Docker command runner hangs

[Eric-Arellano]

To reproduce, apply this diff:

diff --git a/src/python/pants/backend/project_info/count_loc.py b/src/python/pants/backend/project_info/count_loc.py
index 9c45298b32..403d972988 100644
--- a/src/python/pants/backend/project_info/count_loc.py
+++ b/src/python/pants/backend/project_info/count_loc.py
@@ -7,6 +7,7 @@ from pants.core.util_rules.external_tool import (
     TemplatedExternalTool,
 )
 from pants.engine.console import Console
+from pants.engine.environment import EnvironmentName
 from pants.engine.fs import Digest, MergeDigests, PathGlobs, SpecsPaths
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.platform import Platform
@@ -79,12 +80,16 @@ async def count_loc(
     input_digest = await Get(Digest, MergeDigests((scc_program.digest, specs_digest)))
     result = await Get(
         ProcessResult,
-        Process(
-            argv=(scc_program.exe, *succinct_code_counter.args),
-            input_digest=input_digest,
-            description=f"Count lines of code for {pluralize(len(specs_paths.files), 'file')}",
-            level=LogLevel.DEBUG,
-        ),
+        {
+            Process(
+                argv=(scc_program.exe, *succinct_code_counter.args),
+                input_digest=input_digest,
+                description=f"Count lines of code for {pluralize(len(specs_paths.files), 'file')}",
+                level=LogLevel.DEBUG,
+            ): Process,
+            EnvironmentName("docker"): EnvironmentName,
+            # EnvironmentName("default_env"): EnvironmentName,
+        },
     )
     console.print_stdout(result.stdout.decode())
     return CountLinesOfCode(exit_code=0)

Then run:

❯ ./pants count-loc build-support/
14:29:43.64 [INFO] Initializing scheduler...
14:29:44.33 [INFO] Scheduler initialized.
⠉ 5.42s Count lines of code for 5 files

[Eric-Arellano]

@tdyas and I figured this out. My Docker was acting up and docker pull was failing with this directly on the CLI:

❯ docker pull python:3.9
Error response from daemon: error creating temporary lease: connection error: desc = "transport: Error while dialing dial unix /var/run/desktop-containerd/containerd.sock: connect: connection refused": unavailable

Pants was not properly logging this nor erroring, and instead hung.

We "fixed it" by restarting Docker

[tdyas]

Pants was not logging when it was pulling an image. #16849 adds this logging.