2d4c375515393e7af7e16f01cd96917fb2105"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
  "pin-project-lite",
  "tracing-attributes",
  "tracing-core",
@@ -1256,6 +1703,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "try-lock"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59547bce71d9c38b83d9c0e92b6066c4253371f15005def0c30d9657f50c7642"
+
+[[package]]
 name = "typenum"
 version = "1.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1312,12 +1765,86 @@ dependencies = [
 ]
 
 [[package]]
+name = "want"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ce8a968cb1cd110d136ff8b819a556d6fb6d919363c61534f6860c7eb172ba0"
+dependencies = [
+ "log",
+ "try-lock",
+]
+
+[[package]]
 name = "wasi"
 version = "0.10.2+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
 
 [[package]]
+name = "wasm-bindgen"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "632f73e236b219150ea279196e54e610f5dbafa5d61786303d4da54f84e47fce"
+dependencies = [
+ "cfg-if 1.0.0",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a317bf8f9fba2476b4b2c85ef4c4af8ff39c3c7f0cdfeed4f82c34a880aa837b"
+dependencies = [
+ "bumpalo",
+ "lazy_static",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d56146e7c495528bf6587663bea13a8eb588d39b36b679d83972e1a2dbbdacf9"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7803e0eea25835f8abdc585cd3021b3deb11543c6fe226dcd30b228857c5c5ab"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0237232789cf037d5480773fe568aac745bfe2afbc11a863e97901780a6b47cc"
+
+[[package]]
+name = "web-sys"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38eb105f1c59d9eaa6b5cdc92b859d85b926e82cb2e0945cd0c9259faa6fe9fb"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
 name = "winapi"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1358,6 +1885,8 @@ dependencies = [
  "eyre",
  "futures",
  "libc",
+ "metrics",
+ "metrics-exporter-prometheus",
  "nix",
  "pbkdf2",
  "thrussh",
diff --git a/users/grfn/xanthous/server/Cargo.toml b/users/grfn/xanthous/server/Cargo.toml
index 929970939933..6772d75ec88f 100644
--- a/users/grfn/xanthous/server/Cargo.toml
+++ b/users/grfn/xanthous/server/Cargo.toml
@@ -11,6 +11,8 @@ thrussh = "0.33.5"
 thrussh-keys = "0.21.0"
 tracing = "0.1.29"
 tracing-subscriber = "0.2.25"
+metrics = "0.17.0"
+metrics-exporter-prometheus = "0.6.1"
 futures = "0.3.17"
 libc = "0.2.103"
 nix = "0.23.0"
diff --git a/users/grfn/xanthous/server/src/main.rs b/users/grfn/xanthous/server/src/main.rs
index b9f2cb4270b4..4476fe48a68d 100644
--- a/users/grfn/xanthous/server/src/main.rs
+++ b/users/grfn/xanthous/server/src/main.rs
@@ -1,5 +1,4 @@
 use std::net::SocketAddr;
-
 use std::pin::Pin;
 use std::process::Command;
 use std::sync::Arc;
@@ -9,6 +8,7 @@ use color_eyre::eyre::Result;
 use eyre::{bail, eyre};
 use futures::future::{ready, Ready};
 use futures::Future;
+use metrics_exporter_prometheus::PrometheusBuilder;
 use nix::pty::Winsize;
 use pty::ChildHandle;
 use thrussh::ChannelId;
@@ -19,13 +19,18 @@ use thrussh::{
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::TcpListener;
 use tokio::select;
+use tokio::time::Instant;
 use tracing::{debug, error, info, info_span, trace, warn, Instrument};
 use tracing_subscriber::EnvFilter;
 
 use crate::pty::WaitPid;
 
+mod metrics;
 mod pty;
 
+use crate::metrics::reported::*;
+use crate::metrics::{decrement_gauge, histogram, increment_counter, increment_gauge};
+
 /// SSH-compatible server for playing Xanthous
 #[derive(Parser, Debug)]
 struct Opts {
@@ -33,6 +38,10 @@ struct Opts {
     #[clap(long, short = 'a', default_value = "0.0.0.0:22")]
     address: String,
 
+    /// Address to listen to for metrics
+    #[clap(long, default_value = "0.0.0.0:9000")]
+    metrics_address: SocketAddr,
+
     /// Format to use when emitting log events
     #[clap(
         long,
@@ -132,6 +141,7 @@ impl Handler {
 
         let child = pty::spawn(cmd, Some(winsize), None).await?;
         info!(pid = %child.pid, "Spawned child");
+        increment_gauge!(RUNNING_PROCESSES, 1.0);
         self.child = Some(child.handle().await?);
         tokio::spawn(
             async move {
@@ -143,6 +153,7 @@ impl Handler {
                     span.in_scope(|| error!(%error, "Error running child"));
                     let _ = handle.close(channel_id).await;
                 }
+                decrement_gauge!(RUNNING_PROCESSES, 1.0);
             }
             .in_current_span(),
         );
@@ -285,12 +296,19 @@ async fn main() -> Result<()> {
     color_eyre::install()?;
     let opts = Box::leak::<'static>(Box::new(Opts::parse()));
     opts.init_logging()?;
+    PrometheusBuilder::new()
+        .listen_address(opts.metrics_address)
+        .install()?;
+    metrics::register();
+
     let config = Arc::new(opts.ssh_server_config()?);
     info!(address = %opts.address, "Listening for new SSH connections");
     let listener = TcpListener::bind(&opts.address).await?;
 
     loop {
         let (stream, address) = listener.accept().await?;
+        increment_counter!(CONNECTIONS_ACCEPTED);
+        increment_gauge!(ACTIVE_CONNECTIONS, 1.0);
         let config = config.clone();
         let handler = Handler {
             xanthous_binary_path: &opts.xanthous_binary_path,
@@ -300,12 +318,17 @@ async fn main() -> Result<()> {
         };
         tokio::spawn(async move {
             let span = info_span!("client", address = %handler.address);
+            let start = Instant::now();
             if let Err(error) = server::run_stream(config, stream, handler)
                 .instrument(span.clone())
                 .await
             {
                 span.in_scope(|| error!(%error));
             }
+            let duration = start.elapsed();
+            span.in_scope(|| info!(duration_ms = %duration.as_millis(), "Client disconnected"));
+            histogram!(CONNECTION_DURATION, duration);
+            decrement_gauge!(ACTIVE_CONNECTIONS, 1.0);
         });
     }
 }
diff --git a/users/grfn/xanthous/server/src/metrics.rs b/users/grfn/xanthous/server/src/metrics.rs
new file mode 100644
index 000000000000..6912cdd9c9ee
--- /dev/null
+++ b/users/grfn/xanthous/server/src/metrics.rs
@@ -0,0 +1,24 @@
+pub use ::metrics::*;
+
+pub mod reported {
+    /// Counter: Connections accepted on the TCP listener
+    pub const CONNECTIONS_ACCEPTED: &str = "ssh.connections.accepted";
+
+    /// Histogram: Connection duration
+    pub const CONNECTION_DURATION: &str = "ssh.connections.duration";
+
+    /// Gauge: Currently active connections
+    pub const ACTIVE_CONNECTIONS: &str = "ssh.connections.active";
+
+    /// Gauge: Currently running xanthous processes
+    pub const RUNNING_PROCESSES: &str = "ssh.child.processes";
+}
+
+pub fn register() {
+    use reported::*;
+
+    register_counter!(CONNECTIONS_ACCEPTED);
+    register_histogram!(CONNECTION_DURATION);
+    register_gauge!(ACTIVE_CONNECTIONS);
+    register_gauge!(RUNNING_PROCESSES);
+}