#639 Remove the dependency on systemd (#729)

* The purpose of this change is to get rid of the hard-coded dependencies on systemd from tedge connect/disconnect,  to allow users to use other system managers, e.g. OpenRC, initd, etc..

* If /etc/tedge/system.toml exists, tedge connect/disconnect uses the service manager defined in the file.

* If the file is not given by user, tedge connect/disconnect uses /bin/systemctl as the service manager. (the same behaviour as we have it so far)

* Delete old service implementation files for BSD, OpenRC, systemd, and NULL.

* Add system.toml example files for BSD and OpenRC.

* Add a reference guide to explain the format of system.toml configuration file.

Signed-off-by: Rina Fujino <18257209+rina23q@users.noreply.github.com>

2 files changed, 14 insertions, 5 deletions

diff --git a/crates/core/tedge/src/cli/connect/cli.rs b/crates/core/tedge/src/cli/connect/cli.rs
index 42e68885..1f3e2643 100644
--- a/crates/core/tedge/src/cli/connect/cli.rs
+++ b/crates/core/tedge/src/cli/connect/cli.rs
@@ -1,5 +1,6 @@
 use crate::cli::connect::*;
 use crate::command::{BuildCommand, BuildContext, Command};
+use crate::system_services::service_manager;
 use structopt::StructOpt;
 
 #[derive(StructOpt, Debug, PartialEq)]
@@ -27,20 +28,26 @@ impl BuildCommand for TEdgeConnectOpt {
     fn build_command(self, context: BuildContext) -> Result<Box<dyn Command>, crate::ConfigError> {
         Ok(match self {
             TEdgeConnectOpt::C8y { is_test_connection } => ConnectCommand {
-                config_location: context.config_location,
+                config_location: context.config_location.clone(),
                 config_repository: context.config_repository,
                 cloud: Cloud::C8y,
                 common_mosquitto_config: CommonMosquittoConfig::default(),
                 is_test_connection,
-                service_manager: context.service_manager.clone(),
+                service_manager: service_manager(
+                    context.user_manager.clone(),
+                    context.config_location.tedge_config_root_path,
+                )?,
             },
             TEdgeConnectOpt::Az { is_test_connection } => ConnectCommand {
-                config_location: context.config_location,
+                config_location: context.config_location.clone(),
                 config_repository: context.config_repository,
                 cloud: Cloud::Azure,
                 common_mosquitto_config: CommonMosquittoConfig::default(),
                 is_test_connection,
-                service_manager: context.service_manager.clone(),
+                service_manager: service_manager(
+                    context.user_manager.clone(),
+                    context.config_location.tedge_config_root_path,
+                )?,
             },
         }
         .into_boxed())
diff --git a/crates/core/tedge/src/cli/connect/command.rs b/crates/core/tedge/src/cli/connect/command.rs
index fb2f9d17..262e6163 100644
--- a/crates/core/tedge/src/cli/connect/command.rs
+++ b/crates/core/tedge/src/cli/connect/command.rs
@@ -431,7 +431,9 @@ fn new_bridge(
     println!("Checking if {} is available.\n", service_manager.name());
     let service_manager_result = service_manager.check_operational();
 
-    if let Err(SystemServiceError::ServiceManagerUnavailable(name)) = &service_manager_result {
+    if let Err(SystemServiceError::ServiceManagerUnavailable { cmd: _, name }) =
+        &service_manager_result
+    {
         println!(
             "Warning: '{}' service manager is not available on the system.\n",
             name