Add exec support for service context and "pebble exec --context" arg

client/exec.go

@@ -30,6 +30,12 @@ type ExecOptions struct {
 	// Required: command and arguments (first element is the executable).
 	Command []string
 
+	// Optional service name to run the command in the context of this service,
+	// that is, inherit its environment variables, user/group settings,
+	// and working directory. The other options in this struct will override
+	// the service context; Environment will be merged on top of the service's.
+	Context string
+
 	// Optional environment variables.
 	Environment map[string]string
 
@@ -75,6 +81,7 @@ type ExecOptions struct {
 
 type execPayload struct {
 	Command     []string          `json:"command"`
+	Context     string            `json:"context,omitempty"`
 	Environment map[string]string `json:"environment,omitempty"`
 	WorkingDir  string            `json:"working-dir,omitempty"`
 	Timeout     string            `json:"timeout,omitempty"`
@@ -123,6 +130,7 @@ func (client *Client) Exec(opts *ExecOptions) (*ExecProcess, error) {
 	}
 	payload := execPayload{
 		Command:     opts.Command,
+		Context:     opts.Context,
 		Environment: opts.Environment,
 		WorkingDir:  opts.WorkingDir,
 		Timeout:     timeoutStr,

internals/cli/cmd_exec.go

@@ -39,6 +39,7 @@ type cmdExec struct {
 	GroupID        *int          `long:"gid"`
 	Group          string        `long:"group"`
 	Timeout        time.Duration `long:"timeout"`
+	Context        string        `long:"context"`
 	Terminal       bool          `short:"t"`
 	NoTerminal     bool          `short:"T"`
 	Interactive    bool          `short:"i"`
@@ -56,6 +57,7 @@ var execDescs = map[string]string{
 	"gid":     "Group ID to run command as",
 	"group":   "Group name to run command as (group's GID must match gid if both present)",
 	"timeout": "Timeout after which to terminate command",
+	"context": "Run the command in the context of this service (overridden by -w, --env, --user, --uid, --group, --gid)",
 	"t":       "Allocate remote pseudo-terminal and connect stdout to it (default if stdout is a TTY)",
 	"T":       "Disable remote pseudo-terminal allocation",
 	"i":       "Interactive mode: connect stdin to the pseudo-terminal (default if stdin and stdout are TTYs)",
@@ -144,6 +146,7 @@ func (cmd *cmdExec) Execute(args []string) error {
 
 	opts := &client.ExecOptions{
 		Command:     command,
+		Context:     cmd.Context,
 		Environment: env,
 		WorkingDir:  cmd.WorkingDir,
 		Timeout:     cmd.Timeout,

internals/daemon/api_exec.go

@@ -24,10 +24,12 @@ import (
 	"github.com/canonical/pebble/internals/osutil"
 	"github.com/canonical/pebble/internals/overlord/cmdstate"
 	"github.com/canonical/pebble/internals/overlord/state"
+	"github.com/canonical/pebble/internals/plan"
 )
 
 type execPayload struct {
 	Command     []string          `json:"command"`
+	Context     string            `json:"context"`
 	Environment map[string]string `json:"environment"`
 	WorkingDir  string            `json:"working-dir"`
 	Timeout     string            `json:"timeout"`
@@ -67,8 +69,25 @@ func v1PostExec(c *Command, req *http.Request, _ *userState) Response {
 		return statusBadRequest("%v", err)
 	}
 
+	p, err := c.d.overlord.ServiceManager().Plan()
+	if err != nil {
+		return statusBadRequest("%v", err)
+	}
+	overrides := plan.ContextOptions{
+		Environment: payload.Environment,
+		UserID:      payload.UserID,
+		User:        payload.User,
+		GroupID:     payload.GroupID,
+		Group:       payload.Group,
+		WorkingDir:  payload.WorkingDir,
+	}
+	merged, err := plan.MergeServiceContext(p, payload.Context, overrides)
+	if err != nil {
+		return statusBadRequest("%v", err)
+	}
+
 	// Convert User/UserID and Group/GroupID combinations into raw uid/gid.
-	uid, gid, err := osutil.NormalizeUidGid(payload.UserID, payload.GroupID, payload.User, payload.Group)
+	uid, gid, err := osutil.NormalizeUidGid(merged.UserID, merged.GroupID, merged.User, merged.Group)
 	if err != nil {
 		return statusBadRequest("%v", err)
 	}
@@ -79,8 +98,8 @@ func v1PostExec(c *Command, req *http.Request, _ *userState) Response {
 
 	args := &cmdstate.ExecArgs{
 		Command:     payload.Command,
-		Environment: payload.Environment,
-		WorkingDir:  payload.WorkingDir,
+		Environment: merged.Environment,
+		WorkingDir:  merged.WorkingDir,
 		Timeout:     timeout,
 		UserID:      uid,
 		GroupID:     gid,

internals/daemon/api_exec_test.go

@@ -31,6 +31,7 @@ import (
 
 	"github.com/canonical/pebble/client"
 	"github.com/canonical/pebble/internals/logger"
+	"github.com/canonical/pebble/internals/plan"
 )
 
 var _ = Suite(&execSuite{})
@@ -164,6 +165,54 @@ func (s *execSuite) TestTimeout(c *C) {
 	c.Check(stderr, Equals, "")
 }
 
+func (s *execSuite) TestContextNoOverrides(c *C) {
+	dir := c.MkDir()
+	err := s.daemon.overlord.ServiceManager().AppendLayer(&plan.Layer{
+		Label: "layer1",
+		Services: map[string]*plan.Service{"svc1": {
+			Name:        "svc1",
+			Override:    "replace",
+			Command:     "dummy",
+			Environment: map[string]string{"FOO": "foo", "BAR": "bar"},
+			WorkingDir:  dir,
+		}},
+	})
+	c.Assert(err, IsNil)
+
+	stdout, stderr, err := s.exec(c, "", &client.ExecOptions{
+		Command: []string{"/bin/sh", "-c", "echo FOO=$FOO BAR=$BAR; pwd"},
+		Context: "svc1",
+	})
+	c.Assert(err, IsNil)
+	c.Check(stdout, Equals, "FOO=foo BAR=bar\n"+dir+"\n")
+	c.Check(stderr, Equals, "")
+}
+
+func (s *execSuite) TestContextOverrides(c *C) {
+	err := s.daemon.overlord.ServiceManager().AppendLayer(&plan.Layer{
+		Label: "layer1",
+		Services: map[string]*plan.Service{"svc1": {
+			Name:        "svc1",
+			Override:    "replace",
+			Command:     "dummy",
+			Environment: map[string]string{"FOO": "foo", "BAR": "bar"},
+			WorkingDir:  c.MkDir(),
+		}},
+	})
+	c.Assert(err, IsNil)
+
+	overrideDir := c.MkDir()
+	stdout, stderr, err := s.exec(c, "", &client.ExecOptions{
+		Command:     []string{"/bin/sh", "-c", "echo FOO=$FOO BAR=$BAR; pwd"},
+		Context:     "svc1",
+		Environment: map[string]string{"FOO": "oof"},
+		WorkingDir:  overrideDir,
+	})
+	c.Assert(err, IsNil)
+	c.Check(stdout, Equals, "FOO=oof BAR=bar\n"+overrideDir+"\n")
+	c.Check(stderr, Equals, "")
+}
+
 func (s *execSuite) TestCurrentUserGroup(c *C) {
 	current, err := user.Current()
 	c.Assert(err, IsNil)