feat: use list of images from data source as fallback

examples/terraform/oracle cloud/create a free tier ampere instance/example.tfvars

@@ -4,8 +4,11 @@ compartment_id      = "FIXME" # get it with `oci iam compartment list`
 memory_in_gbs = 24
 ocpus         = 4
 
-# get it with `oci compute image list -c 'tenancy_id'`
-# or check https://docs.oracle.com/en-us/iaas/images/
+# get the list of images using
+# - `oci compute image list -c 'tenancy_id' --lifecycle-state 'AVAILABLE' --shape 'VM.Standard.A1.Flex'`
+# - the 'oci_core_images' data source
+#   see https://registry.terraform.io/providers/oracle/oci/latest/docs/data-sources/core_images
+# - https://docs.oracle.com/en-us/iaas/images/
 source_id = "ocid1.image.oc1.eu-amsterdam-1.aaaaaaaavmra3s4va4fqd4vlcrqc5v5jyqov5vdla3x3b6gzc64n6dkpuqua"
 
 ssh_authorized_keys = <<-EOT

examples/terraform/oracle cloud/create a free tier ampere instance/main.tf

@@ -9,50 +9,64 @@ terraform {
   }
 }
 
-# See https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_vcn
-resource "oci_core_vcn" "this" {
+resource "oci_core_vcn" "default" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_vcn
   compartment_id = var.compartment_id
   cidr_blocks    = ["10.0.0.0/16"]
 }
 
-# See https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_subnet
-resource "oci_core_subnet" "this" {
+resource "oci_core_subnet" "default" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_subnet
   compartment_id = var.compartment_id
-  vcn_id         = oci_core_vcn.this.id
+  vcn_id         = oci_core_vcn.default.id
   cidr_block     = "10.0.0.0/24"
 }
 
-# Needed to be able to connect to the instance from the Internet.
-# Need to create a route table with the default route 0.0.0.0/0 pointing to the
-# internet gateway, and associate the subnet to it.
-# See https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_internet_gateway
-resource "oci_core_internet_gateway" "this" {
+# To be able to connect to the instance from the Internet, one needs to create a
+# route table with the default route 0.0.0.0/0 pointing to an internet gateway,
+# and associate the subnet to it.
+
+resource "oci_core_internet_gateway" "default" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_internet_gateway
   compartment_id = var.compartment_id
-  vcn_id         = oci_core_vcn.this.id
+  vcn_id         = oci_core_vcn.default.id
 }
-resource "oci_core_route_table" "this" {
+resource "oci_core_route_table" "default" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_route_table
   compartment_id = var.compartment_id
-  vcn_id         = oci_core_vcn.this.id
+  vcn_id         = oci_core_vcn.default.id
 
   route_rules {
     destination       = "0.0.0.0/0"
     destination_type  = "CIDR_BLOCK"
-    network_entity_id = oci_core_internet_gateway.this.id
+    network_entity_id = oci_core_internet_gateway.default.id
   }
 }
-resource "oci_core_route_table_attachment" "this" {
-  subnet_id      = oci_core_subnet.this.id
-  route_table_id = oci_core_route_table.this.id
+resource "oci_core_route_table_attachment" "default" {
+  # See https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_route_table_attachment
+  subnet_id      = oci_core_subnet.default.id
+  route_table_id = oci_core_route_table.default.id
+}
+
+data "oci_core_images" "available" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/data-sources/core_images
+  compartment_id = var.compartment_id
+  operating_system = var.operating_system
+  operating_system_version = var.operating_system_version
+  shape = var.shape
+  state = "AVAILABLE"
+  sort_by = "DISPLAYNAME"
+  sort_order = "DESC"
 }
 
-# See https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_instance
 resource "oci_core_instance" "this" {
+  # https://registry.terraform.io/providers/oracle/oci/latest/docs/resources/core_instance
   compartment_id      = var.compartment_id
   availability_domain = var.availability_domain
   shape               = var.shape
 
   create_vnic_details {
-    subnet_id = oci_core_subnet.this.id
+    subnet_id = oci_core_subnet.default.id
   }
 
   extended_metadata = {}
@@ -67,7 +81,13 @@ resource "oci_core_instance" "this" {
 
   source_details {
     boot_volume_size_in_gbs = var.boot_volume_size_in_gbs
-    source_id               = var.source_id
+    source_id               = coalesce(var.source_id, data.oci_core_images.available.images[0].id)
     source_type             = var.source_type
   }
+
+  lifecycle {
+    ignore_changes = [
+      source_details["source_id"]
+    ]
+  }
 }

examples/terraform/oracle cloud/create a free tier ampere instance/variables.tf

@@ -13,11 +13,6 @@ variable "compartment_id" {
 # Instance
 ####################
 
-variable "shape" {
-  type    = string
-  default = "VM.Standard.A1.Flex"
-}
-
 variable "memory_in_gbs" {
   type    = number
   default = 24
@@ -31,8 +26,21 @@ variable "boot_volume_size_in_gbs" {
   type    = number
   default = 50
 }
+variable "operating_system" {
+  type = string
+  default = "Oracle Linux"
+}
+variable "operating_system_version" {
+  type = number
+  default = 9
+}
+variable "shape" {
+  type = string
+  default = "VM.Standard.A1.Flex"
+}
 variable "source_id" {
   type = string
+  default = null
 }
 variable "source_type" {
   type    = string

knowledge base/oci-cli.md

@@ -3,8 +3,8 @@
 Oracle Cloud Infrastructure CLI.
 
 1. [TL;DR](#tldr)
-2. [Configuration](#configuration)
-3. [Further readings](#further-readings)
+1. [Configuration](#configuration)
+1. [Further readings](#further-readings)
 
 ## TL;DR
 
@@ -37,8 +37,9 @@ oci iam availability-domain list -c 'tenancy_id'
 # Output is paginated.
 oci compute image list -c 'tenancy_id' --all
 oci compute image list -c 'tenancy_id' \
+  --lifecycle-state 'AVAILABLE' --shape 'VM.Standard.A1.Flex' \
   --operating-system 'Oracle Linux' --operating-system-version '8' \
-  --lifecycle-state 'AVAILABLE'
+  --sort-by 'DISPLAYNAME' --sort-order 'DESC'
 
 # List available compute instance plugins.
 # Requires to be given the OS and its version.