From 675b65b5da9c9f0ff944e268873a81e9f4cc8943 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <hg@lukegb.com>
Date: Sat, 9 Apr 2022 20:17:32 +0100
Subject: [PATCH] nix/docker/heptapod: add update script for image

---
 nix/docker/heptapod/default.nix | 10 ++-------
 nix/docker/heptapod/image.json  |  7 ++++++
 nix/docker/heptapod/update.sh   | 38 +++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 8 deletions(-)
 create mode 100644 nix/docker/heptapod/image.json
 create mode 100755 nix/docker/heptapod/update.sh

diff --git a/nix/docker/heptapod/default.nix b/nix/docker/heptapod/default.nix
index 5ffd06c7b8..963e16c6a9 100644
--- a/nix/docker/heptapod/default.nix
+++ b/nix/docker/heptapod/default.nix
@@ -4,13 +4,7 @@
 
 { pkgs, ... }:
 let
-  origImageArgs = {
-    imageName = "octobus/heptapod";
-    imageDigest = "sha256:af6a7f47a15410c521a0d620377b98fa6f5715d6f091ea39d7e332146d20786c";
-    sha256 = "sha256:1gdi9q02g2a5y2vmpxray4l8rq3yapqpdbg0fg7xxk9f99ysng7j";
-    finalImageName = "octobus/heptapod";
-    finalImageTag = "0.30.1";
-  };
+  origImageArgs = builtins.fromJSON (builtins.readFile ./image.json);
   origImage = pkgs.dockerTools.pullImage origImageArgs;
 
   name = origImageArgs.imageName;
@@ -45,5 +39,5 @@ in pkgs.dockerTools.buildImage rec {
   '';
   config.Cmd = ["/assets/wrapper_wrapper"];
 } // {
-  meta = { inherit name tag; };
+  meta = { inherit name tag origImage; };
 }
diff --git a/nix/docker/heptapod/image.json b/nix/docker/heptapod/image.json
new file mode 100644
index 0000000000..61cd890913
--- /dev/null
+++ b/nix/docker/heptapod/image.json
@@ -0,0 +1,7 @@
+{
+  "imageName": "octobus/heptapod",
+  "imageDigest": "sha256:af6a7f47a15410c521a0d620377b98fa6f5715d6f091ea39d7e332146d20786c",
+  "sha256": "1gdi9q02g2a5y2vmpxray4l8rq3yapqpdbg0fg7xxk9f99ysng7j",
+  "finalImageName": "octobus/heptapod",
+  "finalImageTag": "0.30.1"
+}
diff --git a/nix/docker/heptapod/update.sh b/nix/docker/heptapod/update.sh
new file mode 100755
index 0000000000..2d8dd64cc5
--- /dev/null
+++ b/nix/docker/heptapod/update.sh
@@ -0,0 +1,38 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -p go-containerregistry.crane -p jq -i bash
+
+set -euo pipefail
+
+repo="index.docker.io/octobus/heptapod"
+path="nix.docker.heptapod"
+depot="$(pwd | grep -o '.*/depot')"
+
+latest_digest="$(crane digest "$repo:latest")"
+current_digest="$(jq -r .imageDigest image.json)"
+
+if [[ "$latest_digest" == "$current_digest" ]]; then
+  echo already up to date
+  exit 0
+fi
+
+crane ls "$repo" | grep -E '^([0-9]+\.)+[0-9]+$' | sort -rV | while read -r tag; do
+  tag_digest="$(crane digest "$repo:$tag")"
+  if [[ "$tag_digest" == "$latest_digest" ]]; then
+    echo "$tag $tag_digest"
+
+    mv image.json image.orig.json
+    jq ".finalImageTag = \"$tag\" | .imageDigest = \"$tag_digest\" | .sha256 = \"sha256:0000000000000000000000000000000000000000000000000000\"" image.orig.json > image.json
+
+    nix-build "$depot" --no-out-link -A "$path.meta.origImage" 2>"image.fetchlog" >/dev/null || true
+    new_hash=$(sed '1,/hash mismatch in fixed-output derivation/d' "image.fetchlog" | grep --perl-regexp --only-matching 'got: +.+[:-]\K.+' | head -n +1)
+    if [[ -z "$new_hash" ]]; then
+      echo "Couldn't figure out new hash"
+      exit 1
+    fi
+
+    jq ".finalImageTag = \"$tag\" | .imageDigest = \"$tag_digest\" | .sha256 = \"$new_hash\"" image.orig.json > image.json
+    rm image.fetchlog image.orig.json
+    break
+  fi
+done
+exit $?