Added in dynamic version support

Author: Patrick McCarthy

Diff for: README.md

@@ -95,6 +95,19 @@ example:
 source: "https://github.com/joeblogs/example.git"
 version: "master"
 ```
+
+## Dynamic Version support
+Once you modularize your terraform modules and begin versioning them. The consuming terrafile repo, see environments example above often requires separate PR against it just to uptake the latest version. In non prod environments you might want to bypass this by utilizing dynamic versioning.
+You can use dynamic versioning to allow auto update, so instead of just having master as the version, you can provide tf1.+, or tf1.3.+ etc... to provide more flexibility.
+When might you require more flexibility:
+Often terraform is kept in a subfolder alondside the service source code, but it will be released on a different cadence, so it should have its own independent versioning. For example you may be using semantic versioning for your service code, v1.0,0, but you want to distinguish terraform changes using a different  prefix, for example tf1.0.0 In this way you can release terraform changes separately to service code changes. If you have pure terraform modules you can then use same prefix tfx.x.x
+Terraform versioning isn't quite the same as semantic versioning for application code. 
+First digit indicates manual changes that need to be applied,
+Second digit indicates a change that could be automatically applied(you may not have automatic system yet, but still use this critieria until you do)
+Third digit is for hotpatch fixes. You have something in production but you cannot rollback, or apply all the changes  in your module since, so you branch at production version and release a patch version.
+
+
+
 
 ## Local installation, useful for Testing (python 3)
 ```shell

Diff for: terrafile/__init__.py

@@ -41,7 +41,53 @@ def add_github_token(github_download_url,token):
     return url
 
 
+def prevent_injection(input_variable):
+    if ';' in format(input_variable):
+        print("No semi colons allowed !!! input variable = {}".format(input_variables))
+        sys.exit(1) 
+
+
+def retrieve_tag_refs(l_refs, grep_version):
+    prevent_injection(grep_version)
+    remote_refs = {}
+    refs = set()
+    refs = ([t.decode('utf-8') for t in l_refs.split()])
+    grep_version = grep_version.replace('+','\d*')
+    grep_version = grep_version.replace('.','\.')
+    for ref in refs:
+        if ref is '':
+            break
+        hash_ref_list = ref.split('\t')
+        versionre = re.compile('refs/tags/({}.*$)'.format(grep_version))
+        m = versionre.match(hash_ref_list[0])
+        if m:
+            remote_refs[m.group(1)] = "found"
+            return m.group(1)
+
+    logger.info("Version {} doesn't exist in repo ".format(grep_version))
+    sys.exit(1)
+
+
+def conform_to_version_format(version, source, grep_version):
+    special_git_versions = ['master',' MASTER', 'HEAD', 'head']
+    version_prefix = "^[{}]+[\d.|\+]+[\+|-]*[\w]*$".format(grep_version)
+    if version not in special_git_versions and '+' in version:
+        pattern = re.compile("{}".format(version_prefix))
+        validVersionFormat = pattern.match(version)
+        if not validVersionFormat:
+            sys.stderr.write('version {} format isnt valid {}\n'.format(version,version_prefix))
+            sys.exit(1)
+        git_output ,returncode = run("/usr/bin/git", "ls-remote","--tags", "--sort=-v:refname", "--exit-code", "--refs", "{}".format(source))
+        if returncode != 0:
+            sys.stderr.write('problem with git ls-remote {}\n'.format(git_output))
+            sys.exit(1)
+        output = retrieve_tag_refs(git_output, version)
+        return output
+    return version
+
+
 def run(*args, **kwargs):
+    prevent_injection(args)
     proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kwargs)
     stdout, stderr = proc.communicate()
     return (stdout, proc.returncode)
@@ -149,7 +195,7 @@ def clone_remote_git( source, target, module_path, name, version):
     if 'GITHUB_TOKEN' in os.environ:
        source = self._add_github_token(source, os.getenv('GITHUB_TOKEN'))
     # Delete the old directory and clone it from scratch.
-    print('Fetching {}/{}'.format(os.path.basename(os.path.abspath(module_path)), name))
+    print('Fetching {}/{} at version {}'.format(os.path.basename(os.path.abspath(module_path)), name, version))
     shutil.rmtree(target, ignore_errors=True)
     output, returncode = run('git', 'clone', '--branch={}'.format(version), source, target)
     if returncode != 0:
@@ -176,7 +222,7 @@ def filter_modules(terrafile,found_modules):
     return remove_dups(terrafile)
 
 
-def update_modules(path, optimize_downloads):
+def update_modules(path, optimize_downloads, grep_version):
     terrafile_path = get_terrafile_path(path)
     module_path = os.path.dirname(terrafile_path)
     module_path_name = os.path.basename(os.path.abspath(module_path))
@@ -204,7 +250,7 @@ def update_modules(path, optimize_downloads):
             continue
 
         version = repository_details['version']
-
+        version = conform_to_version_format(version, source, grep_version)
         # Support Terraform Registry sources.
         if is_valid_registry_source(source):
             print('Checking {}/{}'.format(module_path_name, name))

Diff for: terrafile/__main__.py

@@ -5,6 +5,7 @@
 from terrafile import update_modules
 
 optimizedownloads = False
+versionprefix = "tf"
 if len(sys.argv) < 3:
     if len(sys.argv) < 2:
         path = os.getcwd()
@@ -14,9 +15,11 @@
     parser = argparse.ArgumentParser()
     parser.add_argument('--terrafile', required=False, default=os.getcwd(), dest='path', help='location of Terrafile')
     parser.add_argument('--optimizedownloads', required=False, default=False, dest='optimizedownloads', help='Switch on opinionated distinct module downloads')
+    parser.add_argument('--versionprefix', required=False, default="tf", dest='versionprefix', help='terraform module version prefix tf or v as in tf1.0.0 or v1.0.0')
+    
     args = parser.parse_args()
     path = args.path
     optimizedownloads = args.optimizedownloads
 
 
-update_modules(path, optimizedownloads)
+update_modules(path, optimizedownloads, versionprefix)