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kylecarbskylecarbs
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fix: Use environment variables for agent authentication
Using files led to situations where running "coder server --dev" would break `gitssh`. This is applicable in a production environment too. Users should be able to log into another Coder deployment from their workspace. Users can still set "CODER_URL" if they'd like with agent env vars!
1 parent 81bb820 commit 2745dcd

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17 files changed

+140
-102
lines changed

17 files changed

+140
-102
lines changed

‎agent/agent.go

+32-24
Original file line numberDiff line numberDiff line change
@@ -40,6 +40,7 @@ import (
4040

4141
type Options struct {
4242
ReconnectingPTYTimeout time.Duration
43+
EnvironmentVariables map[string]string
4344
Logger slog.Logger
4445
}
4546

@@ -66,6 +67,7 @@ func New(dialer Dialer, options *Options) io.Closer {
6667
logger: options.Logger,
6768
closeCancel: cancelFunc,
6869
closed: make(chan struct{}),
70+
envVars: options.EnvironmentVariables,
6971
}
7072
server.init(ctx)
7173
return server
@@ -83,23 +85,21 @@ type agent struct {
8385
closeMutex sync.Mutex
8486
closed chan struct{}
8587

86-
// Environment variables sent by Coder to inject for shell sessions.
87-
// These are atomic because values can change after reconnect.
88-
envVars atomic.Value
89-
ownerEmail atomic.String
90-
ownerUsername atomic.String
88+
envVars map[string]string
89+
// metadata is atomic because values can change after reconnection.
90+
metadata atomic.Value
9191
startupScript atomic.Bool
9292
sshServer *ssh.Server
9393
}
9494

9595
func (a *agent) run(ctx context.Context) {
96-
var options Metadata
96+
var metadata Metadata
9797
var peerListener *peerbroker.Listener
9898
var err error
9999
// An exponential back-off occurs when the connection is failing to dial.
100100
// This is to prevent server spam in case of a coderd outage.
101101
for retrier := retry.New(50*time.Millisecond, 10*time.Second); retrier.Wait(ctx); {
102-
options, peerListener, err = a.dialer(ctx, a.logger)
102+
metadata, peerListener, err = a.dialer(ctx, a.logger)
103103
if err != nil {
104104
if errors.Is(err, context.Canceled) {
105105
return
@@ -118,14 +118,12 @@ func (a *agent) run(ctx context.Context) {
118118
return
119119
default:
120120
}
121-
a.envVars.Store(options.EnvironmentVariables)
122-
a.ownerEmail.Store(options.OwnerEmail)
123-
a.ownerUsername.Store(options.OwnerUsername)
121+
a.metadata.Store(metadata)
124122

125123
if a.startupScript.CAS(false, true) {
126124
// The startup script has not ran yet!
127125
go func() {
128-
err := a.runStartupScript(ctx, options.StartupScript)
126+
err := a.runStartupScript(ctx, metadata.StartupScript)
129127
if errors.Is(err, context.Canceled) {
130128
return
131129
}
@@ -172,7 +170,7 @@ func (*agent) runStartupScript(ctx context.Context, script string) error {
172170
writer, err = gsyslog.NewLogger(gsyslog.LOG_INFO, "USER", "coder-startup-script")
173171
if err != nil {
174172
// If the syslog isn't supported or cannot be created, use a text file in temp.
175-
writer, err = os.CreateTemp("", "coder-startup-script.txt")
173+
writer, err = os.CreateTemp("", "coder-startup-script-*.txt")
176174
if err != nil {
177175
return xerrors.Errorf("open startup script log file: %w", err)
178176
}
@@ -319,6 +317,15 @@ func (a *agent) createCommand(ctx context.Context, rawCommand string, env []stri
319317
return nil, xerrors.Errorf("get user shell: %w", err)
320318
}
321319

320+
rawMetadata := a.metadata.Load()
321+
if rawMetadata == nil {
322+
return nil, xerrors.Errorf("no metadata was provided: %w", err)
323+
}
324+
metadata, valid := rawMetadata.(Metadata)
325+
if !valid {
326+
return nil, xerrors.Errorf("metadata is the wrong type: %T", metadata)
327+
}
328+
322329
// gliderlabs/ssh returns a command slice of zero
323330
// when a shell is requested.
324331
command := rawCommand
@@ -344,22 +351,23 @@ func (a *agent) createCommand(ctx context.Context, rawCommand string, env []stri
344351
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_SSH_COMMAND=%s gitssh --`, executablePath))
345352
// These prevent the user from having to specify _anything_ to successfully commit.
346353
// Both author and committer must be set!
347-
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_AUTHOR_EMAIL=%s`, a.ownerEmail.Load()))
348-
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_COMMITTER_EMAIL=%s`, a.ownerEmail.Load()))
349-
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_AUTHOR_NAME=%s`, a.ownerUsername.Load()))
350-
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_COMMITTER_NAME=%s`, a.ownerUsername.Load()))
354+
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_AUTHOR_EMAIL=%s`, metadata.OwnerEmail))
355+
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_COMMITTER_EMAIL=%s`, metadata.OwnerEmail))
356+
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_AUTHOR_NAME=%s`, metadata.OwnerUsername))
357+
cmd.Env = append(cmd.Env, fmt.Sprintf(`GIT_COMMITTER_NAME=%s`, metadata.OwnerUsername))
351358

352359
// Load environment variables passed via the agent.
353360
// These should override all variables we manually specify.
354-
envVars := a.envVars.Load()
355-
if envVars != nil {
356-
envVarMap, ok := envVars.(map[string]string)
357-
if ok {
358-
for key, value := range envVarMap {
359-
cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", key, value))
360-
}
361-
}
361+
for key, value := range metadata.EnvironmentVariables {
362+
cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", key, value))
363+
}
364+
365+
// Agent-level environment variables should take over all!
366+
// This is used for setting agent-specific variables like "CODER_AGENT_TOKEN".
367+
for key, value := range a.envVars {
368+
cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", key, value))
362369
}
370+
363371
return cmd, nil
364372
}
365373

‎cli/agent.go

+13-21
Original file line numberDiff line numberDiff line change
@@ -21,17 +21,16 @@ import (
2121

2222
func workspaceAgent() *cobra.Command {
2323
var (
24-
rawURL string
25-
auth string
26-
token string
24+
auth string
2725
)
2826
cmd := &cobra.Command{
2927
Use: "agent",
3028
// This command isn't useful to manually execute.
3129
Hidden: true,
3230
RunE: func(cmd *cobra.Command, args []string) error {
33-
if rawURL == "" {
34-
return xerrors.New("CODER_URL must be set")
31+
rawURL, err := cmd.Flags().GetString(varAgentURL)
32+
if err != nil {
33+
return xerrors.Errorf("CODER_AGENT_URL must be set: %w", err)
3534
}
3635
coderURL, err := url.Parse(rawURL)
3736
if err != nil {
@@ -46,8 +45,9 @@ func workspaceAgent() *cobra.Command {
4645
var exchangeToken func(context.Context) (codersdk.WorkspaceAgentAuthenticateResponse, error)
4746
switch auth {
4847
case "token":
49-
if token == "" {
50-
return xerrors.Errorf("CODER_TOKEN must be set for token auth")
48+
token, err := cmd.Flags().GetString(varAgentToken)
49+
if err != nil {
50+
return xerrors.Errorf("CODER_AGENT_TOKEN must be set for token auth: %w", err)
5151
}
5252
client.SessionToken = token
5353
case "google-instance-identity":
@@ -115,27 +115,19 @@ func workspaceAgent() *cobra.Command {
115115
}
116116
}
117117

118-
cfg := createConfig(cmd)
119-
err = cfg.AgentSession().Write(client.SessionToken)
120-
if err != nil {
121-
return xerrors.Errorf("writing agent session token to config: %w", err)
122-
}
123-
err = cfg.URL().Write(client.URL.String())
124-
if err != nil {
125-
return xerrors.Errorf("writing agent url to config: %w", err)
126-
}
127-
128118
closer := agent.New(client.ListenWorkspaceAgent, &agent.Options{
129119
Logger: logger,
120+
EnvironmentVariables: map[string]string{
121+
// Override the "CODER_AGENT_TOKEN" variable in all
122+
// shells so "gitssh" works!
123+
"CODER_AGENT_TOKEN": client.SessionToken,
124+
},
130125
})
131126
<-cmd.Context().Done()
132127
return closer.Close()
133128
},
134129
}
135130

136-
cliflag.StringVarP(cmd.Flags(), &auth, "auth", "", "CODER_AUTH", "token", "Specify the authentication type to use for the agent")
137-
cliflag.StringVarP(cmd.Flags(), &rawURL, "url", "", "CODER_URL", "", "Specify the URL to access Coder")
138-
cliflag.StringVarP(cmd.Flags(), &token, "token", "", "CODER_TOKEN", "", "Specifies the authentication token to access Coder")
139-
131+
cliflag.StringVarP(cmd.Flags(), &auth, "auth", "", "CODER_AGENT_AUTH", "token", "Specify the authentication type to use for the agent")
140132
return cmd
141133
}

‎cli/agent_test.go

+3-3
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,7 @@ func TestWorkspaceAgent(t *testing.T) {
4646
workspace := coderdtest.CreateWorkspace(t, client, user.OrganizationID, template.ID)
4747
coderdtest.AwaitWorkspaceBuildJob(t, client, workspace.LatestBuild.ID)
4848

49-
cmd, _ := clitest.New(t, "agent", "--auth", "azure-instance-identity", "--url", client.URL.String())
49+
cmd, _ := clitest.New(t, "agent", "--auth", "azure-instance-identity", "--agent-url", client.URL.String())
5050
ctx, cancelFunc := context.WithCancel(context.Background())
5151
defer cancelFunc()
5252
go func() {
@@ -100,7 +100,7 @@ func TestWorkspaceAgent(t *testing.T) {
100100
workspace := coderdtest.CreateWorkspace(t, client, user.OrganizationID, template.ID)
101101
coderdtest.AwaitWorkspaceBuildJob(t, client, workspace.LatestBuild.ID)
102102

103-
cmd, _ := clitest.New(t, "agent", "--auth", "aws-instance-identity", "--url", client.URL.String())
103+
cmd, _ := clitest.New(t, "agent", "--auth", "aws-instance-identity", "--agent-url", client.URL.String())
104104
ctx, cancelFunc := context.WithCancel(context.Background())
105105
defer cancelFunc()
106106
go func() {
@@ -154,7 +154,7 @@ func TestWorkspaceAgent(t *testing.T) {
154154
workspace := coderdtest.CreateWorkspace(t, client, user.OrganizationID, template.ID)
155155
coderdtest.AwaitWorkspaceBuildJob(t, client, workspace.LatestBuild.ID)
156156

157-
cmd, _ := clitest.New(t, "agent", "--auth", "google-instance-identity", "--url", client.URL.String())
157+
cmd, _ := clitest.New(t, "agent", "--auth", "google-instance-identity", "--agent-url", client.URL.String())
158158
ctx, cancelFunc := context.WithCancel(context.Background())
159159
defer cancelFunc()
160160
go func() {

‎cli/cliflag/cliflag.go

+9
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,15 @@ import (
1919
"github.com/spf13/pflag"
2020
)
2121

22+
// String sets a string flag on the given flag set.
23+
func String(flagset *pflag.FlagSet, name, shorthand, env, def, usage string) {
24+
v, ok := os.LookupEnv(env)
25+
if !ok || v == "" {
26+
v = def
27+
}
28+
flagset.StringP(name, shorthand, v, fmtUsage(usage, env))
29+
}
30+
2231
// StringVarP sets a string flag on the given flag set.
2332
func StringVarP(flagset *pflag.FlagSet, p *string, name string, shorthand string, env string, def string, usage string) {
2433
v, ok := os.LookupEnv(env)

‎cli/cliflag/cliflag_test.go

+23-1
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,28 @@ import (
1616
//nolint:paralleltest
1717
func TestCliflag(t *testing.T) {
1818
t.Run("StringDefault", func(t *testing.T) {
19+
flagset, name, shorthand, env, usage := randomFlag()
20+
def, _ := cryptorand.String(10)
21+
cliflag.String(flagset, name, shorthand, env, def, usage)
22+
got, err := flagset.GetString(name)
23+
require.NoError(t, err)
24+
require.Equal(t, def, got)
25+
require.Contains(t, flagset.FlagUsages(), usage)
26+
require.Contains(t, flagset.FlagUsages(), fmt.Sprintf(" - consumes $%s", env))
27+
})
28+
29+
t.Run("StringEnvVar", func(t *testing.T) {
30+
flagset, name, shorthand, env, usage := randomFlag()
31+
envValue, _ := cryptorand.String(10)
32+
t.Setenv(env, envValue)
33+
def, _ := cryptorand.String(10)
34+
cliflag.String(flagset, name, shorthand, env, def, usage)
35+
got, err := flagset.GetString(name)
36+
require.NoError(t, err)
37+
require.Equal(t, envValue, got)
38+
})
39+
40+
t.Run("StringVarPDefault", func(t *testing.T) {
1941
var ptr string
2042
flagset, name, shorthand, env, usage := randomFlag()
2143
def, _ := cryptorand.String(10)
@@ -28,7 +50,7 @@ func TestCliflag(t *testing.T) {
2850
require.Contains(t, flagset.FlagUsages(), fmt.Sprintf(" - consumes $%s", env))
2951
})
3052

31-
t.Run("StringEnvVar", func(t *testing.T) {
53+
t.Run("StringVarPEnvVar", func(t *testing.T) {
3254
var ptr string
3355
flagset, name, shorthand, env, usage := randomFlag()
3456
envValue, _ := cryptorand.String(10)

‎cli/config/file.go

-4
Original file line numberDiff line numberDiff line change
@@ -21,10 +21,6 @@ func (r Root) Organization() File {
2121
return File(filepath.Join(string(r), "organization"))
2222
}
2323

24-
func (r Root) AgentSession() File {
25-
return File(filepath.Join(string(r), "agentsession"))
26-
}
27-
2824
// File provides convenience methods for interacting with *os.File.
2925
type File string
3026

‎cli/gitssh.go

+2-16
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,6 @@ package cli
22

33
import (
44
"fmt"
5-
"net/url"
65
"os"
76
"os/exec"
87
"strings"
@@ -11,7 +10,6 @@ import (
1110
"golang.org/x/xerrors"
1211

1312
"github.com/coder/coder/cli/cliui"
14-
"github.com/coder/coder/codersdk"
1513
)
1614

1715
func gitssh() *cobra.Command {
@@ -20,22 +18,10 @@ func gitssh() *cobra.Command {
2018
Hidden: true,
2119
Short: `Wraps the "ssh" command and uses the coder gitssh key for authentication`,
2220
RunE: func(cmd *cobra.Command, args []string) error {
23-
cfg := createConfig(cmd)
24-
rawURL, err := cfg.URL().Read()
21+
client, err := createAgentClient(cmd)
2522
if err != nil {
26-
return xerrors.Errorf("read agent url from config: %w", err)
23+
return xerrors.Errorf("create agent client: %w", err)
2724
}
28-
parsedURL, err := url.Parse(rawURL)
29-
if err != nil {
30-
return xerrors.Errorf("parse agent url from config: %w", err)
31-
}
32-
session, err := cfg.AgentSession().Read()
33-
if err != nil {
34-
return xerrors.Errorf("read agent session from config: %w", err)
35-
}
36-
client := codersdk.New(parsedURL)
37-
client.SessionToken = session
38-
3925
key, err := client.AgentGitSSHKey(cmd.Context())
4026
if err != nil {
4127
return xerrors.Errorf("get agent git ssh token: %w", err)

‎cli/gitssh_test.go

+3-6
Original file line numberDiff line numberDiff line change
@@ -61,7 +61,7 @@ func TestGitSSH(t *testing.T) {
6161
coderdtest.AwaitWorkspaceBuildJob(t, client, workspace.LatestBuild.ID)
6262

6363
// start workspace agent
64-
cmd, root := clitest.New(t, "agent", "--token", agentToken, "--url", client.URL.String())
64+
cmd, root := clitest.New(t, "agent", "--agent-token", agentToken, "--agent-url", client.URL.String())
6565
agentClient := &*client
6666
clitest.SetupConfig(t, agentClient, root)
6767
ctx, cancelFunc := context.WithCancel(context.Background())
@@ -92,7 +92,7 @@ func TestGitSSH(t *testing.T) {
9292
// as long as we get a successful session we don't care if the server errors
9393
_ = ssh.Serve(l, func(s ssh.Session) {
9494
atomic.AddInt64(&inc, 1)
95-
t.Log("got authenticated sesion")
95+
t.Log("got authenticated session")
9696
err := s.Exit(0)
9797
require.NoError(t, err)
9898
}, publicKeyOption)
@@ -101,11 +101,8 @@ func TestGitSSH(t *testing.T) {
101101
// start ssh session
102102
addr, ok := l.Addr().(*net.TCPAddr)
103103
require.True(t, ok)
104-
cfgDir := createConfig(cmd)
105104
// set to agent config dir
106-
cmd, root = clitest.New(t, "gitssh", "--global-config="+string(cfgDir), "--", fmt.Sprintf("-p%d", addr.Port), "-o", "StrictHostKeyChecking=no", "127.0.0.1")
107-
clitest.SetupConfig(t, agentClient, root)
108-
105+
cmd, _ = clitest.New(t, "gitssh", "--agent-url", agentClient.URL.String(), "--agent-token", agentToken, "--", fmt.Sprintf("-p%d", addr.Port), "-o", "StrictHostKeyChecking=no", "127.0.0.1")
109106
err = cmd.ExecuteContext(context.Background())
110107
require.NoError(t, err)
111108
require.EqualValues(t, 1, inc)

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