When working with Docker containers for Go test execution, many developers encounter a specific challenge with command nesting. The typical scenario involves running:

docker exec container_name /bin/sh -c "go test ./..."

However, this becomes problematic when needing to exclude certain directories (like vendor/) using subshell commands with $(...) syntax.

When you directly access the container shell via:

docker exec -it container_id /bin/sh

The command go test $(go list ./... | grep -v vendor) works perfectly. This reveals that the issue isn't with the command itself, but with how Docker processes the command through its exec/run interface.

The root cause lies in how shells process commands at different levels:

• Direct shell access: Full shell processing capabilities including command substitution
• Docker exec: Limited shell parsing capabilities where nested commands might be stripped

Solution 1: Escape the subshell properly

docker exec container_name /bin/sh -c "go test \$(go list ./... | grep -v vendor)"

Solution 2: Use single quotes differently

docker exec container_name /bin/sh -c 'go test $(go list ./... | grep -v vendor)'

Solution 3: Create a helper script

#!/bin/sh
go test $(go list ./... | grep -v vendor)

Then execute:

docker exec container_name /path/to/helper/script.sh

For more complex scenarios, consider these patterns:

# Using environment variables
docker exec -e EXCLUDE=vendor container_name /bin/sh -c \
'go test $(go list ./... | grep -v "$EXCLUDE")'

# Multi-line approach in Dockerfile
RUN go test $(go list ./... | grep -v vendor)

To ensure consistent behavior across different Docker environments:

• Always test commands in both direct shell and docker exec contexts
• Consider using explicit path references rather than relative paths
• For production environments, prefer script files over complex inline commands
• Document any special shell escaping requirements for your team

When troubleshooting similar issues:

# Check what's actually being executed
docker exec container_name /bin/sh -x -c "go test $(go list ./... | grep -v vendor)"

# Compare with direct shell output
docker exec -it container_name /bin/sh
go list ./... | grep -v vendor

---

When working with Docker containers for Go test execution, developers often encounter a puzzling limitation with command nesting. The standard approach:

docker exec <container> /bin/sh -c "go test ./..."

works perfectly until you need more complex shell operations like subshell commands with $(...).

Consider this common scenario where we want to exclude the vendor directory:

# Works in interactive shell but fails in docker exec/run
go test $(go list ./... | grep -v vendor)

The Docker equivalent:

docker run golang:1.6.2-alpine /bin/sh -c "go test $(go list ./... | grep -v vendor)"

Unexpectedly returns just:

go test

The root cause lies in how command evaluation happens:

1. Host shell evaluates $(...) first
2. Then passes result to Docker
3. Container shell receives already-evaluated command

Solution 1: Escape the $ character

docker exec container /bin/sh -c "go test \$(go list ./... | grep -v vendor)"

Solution 2: Use single quotes for inner command

docker run golang:1.6.2-alpine /bin/sh -c 'go test $(go list ./... | grep -v vendor)'

Solution 3: Multi-level escaping for complex commands

docker exec -it container /bin/sh -c "go test \\\$(go list ./... | grep -v 'vendor')"

For enterprise projects with complex test requirements:

docker exec go-container /bin/sh -c \
'go test $(go list ./... | grep -v -E "vendor|integration|generated")'

• Always test commands interactively first in the container shell
• Use shellcheck to validate quoting and escaping
• Consider creating custom entrypoint scripts for complex workflows
• Document the escaping requirements in your project README

If you still experience issues:

# Debug the actual command being executed
docker exec container /bin/sh -xc "echo Command: go test \$(go list ./... | grep -v vendor)"