First working version

[safcm/safcm.git] / cmd / safcm / config / templates.go

diff --git a/cmd/safcm/config/templates.go b/cmd/safcm/config/templates.go
new file mode 100644 (file)
index 0000000..b84b494
--- /dev/null
+++ b/cmd/safcm/config/templates.go
@@ -0,0 +1,124 @@
+// Config: parse templates.yaml and expand templates
+
+// Copyright (C) 2021  Simon Ruderich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package config
+
+import (
+       "bytes"
+       "fmt"
+       "os"
+       "path/filepath"
+       "strings"
+       "text/template"
+
+       "gopkg.in/yaml.v2"
+
+       "ruderich.org/simon/safcm"
+)
+
+func LoadTemplates(group string, files map[string]*safcm.File,
+       host string, groups []string,
+       allHosts *Hosts, allGroups map[string][]string) error {
+
+       path := filepath.Join(group, "templates.yaml")
+
+       var templates []string
+       x, err := os.ReadFile(path)
+       if err != nil {
+               if os.IsNotExist(err) {
+                       return nil
+               }
+               return err
+       }
+       err = yaml.UnmarshalStrict(x, &templates)
+       if err != nil {
+               return fmt.Errorf("%s: failed to load: %v", path, err)
+       }
+
+       groupsMap := make(map[string]bool)
+       for _, x := range groups {
+               groupsMap[x] = true
+       }
+       allHostsMap := make(map[string]bool)
+       for x := range allHosts.Map {
+               allHostsMap[x] = true
+       }
+       allGroupsMap := make(map[string]bool)
+       for x := range allGroups {
+               allGroupsMap[x] = true
+       }
+
+       for _, x := range templates {
+               f, ok := files[x]
+               if !ok {
+                       return fmt.Errorf("%s: %q does not exist in files/",
+                               path, x)
+               }
+               if f.Mode.Type() != 0 /* regular file */ {
+                       return fmt.Errorf("%s: %q is not a regular file",
+                               path, x)
+               }
+
+               tmplPath := filepath.Join(group, "files", x)
+
+               // Parse and expand template
+               var buf bytes.Buffer
+               tmpl, err := template.New(tmplPath).Parse(string(f.Data))
+               if err != nil {
+                       return fmt.Errorf("%s: invalid %v", path, err)
+               }
+               err = tmpl.Execute(&buf, &templateArgs{
+                       host:      host,
+                       groups:    groupsMap,
+                       allHosts:  allHostsMap,
+                       allGroups: allGroupsMap,
+               })
+               if err != nil {
+                       return fmt.Errorf("%s: %v", path, err)
+               }
+               f.Data = buf.Bytes()
+       }
+
+       return nil
+}
+
+// templateArgs is passed to .Execute() of the template.
+type templateArgs struct {
+       host      string
+       groups    map[string]bool
+       allHosts  map[string]bool
+       allGroups map[string]bool
+}
+
+// TODO: extend data passed to template
+
+func (t *templateArgs) IsHost(host string) bool {
+       // Don't permit invalid hosts to detect typos
+       if !t.allHosts[host] {
+               panic(fmt.Sprintf("host %q does not exist", host))
+       }
+       return t.host == host
+}
+func (t *templateArgs) InGroup(group string) bool {
+       // Don't permit invalid groups to detect typos; detected groups cannot
+       // be checked
+       if !t.allGroups[group] &&
+               !strings.HasPrefix(group, GroupDetectedPrefix) {
+               panic(fmt.Sprintf("group %q does not exist", group))
+       }
+       return t.groups[group]
+}