Explore planner pattern using steam deck example

src/actions/base/create_directory.rs

@@ -14,6 +14,7 @@ pub struct CreateDirectory {
     group: String,
     mode: u32,
     action_state: ActionState,
+    force_prune_on_revert: bool,
 }
 
 impl CreateDirectory {
@@ -23,23 +24,37 @@ impl CreateDirectory {
         user: String,
         group: String,
         mode: u32,
-        force: bool,
+        force_prune_on_revert: bool,
     ) -> Result<Self, CreateDirectoryError> {
         let path = path.as_ref();
 
-        if path.exists() && !force {
+        let action_state = if path.exists() {
-            return Err(CreateDirectoryError::Exists(std::io::Error::new(
+            let metadata = tokio::fs::metadata(path)
-                std::io::ErrorKind::AlreadyExists,
+                .await
-                format!("Directory `{}` already exists", path.display()),
+                .map_err(|e| CreateDirectoryError::GettingMetadata(path.to_path_buf(), e))?;
-            )));
+            if metadata.is_dir() {
-        }
+                // TODO: Validate owner/group...
+                ActionState::Completed
+            } else {
+                return Err(CreateDirectoryError::Exists(std::io::Error::new(
+                    std::io::ErrorKind::AlreadyExists,
+                    format!(
+                        "Path `{}` already exists and is not directory",
+                        path.display()
+                    ),
+                )));
+            }
+        } else {
+            ActionState::Uncompleted
+        };
 
         Ok(Self {
             path: path.to_path_buf(),
             user,
             group,
             mode,
-            action_state: ActionState::Uncompleted,
+            force_prune_on_revert,
+            action_state,
         })
     }
 }
@@ -54,6 +69,7 @@ impl Actionable for CreateDirectory {
             user,
             group,
             mode,
+            force_prune_on_revert: _,
             action_state: _,
         } = &self;
         if self.action_state == ActionState::Completed {
@@ -81,6 +97,7 @@ impl Actionable for CreateDirectory {
             user,
             group,
             mode,
+            force_prune_on_revert: _,
             action_state,
         } = self;
         if *action_state == ActionState::Completed {
@@ -118,13 +135,22 @@ impl Actionable for CreateDirectory {
             user: _,
             group: _,
             mode: _,
+            force_prune_on_revert,
             action_state: _,
         } = &self;
         if self.action_state == ActionState::Uncompleted {
             vec![]
         } else {
             vec![ActionDescription::new(
-                format!("Remove the directory `{}`", path.display()),
+                format!(
+                    "Remove the directory `{}`{}",
+                    path.display(),
+                    if *force_prune_on_revert {
+                        ""
+                    } else {
+                        " if no other contents exists"
+                    }
+                ),
                 vec![],
             )]
         }
@@ -142,6 +168,7 @@ impl Actionable for CreateDirectory {
             user: _,
             group: _,
             mode: _,
+            force_prune_on_revert,
             action_state,
         } = self;
         if *action_state == ActionState::Uncompleted {
@@ -151,9 +178,18 @@ impl Actionable for CreateDirectory {
         tracing::debug!("Removing directory");
 
         tracing::trace!(path = %path.display(), "Removing directory");
-        remove_dir_all(path.clone())
+
-            .await
+        let is_empty = path
-            .map_err(|e| Self::Error::Removing(path.clone(), e))?;
+            .read_dir()
+            .map_err(|e| CreateDirectoryError::ReadDir(path.clone(), e))?
+            .next()
+            .is_some();
+        match (is_empty, force_prune_on_revert) {
+            (true, _) | (false, true) => remove_dir_all(path.clone())
+                .await
+                .map_err(|e| Self::Error::Removing(path.clone(), e))?,
+            (false, false) => {},
+        };
 
         tracing::trace!("Removed directory");
         *action_state = ActionState::Uncompleted;
@@ -185,6 +221,20 @@ pub enum CreateDirectoryError {
         #[serde(serialize_with = "crate::serialize_error_to_display")]
         std::io::Error,
     ),
+    #[error("Getting metadata for {0}`")]
+    GettingMetadata(
+        std::path::PathBuf,
+        #[source]
+        #[serde(serialize_with = "crate::serialize_error_to_display")]
+        std::io::Error,
+    ),
+    #[error("Reading directory `{0}``")]
+    ReadDir(
+        std::path::PathBuf,
+        #[source]
+        #[serde(serialize_with = "crate::serialize_error_to_display")]
+        std::io::Error,
+    ),
     #[error("Set mode `{0}` on `{1}`")]
     SetPermissions(
         u32,

src/actions/base/mod.rs

@@ -10,6 +10,7 @@ mod fetch_nix;
 mod move_unpacked_nix;
 mod setup_default_profile;
 mod start_systemd_unit;
+mod systemd_sysext_merge;
 
 pub use configure_nix_daemon_service::{ConfigureNixDaemonService, ConfigureNixDaemonServiceError};
 pub use create_directory::{CreateDirectory, CreateDirectoryError};
@@ -21,3 +22,4 @@ pub use fetch_nix::{FetchNix, FetchNixError};
 pub use move_unpacked_nix::{MoveUnpackedNix, MoveUnpackedNixError};
 pub use setup_default_profile::{SetupDefaultProfile, SetupDefaultProfileError};
 pub use start_systemd_unit::{StartSystemdUnit, StartSystemdUnitError};
+pub use systemd_sysext_merge::{SystemdSysextMerge, SystemdSysextMergeError};

src/actions/base/systemd_sysext_merge.rs

@@ -0,0 +1,120 @@
+use std::path::PathBuf;
+
+use serde::Serialize;
+use tokio::process::Command;
+
+use crate::execute_command;
+
+use crate::actions::{Action, ActionDescription, ActionState, Actionable};
+
+#[derive(Debug, serde::Deserialize, serde::Serialize, Clone)]
+pub struct SystemdSysextMerge {
+    device: PathBuf,
+    action_state: ActionState,
+}
+
+impl SystemdSysextMerge {
+    #[tracing::instrument(skip_all)]
+    pub async fn plan(device: PathBuf) -> Result<Self, SystemdSysextMergeError> {
+        Ok(Self {
+            device,
+            action_state: ActionState::Uncompleted,
+        })
+    }
+}
+
+#[async_trait::async_trait]
+impl Actionable for SystemdSysextMerge {
+    type Error = SystemdSysextMergeError;
+
+    fn describe_execute(&self) -> Vec<ActionDescription> {
+        let Self {
+            action_state,
+            device,
+        } = self;
+        if *action_state == ActionState::Completed {
+            vec![]
+        } else {
+            vec![ActionDescription::new(
+                format!("Run `systemd-sysext merge `{}`", device.display()),
+                vec![],
+            )]
+        }
+    }
+
+    #[tracing::instrument(skip_all, fields(
+        device = %self.device.display(),
+    ))]
+    async fn execute(&mut self) -> Result<(), Self::Error> {
+        let Self {
+            device,
+            action_state,
+        } = self;
+        if *action_state == ActionState::Completed {
+            tracing::trace!("Already completed: Merging systemd-sysext");
+            return Ok(());
+        }
+        tracing::debug!("Merging systemd-sysext");
+
+        execute_command(Command::new("systemd-sysext").arg("merge").arg(device))
+            .await
+            .map_err(SystemdSysextMergeError::Command)?;
+
+        tracing::trace!("Merged systemd-sysext");
+        *action_state = ActionState::Completed;
+        Ok(())
+    }
+
+    fn describe_revert(&self) -> Vec<ActionDescription> {
+        if self.action_state == ActionState::Uncompleted {
+            vec![]
+        } else {
+            vec![ActionDescription::new(
+                "Stop the systemd Nix service and socket".to_string(),
+                vec![
+                    "The `nix` command line tool communicates with a running Nix daemon managed by your init system".to_string()
+                ]
+            )]
+        }
+    }
+
+    #[tracing::instrument(skip_all, fields(
+        device = %self.device.display(),
+    ))]
+    async fn revert(&mut self) -> Result<(), Self::Error> {
+        let Self {
+            device,
+            action_state,
+        } = self;
+        if *action_state == ActionState::Uncompleted {
+            tracing::trace!("Already reverted: Stopping systemd unit");
+            return Ok(());
+        }
+        tracing::debug!("Unmrging systemd-sysext");
+
+        // TODO(@Hoverbear): Handle proxy vars
+        execute_command(Command::new("systemd-sysext").arg("unmerge").arg(device))
+            .await
+            .map_err(SystemdSysextMergeError::Command)?;
+
+        tracing::trace!("Unmerged systemd-sysext");
+        *action_state = ActionState::Completed;
+        Ok(())
+    }
+}
+
+impl From<SystemdSysextMerge> for Action {
+    fn from(v: SystemdSysextMerge) -> Self {
+        Action::SystemdSysextMerge(v)
+    }
+}
+
+#[derive(Debug, thiserror::Error, Serialize)]
+pub enum SystemdSysextMergeError {
+    #[error("Failed to execute command")]
+    Command(
+        #[source]
+        #[serde(serialize_with = "crate::serialize_error_to_display")]
+        std::io::Error,
+    ),
+}

src/actions/meta/create_nix_tree.rs

@@ -27,12 +27,12 @@ pub struct CreateNixTree {
 
 impl CreateNixTree {
     #[tracing::instrument(skip_all)]
-    pub async fn plan(force: bool) -> Result<Self, CreateNixTreeError> {
+    pub async fn plan() -> Result<Self, CreateNixTreeError> {
         let mut create_directories = Vec::default();
         for path in PATHS {
             // We use `create_dir` over `create_dir_all` to ensure we always set permissions right
             create_directories.push(
-                CreateDirectory::plan(path, "root".into(), "root".into(), 0o0755, force).await?,
+                CreateDirectory::plan(path, "root".into(), "root".into(), 0o0755, false).await?,
             )
         }
 

src/actions/meta/create_systemd_sysext.rs

@@ -0,0 +1,216 @@
+use serde::Serialize;
+use std::path::{Path, PathBuf};
+
+use crate::actions::base::{CreateDirectory, CreateDirectoryError, CreateFile, CreateFileError};
+use crate::actions::{Action, ActionDescription, ActionState, Actionable};
+
+const PATHS: &[&str] = &[
+    "usr",
+    "usr/lib",
+    "usr/lib/extension-release.d",
+    "usr/lib/systemd",
+    "usr/lib/systemd/system",
+];
+
+#[derive(Debug, serde::Deserialize, serde::Serialize, Clone)]
+pub struct CreateSystemdSysext {
+    destination: PathBuf,
+    create_directories: Vec<CreateDirectory>,
+    create_extension_release: CreateFile,
+    create_bind_mount_unit: CreateFile,
+    action_state: ActionState,
+}
+
+impl CreateSystemdSysext {
+    #[tracing::instrument(skip_all)]
+    pub async fn plan(destination: impl AsRef<Path>) -> Result<Self, CreateSystemdSysextError> {
+        let destination = destination.as_ref();
+
+        let mut create_directories = vec![
+            CreateDirectory::plan(destination, "root".into(), "root".into(), 0o0755, true).await?,
+        ];
+        for path in PATHS {
+            create_directories.push(
+                CreateDirectory::plan(
+                    destination.join(path),
+                    "root".into(),
+                    "root".into(),
+                    0o0755,
+                    false,
+                )
+                .await?,
+            )
+        }
+
+        let version_id = tokio::fs::read_to_string("/etc/os-release")
+            .await
+            .map(|buf| {
+                buf.lines()
+                    .find_map(|line| match line.starts_with("VERSION_ID") {
+                        true => line.rsplit("=").next().map(|inner| inner.to_owned()),
+                        false => None,
+                    })
+            })
+            .map_err(CreateSystemdSysextError::ReadingOsRelease)?
+            .ok_or(CreateSystemdSysextError::NoVersionId)?;
+        let extension_release_buf =
+            format!("SYSEXT_LEVEL=1.0\nID=steamos\nVERSION_ID={version_id}");
+        let create_extension_release = CreateFile::plan(
+            destination.join("usr/lib/extension-release.d/extension-release.nix"),
+            "root".into(),
+            "root".into(),
+            0o0755,
+            extension_release_buf,
+            false,
+        )
+        .await?;
+
+        let create_bind_mount_buf = format!(
+            "
+            [Mount]\n\
+            What={}\n\
+            Where=/nix\n\
+            Type=none\n\
+            Options=bind\n\
+        ",
+            destination.display(),
+        );
+        let create_bind_mount_unit = CreateFile::plan(
+            destination.join("usr/lib/systemd/system/nix.mount"),
+            "root".into(),
+            "root".into(),
+            0o0755,
+            create_bind_mount_buf,
+            false,
+        )
+        .await?;
+
+        Ok(Self {
+            destination: destination.to_path_buf(),
+            create_directories,
+            create_extension_release,
+            create_bind_mount_unit,
+            action_state: ActionState::Uncompleted,
+        })
+    }
+}
+
+#[async_trait::async_trait]
+impl Actionable for CreateSystemdSysext {
+    type Error = CreateSystemdSysextError;
+
+    fn describe_execute(&self) -> Vec<ActionDescription> {
+        let Self {
+            action_state: _,
+            destination,
+            create_bind_mount_unit: _,
+            create_directories: _,
+            create_extension_release: _,
+        } = &self;
+        if self.action_state == ActionState::Completed {
+            vec![]
+        } else {
+            vec![ActionDescription::new(
+                format!("Create a systemd sysext at `{}`", destination.display()),
+                vec![format!(
+                    "Create a writable, persistent systemd system extension.",
+                )],
+            )]
+        }
+    }
+
+    #[tracing::instrument(skip_all, fields(destination,))]
+    async fn execute(&mut self) -> Result<(), Self::Error> {
+        let Self {
+            destination: _,
+            action_state,
+            create_directories,
+            create_extension_release,
+            create_bind_mount_unit,
+        } = self;
+        if *action_state == ActionState::Completed {
+            tracing::trace!("Already completed: Creating sysext");
+            return Ok(());
+        }
+        tracing::debug!("Creating sysext");
+
+        for create_directory in create_directories {
+            create_directory.execute().await?;
+        }
+        create_extension_release.execute().await?;
+        create_bind_mount_unit.execute().await?;
+
+        tracing::trace!("Created sysext");
+        *action_state = ActionState::Completed;
+        Ok(())
+    }
+
+    fn describe_revert(&self) -> Vec<ActionDescription> {
+        let Self {
+            destination,
+            action_state: _,
+            create_directories: _,
+            create_extension_release: _,
+            create_bind_mount_unit: _,
+        } = &self;
+        if self.action_state == ActionState::Uncompleted {
+            vec![]
+        } else {
+            vec![ActionDescription::new(
+                format!("Remove the sysext located at `{}`", destination.display()),
+                vec![],
+            )]
+        }
+    }
+
+    #[tracing::instrument(skip_all, fields(destination,))]
+    async fn revert(&mut self) -> Result<(), Self::Error> {
+        let Self {
+            destination: _,
+            action_state,
+            create_directories,
+            create_extension_release,
+            create_bind_mount_unit,
+        } = self;
+        if *action_state == ActionState::Uncompleted {
+            tracing::trace!("Already reverted: Removing sysext");
+            return Ok(());
+        }
+        tracing::debug!("Removing sysext");
+
+        create_bind_mount_unit.revert().await?;
+
+        create_extension_release.revert().await?;
+
+        for create_directory in create_directories.iter_mut().rev() {
+            create_directory.revert().await?;
+        }
+
+        tracing::trace!("Removed sysext");
+        *action_state = ActionState::Uncompleted;
+        Ok(())
+    }
+}
+
+impl From<CreateSystemdSysext> for Action {
+    fn from(v: CreateSystemdSysext) -> Self {
+        Action::CreateSystemdSysext(v)
+    }
+}
+
+#[derive(Debug, thiserror::Error, Serialize)]
+pub enum CreateSystemdSysextError {
+    #[error(transparent)]
+    CreateDirectory(#[from] CreateDirectoryError),
+    #[error(transparent)]
+    CreateFile(#[from] CreateFileError),
+    #[error("Reading /etc/os-release")]
+    ReadingOsRelease(
+        #[source]
+        #[from]
+        #[serde(serialize_with = "crate::serialize_error_to_display")]
+        std::io::Error,
+    ),
+    #[error("No `VERSION_ID` line in /etc/os-release")]
+    NoVersionId,
+}

src/actions/meta/mod.rs

@@ -3,6 +3,7 @@
 mod configure_nix;
 mod configure_shell_profile;
 mod create_nix_tree;
+mod create_systemd_sysext;
 mod create_users_and_group;
 mod place_channel_configuration;
 mod place_nix_configuration;
@@ -12,6 +13,7 @@ mod start_nix_daemon;
 pub use configure_nix::{ConfigureNix, ConfigureNixError};
 pub use configure_shell_profile::{ConfigureShellProfile, ConfigureShellProfileError};
 pub use create_nix_tree::{CreateNixTree, CreateNixTreeError};
+pub use create_systemd_sysext::{CreateSystemdSysext, CreateSystemdSysextError};
 pub use create_users_and_group::{CreateUsersAndGroup, CreateUsersAndGroupError};
 pub use place_channel_configuration::{PlaceChannelConfiguration, PlaceChannelConfigurationError};
 pub use place_nix_configuration::{PlaceNixConfiguration, PlaceNixConfigurationError};

src/actions/meta/provision_nix.rs

@@ -27,8 +27,7 @@ impl ProvisionNix {
     #[tracing::instrument(skip_all)]
     pub async fn plan(settings: InstallSettings) -> Result<Self, ProvisionNixError> {
         let create_nix_dir =
-            CreateDirectory::plan("/nix", "root".into(), "root".into(), 0o0755, settings.force)
+            CreateDirectory::plan("/nix", "root".into(), "root".into(), 0o0755, true).await?;
-                .await?;
 
         let fetch_nix = FetchNix::plan(
             settings.nix_package_url.clone(),
@@ -36,7 +35,7 @@ impl ProvisionNix {
         )
         .await?;
         let create_users_and_group = CreateUsersAndGroup::plan(settings.clone()).await?;
-        let create_nix_tree = CreateNixTree::plan(settings.force).await?;
+        let create_nix_tree = CreateNixTree::plan().await?;
         let move_unpacked_nix =
             MoveUnpackedNix::plan(PathBuf::from("/nix/temp-install-dir")).await?;
         Ok(Self {

src/actions/mod.rs

@@ -6,19 +6,18 @@ use base::{
     CreateDirectoryError, CreateFile, CreateFileError, CreateGroup, CreateGroupError,
     CreateOrAppendFile, CreateOrAppendFileError, CreateUser, CreateUserError, FetchNix,
     FetchNixError, MoveUnpackedNix, MoveUnpackedNixError, SetupDefaultProfile,
-    SetupDefaultProfileError,
+    SetupDefaultProfileError, StartSystemdUnit, StartSystemdUnitError, SystemdSysextMerge,
+    SystemdSysextMergeError,
 };
 use meta::{
     ConfigureNix, ConfigureNixError, ConfigureShellProfile, ConfigureShellProfileError,
-    CreateNixTree, CreateNixTreeError, CreateUsersAndGroup, CreateUsersAndGroupError,
+    CreateNixTree, CreateNixTreeError, CreateSystemdSysext, CreateSystemdSysextError,
-    PlaceChannelConfiguration, PlaceChannelConfigurationError, PlaceNixConfiguration,
+    CreateUsersAndGroup, CreateUsersAndGroupError, PlaceChannelConfiguration,
-    PlaceNixConfigurationError, ProvisionNix, ProvisionNixError, StartNixDaemon,
+    PlaceChannelConfigurationError, PlaceNixConfiguration, PlaceNixConfigurationError,
-    StartNixDaemonError,
+    ProvisionNix, ProvisionNixError, StartNixDaemon, StartNixDaemonError,
 };
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
-use self::base::{StartSystemdUnit, StartSystemdUnitError};
-
 #[async_trait::async_trait]
 pub trait Actionable: DeserializeOwned + Serialize + Into<Action> {
     type Error: std::error::Error + std::fmt::Debug + Serialize + Into<ActionError>;
@@ -61,6 +60,7 @@ pub enum Action {
     ConfigureNix(ConfigureNix),
     ConfigureShellProfile(ConfigureShellProfile),
     CreateDirectory(CreateDirectory),
+    CreateSystemdSysext(CreateSystemdSysext),
     CreateFile(CreateFile),
     CreateGroup(CreateGroup),
     CreateOrAppendFile(CreateOrAppendFile),
@@ -74,6 +74,7 @@ pub enum Action {
     SetupDefaultProfile(SetupDefaultProfile),
     StartNixDaemon(StartNixDaemon),
     StartSystemdUnit(StartSystemdUnit),
+    SystemdSysextMerge(SystemdSysextMerge),
     ProvisionNix(ProvisionNix),
 }
 
@@ -94,6 +95,8 @@ pub enum ActionError {
     #[error(transparent)]
     CreateDirectory(#[from] CreateDirectoryError),
     #[error(transparent)]
+    CreateSystemdSysext(#[from] CreateSystemdSysextError),
+    #[error(transparent)]
     CreateFile(#[from] CreateFileError),
     #[error(transparent)]
     CreateGroup(#[from] CreateGroupError),
@@ -120,6 +123,8 @@ pub enum ActionError {
     #[error(transparent)]
     StartSystemdUnit(#[from] StartSystemdUnitError),
     #[error(transparent)]
+    SystemdSysExtMerge(#[from] SystemdSysextMergeError),
+    #[error(transparent)]
     ProvisionNix(#[from] ProvisionNixError),
 }
 
@@ -132,6 +137,7 @@ impl Actionable for Action {
             Action::ConfigureNix(i) => i.describe_execute(),
             Action::ConfigureShellProfile(i) => i.describe_execute(),
             Action::CreateDirectory(i) => i.describe_execute(),
+            Action::CreateSystemdSysext(i) => i.describe_execute(),
             Action::CreateFile(i) => i.describe_execute(),
             Action::CreateGroup(i) => i.describe_execute(),
             Action::CreateOrAppendFile(i) => i.describe_execute(),
@@ -145,6 +151,7 @@ impl Actionable for Action {
             Action::SetupDefaultProfile(i) => i.describe_execute(),
             Action::StartNixDaemon(i) => i.describe_execute(),
             Action::StartSystemdUnit(i) => i.describe_execute(),
+            Action::SystemdSysextMerge(i) => i.describe_execute(),
             Action::ProvisionNix(i) => i.describe_execute(),
         }
     }
@@ -155,6 +162,7 @@ impl Actionable for Action {
             Action::ConfigureNix(i) => i.execute().await?,
             Action::ConfigureShellProfile(i) => i.execute().await?,
             Action::CreateDirectory(i) => i.execute().await?,
+            Action::CreateSystemdSysext(i) => i.execute().await?,
             Action::CreateFile(i) => i.execute().await?,
             Action::CreateGroup(i) => i.execute().await?,
             Action::CreateOrAppendFile(i) => i.execute().await?,
@@ -168,6 +176,7 @@ impl Actionable for Action {
             Action::SetupDefaultProfile(i) => i.execute().await?,
             Action::StartNixDaemon(i) => i.execute().await?,
             Action::StartSystemdUnit(i) => i.execute().await?,
+            Action::SystemdSysextMerge(i) => i.execute().await?,
             Action::ProvisionNix(i) => i.execute().await?,
         };
         Ok(())
@@ -179,6 +188,7 @@ impl Actionable for Action {
             Action::ConfigureNix(i) => i.describe_revert(),
             Action::ConfigureShellProfile(i) => i.describe_revert(),
             Action::CreateDirectory(i) => i.describe_revert(),
+            Action::CreateSystemdSysext(i) => i.describe_revert(),
             Action::CreateFile(i) => i.describe_revert(),
             Action::CreateGroup(i) => i.describe_revert(),
             Action::CreateOrAppendFile(i) => i.describe_revert(),
@@ -192,6 +202,7 @@ impl Actionable for Action {
             Action::SetupDefaultProfile(i) => i.describe_revert(),
             Action::StartNixDaemon(i) => i.describe_revert(),
             Action::StartSystemdUnit(i) => i.describe_revert(),
+            Action::SystemdSysextMerge(i) => i.describe_revert(),
             Action::ProvisionNix(i) => i.describe_revert(),
         }
     }
@@ -202,6 +213,7 @@ impl Actionable for Action {
             Action::ConfigureNix(i) => i.revert().await?,
             Action::ConfigureShellProfile(i) => i.revert().await?,
             Action::CreateDirectory(i) => i.revert().await?,
+            Action::CreateSystemdSysext(i) => i.revert().await?,
             Action::CreateFile(i) => i.revert().await?,
             Action::CreateGroup(i) => i.revert().await?,
             Action::CreateOrAppendFile(i) => i.revert().await?,
@@ -215,6 +227,7 @@ impl Actionable for Action {
             Action::SetupDefaultProfile(i) => i.revert().await?,
             Action::StartNixDaemon(i) => i.revert().await?,
             Action::StartSystemdUnit(i) => i.revert().await?,
+            Action::SystemdSysextMerge(i) => i.revert().await?,
             Action::ProvisionNix(i) => i.revert().await?,
         }
         Ok(())

src/plan.rs

@@ -1,10 +1,7 @@
 use std::path::PathBuf;
 
 use crate::{
-    actions::{
+    actions::{Action, ActionDescription, ActionError, Actionable},
-        meta::{ConfigureNix, ProvisionNix, StartNixDaemon},
-        Action, ActionDescription, ActionError, Actionable,
-    },
     planner::PlannerError,
     settings::InstallSettings,
     HarmonicError, Planner,

src/planner/mod.rs

@@ -2,9 +2,7 @@ mod darwin;
 mod linux;
 mod specific;
 
-use std::{ffi::OsStr, str::FromStr};
+use crate::{actions::ActionError, InstallPlan, InstallSettings};
-
-use crate::{actions::ActionError, HarmonicError, InstallPlan, InstallSettings};
 
 #[derive(Debug, Clone, clap::ValueEnum, serde::Serialize, serde::Deserialize)]
 pub enum Planner {

src/planner/specific/steam_deck.rs

@@ -1,4 +1,11 @@
-use crate::{planner::Plannable, Planner};
+use crate::{
+    actions::{
+        meta::{CreateSystemdSysext, ProvisionNix, StartNixDaemon},
+        Action, ActionError,
+    },
+    planner::Plannable,
+    InstallPlan, Planner,
+};
 
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize, Default)]
 pub struct SteamDeck;
@@ -11,7 +18,24 @@ impl Plannable for SteamDeck {
     async fn plan(
         settings: crate::InstallSettings,
     ) -> Result<crate::InstallPlan, crate::planner::PlannerError> {
-        todo!()
+        Ok(InstallPlan {
+            planner: Self.into(),
+            settings: settings.clone(),
+            actions: vec![
+                CreateSystemdSysext::plan("/var/lib/extensions")
+                    .await
+                    .map(Action::from)
+                    .map_err(ActionError::from)?,
+                ProvisionNix::plan(settings.clone())
+                    .await
+                    .map(Action::from)
+                    .map_err(ActionError::from)?,
+                StartNixDaemon::plan()
+                    .await
+                    .map(Action::from)
+                    .map_err(ActionError::from)?,
+            ],
+        })
     }
 }
 

src/settings.rs

@@ -1,4 +1,4 @@
-use crate::{planner, Planner};
+use crate::planner;
 use target_lexicon::Triple;
 use url::Url;