containers: Make config path configurable

Container configuration directory can be set in the .env file which is
automatically used by docker-compose.  The default value is the one used
previously (containers/config).
The HACKING.md guide is updated to describe how to set this and how it
affects other commands.

HACKING.md

@@ -52,20 +52,37 @@ containers. Building and starting containers is generally faster than building
 RPMs and installing them in a VM, so this method is more convenient for
 developing and testing changes quickly.
 
+### Configuration
+
 Each service (*composer* and *worker*) requires a configuration file and a set
-of certificates. Use the [`tools/gen-certs.sh`](./tools/gen-certs.sh) script to
+of certificates. The storage location for these is shared between the
+containers for simplicity. By default it's configured to be at
+`./containers/config`, but this can be changed in the
+[`./distribution/.env`](./distribution/.env) file by modifying the value of the
+`$CONTAIN£R_CONFIG_DIR` variable (both absolute and relative paths work).
+
+Use the [`tools/gen-certs.sh`](./tools/gen-certs.sh) script to
 generate the certificates (using the test OpenSSL config file):
 
     ./tools/gen-certs.sh ./test/data/x509/openssl.cnf ./containers/config  ./containers/config/ca
 
-The services also require a config file (each) which they expect to be in the
+Note that the two arguments `./containers/config` and `./containers/config/ca`
+should be the same location as the `$CONTAINER_CONFIG_DIR` described above
+
+The services also require a config file each which they expect to be in the
 same directory. The following test files can be copied into it:
 
     cp ./test/data/composer/osbuild-composer.toml ./test/data/composer/osbuild-worker.toml ./containers/config/
 
-The `containers/config` directory will be mounted inside both containers (see
+The `$CONTAINER_CONFIG_DIR` (default `containers/config`) directory will be mounted inside both containers (see
 the [`docker-composer.yml`](./distribution/docker-compose.yml) file).
 
+### Build and run
+
+To build the containers, change into the `distribution/` directory and run:
+
+    docker-compose build
+
 To start the containers, change into the `distribution/` directory and run:
 
     docker-compose up

distribution/.env

@@ -1 +1,2 @@
 COMPOSE_PROJECT_NAME=osbuild
+CONTAINER_CONFIG_DIR=../containers/config

distribution/docker-compose.yml

@@ -6,7 +6,7 @@ services:
       context: ..
       dockerfile: ./distribution/Dockerfile-ubi
     volumes:
-      - ../containers/config:/etc/osbuild-composer
+      - ${CONTAINER_CONFIG_DIR}/:/etc/osbuild-composer
     networks:
       net:
         ipv4_address: 172.30.0.10
@@ -18,7 +18,7 @@ services:
     # override the entrypoint to specify composer hostname and port
     entrypoint: /usr/libexec/osbuild-composer/osbuild-worker composer:8700
     volumes:
-      - ../containers/config:/etc/osbuild-composer
+      - ${CONTAINER_CONFIG_DIR}/:/etc/osbuild-composer
     environment:
       - CACHE_DIRECTORY=/var/cache/osbuild-worker
     privileged: true