Run tests Docker in Docker (#261)

* Try running tests in Docker

* Spawn new container for each test

* Store test artifacts outside of mount

* When requested, build up to date image in test script

* sudo is unneccessary in containerized test env

* Skip azure test

* Backdate fixture file in JSON database

* Pin versions for azure tools

* Mount temp volume for /var/lib/docker to prevent dangling ones created by VOLUME instruction

* Fail backdating tests with message

* Add some documentation on test setup

* Cache images

* Run compose stacks with shortened default timeout

test/confd/.gitignore

@@ -1 +0,0 @@
-local

test/confd/docker-compose.yml

@@ -5,7 +5,7 @@ services:
     image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     restart: always
     volumes:
-      - ./local:/archive
+      - ${LOCAL_DIR:-./local}:/archive
       - app_data:/backup/app_data:ro
       - ./01backup.env:/etc/dockervolumebackup/conf.d/01backup.env
       - ./02backup.env:/etc/dockervolumebackup/conf.d/02backup.env

test/confd/run.sh

@@ -6,26 +6,24 @@ cd $(dirname $0)
 . ../util.sh
 current_test=$(basename $(pwd))
 
-mkdir -p local
+export LOCAL_DIR=$(mktemp -d)
 
 docker compose up -d --quiet-pull
 
 # sleep until a backup is guaranteed to have happened on the 1 minute schedule
 sleep 100
 
-docker compose down --volumes
-
-if [ ! -f ./local/conf.tar.gz ]; then
+if [ ! -f "$LOCAL_DIR/conf.tar.gz" ]; then
   fail "Config from file was not used."
 fi
 pass "Config from file was used."
 
-if [ ! -f ./local/other.tar.gz ]; then
+if [ ! -f "$LOCAL_DIR/other.tar.gz" ]; then
   fail "Run on same schedule did not succeed."
 fi
 pass "Run on same schedule succeeded."
 
-if [ -f ./local/never.tar.gz ]; then
+if [ -f "$LOCAL_DIR/never.tar.gz" ]; then
   fail "Unexpected file was found."
 fi
 pass "Unexpected cron did not run."