feat: Add UI for awaiting agent connections (#578)

* feat: Add stage to build logs

This adds a stage property to logs, and refactors the job logs
cliui.

It also adds tests to the cliui for build logs!

* feat: Add stage to build logs

This adds a stage property to logs, and refactors the job logs
cliui.

It also adds tests to the cliui for build logs!

* feat: Add config-ssh and tests for resiliency

* Rename "Echo" test to "ImmediateExit"

* Fix Terraform resource agent association

* Fix logs post-cancel

* Fix select on Windows

* Remove terraform init logs

* Move timer into it's own loop

* Fix race condition in provisioner jobs

* Fix requested changes

cli/cliui/agent.go

@@ -0,0 +1,87 @@
+package cliui
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/briandowns/spinner"
+	"github.com/spf13/cobra"
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/codersdk"
+)
+
+type AgentOptions struct {
+	WorkspaceName string
+	Fetch         func(context.Context) (codersdk.WorkspaceResource, error)
+	FetchInterval time.Duration
+	WarnInterval  time.Duration
+}
+
+// Agent displays a spinning indicator that waits for a workspace agent to connect.
+func Agent(cmd *cobra.Command, opts AgentOptions) error {
+	if opts.FetchInterval == 0 {
+		opts.FetchInterval = 500 * time.Millisecond
+	}
+	if opts.WarnInterval == 0 {
+		opts.WarnInterval = 30 * time.Second
+	}
+	var resourceMutex sync.Mutex
+	resource, err := opts.Fetch(cmd.Context())
+	if err != nil {
+		return xerrors.Errorf("fetch: %w", err)
+	}
+	if resource.Agent.Status == codersdk.WorkspaceAgentConnected {
+		return nil
+	}
+	if resource.Agent.Status == codersdk.WorkspaceAgentDisconnected {
+		opts.WarnInterval = 0
+	}
+	spin := spinner.New(spinner.CharSets[78], 100*time.Millisecond, spinner.WithColor("fgHiGreen"))
+	spin.Writer = cmd.OutOrStdout()
+	spin.Suffix = " Waiting for connection from " + Styles.Field.Render(resource.Type+"."+resource.Name) + "..."
+	spin.Start()
+	defer spin.Stop()
+
+	ticker := time.NewTicker(opts.FetchInterval)
+	defer ticker.Stop()
+	timer := time.NewTimer(opts.WarnInterval)
+	defer timer.Stop()
+	go func() {
+		select {
+		case <-cmd.Context().Done():
+			return
+		case <-timer.C:
+		}
+		resourceMutex.Lock()
+		defer resourceMutex.Unlock()
+		message := "Don't panic, your workspace is booting up!"
+		if resource.Agent.Status == codersdk.WorkspaceAgentDisconnected {
+			message = "The workspace agent lost connection! Wait for it to reconnect or run: " + Styles.Code.Render("coder workspaces rebuild "+opts.WorkspaceName)
+		}
+		// This saves the cursor position, then defers clearing from the cursor
+		// position to the end of the screen.
+		_, _ = fmt.Fprintf(cmd.OutOrStdout(), "\033[s\r\033[2K%s\n\n", Styles.Paragraph.Render(Styles.Prompt.String()+message))
+		defer fmt.Fprintf(cmd.OutOrStdout(), "\033[u\033[J")
+	}()
+	for {
+		select {
+		case <-cmd.Context().Done():
+			return cmd.Context().Err()
+		case <-ticker.C:
+		}
+		resourceMutex.Lock()
+		resource, err = opts.Fetch(cmd.Context())
+		if err != nil {
+			return xerrors.Errorf("fetch: %w", err)
+		}
+		if resource.Agent.Status != codersdk.WorkspaceAgentConnected {
+			resourceMutex.Unlock()
+			continue
+		}
+		resourceMutex.Unlock()
+		return nil
+	}
+}