From 99b1b0669d16d857e203201f536f8784da7cb325 Mon Sep 17 00:00:00 2001
From: Manuel Kaufmann <humitos@gmail.com>
Date: Tue, 3 Dec 2024 11:17:50 +0100
Subject: [PATCH 1/3] Development: use `--build-arg` to invalidate cache

Create a hash of all the dependencies files and use it as a `--build-arg` to
invalidate the cache when the hash changes.

Related https://github.com/readthedocs/common/pull/241
---
 dockerfiles/tasks.py | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/dockerfiles/tasks.py b/dockerfiles/tasks.py
index e4b7048..ad480f5 100644
--- a/dockerfiles/tasks.py
+++ b/dockerfiles/tasks.py
@@ -1,5 +1,6 @@
 import os
 import sys
+import hashlib
 
 from invoke import task
 
@@ -14,8 +15,32 @@
 })
 def build(c, cache=False):
     """Build docker image for servers."""
-    cache_opt = '' if cache else '--no-cache'
-    c.run(f'{DOCKER_COMPOSE_COMMAND} build {cache_opt}', pty=True)
+    cache_opt = '--no-cache'
+    cache_hash = ""
+    build_arg = ""
+    if cache:
+        cache_opt = ""
+        files_to_cache = [
+            # Community
+            "requirements/docker.txt",
+
+            # Corporate
+            "../readthedocs.org/requirements/docker.txt",
+            "setup.cfg",
+
+            # Both
+            "../ext-theme/setup.cfg",
+            "../readthedocs-ext/setup.cfg",
+        ]
+
+        for f in files_to_cache:
+            if os.path.exists(f):
+                cache_hash += hashlib.md5(open(f, mode="rb").read()).hexdigest()
+
+    if cache_hash:
+        build_arg = f"--build-arg PRUNE_PACKAGE_CACHE={cache_hash}"
+
+    c.run(f'{DOCKER_COMPOSE_COMMAND} build {cache_opt} {build_arg}', echo=True, pty=True)
 
 @task(help={
     'command': 'Command to pass directly to "docker compose"',

From ff89487e0dc8d2223d2ef9b91e1092bee596220e Mon Sep 17 00:00:00 2001
From: Manuel Kaufmann <humitos@gmail.com>
Date: Wed, 4 Dec 2024 15:34:56 +0100
Subject: [PATCH 2/3] Update the cache hash instead of appending each of them

---
 dockerfiles/tasks.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/dockerfiles/tasks.py b/dockerfiles/tasks.py
index ad480f5..5dcaf0e 100644
--- a/dockerfiles/tasks.py
+++ b/dockerfiles/tasks.py
@@ -16,7 +16,6 @@
 def build(c, cache=False):
     """Build docker image for servers."""
     cache_opt = '--no-cache'
-    cache_hash = ""
     build_arg = ""
     if cache:
         cache_opt = ""
@@ -33,12 +32,12 @@ def build(c, cache=False):
             "../readthedocs-ext/setup.cfg",
         ]
 
+        cache_hash = hashlib.md5()
         for f in files_to_cache:
             if os.path.exists(f):
-                cache_hash += hashlib.md5(open(f, mode="rb").read()).hexdigest()
-
-    if cache_hash:
-        build_arg = f"--build-arg PRUNE_PACKAGE_CACHE={cache_hash}"
+                cache_hash.update(open(f, mode="rb").read())
+        cache_hash = cache_hash.hexdigest()
+        build_arg = f"--build-arg PRUNE_PYTHON_PACKAGE_CACHE={cache_hash}"
 
     c.run(f'{DOCKER_COMPOSE_COMMAND} build {cache_opt} {build_arg}', echo=True, pty=True)
 

From b8fc02084a4902d097ed0ad136c742232f002d89 Mon Sep 17 00:00:00 2001
From: Manuel Kaufmann <humitos@gmail.com>
Date: Wed, 4 Dec 2024 15:35:15 +0100
Subject: [PATCH 3/3] Accept `PRUNE_PYTHON_PACKAGE_CACHE` as an environment
 variable

---
 dockerfiles/docker-compose.yml |  2 ++
 dockerfiles/tasks.py           | 11 +++++------
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/dockerfiles/docker-compose.yml b/dockerfiles/docker-compose.yml
index 8695b12..3f2d6c2 100644
--- a/dockerfiles/docker-compose.yml
+++ b/dockerfiles/docker-compose.yml
@@ -11,6 +11,8 @@ services:
     build:
       context: ${PWD}
       dockerfile: ${PWD}/dockerfiles/Dockerfile
+      args:
+        PRUNE_PYTHON_PACKAGE_CACHE: ${PRUNE_PYTHON_PACKAGE_CACHE:-0}
 
   nginx:
     stop_grace_period: 1s
diff --git a/dockerfiles/tasks.py b/dockerfiles/tasks.py
index 5dcaf0e..e61f54c 100644
--- a/dockerfiles/tasks.py
+++ b/dockerfiles/tasks.py
@@ -15,10 +15,9 @@
 })
 def build(c, cache=False):
     """Build docker image for servers."""
-    cache_opt = '--no-cache'
-    build_arg = ""
-    if cache:
-        cache_opt = ""
+    cache_opt = '--no-cache' if not cache else ""
+    cache_env_var = ""
+    if cache and not os.environ.get("PRUNE_PYTHON_PACKAGE_CACHE"):
         files_to_cache = [
             # Community
             "requirements/docker.txt",
@@ -37,9 +36,9 @@ def build(c, cache=False):
             if os.path.exists(f):
                 cache_hash.update(open(f, mode="rb").read())
         cache_hash = cache_hash.hexdigest()
-        build_arg = f"--build-arg PRUNE_PYTHON_PACKAGE_CACHE={cache_hash}"
+        cache_env_var = f"PRUNE_PYTHON_PACKAGE_CACHE={cache_hash}"
 
-    c.run(f'{DOCKER_COMPOSE_COMMAND} build {cache_opt} {build_arg}', echo=True, pty=True)
+    c.run(f'{cache_env_var} {DOCKER_COMPOSE_COMMAND} build {cache_opt}', echo=True, pty=True)
 
 @task(help={
     'command': 'Command to pass directly to "docker compose"',