Handlers for `generate systemd` with custom dependencies

This commit includes:
* Handlers for generate systemd unit
  with manually defined dependencies such as:
  Wants=, After= and Requires=

* The new unit and e2e tests for checking generated systemd units
  for container and pod with custom dependencies

* Documented descriptions for custom dependencies options

Signed-off-by: Eugene (Evgenii) Shubin <esendjer@gmail.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/pkg/systemd/generate/containers.go b/pkg/systemd/generate/containers.go
index fd5c247f3..ea829c810 100644
--- a/pkg/systemd/generate/containers.go
+++ b/pkg/systemd/generate/containers.go
@@ -94,6 +94,13 @@ type containerInfo struct {
 	RunRoot string
 	// Add %i and %I to description and execute parts
 	IdentifySpecifier bool
+	// Wants are the list of services that this service is (weak) dependent on. This
+	// option does not influence the order in which services are started or stopped.
+	Wants []string
+	// After ordering dependencies between the list of services and this service.
+	After []string
+	// Similar to Wants, but declares a stronger requirement dependency.
+	Requires []string
 }
 
 const containerTemplate = headerTemplate + `
@@ -101,6 +108,19 @@ const containerTemplate = headerTemplate + `
 BindsTo={{{{- range $index, $value := .BoundToServices -}}}}{{{{if $index}}}} {{{{end}}}}{{{{ $value }}}}.service{{{{end}}}}
 After={{{{- range $index, $value := .BoundToServices -}}}}{{{{if $index}}}} {{{{end}}}}{{{{ $value }}}}.service{{{{end}}}}
 {{{{- end}}}}
+{{{{- if or .Wants .After .Requires }}}}
+
+# User-defined dependencies
+{{{{- end}}}}
+{{{{- if .Wants}}}}
+Wants={{{{- range $index, $value := .Wants }}}}{{{{ if $index}}}} {{{{end}}}}{{{{ $value }}}}{{{{end}}}}
+{{{{- end}}}}
+{{{{- if .After}}}}
+After={{{{- range $index, $value := .After }}}}{{{{ if $index}}}} {{{{end}}}}{{{{ $value }}}}{{{{end}}}}
+{{{{- end}}}}
+{{{{- if .Requires}}}}
+Requires={{{{- range $index, $value := .Requires }}}}{{{{ if $index}}}} {{{{end}}}}{{{{ $value }}}}{{{{end}}}}
+{{{{- end}}}}
 
 [Service]
 Environment={{{{.EnvVariable}}}}=%n{{{{- if (eq .IdentifySpecifier true) }}}}-%i{{{{- end}}}}
@@ -201,6 +221,9 @@ func generateContainerInfo(ctr *libpod.Container, options entities.GenerateSyste
 		CreateCommand:     createCommand,
 		RunRoot:           runRoot,
 		containerEnv:      envs,
+		Wants:             options.Wants,
+		After:             options.After,
+		Requires:          options.Requires,
 	}
 
 	return &info, nil