This is based on the respectve patch from NixPkgs, but with the parts pinning
mysql and postgresql executables removed. See our package definition on why.

diff --git a/src/akonadicontrol/agentmanager.cpp b/src/akonadicontrol/agentmanager.cpp
--- a/src/akonadicontrol/agentmanager.cpp
+++ b/src/akonadicontrol/agentmanager.cpp
@@ -47,7 +47,7 @@ public:
         connect(this, &Akonadi::ProcessControl::unableToStart, this, []() {
             QCoreApplication::instance()->exit(255);
         });
-        start(QStringLiteral("akonadiserver"), args, RestartOnCrash);
+        start(QStringLiteral(NIX_OUT "/bin/akonadiserver"), args, RestartOnCrash);
     }

     ~StorageProcessControl() override
@@ -69,7 +69,7 @@ public:
         connect(this, &Akonadi::ProcessControl::unableToStart, this, []() {
             qCCritical(AKONADICONTROL_LOG) << "Failed to start AgentServer!";
         });
-        start(QStringLiteral("akonadi_agent_server"), args, RestartOnCrash);
+        start(QStringLiteral(NIX_OUT "/bin/akonadi_agent_server"), args, RestartOnCrash);
     }

     ~AgentServerProcessControl() override
diff --git a/src/akonadicontrol/agentprocessinstance.cpp b/src/akonadicontrol/agentprocessinstance.cpp
--- a/src/akonadicontrol/agentprocessinstance.cpp
+++ b/src/akonadicontrol/agentprocessinstance.cpp
@@ -62,7 +62,7 @@ bool AgentProcessInstance::start(const AgentType &agentInfo)
     } else {
         Q_ASSERT(agentInfo.launchMethod == AgentType::Launcher);
         const QStringList arguments = QStringList() << executable << identifier();
-        const QString agentLauncherExec = Akonadi::StandardDirs::findExecutable(QStringLiteral("akonadi_agent_launcher"));
+        const QString agentLauncherExec = QLatin1String(NIX_OUT "/bin/akonadi_agent_launcher");
         mController->start(agentLauncherExec, arguments);
     }
     return true;
diff --git a/src/server/storage/dbconfigmysql.cpp b/src/server/storage/dbconfigmysql.cpp
--- a/src/server/storage/dbconfigmysql.cpp
+++ b/src/server/storage/dbconfigmysql.cpp
@@ -215,7 +215,7 @@ bool DbConfigMysql::startInternalServer()
 #endif

     // generate config file
-    const QString globalConfig = StandardDirs::locateResourceFile("config", QStringLiteral("mysql-global.conf"));
+    const QString globalConfig = QLatin1String(NIX_OUT "/etc/xdg/akonadi/mysql-global.conf");
     const QString localConfig = StandardDirs::locateResourceFile("config", QStringLiteral("mysql-local.conf"));
     const QString actualConfig = StandardDirs::saveDir("data") + QLatin1String("/mysql.conf");
     if (globalConfig.isEmpty()) {
id=01d7ce85c89bc25876538f191be6bed4226d1593&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-08-15 23:30:44 +0200'>2023-08-15</span></td><td><a href='/guix/commit/gnu/tests/cachefilesd.scm?id=b8ee6b8a59bf02f47a6668e016905308b441523e'>services: Add cachefilesd service.</a><span class='msg-avail'>...<span class='msg-tooltip'>Thanks to Bruno Victal "mirai" for cooperating on this patch and for
generously sharing a wealth of insights about Guix services.

Thanks to Jean-Baptiste Note for an early version of this service!

* doc/guix.texi (Linux Services)[Cachefilesd Service]: New heading.
* gnu/services/linux.scm (serialize-string, non-negative-integer?)
(serialize-non-negative-integer, string, non-negative-integer)
(make-option-serializer, make-percentage-threshold-serializer): New
procedures.
(cachefilesd-configuration): New record type.
(cachefilesd-service-type): New variable.
* gnu/tests/cachefilesd.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.

Co-authored-by: Bruno Victal &lt;mirai@makinata.eu&gt;
Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Felix Lechner</td></tr>