deploy: Support multiple backends

Author: bgamari

deploy.nix

@@ -1,5 +1,5 @@
 { hoogle, cores ? 4 }:
-{ config, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 
 # The Plan:
 # Hoogle serves on a uniquely-named UNIX domain socket which we
@@ -12,7 +12,8 @@
 let
   hoogleRun = "/run/hoogle";
   nginxConf = "${hoogleRun}/nginx.conf";
-  socket = "/run/hoogle/hoogle.sock";
+  socket = inst: "/run/hoogle/hoogle-${inst}.sock";
+  nServers = 12;
 in
 {
   users.users.hoogle = {
@@ -35,78 +36,86 @@ in
     wantedBy = [ "timers.target" ];
   };
 
-  systemd.services."generate-hoogle" = {
-    script = ''
-      hoogle generate --database=$DB_DIR/haskell-new.hoo --insecure --download +RTS -N${toString cores} -RTS
-      mv $DB_DIR/haskell-new.hoo $DB_DIR/haskell.hoo
-    '';
-    path = [ hoogle ];
-    after = [ "network.target" ];
-    serviceConfig = {
-      User = "hoogle";
-      Group = "hoogle";
-      Type = "oneshot";
-      TimeoutStartSec = 600;
-      ExecStartPost = "+systemctl restart hoogle.service";
-      BindReadOnlyPaths = [
-        # mount the nix store read-only
-        "/nix/store"
-        # getAppUserDataDirectory needs getUserEntryForID
-        "/etc/passwd"
-      ];
-      PrivateNetwork = false;
-      RuntimeDirectory = "generate-hoogle";
-      StateDirectory = [ "hoogle" ];
+  systemd.services = {
+    "generate-hoogle" = {
+      script = ''
+        hoogle generate --database=$DB_DIR/haskell-new.hoo --insecure --download +RTS -N${toString cores} -RTS
+        mv $DB_DIR/haskell-new.hoo $DB_DIR/haskell.hoo
+      '';
+      path = [ hoogle ];
+      after = [ "network.target" ];
+      serviceConfig = {
+        User = "hoogle";
+        Group = "hoogle";
+        Type = "oneshot";
+        TimeoutStartSec = 600;
+        ExecStartPost = "+systemctl restart 'hoogle@*'";
+        BindReadOnlyPaths = [
+          # mount the nix store read-only
+          "/nix/store"
+          # getAppUserDataDirectory needs getUserEntryForID
+          "/etc/passwd"
+        ];
+        PrivateNetwork = false;
+        RuntimeDirectory = "generate-hoogle";
+        StateDirectory = [ "hoogle" ];
+      };
+      environment = {
+        DB_DIR = "%S/hoogle";
+      };
     };
-    environment = {
-      DB_DIR = "%S/hoogle";
-    };
-  };
 
-  systemd.services."hoogle" = {
-    script = ''
-      hoogle serve \
-        --database=$DB_DIR/haskell.hoo \
-        --scope=set:stackage \
-        --socket=${socket} \
-        --links \
-        +RTS -T -N${toString cores} -RTS;
-    '';
-    path = [ hoogle ];
-    serviceConfig = {
-      User = "nginx";
-      Group = "hoogle";
-      BindReadOnlyPaths = [
-        # mount the nix store read-only
-        "/nix/store"
-        # getAppUserDataDirectory needs getUserEntryForID
-        "/etc/passwd"
-        #"/etc/ssl" "/etc/ssl/certs"
-      ];
-      PrivateTmp = false;
-      ProtectSystem = false;
-      ProtectHome = false;
-      NoNewPrivileges = false;
-      Restart = "on-failure";
-      RestartSec = "5s";
-      RuntimeDirectory = "hoogle";
-    };
-    environment = {
-      DB_DIR = "%S/hoogle";
-      SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
-      NIX_SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+    "hoogle@" = {
+      script = ''
+        ${hoogle}/bin/hoogle serve \
+          --database=$DB_DIR/haskell.hoo \
+          --scope=set:stackage \
+          --socket=$SOCKET \
+          --links \
+          +RTS -T -RTS;
+      '';
+      serviceConfig = {
+        User = "nginx";
+        Group = "hoogle";
+        BindReadOnlyPaths = [
+          # mount the nix store read-only
+          "/nix/store"
+          # getAppUserDataDirectory needs getUserEntryForID
+          "/etc/passwd"
+          #"/etc/ssl" "/etc/ssl/certs"
+        ];
+        PrivateTmp = false;
+        ProtectSystem = false;
+        ProtectHome = false;
+        NoNewPrivileges = false;
+        Restart = "on-failure";
+        RestartSec = "5s";
+        RuntimeDirectory = "hoogle";
+      };
+      environment = {
+        DB_DIR = "%S/hoogle";
+        SOCKET = socket "%i";
+        SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+        NIX_SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+      };
     };
-    wantedBy = [ "multi-user.target" ];
-  };
+  } // (
+    let
+      mkInst = n:
+        lib.attrsets.nameValuePair "hoogle@${toString n}"
+        {
+          wantedBy = [ "multi-user.target" ];
+          overrideStrategy = "asDropin";
+        };
+    in lib.listToAttrs (map mkInst (lib.range 1 nServers))
+  );
 
   systemd.tmpfiles.rules = [
     "f ${nginxConf} 0755 nginx nginx -"
   ];
 
-  services.nginx = {
-    upstreams.hoogle.extraConfig = ''
-      server unix:${socket};
-    '';
-  };
+  services.nginx.upstreams.hoogle.servers =
+    let mkInst = n: lib.attrsets.nameValuePair "unix:${socket (toString n)}" { };
+    in lib.listToAttrs (map mkInst (lib.range 1 nServers));
 }