Merge ~hloeung/charm-k8s-content-cache:non-charm into charm-k8s-content-cache:master

[Haw Loeung]

Non-charm related changes

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Tom Haddon (mthaddon)]

This LGTM, but can we also change the metadata.yaml from "name: charm-k8s-content-cache" to "name: content-cache". This is used by charmcraft build to determine the name of the file to build, and this also makes it consistent with our other k8s charms.

Feel free to merge with that change.

review: Approve

[Tom Haddon (mthaddon)]

Lgtm, thx

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change must be approved by a member of one of the following teams:
Setting status to needs review.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 307ffcb581de26b080df940a37712801f7001e96

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9759e36
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,8 @@
+*~
+*.charm
+*.py[cod]
+*.swp
+.coverage
+.tox/
+build/
+__pycache__/
diff --git a/.jujuignore b/.jujuignore
index 6ccd559..4365792 100644
--- a/.jujuignore
+++ b/.jujuignore
@@ -1,3 +1,13 @@
-/venv
-*.py[cod]
+/venv/
+*~
 *.charm
+*.py[cod]
+*.swp
+.coverage
+.gitignore
+.tox/
+Makefile
+build/
+docker/
+tests/
+__pycache__/
diff --git a/COPYRIGHT b/COPYRIGHT
new file mode 100644
index 0000000..1889423
--- /dev/null
+++ b/COPYRIGHT
@@ -0,0 +1,16 @@
+Format: http://dep.debian.net/deps/dep5/
+
+Files: *
+Copyright: Copyright 2020, Canonical Ltd.
+License: GPL-3
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License version 3, as
+ published by the Free Software Foundation.
+ .
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranties of
+ MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
+ PURPOSE.  See the GNU General Public License for more details.
+ .
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..af2c5d1
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,24 @@
+# Copyright (C) 2020 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+lint:
+	@echo "Normalising python layout with black."
+	@tox -e black
+	@echo "Running flake8"
+	@tox -e lint
+
+# We actually use the build directory created by charmcraft,
+# but the .charm file makes a much more convenient sentinel.
+unittest: content-cache.charm
+	@tox -e unit
+
+test: lint unittest
+
+clean:
+	@echo "Cleaning files"
+	@git clean -fXd
+
+content-cache.charm: src/*.py requirements.txt
+	charmcraft build
+
+.PHONY: lint test unittest clean
diff --git a/README.md b/README.md
index aabaf43..aaaae75 100644
--- a/README.md
+++ b/README.md
@@ -2,27 +2,37 @@
 
 ## Description
 
-TODO: fill out the description
+Deploy content caching layer into K8s.
 
 ## Usage
 
-TODO: explain how to use the charm
+Build the docker image:
+
+    `cd docker`
+    `docker build . -t myimage:v<revision>`
+    `docker tag myimage:v<revision> localhost:32000/myimage:v<revision>`
+    `docker push localhost:32000/myimage:v<revision>`
+
+Build the charm:
+
+    `charmcraft build`
+
+Deploy:
+
+    `juju deploy ./content-cache.charm --config image_path=localhost:32000/myimage:v<revision> --config site=mysite.local --config backend=http://mybackend.local:80`
+
+### Test Deployment
+
+`curl --resolve mysite.local:80:<ingress IP> http://mysite.local`
 
 ### Scale Out Usage
 
-...
+Just run `juju add-unit <application name>`.
 
 ## Developing
 
-Create and activate a virtualenv,
-and install the development requirements,
-
-    virtualenv -p python3 venv
-    source venv/bin/activate
-    pip install -r requirements-dev.txt
+Just run `make lint`.
 
 ## Testing
 
-Just run `run_tests`:
-
-    ./run_tests
+Just run `make unittest`.
diff --git a/docker/Dockerfile b/docker/Dockerfile
new file mode 100644
index 0000000..7f89b21
--- /dev/null
+++ b/docker/Dockerfile
@@ -0,0 +1,27 @@
+# Copyright (C) 2020 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+FROM ubuntu:latest
+
+ENV LANG C.UTF-8
+ENV DEBIAN_FRONTEND noninteractive
+
+# Don't install recommends to keep image small and avoid nasty surprises
+# e.g. rpcbind being pulled in by nrpe.
+RUN apt-get -qy update && \
+    apt-get -qy dist-upgrade --no-install-recommends && \
+    apt-get -qy install --no-install-recommends nginx-light && \
+    apt-get -qy clean && \
+    rm -f /var/lib/apt/lists/*_*
+
+RUN mkdir -p /srv/content-cache
+
+COPY entrypoint.sh /srv/content-cache
+COPY files /srv/content-cache/files/
+COPY templates /srv/content-cache/templates/
+
+ENTRYPOINT ["/srv/content-cache/entrypoint.sh"]
+
+CMD ["nginx", "-g", "daemon off;"]
+
+EXPOSE 80
diff --git a/docker/entrypoint.sh b/docker/entrypoint.sh
new file mode 100755
index 0000000..1f3fb10
--- /dev/null
+++ b/docker/entrypoint.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+# Copyright (C) 2020 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+set -eu
+
+# https://pempek.net/articles/2013/07/08/bash-sh-as-template-engine/
+render_template() {
+    eval "echo \"$(cat "$1")\""
+}
+
+cp /srv/content-cache/files/nginx-logging-format.conf /etc/nginx/conf.d/nginx-logging-format.conf
+
+# https://bugs.launchpad.net/juju/+bug/1894782
+JUJU_UNIT=$(basename /var/lib/juju/tools/unit-* | sed -e 's/^unit-//' -e 's/-\([0-9]\+\)$/\/\1/')
+export JUJU_UNIT
+
+render_template /srv/content-cache/templates/nginx_cfg.tmpl > /etc/nginx/sites-available/default
+
+# Run the real command
+exec "$@"
diff --git a/docker/files/nginx-logging-format.conf b/docker/files/nginx-logging-format.conf
new file mode 100644
index 0000000..8591b3e
--- /dev/null
+++ b/docker/files/nginx-logging-format.conf
@@ -0,0 +1,4 @@
+log_format content_cache '$http_x_forwarded_for - $remote_user [$time_local] '
+                         '"$request" $status $bytes_sent '
+                         '"$http_referer" "$http_user_agent" $request_time '
+                         '$upstream_cache_status $upstream_response_time';
diff --git a/docker/templates/nginx_cfg.tmpl b/docker/templates/nginx_cfg.tmpl
new file mode 100644
index 0000000..4e1ceb3
--- /dev/null
+++ b/docker/templates/nginx_cfg.tmpl
@@ -0,0 +1,32 @@
+proxy_cache_path ${NGINX_CACHE_PATH} use_temp_path=off levels=1:2 keys_zone=${NGINX_KEYS_ZONE}:10m inactive=${NGINX_CACHE_INACTIVE_TIME} max_size=${NGINX_CACHE_MAX_SIZE};
+
+server {
+    server_name ${NGINX_SITE_NAME};
+    listen *:80;
+
+    client_max_body_size ${NGINX_CLIENT_MAX_BODY_SIZE};
+
+    port_in_redirect off;
+    absolute_redirect off;
+
+    location / {
+        proxy_pass \"${NGINX_BACKEND}\";
+        proxy_set_header Host \"${NGINX_SITE_NAME}\";
+        # Removed the following headers to avoid cache poisoning.
+        proxy_set_header Forwarded \"\";
+        proxy_set_header X-Forwarded-Host \"\";
+        proxy_set_header X-Forwarded-Port \"\";
+        proxy_set_header X-Forwarded-Proto \"\";
+        proxy_set_header X-Forwarded-Scheme \"\";
+
+        add_header X-Cache-Status \"\$upstream_cache_status from ${JUJU_NODE_NAME} (${JUJU_POD_NAME})\";
+
+        proxy_force_ranges on;
+        proxy_cache ${NGINX_KEYS_ZONE};
+        proxy_cache_use_stale ${NGINX_CACHE_USE_STALE};
+        proxy_cache_valid ${NGINX_CACHE_VALID};
+    }
+
+    access_log /dev/stdout content_cache;
+    error_log /dev/stdout info;
+}
diff --git a/metadata.yaml b/metadata.yaml
index 2874a21..dacd17e 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -1,4 +1,4 @@
-name: charm-k8s-content-cache
+name: content-cache
 description: |
   Useful for providing local mirrors of HTTP servers and building
   content delivery networks (CDN).
diff --git a/tests/requirements.txt b/tests/requirements.txt
new file mode 100644
index 0000000..f6c26b8
--- /dev/null
+++ b/tests/requirements.txt
@@ -0,0 +1,4 @@
+freezegun
+mock
+pytest
+pytest-cov
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..2daecb5
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,37 @@
+[tox]
+skipsdist=True
+envlist = unit
+skip_missing_interpreters = True
+
+[testenv]
+basepython = python3
+setenv =
+  PYTHONPATH = {toxinidir}/src:{toxinidir}/build/lib:{toxinidir}/build/venv
+
+[testenv:unit]
+commands =
+    pytest \
+      {posargs:-v  --cov=src --cov-report=term-missing --cov-branch}
+deps = -r{toxinidir}/tests/requirements.txt
+       -r{toxinidir}/requirements.txt
+setenv =
+  PYTHONPATH={toxinidir}/src:{toxinidir}/build/lib:{toxinidir}/build/venv
+  TZ=UTC
+
+[testenv:black]
+commands = black --skip-string-normalization --line-length=120 src/ tests/
+deps = black
+
+[testenv:lint]
+commands = flake8 src/ tests/
+# Pin flake8 to 3.7.9 to match focal
+deps =
+    flake8==3.7.9
+
+[flake8]
+exclude =
+    .git,
+    __pycache__,
+    .tox,
+max-line-length = 120
+max-complexity = 10