Call conda more resiliently

tljh/conda.py

@@ -4,6 +4,10 @@ Wrap conda commandline program
 import os
 import subprocess
 import json
+import sys
+
+# Use sys.executable to call conda to avoid needing to fudge PATH
+CONDA_EXECUTABLE = [sys.executable, '-m', 'conda']
 
 
 def ensure_conda_env(prefix):
@@ -13,7 +17,7 @@ def ensure_conda_env(prefix):
     abspath = os.path.abspath(prefix)
     try:
         output = json.loads(
-            subprocess.check_output(['conda', 'create', '--json', '--prefix', abspath]).decode()
+            subprocess.check_output(CONDA_EXECUTABLE + ['create', '--json', '--prefix', abspath]).decode()
         )
     except subprocess.CalledProcessError as e:
         output = json.loads(e.output.decode())
@@ -31,8 +35,8 @@ def ensure_conda_packages(prefix, packages):
     abspath = os.path.abspath(prefix)
     # Let subprocess errors propagate
     # FIXME: raise different exception when using
-    raw_output = subprocess.check_output([
-        'conda', 'install',
+    raw_output = subprocess.check_output(CONDA_EXECUTABLE + [
+        'install',
         '--json',
         '--prefix', abspath
     ] + packages).decode()

tljh/systemd.py

@@ -0,0 +1,59 @@
+"""
+Wraps systemctl to install, uninstall, start & stop systemd services.
+
+We use sudo + subprocess calls for everything. This works when we
+are running as root & as normal user (with arbitrary sudo privileges).
+Arbitrary sudo privileges suck, but are better than running the whole
+process as root.
+
+If we use a debian package instead, we can get rid of all this code.
+"""
+import subprocess
+import os
+
+
+def reload_daemon():
+    """
+    Equivalent to systemctl daemon-reload.
+
+    Makes systemd discover new units.
+    """
+    subprocess.run([
+        'sudo',
+        'systemctl',
+        'daemon-reload'
+    ], check=True)
+
+
+def install_unit(name, unit, path='/etc/systemd/system'):
+    """
+    Install unit wih given name
+    """
+    subprocess.run([
+        'sudo',
+        'tee',
+        os.path.join(path, name)
+    ], input=unit.encode('utf-8'), check=True)
+
+
+def uninstall_unit(name, path='/etc/systemd/system'):
+    """
+    Uninstall unit with given name
+    """
+    subprocess.run([
+        'sudo',
+        'rm',
+        os.path.join(path, name)
+    ], check=True)
+
+
+def start_service(name):
+    """
+    Start service with given name.
+    """
+    subprocess.run([
+        'sudo',
+        'systemctl',
+        'start',
+        name
+    ], check=True)