Add support for LUCI_CONTEXT.

recipe_engine/step_runner.py

Index: recipe_engine/step_runner.py
diff --git a/recipe_engine/step_runner.py b/recipe_engine/step_runner.py
index 380eeb4421fbe8c918d41942a5bc18c7d9a29664..fb432df2f28c893e8b24075417b4d20ea38cdda5 100644
--- a/recipe_engine/step_runner.py
+++ b/recipe_engine/step_runner.py
@@ -23,6 +23,8 @@ from . import stream
 from . import types
 from . import util
 
+from libs import luci_context as luci_ctx
+
 import subprocess42
 
 
@@ -211,7 +213,8 @@ class SubprocessStepRunner(StepRunner):
           # The subprocess will inherit and close these handles.
           retcode = self._run_cmd(
               cmd=step_config.cmd, timeout=step_config.timeout, handles=handles,
-              env=step_env, cwd=step_config.cwd)
+              env=step_env, luci_context=rendered_step.config.luci_context,
+              cwd=step_config.cwd)
         except subprocess42.TimeoutExpired as e:
           #FIXME: Make this respect the infra_step argument
           step_stream.set_step_status('FAILURE')
@@ -307,7 +310,7 @@ class SubprocessStepRunner(StepRunner):
       yield ''
     stream.output_iter(step_stream, gen_step_prelude())
 
-  def _run_cmd(self, cmd, timeout, handles, env, cwd):
+  def _run_cmd(self, cmd, timeout, handles, env, luci_context, cwd):
     """Runs cmd (subprocess-style).
 
     Args:
@@ -315,6 +318,7 @@ class SubprocessStepRunner(StepRunner):
       handles: A dictionary from ('stdin', 'stdout', 'stderr'), each value
         being *either* a stream.StreamEngine.Stream or a python file object
         to direct that subprocess's filehandle to.
+      luci_context: full value of LUCI_CONTEXT dict.

[iannucci, 2017/08/04 18:55:50]

Maybe "entire intended value of the LUCI_CONTEXT dict for this step. e.g. if
this is empty, then the step will be run without any LUCI_CONTEXT parameters at
all"

       env: the full environment to run the command in -- this is passed
         unaltered to subprocess.Popen.
       cwd: the working directory of the command.
@@ -333,47 +337,52 @@ class SubprocessStepRunner(StepRunner):
     # stdin must be a real handle, if it exists
     fhandles['stdin'] = handles.get('stdin')
 
-    with _modify_lookup_path(env.get('PATH')):
-      proc = subprocess42.Popen(
-          cmd,
-          env=env,
-          cwd=cwd,
-          detached=True,
-          universal_newlines=True,
-          **fhandles)
-
-    # Safe to close file handles now that subprocess has inherited them.
-    for handle in fhandles.itervalues():
-      if isinstance(handle, file):
-        handle.close()
-
-    outstreams = {}
-    linebufs = {}
-
-    for key in ('stdout', 'stderr'):
-      handle = handles.get(key)
-      if isinstance(handle, stream.StreamEngine.Stream):
-        outstreams[key] = handle
-        linebufs[key] = _streamingLinebuf()
-
-    if linebufs:
-      # manually check the timeout, because we poll
-      start_time = time.time()
-      for pipe, data in proc.yield_any(timeout=1):
-        if timeout and time.time() - start_time > timeout:
-          # Don't know the name of the step, so raise this and it'll get caught
-          raise subprocess42.TimeoutExpired(cmd, timeout)
-
-        if pipe is None:
-          continue
-        buf = linebufs.get(pipe)
-        if not buf:
-          continue
-        buf.ingest(data)
-        for line in buf.get_buffered():
-          outstreams[pipe].write_line(line)
-    else:
-      proc.wait(timeout)
+    with luci_ctx.replace(luci_context) as path:

[Vadim Sh., 2017/07/29 00:40:55]

no changes here except lines 340-343
Rietveld is too dumb to realize.

+      if path:

[iannucci, 2017/08/04 18:55:50]

nit: I would rename path to luci_ctx_path or something, since this with
statement holds a bunch of lines where 'path' may be ambiguous

+        env = env.copy()
+        env['LUCI_CONTEXT'] = path
+
+      with _modify_lookup_path(env.get('PATH')):
+        proc = subprocess42.Popen(
+            cmd,
+            env=env,
+            cwd=cwd,
+            detached=True,
+            universal_newlines=True,
+            **fhandles)
+
+      # Safe to close file handles now that subprocess has inherited them.
+      for handle in fhandles.itervalues():
+        if isinstance(handle, file):
+          handle.close()
+
+      outstreams = {}
+      linebufs = {}
+
+      for key in ('stdout', 'stderr'):
+        handle = handles.get(key)
+        if isinstance(handle, stream.StreamEngine.Stream):
+          outstreams[key] = handle
+          linebufs[key] = _streamingLinebuf()
+
+      if linebufs:
+        # manually check the timeout, because we poll
+        start_time = time.time()
+        for pipe, data in proc.yield_any(timeout=1):
+          if timeout and time.time() - start_time > timeout:
+            # Don't know the name of the step, so raise this and it'll get caught
+            raise subprocess42.TimeoutExpired(cmd, timeout)
+
+          if pipe is None:
+            continue
+          buf = linebufs.get(pipe)
+          if not buf:
+            continue
+          buf.ingest(data)
+          for line in buf.get_buffered():
+            outstreams[pipe].write_line(line)
+      else:
+        proc.wait(timeout)
 
     return proc.returncode