Create levant tf module

Also a template service Nomad job that can be used for some straighforward services

.terraform.lock.hcl

@@ -19,6 +19,25 @@ provider "registry.terraform.io/hashicorp/consul" {
   ]
 }
 
+provider "registry.terraform.io/hashicorp/external" {
+  version = "2.2.2"
+  hashes = [
+    "h1:BKQ5f5ijzeyBSnUr+j0wUi+bYv6KBQVQNDXNRVEcfJE=",
+    "zh:0b84ab0af2e28606e9c0c1289343949339221c3ab126616b831ddb5aaef5f5ca",
+    "zh:10cf5c9b9524ca2e4302bf02368dc6aac29fb50aeaa6f7758cce9aa36ae87a28",
+    "zh:56a016ee871c8501acb3f2ee3b51592ad7c3871a1757b098838349b17762ba6b",
+    "zh:719d6ef39c50e4cffc67aa67d74d195adaf42afcf62beab132dafdb500347d39",
+    "zh:78d5eefdd9e494defcb3c68d282b8f96630502cac21d1ea161f53cfe9bb483b3",
+    "zh:7fbfc4d37435ac2f717b0316f872f558f608596b389b895fcb549f118462d327",
+    "zh:8ac71408204db606ce63fe8f9aeaf1ddc7751d57d586ec421e62d440c402e955",
+    "zh:a4cacdb06f114454b6ed0033add28006afa3f65a0ea7a43befe45fc82e6809fb",
+    "zh:bb5ce3132b52ae32b6cc005bc9f7627b95259b9ffe556de4dad60d47d47f21f0",
+    "zh:bb60d2976f125ffd232a7ccb4b3f81e7109578b23c9c6179f13a11d125dca82a",
+    "zh:f9540ecd2e056d6e71b9ea5f5a5cf8f63dd5c25394b9db831083a9d4ea99b372",
+    "zh:ffd998b55b8a64d4335a090b6956b4bf8855b290f7554dd38db3302de9c41809",
+  ]
+}
+
 provider "registry.terraform.io/hashicorp/nomad" {
   version = "1.4.16"
   hashes = [

levant/.terraform.lock.hcl

@@ -0,0 +1,40 @@
+# This file is maintained automatically by "terraform init".
+# Manual edits may be lost in future updates.
+
+provider "registry.terraform.io/hashicorp/external" {
+  version = "2.2.2"
+  hashes = [
+    "h1:BKQ5f5ijzeyBSnUr+j0wUi+bYv6KBQVQNDXNRVEcfJE=",
+    "zh:0b84ab0af2e28606e9c0c1289343949339221c3ab126616b831ddb5aaef5f5ca",
+    "zh:10cf5c9b9524ca2e4302bf02368dc6aac29fb50aeaa6f7758cce9aa36ae87a28",
+    "zh:56a016ee871c8501acb3f2ee3b51592ad7c3871a1757b098838349b17762ba6b",
+    "zh:719d6ef39c50e4cffc67aa67d74d195adaf42afcf62beab132dafdb500347d39",
+    "zh:78d5eefdd9e494defcb3c68d282b8f96630502cac21d1ea161f53cfe9bb483b3",
+    "zh:7fbfc4d37435ac2f717b0316f872f558f608596b389b895fcb549f118462d327",
+    "zh:8ac71408204db606ce63fe8f9aeaf1ddc7751d57d586ec421e62d440c402e955",
+    "zh:a4cacdb06f114454b6ed0033add28006afa3f65a0ea7a43befe45fc82e6809fb",
+    "zh:bb5ce3132b52ae32b6cc005bc9f7627b95259b9ffe556de4dad60d47d47f21f0",
+    "zh:bb60d2976f125ffd232a7ccb4b3f81e7109578b23c9c6179f13a11d125dca82a",
+    "zh:f9540ecd2e056d6e71b9ea5f5a5cf8f63dd5c25394b9db831083a9d4ea99b372",
+    "zh:ffd998b55b8a64d4335a090b6956b4bf8855b290f7554dd38db3302de9c41809",
+  ]
+}
+
+provider "registry.terraform.io/hashicorp/nomad" {
+  version = "1.4.17"
+  hashes = [
+    "h1:oWV3VXZhqPZ8Ia07nlIZLeXDBqVULMg9lP3dVMczDCo=",
+    "zh:146f97eacd9a0c78b357a6cfd2cb12765d4b18e9660a75500ee3e748c6eba41a",
+    "zh:2eb89a6e5cee9aea03a96ea9f141096fe3baf219b2700ce30229d2d882f5015f",
+    "zh:3d0f971f79b615c1014c75e2f99f34bd4b4da542ca9f31d5ea7fadc4e9de39c1",
+    "zh:46099a750c752ce05aa14d663a86478a5ad66d95aff3d69367f1d3628aac7792",
+    "zh:71e56006b013dcfe1e4e059b2b07148b44fcd79351ae2c357e0d97e27ae0d916",
+    "zh:74febd25d776688f0558178c2f5a0e6818bbf4cdaa2e160d7049da04103940f0",
+    "zh:78d5eefdd9e494defcb3c68d282b8f96630502cac21d1ea161f53cfe9bb483b3",
+    "zh:af18c064a5f0dd5422d6771939274841f635b619ab392c73d5bf9720945fdb85",
+    "zh:c133d7a862079da9f06e301c530eacbd70e9288fa2276ec0704df907270ee328",
+    "zh:c894cf98d239b9f5a4b7cde9f5c836face0b5b93099048ee817b0380ea439c65",
+    "zh:c918642870f0cafdbe4d7dd07c909701fc3ddb47cac8357bdcde1327bf78c11d",
+    "zh:f8f5655099a57b4b9c0018a2d49133771e24c7ff8262efb1ceb140fd224aa9b6",
+  ]
+}

levant/README.md

@@ -0,0 +1,7 @@
+# Terraform Levant
+
+This module renders a levant template and then creates a Nomad job based on that template.
+
+It only covers a subset of levant capabilities because much else can be done with Terraform already.
+
+required:

levant/levant.py

@@ -0,0 +1,60 @@
+#! /usr/bin/env python3
+import json
+import sys
+from subprocess import check_output
+from typing import Optional
+from typing import overload
+from typing import TypeVar
+
+
+T = TypeVar("T")
+
+
+@overload
+def get_json(d: dict[str, str], key: str, default: None = None) -> None:
+    ...
+
+
+@overload
+def get_json(d: dict[str, str], key: str, default: T = None) -> T:
+    ...
+
+
+def get_json(d: dict[str, str], key: str, default: Optional[T] = None) -> Optional[T]:
+    if key not in d:
+        return default
+
+    return json.loads(d[key])
+
+
+query = json.load(sys.stdin)
+
+# Required
+template_path = query["template_path"]
+
+# Optional
+consul_address = query.get("consul_address")
+# Need to parse JSON back
+variables = [
+    f'--var={key}={value}' for key, value in get_json(query, "variables", {}).items()
+]
+variable_files = [
+    f'--var-file={value}' for value in get_json(query, "var_files", [])
+]
+
+args: list[str] = list(
+    filter(
+        None,
+        ["levant", "render", consul_address]
+        + variables
+        + variable_files
+        + [template_path],
+    )
+)
+
+# print(" ".join(args), file=sys.stderr)
+# exit(1)
+
+template = check_output(args, stderr=sys.stderr)
+
+print(json.dumps({"template": template.decode()}))

levant/main.tf

@@ -0,0 +1,37 @@
+variable "template_path" {
+  type     = string
+  nullable = false
+}
+variable "consul_address" {
+  type        = string
+  default     = null
+  nullable    = true
+  description = "Consul host and port for making KeyValue lookups"
+}
+
+variable "variables" {
+  type        = map(string)
+  description = "Variables to be passed into nomad-pack with values in JSON form"
+  default     = {}
+}
+
+variable "var_files" {
+  type        = list(string)
+  description = "HCL files containing variables to be used by nomad-pack"
+  default     = []
+}
+
+data "external" "levant" {
+  program = ["${path.module}/levant.py"]
+
+  query = {
+    template_path  = var.template_path
+    consul_address = var.consul_address
+    variables      = jsonencode(var.variables)
+    var_files      = jsonencode(var.var_files)
+  }
+}
+
+resource "nomad_job" "levant" {
+  jobspec = data.external.levant.result.template
+}

levant/test.nomad

@@ -0,0 +1,2 @@
+job {
+}

service.nomad

@@ -0,0 +1,145 @@
+# Vars
+# name = string*
+# image = string*
+# service_port = int
+# ingress = bool
+# args = json(list[str])
+# resources = dict(cpu = int, mem = int)
+# templates = json(list(dict(
+#   data = str,
+#   dest = str,
+#   change_mode = str,
+#   change_signal = str,
+#   left_delimiter = str,
+#   right_delimiter = str,
+# )))
+# healthcheck = "/"
+# mysql = bool
+# redis = bool
+job "[[.name]]" {
+  region = "global"
+  datacenters = ["dc1"]
+
+  type = "service"
+
+  group "[[.name]]" {
+    [[ with .count ]]count = [[ . ]][[end]]
+    network {
+      mode = "bridge"
+      [[ if not (empty .service_port) ]]
+      port "main" {
+        [[ if default false .ingress ]]
+        host_network = "loopback"
+        [[ end ]]
+        to = [[.service_port]]
+      }
+      [[ end ]]
+    }
+
+    [[ if not (empty .service_port) ]]
+    service {
+      name = "[[.name | replace "_" "-"]]"
+      port = "main"
+
+      [[ if default false .ingress ]]
+      connect {
+        sidecar_service {
+          proxy {
+            local_service_port = [[.service_port]]
+            [[ if default false .mysql ]]
+            upstreams {
+              destination_name = "mysql-server"
+              local_bind_port = 4040
+            }
+            [[ end -]]
+            [[ if default false .redis ]]
+            upstreams {
+              destination_name = "redis"
+              local_bind_port = 6379
+            }
+            [[ end ]]
+          }
+        }
+
+        sidecar_task {
+          resources {
+            cpu    = 50
+            memory = 50
+          }
+        }
+      }
+      [[ end ]]
+
+      check {
+        type = "http"
+        path = "[[ or .healthcheck "/" ]]"
+        port = "main"
+        interval = "10s"
+        timeout = "10s"
+      }
+
+      tags = [
+        [[ if default false .ingress -]]
+        "traefik.enable=true",
+        "traefik.http.routers.[[.name]].entryPoints=websecure",
+        [[ end -]]
+      ]
+    }
+    [[ end ]]
+
+    task "[[.name]]" {
+      driver = "docker"
+
+      config {
+        image = "[[.image]]"
+        [[ if not (empty .service_port) -]]
+        ports = ["main"]
+        [[- end ]]
+        [[ if not (empty .args) -]]
+        args = ["[[ .args | parseJSON | join `", "` ]]"]
+        [[- end ]]
+
+        [[ with .templates]]
+        [[ range $t := . | parseJSON ]]
+        mount {
+          type = "bind"
+          target = "[[ $t.dest ]]"
+          source = "local/[[ $t.dest ]]"
+        }
+        [[ end ]]
+        [[ end ]]
+      }
+
+      [[ with .env -]]
+      env = {
+        [[- range $k, $v := . ]]
+        "[[$k]]" = "[[$v]]"
+        [[- end ]]
+      }
+      [[ end ]]
+
+      [[ with .templates ]]
+      [[ range $t :=  . | parseJSON ]]
+      template {
+        data = <<EOF
+[[ $t.data ]]
+EOF
+        destination = "local/[[ $t.dest ]]"
+        [[ with $t.left_delimiter ]]left_delimiter = "[[ . ]]"[[ end -]]
+        [[ with $t.right_delimiter ]]right_delimiter = "[[ . ]]"[[ end -]]
+        [[ with $t.change_mode ]]change_mode = "[[ . ]]"[[ end -]]
+        [[ with $t.change_signal ]]change_signal = "[[ . ]]"[[ end -]]
+        [[ with $t.env ]]env = [[ . ]][[ end ]]
+      }
+      [[ end ]]
+      [[ end ]]
+
+      [[ with .resources ]]
+      resources {
+        cpu = [[ .cpu ]]
+        memory = [[ .memory ]]
+      }
+      [[ end ]]
+    }
+  }
+}