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/user/run.sh

@@ -6,25 +6,25 @@ cd $(dirname $0)
 . ../util.sh
 current_test=$(basename $(pwd))
 
-docker compose up -d --quiet-pull
+export LOCAL_DIR=$(mktemp -d)
+export TMP_DIR=$(mktemp -d)
 
+echo "LOCAL_DIR $LOCAL_DIR"
+echo "TMP_DIR $TMP_DIR"
+
+docker compose up -d --quiet-pull
 user_name=testuser
 docker exec user-alpine-1 adduser --disabled-password "$user_name"
 
 docker compose exec backup backup
 
-tar -xvf ./local/test.tar.gz
-if [ ! -f ./backup/data/whoami.txt ]; then
+tar -xvf "$LOCAL_DIR/test.tar.gz" -C "$TMP_DIR"
+if [ ! -f "$TMP_DIR/backup/data/whoami.txt" ]; then
   fail "Could not find file written by pre command."
 fi
 pass "Found expected file."
 
-tar -xvf ./local/test.tar.gz
-if [ "$(cat ./backup/data/whoami.txt)" != "$user_name" ]; then
+if [ "$(cat $TMP_DIR/backup/data/whoami.txt)" != "$user_name" ]; then
   fail "Could not find expected user name."
 fi
 pass "Found expected user."
-
-docker compose down --volumes
-sudo rm -rf ./local
-