Running Docker Exec containing a quote

[pascalberger]

I try to run a docker exec command for a command which contains a quote. Use case is that I want to redirect STDOUT output into a file, like in the following example on command line:

docker exec 8e233d28502a36f6490439c9fd68e8f49a29c8de548ae820618cdb7f25587b58 sh -c 'terraform validate -json > /terraform/dist/logs/validate.json'

I tried the following in my build script:

context.DockerExec(
    containerId,
    "sh -c 'terraform validate -json > /terraform/dist/logs/validate.json'");

Which ends with:

Executing: "C:/ProgramData/DockerDesktop/version-bin/docker.exe" exec e8cff8d8ad417747c48e91d5f14943b6f2e568ffc05c99c1d54aff5de2fbd686 sh -c 'terraform validate -json > /terraform/dist/logs/validate.json'
validate: line 1: syntax error: unterminated quoted string

[gitfool]

Try splitting the arguments from the command? (Try both with and without the single quotes.)

context.DockerExec(
    containerId,
    "sh", "-c", "terraform validate -json > /terraform/dist/logs/validate.json");

[gitfool]

Capture a trace with Sysinternals Process Monitor and verify the Docker executable and process arguments are as expected and the same in both cases.

[gitfool]

Maybe it's a Windows related issue? If your Cake build is portable, try running it on Linux.

[pascalberger]

On Linux same behavior as on Windows

[pascalberger]

Looking at what exactly is called showes some difference.

Call from a Powershell:

docker exec 8e233d28502a36f6490439c9fd68e8f49a29c8de548ae820618cdb7f25587b58 sh -c 'terraform validate -json > /terraform/dist/logs/validate.json'

Executed commandline:

"C:\ProgramData\DockerDesktop\version-bin\docker.exe" exec 8e233d28502a36f6490439c9fd68e8f49a29c8de548ae820618cdb7f25587b58 sh -c "terraform validate -json > /terraform/dist/logs/validate.json"

Call from Cake:

context.DockerExec(
    containerId,
    "sh", "-c", "'terraform validate -json > /terraform/dist/logs/validate.json'");

Executed commandline:

"C:/ProgramData/DockerDesktop/version-bin/docker.exe" exec d8de6a8d25179f3cb1e3de4b233d53454320b6a4a62552c55f23a3dd044da7a6 sh -c 'terraform validate -json > /terraform/dist/logs/validate.json'

Seems like when calling from Powershell the ' is translated to "

[pascalberger]

So solution is as simple as using " instead of ' when calling from Cake:

context.DockerExec(
    containerId,
    "sh", "-c", "\"terraform validate -json > /terraform/dist/logs/validate.json\"");

Thanks @gitfool 👍 The idea with Process Monitor did the trick.

[pascalberger]

This is a workaround using StartProcess, capturing the output and writing it to a file:

IEnumerable<string> dockerToolName;
if (context.Environment.Platform.IsUnix())
{
    dockerToolName = new[] { "docker", "docker.exe" };
}
else
{
    dockerToolName = new[] { "docker.exe", "docker" };
}
var dockerPath = context.Tools.Resolve(dockerToolName);

IEnumerable<string> dockerOutput;
var exitCode =
    context.StartProcess(
        dockerPath,
        new ProcessSettings {
            Arguments =
                new ProcessArgumentBuilder()
                    .Append("exec")
                    .Append(containerId)
                    .Append("terraform")
                    .Append("validate")
                    .Append("-json"),
            RedirectStandardOutput = true,
        },
        out dockerOutput);
if (exitCode != 0)
{
    throw new System.Exception($"Docker exec failed. Exit code: {exitCode}");
}

var logDirectoryPath = context.RepositoryRootPath.Combine("dist").Combine("logs");
var logFilePath = logDirectoryPath.CombineWithFilePath("validate.json");
context.EnsureDirectoryExists(logDirectoryPath);
if (context.FileExists(logFilePath))
{
    context.DeleteFile(logFilePath);
}
File.WriteAllLines(logFilePath.FullPath, dockerOutput);