Support env expansion and pre/post build scripts (#17)

* Initial changes to dockerutils to support env expansion and also pre/post build scripts

* Fixed a couple of little items in the build-image command

* Added the changes requested on the PR

.gitignore

@@ -10,3 +10,4 @@ build
 activate
 .coverage
 .pytest_cache
+.venv

README.md

@@ -77,6 +77,8 @@ docker directory tree. Each of these sections may contain one of the following:
 * `pull_FROM_on_force` - defaults to False, if True, add --pull to build command when force building image (or base image)
 * `image_repo` - the repository to publish the image to
 * `publication_tag` - the tag for publication (full image name + tag) 
+* `pre_build_script` - A shell command or script to run before a docker build is issued
+* `post_build_script` - A shell command or script to run after a docker build has been compeleted (successfully)
 
 ### Synthetic Images
 Additionally, "synthetic" images can be specified by adding a `run-image` section with a `synthetic_images` definition
@@ -102,14 +104,19 @@ tag=experiment.2017.12.16
 ...
 ```
 ### Volume Replacement Variables
-The volume specification may contain replacement variable designations of the form `{var}`. The supported variables
-include:
+
+The volume specification may contain either environment variables (`$name` and `${name}` formats) as well as specific
+variable replacement designations of the form `{var}`.  The supported variables include:
 
 * `project_root` - will be replaced with the root directory name of the project
 * `user` - will be replaced with the user name of the user running the command
 * `project` - replace with project namge
 
 ### Image Push Replacement Variables
+
+The `publication_tag` may contain either environment variables (`$name` and `${name}` formats) as well as specific
+variable replacement designations of the form `{var}`.  The supported variables include:
+
 * `account` - AWS account designation
 * `region` - AWS region
 * `image` - Image name

scripts/build-image

@@ -16,7 +16,26 @@ def is_multistage(mode):
     return 'as builder' in open(f'docker/{mode}/Dockerfile').read()
 
 
-def build(image, image_name, image_tag, pull=False):
+def run_pre_script(script: str, config: dict) -> int:
+    print(f'Running pre-build-script: "{script}"')
+    return subprocess.call(shlex.split(script), cwd=os.getcwd())
+
+
+def run_post_script(script: str, config: dict) -> int:
+    print(f'Running post-build-script: "{script}"')
+    return subprocess.call(shlex.split(script), cwd=os.getcwd())
+
+
+def build(image, image_name, image_tag, config={}, pull=False):
+    pre_script = config.get('pre_build_script', None)
+    post_script = config.get('post_build_script', None)
+
+    if pre_script:
+        rc = run_pre_script(pre_script, config=config)
+        if rc != 0:
+            print(f'pre-build-script failed: {rc}')
+            return rc
+
     rc = 0
     pull_base = ''
     if pull:
@@ -30,6 +49,14 @@ def build(image, image_name, image_tag, pull=False):
     if not rc:
         rc = image_operation(f'docker build {pull_base} --compress -t {image_name}:{image_tag} '
                              f'-f docker/{image}/Dockerfile .')
+
+    if rc != 0:
+        print(f'docker build failed: {rc}')
+        return rc
+
+    if post_script:
+        rc = run_post_script(post_script, config=config)
+
     return rc
 
 
@@ -92,11 +119,13 @@ if __name__ == '__main__':
                     image_tag = args.image_tag
 
                 pull_FROM_on_force = False
+                image_config = {}
                 if image in config.sections():
-                    if 'pull_FROM_on_force' in config[image]:
+                    image_config = config[image]
+                    if 'pull_FROM_on_force' in image_config:
                         pull_FROM_on_force = config[image]['pull_FROM_on_force']
 
-                rc = fn(image, image_name, image_tag, args.pull_base or (args.force_build_base and pull_FROM_on_force))
+                rc = fn(image, image_name, image_tag, config=image_config, pull=args.pull_base or (args.force_build_base and pull_FROM_on_force))
                 # because an image may not be present on the clean, ignore a non-zero return code
                 if rc and not args.image == 'clean':
                     sys.exit(rc)

scripts/publish-image

@@ -87,6 +87,7 @@ if __name__ == '__main__':
                 tag=image_tag,
                 user=getpass.getuser()
             )
+            publication_tag = os.path.expandvars(publication_tag)
             ecr_client = boto3.client('ecr')
             auth_data = ecr_client.get_authorization_token()
             user, password = base64.b64decode(auth_data['authorizationData'][0]['authorizationToken']).decode().split(
@@ -103,6 +104,7 @@ if __name__ == '__main__':
                 tag=image_tag,
                 user=getpass.getuser()
             )
+            publication_tag = os.path.expandvars(publication_tag)
             # TODO: should we pick up user and password for docker.com? Maybe via credstash?
             rc = docker_login_dockerhub()
 

scripts/run-image

@@ -45,6 +45,8 @@ def run(mode, image_name, image_tag, **kwargs):
         user=user,
         project=os.path.split(get_root_dir())[1]
     )
+    volumes = os.path.expandvars(volumes)
+
     if kwargs['network']:
         kwargs['network'] = f"--network {kwargs['network']}"