Handle missing binary errors (resolves #262) (#263)

Signed-off-by: Simon Stone <sstone1@uk.ibm.com>

plugins/module_utils/module.py

@@ -4,6 +4,11 @@
 #
 
 from ansible.module_utils.basic import AnsibleModule, missing_required_lib
+from ansible.module_utils._text import to_native
+
+import os
+import platform
+import subprocess
 
 HFC_IMPORT_ERR = None
 try:
@@ -22,15 +27,39 @@
     CRYPTOGRAPHY_IMPORT_ERR = str(e)
 
 
+def missing_required_bin(binary, reason=None, url=None):
+    hostname = platform.node()
+    msg = "Failed to execute the required binary (%s) on %s." % (binary, hostname)
+    if reason:
+        msg += " This is required %s." % reason
+    if url:
+        msg += " See %s for more info." % url
+
+    msg += (" Please read module documentation and install in the appropriate location."
+            " If the required binary is installed, then the install directory may not be present in the PATH environment variable (%s)." % os.environ['PATH'])
+    return msg
+
+
 class BlockchainModule(AnsibleModule):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.check_for_missing_libs()
+        self.check_for_missing_bins()
 
     def check_for_missing_libs(self):
         url = 'https://ibm-blockchain.github.io/ansible-collection/installation.html#requirements'
         if not HAS_HFC:
             self.fail_json(msg=missing_required_lib("fabric-sdk-py", url=url), exception=HFC_IMPORT_ERR)
         if not HAS_CRYPTOGRAPHY:
             self.fail_json(msg=missing_required_lib("cryptography", url=url), exception=CRYPTOGRAPHY_IMPORT_ERR)
+
+    def check_for_missing_bins(self):
+        url = 'https://ibm-blockchain.github.io/ansible-collection/installation.html#requirements'
+        for binary in ['peer', 'configtxlator']:
+            try:
+                process = subprocess.run([binary, 'version'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE, text=True, close_fds=True)
+            except Exception as e:
+                self.fail_json(msg=missing_required_bin(binary, url=url), exception=to_native(e), cmd=f'{binary} version')
+            if process.returncode != 0:
+                self.fail_json(msg=missing_required_bin(binary, url=url), rc=process.returncode, stdout=process.stdout, stderr=process.stderr, cmd=f'{binary} version')