feat: add autoscaling configuration for prebuilds

provider/workspace_preset.go

@@ -3,13 +3,18 @@ package provider
 import (
 	"context"
 	"fmt"
+	"strings"
+	"time"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/validation"
 	"github.com/mitchellh/mapstructure"
+	rbcron "github.com/robfig/cron/v3"
 )
 
+var PrebuildsCRONParser = rbcron.NewParser(rbcron.Minute | rbcron.Hour | rbcron.Dom | rbcron.Month | rbcron.Dow)
+
 type WorkspacePreset struct {
 	Name       string            `mapstructure:"name"`
 	Parameters map[string]string `mapstructure:"parameters"`
@@ -29,12 +34,23 @@ type WorkspacePrebuild struct {
 	// for utilities that parse our terraform output using this type. To remain compatible
 	// with those cases, we use a slice here.
 	ExpirationPolicy []ExpirationPolicy `mapstructure:"expiration_policy"`
+	Autoscaling      []Autoscaling      `json:"autoscaling,omitempty"`
 }
 
 type ExpirationPolicy struct {
 	TTL int `mapstructure:"ttl"`
 }
 
+type Autoscaling struct {
+	Timezone string     `json:"timezone"`
+	Schedule []Schedule `json:"schedule"`
+}
+
+type Schedule struct {
+	Cron      string `json:"cron"`
+	Instances int    `json:"instances"`
+}
+
 func workspacePresetDataSource() *schema.Resource {
 	return &schema.Resource{
 		SchemaVersion: 1,
@@ -119,9 +135,77 @@ func workspacePresetDataSource() *schema.Resource {
 								},
 							},
 						},
+						"autoscaling": {
+							Type:     schema.TypeList,
+							Optional: true,
+							MaxItems: 1,
+							Elem: &schema.Resource{
+								Schema: map[string]*schema.Schema{
+									"timezone": {
+										Type:     schema.TypeString,
+										Required: true,
+										ValidateFunc: func(val interface{}, key string) ([]string, []error) {
+											timezone := val.(string)
+
+											_, err := time.LoadLocation(timezone)
+											if err != nil {
+												return nil, []error{fmt.Errorf("failed to load location: %w", err)}
+											}
+
+											return nil, nil
+										},
+									},
+									"schedule": {
+										Type:     schema.TypeList,
+										Required: true,
+										MinItems: 1,
+										Elem: &schema.Resource{
+											Schema: map[string]*schema.Schema{
+												"cron": {
+													Type:     schema.TypeString,
+													Required: true,
+													ValidateFunc: func(val interface{}, key string) ([]string, []error) {
+														cronSpec := val.(string)
+
+														err := validatePrebuildsCronSpec(cronSpec)
+														if err != nil {
+															return nil, []error{fmt.Errorf("cron spec failed validation: %w", err)}
+														}
+
+														_, err = PrebuildsCRONParser.Parse(cronSpec)
+														if err != nil {
+															return nil, []error{fmt.Errorf("failed to parse cron spec: %w", err)}
+														}
+
+														return nil, nil
+													},
+												},
+												"instances": {
+													Type:     schema.TypeInt,
+													Required: true,
+												},
+											},
+										},
+									},
+								},
+							},
+						},
 					},
 				},
 			},
 		},
 	}
 }
+
+// validatePrebuildsCronSpec ensures that the minute, day-of-month and month options of spec are all set to *
+func validatePrebuildsCronSpec(spec string) error {
+	parts := strings.Fields(spec)
+	if len(parts) != 5 {
+		return fmt.Errorf("cron specification should consist of 5 fields")
+	}
+	if parts[0] != "*" || parts[2] != "*" || parts[3] != "*" {
+		return fmt.Errorf("minute, day-of-month and month should be *")
+	}
+
+	return nil
+}

provider/workspace_preset_test.go

@@ -265,6 +265,249 @@ func TestWorkspacePreset(t *testing.T) {
 			}`,
 			ExpectError: regexp.MustCompile("An argument named \"invalid_argument\" is not expected here."),
 		},
+		{
+			Name: "Prebuilds is set with an empty autoscaling field",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`The argument "[^"]+" is required, but no definition was found.`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling field, but without timezone",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+					  	schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = 3
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`The argument "timezone" is required, but no definition was found.`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling field, but without schedule",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`At least 1 "schedule" blocks are required.`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling.schedule field, but without cron",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+						schedule {
+							instances = 3
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`The argument "cron" is required, but no definition was found.`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling.schedule field, but without cron",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+						schedule {
+							cron = "* 8-18 * * 1-5"
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`The argument "instances" is required, but no definition was found.`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling.schedule field, but with invalid type for instances",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+						schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = "not_a_number"
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`Inappropriate value for attribute "instances": a number is required`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling field with 1 schedule",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+					  	schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = 3
+					  	}
+					}
+				}
+			}`,
+			ExpectError: nil,
+			Check: func(state *terraform.State) error {
+				require.Len(t, state.Modules, 1)
+				require.Len(t, state.Modules[0].Resources, 1)
+				resource := state.Modules[0].Resources["data.coder_workspace_preset.preset_1"]
+				require.NotNil(t, resource)
+				attrs := resource.Primary.Attributes
+				require.Equal(t, attrs["name"], "preset_1")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.timezone"], "UTC")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.0.cron"], "* 8-18 * * 1-5")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.0.instances"], "3")
+				return nil
+			},
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling field with 2 schedules",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+					  	schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = 3
+					  	}
+						schedule {
+		    				cron = "* 8-14 * * 6"
+		    				instances = 1
+		  				}
+					}
+				}
+			}`,
+			ExpectError: nil,
+			Check: func(state *terraform.State) error {
+				require.Len(t, state.Modules, 1)
+				require.Len(t, state.Modules[0].Resources, 1)
+				resource := state.Modules[0].Resources["data.coder_workspace_preset.preset_1"]
+				require.NotNil(t, resource)
+				attrs := resource.Primary.Attributes
+				require.Equal(t, attrs["name"], "preset_1")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.timezone"], "UTC")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.0.cron"], "* 8-18 * * 1-5")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.0.instances"], "3")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.1.cron"], "* 8-14 * * 6")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.schedule.1.instances"], "1")
+				return nil
+			},
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling.schedule field, but the cron includes a disallowed minute field",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+						schedule {
+							cron = "30 8-18 * * 1-5"
+							instances = "1"
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`cron spec failed validation: minute, day-of-month and month should be *`),
+		},
+		{
+			Name: "Prebuilds is set with an autoscaling.schedule field, but the cron hour field is invalid",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "UTC"
+						schedule {
+							cron = "* 25-26 * * 1-5"
+							instances = "1"
+					  	}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`failed to parse cron spec: end of range \(26\) above maximum \(23\): 25-26`),
+		},
+		{
+			Name: "Prebuilds is set with a valid autoscaling.timezone field",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "America/Los_Angeles"
+						schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = 3
+						}
+					}
+				}
+			}`,
+			ExpectError: nil,
+			Check: func(state *terraform.State) error {
+				require.Len(t, state.Modules, 1)
+				require.Len(t, state.Modules[0].Resources, 1)
+				resource := state.Modules[0].Resources["data.coder_workspace_preset.preset_1"]
+				require.NotNil(t, resource)
+				attrs := resource.Primary.Attributes
+				require.Equal(t, attrs["name"], "preset_1")
+				require.Equal(t, attrs["prebuilds.0.autoscaling.0.timezone"], "America/Los_Angeles")
+				return nil
+			},
+		},
+		{
+			Name: "Prebuilds is set with an invalid autoscaling.timezone field",
+			Config: `
+			data "coder_workspace_preset" "preset_1" {
+				name = "preset_1"
+				prebuilds {
+					instances = 1
+					autoscaling {
+						timezone = "InvalidLocation"
+						schedule {
+							cron = "* 8-18 * * 1-5"
+							instances = 3
+						}
+					}
+				}
+			}`,
+			ExpectError: regexp.MustCompile(`failed to load location: unknown time zone InvalidLocation`),
+		},
 	}
 
 	for _, testcase := range testcases {