Fix letsencrypt (#60219)

* nixos/acme: Fix ordering of cert requests

When subsequent certificates would be added, they would
not wake up nginx correctly due to target units only being triggered
once. We now added more fine-grained systemd dependencies to make sure
nginx always is aware of new certificates and doesn't restart too early
resulting in a crash.

Furthermore, the acme module has been refactored. Mostly to get
rid of the deprecated PermissionStartOnly systemd options which were
deprecated. Below is a summary of changes made.

* Use SERVICE_RESULT to determine status
This was added in systemd v232. we don't have to keep track
of the EXITCODE ourselves anymore.

* Add regression test for requesting mutliple domains

* Deprecate 'directory' option
We now use systemd's StateDirectory option to manage
create and permissions of the acme state directory.

* The webroot is created using a systemd.tmpfiles.rules rule
instead of the preStart script.

* Depend on certs directly

By getting rid of the target units, we make sure ordering
is correct in the case that you add new certs after already
having deployed some.

Reason it broke before:  acme-certificates.target would
be in active state, and if you then add a new cert, it
would still be active and hence nginx would restart
without even requesting a new cert. Not good!  We
make the dependencies more fine-grained now. this should fix that

* Remove activationDelay option

It complicated the code a lot, and is rather arbitrary. What if
your activation script takes more than activationDelay seconds?

Instead, one should use systemd dependencies to make sure some
action happens before setting the certificate live.

e.g. If you want to wait until your cert is published in DNS DANE /
TLSA, you could create a unit that blocks until it appears in DNS:

```
RequiredBy=acme-${cert}.service
After=acme-${cert}.service
ExecStart=publish-wait-for-dns-script
```

6 files changed, 162 insertions, 143 deletions

diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index 36bea28530b..60f756b78c6 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -318,7 +318,28 @@
       <listitem><para><link linkend="opt-services.strongswan-swanctl.enable"><literal>services.strongswan-swanctl</literal></link></para></listitem>
       <listitem><para><link linkend="opt-services.httpd.enable"><literal>services.httpd</literal></link></para></listitem>
      </itemizedlist>
-    </para>
+   </para>
+   <listitem>
+     <para>
+       The <option>security.acme.directory</option> option has been replaced by a read-only <option>security.acme.certs.&lt;cert&gt;.directory</option> option for each certificate you define. This will be
+       a subdirectory of <literal>/var/lib/acme</literal>. You can use this read-only option to figure out where the certificates are stored for a specific certificate. For example,
+       the <option>services.nginx.virtualhosts.&lt;name&gt;.enableACME</option>  option will use this directory option to find the certs for the virtual host.
+     </para>
+     <para>
+       <option>security.acme.preDelay</option> and <option>security.acme.activationDelay</option> options have been removed. To execute a service before certificates
+       are provisioned or renewed add a <literal>RequiredBy=acme-${cert}.service</literal> to any service.
+     </para>
+     <para>
+       Furthermore, the acme module will not automatically add a dependency on <literal>lighttpd.service</literal> anymore. If you are using certficates provided by letsencrypt
+       for lighttpd, then you should depend on the certificate service <literal>acme-${cert}.service></literal> manually.
+     </para>
+     <para>
+       For nginx, the dependencies are still automatically managed when <option>services.nginx.virtualhosts.&lt;name&gt;.enableACME</option> is enabled just like before. What changed is that nginx now directly depends on the specific certificates that it needs,
+       instead of depending on the catch-all <literal>acme-certificates.target</literal>. This target unit was also removed from the codebase.
+       This will mean nginx will no longer depend on certificates it isn't explicitly managing and fixes a bug with certificate renewal
+       ordering racing with nginx restarting which could lead to nginx getting in a broken state as described at 
+        <link xlink:href="https://github.com/NixOS/nixpkgs/issues/60180">NixOS/nixpkgs#60180</link>.
+     </para>
    </listitem>
   </itemizedlist>
  </section>
diff --git a/nixos/modules/rename.nix b/nixos/modules/rename.nix
index 348ad094e5a..1048c2af2ea 100644
--- a/nixos/modules/rename.nix
+++ b/nixos/modules/rename.nix
@@ -256,6 +256,11 @@ with lib;
 
     # binfmt
     (mkRenamedOptionModule [ "boot" "binfmtMiscRegistrations" ] [ "boot" "binfmt" "registrations" ])
+    
+    # ACME
+    (mkRemovedOptionModule [ "security" "acme" "directory"] "ACME Directory is now hardcoded to /var/lib/acme and its permisisons are managed by systemd. See https://github.com/NixOS/nixpkgs/issues/53852 for more info.")
+    (mkRemovedOptionModule [ "security" "acme" "preDelay"] "This option has been removed. If you want to make sure that something executes before certificates are provisioned, add a RequiredBy=acme-\${cert}.service to the service you want to execute before the cert renewal")
+    (mkRemovedOptionModule [ "security" "acme" "activationDelay"] "This option has been removed. If you want to make sure that something executes before certificates are provisioned, add a RequiredBy=acme-\${cert}.service to the service you want to execute before the cert renewal")
 
     # KSM
     (mkRenamedOptionModule [ "hardware" "enableKSM" ] [ "hardware" "ksm" "enable" ])
diff --git a/nixos/modules/security/acme.nix b/nixos/modules/security/acme.nix
index 092704c6fc3..feb54affbf8 100644
--- a/nixos/modules/security/acme.nix
+++ b/nixos/modules/security/acme.nix
@@ -80,25 +80,11 @@ let
         '';
       };
 
-      activationDelay = mkOption {
-        type = types.nullOr types.str;
-        default = null;
-        description = ''
-          Systemd time span expression to delay copying new certificates to main
-          state directory. See <citerefentry><refentrytitle>systemd.time</refentrytitle>
-          <manvolnum>7</manvolnum></citerefentry>.
-        '';
-      };
-
-      preDelay = mkOption {
-        type = types.lines;
-        default = "";
-        description = ''
-          Commands to run after certificates are re-issued but before they are
-          activated. Typically the new certificate is published to DNS.
-
-          Executed in the same directory with the new certificate.
-        '';
+      directory = mkOption {
+        type = types.str;
+        readOnly = true;
+        default = "/var/lib/acme/${name}";
+        description = "Directory where certificate and other state is stored.";
       };
 
       extraDomains = mkOption {
@@ -126,13 +112,6 @@ in
 
   options = {
     security.acme = {
-      directory = mkOption {
-        default = "/var/lib/acme";
-        type = types.str;
-        description = ''
-          Directory where certs and other state will be stored by default.
-        '';
-      };
 
       validMin = mkOption {
         type = types.int;
@@ -181,7 +160,11 @@ in
         default = { };
         type = with types; attrsOf (submodule certOpts);
         description = ''
-          Attribute set of certificates to get signed and renewed.
+          Attribute set of certificates to get signed and renewed. Creates
+          <literal>acme-''${cert}.{service,timer}</literal> systemd units for
+          each certificate defined here. Other services can add dependencies
+          to those units if they rely on the certificates being present,
+          or trigger restarts of the service if certificates get renewed.
         '';
         example = literalExample ''
           {
@@ -209,8 +192,7 @@ in
           servicesLists = mapAttrsToList certToServices cfg.certs;
           certToServices = cert: data:
               let
-                cpath = lpath + optionalString (data.activationDelay != null) ".staging";
-                lpath = "${cfg.directory}/${cert}";
+                lpath = "acme/${cert}";
                 rights = if data.allowKeysForGroup then "750" else "700";
                 cmdline = [ "-v" "-d" data.domain "--default_root" data.webroot "--valid_min" cfg.validMin ]
                           ++ optionals (data.email != null) [ "--email" data.email ]
@@ -224,79 +206,27 @@ in
                   serviceConfig = {
                     Type = "oneshot";
                     SuccessExitStatus = [ "0" "1" ];
-                    PermissionsStartOnly = true;
                     User = data.user;
                     Group = data.group;
                     PrivateTmp = true;
+                    StateDirectory = lpath;
+                    StateDirectoryMode = rights;
+                    WorkingDirectory = "/var/lib/${lpath}";
+                    ExecStart = "${pkgs.simp_le}/bin/simp_le ${escapeShellArgs cmdline}";
+                    ExecStopPost = 
+                      let
+                        script = pkgs.writeScript "acme-post-stop" ''
+                          #!${pkgs.runtimeShell} -e
+                          ${data.postRun}
+                        '';
+                      in
+                        "+${script}";
                   };
-                  path = with pkgs; [ simp_le systemd ];
-                  preStart = ''
-                    mkdir -p '${cfg.directory}'
-                    chown 'root:root' '${cfg.directory}'
-                    chmod 755 '${cfg.directory}'
-                    if [ ! -d '${cpath}' ]; then
-                      mkdir '${cpath}'
-                    fi
-                    chmod ${rights} '${cpath}'
-                    chown -R '${data.user}:${data.group}' '${cpath}'
-                    mkdir -p '${data.webroot}/.well-known/acme-challenge'
-                    chown -R '${data.user}:${data.group}' '${data.webroot}/.well-known/acme-challenge'
-                  '';
-                  script = ''
-                    cd '${cpath}'
-                    set +e
-                    simp_le ${escapeShellArgs cmdline}
-                    EXITCODE=$?
-                    set -e
-                    echo "$EXITCODE" > /tmp/lastExitCode
-                    exit "$EXITCODE"
-                  '';
-                  postStop = ''
-                    cd '${cpath}'
-
-                    if [ -e /tmp/lastExitCode ] && [ "$(cat /tmp/lastExitCode)" = "0" ]; then
-                      ${if data.activationDelay != null then ''
-
-                      ${data.preDelay}
-
-                      if [ -d '${lpath}' ]; then
-                        systemd-run --no-block --on-active='${data.activationDelay}' --unit acme-setlive-${cert}.service
-                      else
-                        systemctl --wait start acme-setlive-${cert}.service
-                      fi
-                      '' else data.postRun}
-
-                      # noop ensuring that the "if" block is non-empty even if
-                      # activationDelay == null and postRun == ""
-                      true
-                    fi
-                  '';
-
-                  before = [ "acme-certificates.target" ];
-                  wantedBy = [ "acme-certificates.target" ];
-                };
-                delayService = {
-                  description = "Set certificate for ${cert} live";
-                  path = with pkgs; [ rsync ];
-                  serviceConfig = {
-                    Type = "oneshot";
-                  };
-                  script = ''
-                    rsync -a --delete-after '${cpath}/' '${lpath}'
-                  '';
-                  postStop = data.postRun;
+
                 };
                 selfsignedService = {
                   description = "Create preliminary self-signed certificate for ${cert}";
                   path = [ pkgs.openssl ];
-                  preStart = ''
-                      if [ ! -d '${cpath}' ]
-                      then
-                        mkdir -p '${cpath}'
-                        chmod ${rights} '${cpath}'
-                        chown '${data.user}:${data.group}' '${cpath}'
-                      fi
-                  '';
                   script =
                     ''
                       workdir="$(mktemp -d)"
@@ -318,50 +248,41 @@ in
                         -out $workdir/server.crt
 
                       # Copy key to destination
-                      cp $workdir/server.key ${cpath}/key.pem
+                      cp $workdir/server.key /var/lib/${lpath}/key.pem
 
                       # Create fullchain.pem (same format as "simp_le ... -f fullchain.pem" creates)
-                      cat $workdir/{server.crt,ca.crt} > "${cpath}/fullchain.pem"
+                      cat $workdir/{server.crt,ca.crt} > "/var/lib/${lpath}/fullchain.pem"
 
                       # Create full.pem for e.g. lighttpd
-                      cat $workdir/{server.key,server.crt,ca.crt} > "${cpath}/full.pem"
+                      cat $workdir/{server.key,server.crt,ca.crt} > "/var/lib/${lpath}/full.pem"
 
                       # Give key acme permissions
-                      chown '${data.user}:${data.group}' "${cpath}/"{key,fullchain,full}.pem
-                      chmod ${rights} "${cpath}/"{key,fullchain,full}.pem
+                      chown '${data.user}:${data.group}' "/var/lib/${lpath}/"{key,fullchain,full}.pem
+                      chmod ${rights} "/var/lib/${lpath}/"{key,fullchain,full}.pem
                     '';
                   serviceConfig = {
                     Type = "oneshot";
-                    PermissionsStartOnly = true;
                     PrivateTmp = true;
+                    StateDirectory = lpath;
                     User = data.user;
                     Group = data.group;
                   };
                   unitConfig = {
                     # Do not create self-signed key when key already exists
-                    ConditionPathExists = "!${cpath}/key.pem";
+                    ConditionPathExists = "!/var/lib/${lpath}/key.pem";
                   };
-                  before = [
-                    "acme-selfsigned-certificates.target"
-                  ];
-                  wantedBy = [
-                    "acme-selfsigned-certificates.target"
-                  ];
                 };
               in (
                 [ { name = "acme-${cert}"; value = acmeService; } ]
                 ++ optional cfg.preliminarySelfsigned { name = "acme-selfsigned-${cert}"; value = selfsignedService; }
-                ++ optional (data.activationDelay != null) { name = "acme-setlive-${cert}"; value = delayService; }
               );
           servicesAttr = listToAttrs services;
-          injectServiceDep = {
-            after = [ "acme-selfsigned-certificates.target" ];
-            wants = [ "acme-selfsigned-certificates.target" "acme-certificates.target" ];
-          };
         in
-          servicesAttr //
-          (if config.services.nginx.enable then { nginx = injectServiceDep; } else {}) //
-          (if config.services.lighttpd.enable then { lighttpd = injectServiceDep; } else {});
+          servicesAttr;
+
+      systemd.tmpfiles.rules =
+        flip mapAttrsToList cfg.certs
+        (cert: data: "d ${data.webroot}/.well-known/acme-challenge - ${data.user} ${data.group}");
 
       systemd.timers = flip mapAttrs' cfg.certs (cert: data: nameValuePair
         ("acme-${cert}")
@@ -377,9 +298,6 @@ in
           };
         })
       );
-
-      systemd.targets."acme-selfsigned-certificates" = mkIf cfg.preliminarySelfsigned {};
-      systemd.targets."acme-certificates" = {};
     })
 
   ];
diff --git a/nixos/modules/security/acme.xml b/nixos/modules/security/acme.xml
index ef71fe53d0c..9d0a1995e0f 100644
--- a/nixos/modules/security/acme.xml
+++ b/nixos/modules/security/acme.xml
@@ -59,10 +59,8 @@ http {
   <para>
    The private key <filename>key.pem</filename> and certificate
    <filename>fullchain.pem</filename> will be put into
-   <filename>/var/lib/acme/foo.example.com</filename>. The target directory can
-   be configured with the option <xref linkend="opt-security.acme.directory"/>.
+   <filename>/var/lib/acme/foo.example.com</filename>.
   </para>
-
   <para>
    Refer to <xref linkend="ch-options" /> for all available configuration
    options for the <link linkend="opt-security.acme.certs">security.acme</link>
diff --git a/nixos/modules/services/web-servers/nginx/default.nix b/nixos/modules/services/web-servers/nginx/default.nix
index c1a51fbf8b4..5c65a2388d6 100644
--- a/nixos/modules/services/web-servers/nginx/default.nix
+++ b/nixos/modules/services/web-servers/nginx/default.nix
@@ -4,23 +4,25 @@ with lib;
 
 let
   cfg = config.services.nginx;
+  certs = config.security.acme.certs;
+  vhostsConfigs = mapAttrsToList (vhostName: vhostConfig: vhostConfig) virtualHosts;
+  acmeEnabledVhosts = filter (vhostConfig: vhostConfig.enableACME && vhostConfig.useACMEHost == null) vhostsConfigs;
   virtualHosts = mapAttrs (vhostName: vhostConfig:
     let
       serverName = if vhostConfig.serverName != null
         then vhostConfig.serverName
         else vhostName;
-      acmeDirectory = config.security.acme.directory;
     in
     vhostConfig // {
       inherit serverName;
     } // (optionalAttrs vhostConfig.enableACME {
-      sslCertificate = "${acmeDirectory}/${serverName}/fullchain.pem";
-      sslCertificateKey = "${acmeDirectory}/${serverName}/key.pem";
-      sslTrustedCertificate = "${acmeDirectory}/${serverName}/fullchain.pem";
+      sslCertificate = "${certs.${serverName}.directory}/fullchain.pem";
+      sslCertificateKey = "${certs.${serverName}.directory}/key.pem";
+      sslTrustedCertificate = "${certs.${serverName}.directory}/full.pem";
     }) // (optionalAttrs (vhostConfig.useACMEHost != null) {
-      sslCertificate = "${acmeDirectory}/${vhostConfig.useACMEHost}/fullchain.pem";
-      sslCertificateKey = "${acmeDirectory}/${vhostConfig.useACMEHost}/key.pem";
-      sslTrustedCertificate = "${acmeDirectory}/${vhostConfig.useACMEHost}/fullchain.pem";
+      sslCertificate = "${certs.${vhostConfig.useACMEHost}.directory}/fullchain.pem";
+      sslCertificateKey = "${certs.${vhostConfig.useACMEHost}.directory}/key.pem";
+      sslTrustedCertificate = "${certs.${vhostConfig.useACMEHost}.directory}/fullchain.pem";
     })
   ) cfg.virtualHosts;
   enableIPv6 = config.networking.enableIPv6;
@@ -646,8 +648,9 @@ in
 
     systemd.services.nginx = {
       description = "Nginx Web Server";
-      after = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
+      wants = concatLists (map (vhostConfig: ["acme-${vhostConfig.serverName}.service" "acme-selfsigned-${vhostConfig.serverName}.service"]) acmeEnabledVhosts);
+      after = [ "network.target" ] ++ map (vhostConfig: "acme-selfsigned-${vhostConfig.serverName}.service") acmeEnabledVhosts;
       stopIfChanged = false;
       preStart =
         ''
@@ -680,8 +683,6 @@ in
 
     security.acme.certs = filterAttrs (n: v: v != {}) (
       let
-        vhostsConfigs = mapAttrsToList (vhostName: vhostConfig: vhostConfig) virtualHosts;
-        acmeEnabledVhosts = filter (vhostConfig: vhostConfig.enableACME && vhostConfig.useACMEHost == null) vhostsConfigs;
         acmePairs = map (vhostConfig: { name = vhostConfig.serverName; value = {
             user = cfg.user;
             group = lib.mkDefault cfg.group;
diff --git a/nixos/tests/acme.nix b/nixos/tests/acme.nix
index 4669a092433..8cfdea4a16e 100644
--- a/nixos/tests/acme.nix
+++ b/nixos/tests/acme.nix
@@ -3,19 +3,49 @@ let
 in import ./make-test.nix {
   name = "acme";
 
-  nodes = {
+  nodes = rec {
     letsencrypt = ./common/letsencrypt;
 
+    acmeStandalone = { config, pkgs, ... }: {
+      imports = [ commonConfig ];
+      networking.firewall.allowedTCPPorts = [ 80 ];
+      networking.extraHosts = ''
+        ${config.networking.primaryIPAddress} standalone.com
+      '';
+      security.acme.certs."standalone.com" = {
+        webroot = "/var/lib/acme/acme-challenges";
+      };
+      systemd.targets."acme-finished-standalone.com" = {};
+      systemd.services."acme-standalone.com" = {
+        wants = [ "acme-finished-standalone.com.target" ];
+        before = [ "acme-finished-standalone.com.target" ];
+      };
+      services.nginx.enable = true;
+      services.nginx.virtualHosts."standalone.com" = {
+        locations."/.well-known/acme-challenge".root = "/var/lib/acme/acme-challenges";
+      };
+    };
+
     webserver = { config, pkgs, ... }: {
       imports = [ commonConfig ];
       networking.firewall.allowedTCPPorts = [ 80 443 ];
 
       networking.extraHosts = ''
-        ${config.networking.primaryIPAddress} example.com
+        ${config.networking.primaryIPAddress} a.example.com
+        ${config.networking.primaryIPAddress} b.example.com
       '';
 
+      # A target remains active. Use this to probe the fact that
+      # a service fired eventhough it is not RemainAfterExit
+      systemd.targets."acme-finished-a.example.com" = {};
+      systemd.services."acme-a.example.com" = {
+        wants = [ "acme-finished-a.example.com.target" ];
+        before = [ "acme-finished-a.example.com.target" ];
+      };
+
       services.nginx.enable = true;
-      services.nginx.virtualHosts."example.com" = {
+
+      services.nginx.virtualHosts."a.example.com" = {
         enableACME = true;
         forceSSL = true;
         locations."/".root = pkgs.runCommand "docroot" {} ''
@@ -23,17 +53,63 @@ in import ./make-test.nix {
           echo hello world > "$out/index.html"
         '';
       };
+
+      nesting.clone = [
+        ({pkgs, ...}: {
+
+          networking.extraHosts = ''
+            ${config.networking.primaryIPAddress} b.example.com
+          '';
+          systemd.targets."acme-finished-b.example.com" = {};
+          systemd.services."acme-b.example.com" = {
+            wants = [ "acme-finished-b.example.com.target" ];
+            before = [ "acme-finished-b.example.com.target" ];
+          };
+          services.nginx.virtualHosts."b.example.com" = {
+            enableACME = true;
+            forceSSL = true;
+            locations."/".root = pkgs.runCommand "docroot" {} ''
+              mkdir -p "$out"
+              echo hello world > "$out/index.html"
+            '';
+          };
+        })
+      ];
     };
 
     client = commonConfig;
   };
 
-  testScript = ''
-    $letsencrypt->waitForUnit("default.target");
-    $letsencrypt->waitForUnit("boulder.service");
-    $webserver->waitForUnit("default.target");
-    $webserver->waitForUnit("acme-certificates.target");
-    $client->waitForUnit("default.target");
-    $client->succeed('curl https://example.com/ | grep -qF "hello world"');
-  '';
+  testScript = {nodes, ...}: 
+    let
+      newServerSystem = nodes.webserver2.config.system.build.toplevel;
+      switchToNewServer = "${newServerSystem}/bin/switch-to-configuration test";
+    in
+    # Note, waitForUnit does not work for oneshot services that do not have RemainAfterExit=true,
+    # this is because a oneshot goes from inactive => activating => inactive, and never
+    # reaches the active state. To work around this, we create some mock target units which
+    # get pulled in by the oneshot units. The target units linger after activation, and hence we
+    # can use them to probe that a oneshot fired. It is a bit ugly, but it is the best we can do
+    ''
+      $client->waitForUnit("default.target");
+      $letsencrypt->waitForUnit("default.target");
+      $letsencrypt->waitForUnit("boulder.service");
+
+      subtest "can request certificate with HTTPS-01 challenge", sub {
+        $acmeStandalone->waitForUnit("default.target");
+        $acmeStandalone->succeed("systemctl start acme-standalone.com.service");
+        $acmeStandalone->waitForUnit("acme-finished-standalone.com.target");
+      };
+
+      subtest "Can request certificate for nginx service", sub {
+        $webserver->waitForUnit("acme-finished-a.example.com.target");
+        $client->succeed('curl https://a.example.com/ | grep -qF "hello world"');
+      };
+
+      subtest "Can add another certificate for nginx service", sub {
+        $webserver->succeed("/run/current-system/fine-tune/child-1/bin/switch-to-configuration test");
+        $webserver->waitForUnit("acme-finished-b.example.com.target");
+        $client->succeed('curl https://b.example.com/ | grep -qF "hello world"');
+      };
+    '';
 }