feat(coderd): add support for external agents to API's and provisioner (#19286)

This pull request introduces support for external workspace management, allowing users to register and manage workspaces that are provisioned and managed outside of the Coder.

Depends on: https://github.com/coder/terraform-provider-coder/pull/424

* GET /api/v2/init-script - Gets the agent initialization script
  * By default, it returns a script for Linux (amd64), but with query parameters (os and arch) you can get the init script for different platforms
* GET /api/v2/workspaces/{workspace}/external-agent/{agent}/credentials - Gets credentials for an external agent **(enterprise)**
* Updated queries to filter workspaces/templates by the has_external_agent field

enterprise/coderd/workspaceagents.go

@@ -2,9 +2,14 @@ package coderd
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 
+	"github.com/go-chi/chi/v5"
+
+	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/httpapi"
+	"github.com/coder/coder/v2/coderd/httpmw"
 	"github.com/coder/coder/v2/codersdk"
 )
 
@@ -17,3 +22,77 @@ func (api *API) shouldBlockNonBrowserConnections(rw http.ResponseWriter) bool {
 	}
 	return false
 }
+
+// @Summary Get workspace external agent credentials
+// @ID get-workspace-external-agent-credentials
+// @Security CoderSessionToken
+// @Produce json
+// @Tags Enterprise
+// @Param workspace path string true "Workspace ID" format(uuid)
+// @Param agent path string true "Agent name"
+// @Success 200 {object} codersdk.ExternalAgentCredentials
+// @Router /workspaces/{workspace}/external-agent/{agent}/credentials [get]
+func (api *API) workspaceExternalAgentCredentials(rw http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	workspace := httpmw.WorkspaceParam(r)
+	agentName := chi.URLParam(r, "agent")
+
+	build, err := api.Database.GetLatestWorkspaceBuildByWorkspaceID(ctx, workspace.ID)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Failed to get latest workspace build.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+	if !build.HasExternalAgent.Bool {
+		httpapi.Write(ctx, rw, http.StatusNotFound, codersdk.Response{
+			Message: "Workspace does not have an external agent.",
+		})
+		return
+	}
+
+	agents, err := api.Database.GetWorkspaceAgentsByWorkspaceAndBuildNumber(ctx, database.GetWorkspaceAgentsByWorkspaceAndBuildNumberParams{
+		WorkspaceID: workspace.ID,
+		BuildNumber: build.BuildNumber,
+	})
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Failed to get workspace agents.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	var agent *database.WorkspaceAgent
+	for i := range agents {
+		if agents[i].Name == agentName {
+			agent = &agents[i]
+			break
+		}
+	}
+	if agent == nil {
+		httpapi.Write(ctx, rw, http.StatusNotFound, codersdk.Response{
+			Message: fmt.Sprintf("External agent '%s' not found in workspace.", agentName),
+		})
+		return
+	}
+
+	if agent.AuthInstanceID.Valid {
+		httpapi.Write(ctx, rw, http.StatusNotFound, codersdk.Response{
+			Message: "External agent is authenticated with an instance ID.",
+		})
+		return
+	}
+
+	initScriptURL := fmt.Sprintf("%s/api/v2/init-script/%s/%s", api.AccessURL.String(), agent.OperatingSystem, agent.Architecture)
+	command := fmt.Sprintf("CODER_AGENT_TOKEN=%q curl -fsSL %q | sh", agent.AuthToken.String(), initScriptURL)
+	if agent.OperatingSystem == "windows" {
+		command = fmt.Sprintf("$env:CODER_AGENT_TOKEN=%q; iwr -useb %q | iex", agent.AuthToken.String(), initScriptURL)
+	}
+
+	httpapi.Write(ctx, rw, http.StatusOK, codersdk.ExternalAgentCredentials{
+		AgentToken: agent.AuthToken.String(),
+		Command:    command,
+	})
+}