feat: Add Environment Commands

process-compose.override.yaml

@@ -17,6 +17,10 @@ vars:
   PWD: /tmp
   DISABLED: true
   PORT: 80
+env_cmds:
+  DATE: "date"
+  OS_NAME: "awk -F= '/PRETTY/ {print $2}' /etc/os-release"
+  UPTIME: "uptime -p"
 
 processes:
   process0:
@@ -124,6 +128,9 @@ processes:
       success_threshold: 1
       failure_threshold: 3
 
+  env-cmd-test:
+    command: "echo Date: $${DATE}, OS: $${OS_NAME}, Uptime: $${UPTIME}"
+
   nginx:
     command: "docker run -d --rm -p80:80 --name nginx_test nginx"
     # availability:

src/app/project_runner.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"github.com/f1bonacc1/process-compose/src/command"
 	"github.com/f1bonacc1/process-compose/src/config"
 	"github.com/f1bonacc1/process-compose/src/health"
 	"github.com/f1bonacc1/process-compose/src/loader"
@@ -15,6 +16,7 @@ import (
 	"os/user"
 	"runtime"
 	"slices"
+	"strings"
 	"sync"
 	"time"
 
@@ -90,6 +92,7 @@ func (p *ProjectRunner) Run() error {
 		p.logger.Open(p.project.LogLocation, p.project.LoggerConfig)
 		defer p.logger.Close()
 	}
+	p.prepareEnvCmds()
 	//zerolog.SetGlobalLevel(zerolog.PanicLevel)
 	log.Debug().Msgf("Spinning up %d processes. Order: %q", len(runOrder), nameOrder)
 	for _, proc := range runOrder {
@@ -1046,6 +1049,33 @@ func (p *ProjectRunner) UpdateProcess(updated *types.ProcessConfig) error {
 	return nil
 }
 
+func (p *ProjectRunner) prepareEnvCmds() {
+	for env, cmd := range p.project.EnvCommands {
+		output, err := runCmd(cmd)
+		if err != nil {
+			log.Err(err).Msgf("Failed to run Env command %s for %s variable", cmd, env)
+			continue
+		}
+		if p.project.Environment == nil {
+			p.project.Environment = make(types.Environment, 0)
+		}
+		p.project.Environment = append(p.project.Environment, fmt.Sprintf("%s=%s", env, output))
+	}
+}
+
+func runCmd(envCmd string) (string, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	cmd := command.BuildCommandContext(ctx, envCmd)
+	out, err := cmd.Output()
+	if err != nil {
+		log.Err(err).Msgf("Failed to run Env command %s", envCmd)
+		return "", err
+	}
+	return strings.TrimSpace(string(out)), nil
+}
+
 func validateProbes(probe *health.Probe) {
 	if probe != nil {
 		probe.ValidateAndSetDefaults()

src/app/system_test.go

@@ -1079,3 +1079,46 @@ func TestSystem_WaitForStartShutDown(t *testing.T) {
 		t.Fatalf("Failed to stop project: %v", err)
 	}
 }
+
+func TestSystem_TestEnvCmds(t *testing.T) {
+	proc1 := "proc1"
+	shell := command.DefaultShellConfig()
+	project := &types.Project{
+		EnvCommands: map[string]string{
+			"LIVE":    "echo live",
+			"LONG":    "echo long",
+			"PROSPER": "echo prosper",
+		},
+		Processes: map[string]types.ProcessConfig{
+			proc1: {
+				Name:        proc1,
+				ReplicaName: proc1,
+				Executable:  shell.ShellCommand,
+				Args:        []string{shell.ShellArgument, "echo $LIVE $LONG and $PROSPER"},
+			},
+		},
+		ShellConfig: shell,
+	}
+	runner, err := NewProjectRunner(&ProjectOpts{
+		project: project,
+	})
+	if err != nil {
+		t.Error(err.Error())
+		return
+	}
+	err = runner.Run()
+	if err != nil {
+		t.Error(err.Error())
+	}
+	log, err := runner.GetProcessLog(proc1, 1, 1)
+	if err != nil {
+		t.Error(err.Error())
+		return
+	}
+	if len(log) != 1 {
+		t.Fatalf("Expected 1 log message, got %d", len(log))
+	}
+	if log[0] != "live long and prosper" {
+		t.Errorf("Expected log message to be 'live long and prosper', got %s", log[0])
+	}
+}

src/command/command_wrapper.go

@@ -55,3 +55,7 @@ func (c *CmdWrapper) SetEnv(env []string) {
 func (c *CmdWrapper) SetDir(dir string) {
 	c.cmd.Dir = dir
 }
+
+func (c *CmdWrapper) Output() ([]byte, error) {
+	return c.cmd.Output()
+}

src/command/commander.go

@@ -16,4 +16,5 @@ type Commander interface {
 	AttachIo()
 	SetEnv(env []string)
 	SetDir(dir string)
+	Output() ([]byte, error)
 }

src/command/mock_command.go

@@ -66,3 +66,7 @@ func (c *MockCommand) SetEnv(env []string) {
 func (c *MockCommand) SetDir(dir string) {
 	c.dir = dir
 }
+
+func (c *MockCommand) Output() ([]byte, error) {
+	return nil, nil
+}

src/types/process.go

@@ -16,40 +16,43 @@ const DefaultNamespace = "default"
 const PlaceHolderValue = "-"
 const DefaultLaunchTimeout = 5
 
-type Processes map[string]ProcessConfig
-type Environment []string
-type ProcessConfig struct {
-	Name              string
-	Disabled          bool                   `yaml:"disabled,omitempty"`
-	IsDaemon          bool                   `yaml:"is_daemon,omitempty"`
-	Command           string                 `yaml:"command"`
-	Entrypoint        []string               `yaml:"entrypoint,omitempty"`
-	LogLocation       string                 `yaml:"log_location,omitempty"`
-	LoggerConfig      *LoggerConfig          `yaml:"log_configuration,omitempty"`
-	Environment       Environment            `yaml:"environment,omitempty"`
-	RestartPolicy     RestartPolicyConfig    `yaml:"availability,omitempty"`
-	DependsOn         DependsOnConfig        `yaml:"depends_on,omitempty"`
-	LivenessProbe     *health.Probe          `yaml:"liveness_probe,omitempty"`
-	ReadinessProbe    *health.Probe          `yaml:"readiness_probe,omitempty"`
-	ReadyLogLine      string                 `yaml:"ready_log_line,omitempty"`
-	ShutDownParams    ShutDownParams         `yaml:"shutdown,omitempty"`
-	DisableAnsiColors bool                   `yaml:"disable_ansi_colors,omitempty"`
-	WorkingDir        string                 `yaml:"working_dir"`
-	Namespace         string                 `yaml:"namespace"`
-	Replicas          int                    `yaml:"replicas"`
-	Extensions        map[string]interface{} `yaml:",inline"`
-	Description       string                 `yaml:"description,omitempty"`
-	Vars              Vars                   `yaml:"vars,omitempty"`
-	IsForeground      bool                   `yaml:"is_foreground"`
-	IsTty             bool                   `yaml:"is_tty"`
-	IsElevated        bool                   `yaml:"is_elevated"`
-	LaunchTimeout     int                    `yaml:"launch_timeout_seconds"`
-	OriginalConfig    string
-	ReplicaNum        int
-	ReplicaName       string
-	Executable        string
-	Args              []string
-}
+type (
+	Processes     map[string]ProcessConfig
+	Environment   []string
+	EnvCmd        map[string]string
+	ProcessConfig struct {
+		Name              string
+		Disabled          bool                   `yaml:"disabled,omitempty"`
+		IsDaemon          bool                   `yaml:"is_daemon,omitempty"`
+		Command           string                 `yaml:"command"`
+		Entrypoint        []string               `yaml:"entrypoint,omitempty"`
+		LogLocation       string                 `yaml:"log_location,omitempty"`
+		LoggerConfig      *LoggerConfig          `yaml:"log_configuration,omitempty"`
+		Environment       Environment            `yaml:"environment,omitempty"`
+		RestartPolicy     RestartPolicyConfig    `yaml:"availability,omitempty"`
+		DependsOn         DependsOnConfig        `yaml:"depends_on,omitempty"`
+		LivenessProbe     *health.Probe          `yaml:"liveness_probe,omitempty"`
+		ReadinessProbe    *health.Probe          `yaml:"readiness_probe,omitempty"`
+		ReadyLogLine      string                 `yaml:"ready_log_line,omitempty"`
+		ShutDownParams    ShutDownParams         `yaml:"shutdown,omitempty"`
+		DisableAnsiColors bool                   `yaml:"disable_ansi_colors,omitempty"`
+		WorkingDir        string                 `yaml:"working_dir"`
+		Namespace         string                 `yaml:"namespace"`
+		Replicas          int                    `yaml:"replicas"`
+		Extensions        map[string]interface{} `yaml:",inline"`
+		Description       string                 `yaml:"description,omitempty"`
+		Vars              Vars                   `yaml:"vars,omitempty"`
+		IsForeground      bool                   `yaml:"is_foreground"`
+		IsTty             bool                   `yaml:"is_tty"`
+		IsElevated        bool                   `yaml:"is_elevated"`
+		LaunchTimeout     int                    `yaml:"launch_timeout_seconds"`
+		OriginalConfig    string
+		ReplicaNum        int
+		ReplicaName       string
+		Executable        string
+		Args              []string
+	}
+)
 
 func (p *ProcessConfig) GetDependencies() []string {
 	dependencies := make([]string, len(p.DependsOn))

src/types/project.go

@@ -23,6 +23,7 @@ type Project struct {
 	DisableEnvExpansion bool                 `yaml:"disable_env_expansion"`
 	IsTuiDisabled       bool                 `yaml:"is_tui_disabled"`
 	ExtendsProject      string               `yaml:"extends,omitempty"`
+	EnvCommands         EnvCmd               `yaml:"env_cmds,omitempty"`
 	FileNames           []string
 	EnvFileNames        []string
 }

www/docs/configuration.md

@@ -107,6 +107,83 @@ Process Compose provides 2 ways to disable the automatic environment variables e
 >
 >  **Output**: `I am `
 
+## Environment Commands
+
+The `env_cmds` feature allows you to dynamically populate environment variables by executing short commands before starting your processes. This is useful when you need environment values that are determined at runtime or need to be fetched from the system.
+
+### Configuration
+
+Environment commands are defined in the `env_cmds` section of your `process-compose.yaml` file. Each entry consists of:
+- An environment variable name (key)
+- A command to execute (value)
+
+```yaml
+env_cmds:
+  ENV_VAR_NAME: "command to execute"
+```
+
+### Example Configuration
+
+```yaml
+env_cmds:
+  DATE: "date"
+  OS_NAME: "awk -F= '/PRETTY/ {print $2}' /etc/os-release"
+  UPTIME: "uptime -p"
+```
+
+### Usage
+
+To use the environment variables populated by `env_cmds`, reference them in your process definitions using `$${VAR_NAME}` syntax:
+
+```yaml
+processes:
+  my-process:
+    command: "echo Current date is: $${DATE}"
+```
+
+### Constraints and Considerations
+
+1. **Execution Time**: Commands should complete within 2 seconds. Longer-running commands may cause process-compose startup delays or timeouts.
+
+2. **Command Output**: 
+   - Commands should output a single line of text
+   - The output will be trimmed of leading/trailing whitespace
+   - The output becomes the value of the environment variable
+
+3. **Error Handling**:
+   - If a command fails, the environment variable will not be set
+   - Process-compose will log any command execution errors
+
+### Best Practices
+
+1. Keep commands simple and fast-executing
+2. Use commands that produce consistent, predictable output
+3. Validate command output format before using in production
+4. Consider caching values that don't need frequent updates
+
+### Example Use Cases
+
+1. **System Information**:
+```yaml
+env_cmds:
+  HOSTNAME: "hostname"
+  KERNEL_VERSION: "uname -r"
+```
+
+2. **Time-based Values**:
+```yaml
+env_cmds:
+  TIMESTAMP: "date +%s"
+  DATE_ISO: "date -u +%Y-%m-%dT%H:%M:%SZ"
+```
+
+3. **Resource Information**:
+```yaml
+env_cmds:
+  AVAILABLE_MEMORY: "free -m | awk '/Mem:/ {print $7}'"
+  CPU_CORES: "nproc"
+```
+
 ## Variables
 
 Variables in Process Compose rely on [Go template engine](https://pkg.go.dev/text/template)