fix(agent/agentcontainers): correct definition of remoteEnv (coder#16845)

`devcontainer.metadata` is apparently an array, not an object. Missed
this first time round!

```
    error= get container env info:
               github.com/coder/coder/v2/agent/reconnectingpty.(*Server).handleConn
                   /home/runner/work/coder/coder/agent/reconnectingpty/server.go:193
             - read devcontainer remoteEnv:
               github.com/coder/coder/v2/agent/agentcontainers.EnvInfo
                   /home/runner/work/coder/coder/agent/agentcontainers/containers_dockercli.go:119
             - unmarshal devcontainer.metadata:
               github.com/coder/coder/v2/agent/agentcontainers.devcontainerEnv
                   /home/runner/work/coder/coder/agent/agentcontainers/containers_dockercli.go:189
             - json: cannot unmarshal array into Go value of type struct { RemoteEnv map[string]string "json:\"remoteEnv\"" }
```

Author: johnstcn

agent/agentcontainers/containers_dockercli.go

@@ -182,17 +182,18 @@ func devcontainerEnv(ctx context.Context, execer agentexec.Execer, container str
 	if !ok {
 		return nil, nil
 	}
-	meta := struct {
-		RemoteEnv map[string]string `json:"remoteEnv"`
-	}{}
+
+	meta := make([]DevContainerMeta, 0)
 	if err := json.Unmarshal([]byte(rawMeta), &meta); err != nil {
 		return nil, xerrors.Errorf("unmarshal devcontainer.metadata: %w", err)
 	}
 
 	// The environment variables are stored in the `remoteEnv` key.
-	env := make([]string, 0, len(meta.RemoteEnv))
-	for k, v := range meta.RemoteEnv {
-		env = append(env, fmt.Sprintf("%s=%s", k, v))
+	env := make([]string, 0)
+	for _, m := range meta {
+		for k, v := range m.RemoteEnv {
+			env = append(env, fmt.Sprintf("%s=%s", k, v))
+		}
 	}
 	slices.Sort(env)
 	return env, nil

agent/agentcontainers/containers_internal_test.go

@@ -53,7 +53,7 @@ func TestIntegrationDocker(t *testing.T) {
 		Cmd:        []string{"sleep", "infnity"},
 		Labels: map[string]string{
 			"com.coder.test":        testLabelValue,
-			"devcontainer.metadata": `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`,
+			"devcontainer.metadata": `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`,
 		},
 		Mounts:       []string{testTempDir + ":" + testTempDir},
 		ExposedPorts: []string{fmt.Sprintf("%d/tcp", testRandPort)},
@@ -437,38 +437,46 @@ func TestDockerEnvInfoer(t *testing.T) {
 	}{
 		{
 			image:  "busybox:latest",
-			labels: map[string]string{`devcontainer.metadata`: `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`},
+			labels: map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`},
 
 			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
 			expectedUsername:  "root",
 			expectedUserShell: "/bin/sh",
 		},
 		{
 			image:             "busybox:latest",
-			labels:            map[string]string{`devcontainer.metadata`: `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`},
+			labels:            map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`},
 			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
 			containerUser:     "root",
 			expectedUsername:  "root",
 			expectedUserShell: "/bin/sh",
 		},
 		{
 			image:             "codercom/enterprise-minimal:ubuntu",
-			labels:            map[string]string{`devcontainer.metadata`: `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`},
+			labels:            map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`},
 			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
 			expectedUsername:  "coder",
 			expectedUserShell: "/bin/bash",
 		},
 		{
 			image:             "codercom/enterprise-minimal:ubuntu",
-			labels:            map[string]string{`devcontainer.metadata`: `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`},
+			labels:            map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`},
 			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
 			containerUser:     "coder",
 			expectedUsername:  "coder",
 			expectedUserShell: "/bin/bash",
 		},
 		{
 			image:             "codercom/enterprise-minimal:ubuntu",
-			labels:            map[string]string{`devcontainer.metadata`: `{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}`},
+			labels:            map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar", "MULTILINE": "foo\nbar\nbaz"}}]`},
+			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
+			containerUser:     "root",
+			expectedUsername:  "root",
+			expectedUserShell: "/bin/bash",
+		},
+		{
+			image:             "codercom/enterprise-minimal:ubuntu",
+			labels:            map[string]string{`devcontainer.metadata`: `[{"remoteEnv": {"FOO": "bar"}},{"remoteEnv": {"MULTILINE": "foo\nbar\nbaz"}}]`},
 			expectedEnv:       []string{"FOO=bar", "MULTILINE=foo\nbar\nbaz"},
 			containerUser:     "root",
 			expectedUsername:  "root",

agent/agentcontainers/devcontainer_meta.go

@@ -0,0 +1,5 @@
+package agentcontainers
+
+type DevContainerMeta struct {
+	RemoteEnv map[string]string `json:"remoteEnv,omitempty"`
+}