Functional consul template env file support

api/tasks.go

@@ -336,6 +336,7 @@ type Template struct {
 	Perms        *string        `mapstructure:"perms"`
 	LeftDelim    *string        `mapstructure:"left_delimiter"`
 	RightDelim   *string        `mapstructure:"right_delimiter"`
+	Envvars      *bool          `mapstructure:"env"`
 }
 
 func (tmpl *Template) Canonicalize() {
@@ -373,6 +374,9 @@ func (tmpl *Template) Canonicalize() {
 	if tmpl.RightDelim == nil {
 		tmpl.RightDelim = helper.StringToPtr("}}")
 	}
+	if tmpl.Envvars == nil {
+		tmpl.Envvars = helper.BoolToPtr(false)
+	}
 }
 
 type Vault struct {

client/driver/driver.go

@@ -1,6 +1,8 @@
 package driver
 
 import (
+	"bufio"
+	"bytes"
 	"context"
 	"crypto/md5"
 	"errors"
@@ -8,6 +10,7 @@ import (
 	"io"
 	"log"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/hashicorp/nomad/client/allocdir"
@@ -314,6 +317,26 @@ func GetTaskEnv(taskDir *allocdir.TaskDir, node *structs.Node,
 		SetEnvvars(task.Env).
 		SetTaskName(task.Name)
 
+	// Set env vars from env files
+	for _, tmpl := range task.Templates {
+		if !tmpl.Envvars {
+			continue
+		}
+		f, err := os.Open(filepath.Join(taskDir.Dir, tmpl.DestPath))
+		if err != nil {
+			//FIXME GetTaskEnv may be called before env files are written
+			log.Printf("[DEBUG] driver: XXX FIXME Templates not rendered yet, skipping")
+			continue
+		}
+		defer f.Close()
+		vars, err := parseEnvFile(f)
+		if err != nil {
+			//TODO soft or hard fail?!
+			return nil, err
+		}
+		env.AppendEnvvars(vars)
+	}
+
 	// Vary paths by filesystem isolation used
 	drv, err := NewDriver(task.Driver, NewEmptyDriverContext())
 	if err != nil {
@@ -355,6 +378,41 @@ func GetTaskEnv(taskDir *allocdir.TaskDir, node *structs.Node,
 	return env.Build(), nil
 }
 
+// parseEnvFile and return a map of the environment variables suitable for
+// TaskEnvironment.AppendEnvvars or an error.
+//
+// See nomad/structs#Template.Envvars comment for format.
+func parseEnvFile(r io.Reader) (map[string]string, error) {
+	vars := make(map[string]string, 50)
+	lines := 0
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		lines++
+		buf := scanner.Bytes()
+		if len(buf) == 0 {
+			// Skip empty lines
+			continue
+		}
+		if buf[0] == '#' {
+			// Skip lines starting with a #
+			continue
+		}
+		n := bytes.IndexByte(buf, '=')
+		if n == -1 {
+			return nil, fmt.Errorf("error on line %d: no '=' sign: %q", lines, string(buf))
+		}
+		if len(buf) > n {
+			vars[string(buf[0:n])] = string(buf[n+1 : len(buf)])
+		} else {
+			vars[string(buf[0:n])] = ""
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return vars, nil
+}
+
 func mapMergeStrInt(maps ...map[string]int) map[string]int {
 	out := map[string]int{}
 	for _, in := range maps {

client/task_runner.go

@@ -1339,6 +1339,12 @@ func (r *TaskRunner) killTask(killingEvent *structs.TaskEvent) {
 
 // startTask creates the driver, task dir, and starts the task.
 func (r *TaskRunner) startTask() error {
+	// Env vars may have been updated prior to task starting, so update the
+	// env vars before starting the task
+	if err := r.setTaskEnv(); err != nil {
+		return fmt.Errorf("failed updating environment before starting task: %v", err)
+	}
+
 	// Create a driver
 	drv, err := r.createDriver()
 	if err != nil {

command/agent/job_endpoint.go

@@ -680,6 +680,7 @@ func ApiTaskToStructsTask(apiTask *api.Task, structsTask *structs.Task) {
 				Perms:        *template.Perms,
 				LeftDelim:    *template.LeftDelim,
 				RightDelim:   *template.RightDelim,
+				Envvars:      *template.Envvars,
 			}
 		}
 	}

jobspec/parse.go

@@ -861,6 +861,7 @@ func parseTemplates(result *[]*api.Template, list *ast.ObjectList) error {
 			"right_delimiter",
 			"source",
 			"splay",
+			"env",
 		}
 		if err := checkHCLKeys(o.Val, valid); err != nil {
 			return err

nomad/structs/structs.go

@@ -2943,6 +2943,18 @@ type Template struct {
 	// delimiter is utilized when parsing the template.
 	LeftDelim  string
 	RightDelim string
+
+	// Envvars enables exposing the template as environment variables
+	// instead of as a file. The template must be of the form:
+	//
+	//	VAR_NAME_1={{ key service/my-key }}
+	//	VAR_NAME_2=raw string and {{ env "attr.kernel.name" }}
+	//
+	// Lines will be split on the initial "=" with the first part being the
+	// key name and the second part the value.
+	// Empty lines and lines starting with # will be ignored, but to avoid
+	// escaping issues #s within lines will not be treated as comments.
+	Envvars bool
 }
 
 // DefaultTemplate returns a default template.