feat: add trigger to allow retrieving resource properties on the fly

plugins/resource/.gitignore

@@ -6,3 +6,4 @@
 /report
 /docker-args-process-deploy
 /docker-args-process-run
+/resource-get-property

plugins/resource/Makefile

@@ -3,7 +3,7 @@ include ../../common.mk
 GO_ARGS ?= -a
 
 SUBCOMMANDS = subcommands/limit subcommands/limit-clear subcommands/report subcommands/reserve subcommands/reserve-clear
-TRIGGERS = triggers/docker-args-process-deploy triggers/install triggers/post-delete triggers/report
+TRIGGERS = triggers/docker-args-process-deploy triggers/install triggers/post-delete triggers/report triggers/resource-get-property
 build-in-docker: clean
 	docker run --rm \
 		-v $$PWD/../..:$(GO_REPO_ROOT) \
@@ -23,7 +23,7 @@ subcommands/%: src/subcommands/*/%.go
 	go build $(GO_ARGS) -o $@ $<
 
 clean:
-	rm -rf commands subcommands triggers docker-args-process-deploy docker-args-process-run install post-delete report
+	rm -rf commands subcommands triggers docker-args-process-deploy docker-args-process-run install post-delete report resource-get-property
 
 src-clean:
 	rm -rf .gitignore src triggers vendor Makefile *.go

plugins/resource/resource.go

@@ -1,6 +1,7 @@
 package resource
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
@@ -66,6 +67,25 @@ func ReportSingleApp(appName, infoFlag string) {
 	common.LogFail(fmt.Sprintf("Invalid flag passed, valid flags: %s", strings.Join(strkeys, ", ")))
 }
 
+func GetResourceValue(appName string, procType string, resourceType string, prefix string) (string, error) {
+	resources, err := common.PropertyGetAll("resource", appName)
+	if err != nil {
+		return "", err
+	}
+
+	for key, value := range resources {
+		parts := strings.SplitN(strings.TrimPrefix(key, prefix), ".", 2)
+		if parts[0] != resourceType {
+			return "", err
+		}
+		if parts[1] == prefix {
+			return value, nil
+		}
+	}
+
+	return "", errors.New("No value found")
+}
+
 func times(str string, n int) (out string) {
 	for i := 0; i < n; i++ {
 		out += str

plugins/resource/src/triggers/resource-get-property/resource-get-property.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/dokku/dokku/plugins/common"
+	"github.com/dokku/dokku/plugins/resource"
+)
+
+// writes the resource property to stdout for a given app container
+func main() {
+	flag.Parse()
+	appName := flag.Arg(0)
+	procType := flag.Arg(1)
+	resourceType := flag.Arg(1)
+	property := flag.Arg(1)
+
+	value, err := resource.GetResourceValue(appName, procType, resourceType, property)
+	if err != nil {
+		common.LogFail(err.Error())
+	}
+
+	fmt.Fprintln(os.Stdout, value)
+}