Support docker run with --user $(id -u):$(id -g) cli arg (shared process error)

[satlus]

Test environment

Host OS: OSX 10.14.4
Docker: 2.0.0.3 (31259)
image: codercom/code-server:1.621

Request

Hi,

We run docker in a locked down environment where we alias the docker run cli command to prepend --user $(id -u):$(id -g) on all host operating systems. This is a security constraint we can't remove. When i try to execute code server simulating this environment it throws a shared process error. Any ideas on an approach to resolve?

Repro

docker run -it -p 127.0.0.1:8443:8443 -v "${PWD}/codeserver:/home/coder/project" -u $(id -u):$(id -g) -v "${PWD}/codeserver/.cache:/.cache" -v "${PWD}/codeserver/.local:/.local" codercom/code-server:1.621 --allow-http --no-auth
INFO  code-server development
INFO  Additional documentation: http://github.com/codercom/code-server
INFO  Initializing {"data-dir":"/.local/share/code-server","extensions-dir":"/.local/share/code-server/extensions","working-dir":"/home/coder/project","log-dir":"/.cache/code-server/logs/20190405152816797"}
INFO  Starting webserver... {"host":"0.0.0.0","port":8443}
WARN  No certificate specified. This could be insecure.
WARN  Documentation on securing your setup: https://github.com/codercom/code-server/blob/master/doc/security/ssl.md
WARN  Launched without authentication.
INFO   
INFO  Started (click the link below to open):
INFO  http://localhost:8443/
INFO   
INFO  Starting shared process [1/5]...
INFO  Starting shared process [2/5]... {"error":"Exited with 1"}
INFO  Starting shared process [3/5]... {"error":"Exited with 1"}
/src/packages/server/out/cli.js:325
return"boolean"==typeof e.extractComments?(r.preserve=i,r.extract=/^\**!|@preserve|@license|@cc_on/i):"string"==typeof e.extractComments||e.extractComments instanceof RegExp?(r.preserve=i,r.extract=e.extractComments):"function"==typeof e.extractComments?(r.preserve=i,r.extract=e.extractComments):Object.prototype.hasOwnProperty.call(e.extractComments,"condition")?(r.preserve=i,r.extract=e.extractComments.condition):(r.preserve=!1,r.extract=i),["preserve","extract"].forEach(e=>{let t,n;switch(typeof r[e]){case"boolean":r[e]=r[e]?()=>!0:()=>!1;break;case"function":break;case"string":if("all"===r[e]){r[e]=(()=>!0);break}if("some"===r[e]){r[e]=((e,t)=>"comment2"===t.type&&/^\**!|@preserve|@license|@cc_on/i.test(t.value));break}t=r[e],r[e]=((e,n)=>new RegExp(t).test(n.value));break;default:n=r[e],r[e]=((e,t)=>n.test(t.value))}}),(e,t)=>{if(r.extract(e,t)){const e="comment2"===t.type?`/*${t.value}*/`:`//${t.value}`;n.includes(e)||n.push(e)}return r.preserve(e,t)}})(e,c,u));const

Error: ENOENT: no such file or directory, uv_os_get_passwd
    at new t.Server (/src/packages/server/out/cli.js:325:105264)
    at e.exports.w.on (/src/packages/server/out/cli.js:325:102138)
    at emitTwo (events.js:131:20)
    at e.exports.emit (events.js:214:7)
    at handleUpgrade.t (/src/packages/server/out/cli.js:489:29992)
    at e.exports.completeUpgrade (/src/packages/server/out/cli.js:489:32439)
    at e.exports.handleUpgrade (/src/packages/server/out/cli.js:489:31556)
    at upgrade (/src/packages/server/out/cli.js:489:29963)
    at emitThree (events.js:136:13)
    at u.emit (events.js:217:7)
    at onParserExecuteCommon (_http_server.js:542:14)
    at socketOnData (_http_server.js:477:3)
    at emitOne (events.js:116:13)
    at Socket.emit (events.js:211:7)
    at Socket.Readable.read (_stream_readable.js:475:10)
    at flow (_stream_readable.js:846:34)
    at emitReadable_ (_stream_readable.js:514:3)
    at emitReadable (_stream_readable.js:507:7)
    at addChunk (_stream_readable.js:274:7)
    at readableAddChunk (_stream_readable.js:250:11)
    at Socket.Readable.push (_stream_readable.js:208:10)
    at TCP.onread (net.js:601:20)

[satlus]

after educating myself a bit on docker user and group management, this does not appear to be something that is fixable by codercom devs. I will be closing this issue. Here's a brief synopsis:

• coder (properly) adds a user to the image and ensures codeserver is executed as that user
• this user will resolve to 1000:1000 in /etc/passwd in the container per ubuntu defaults
• if you are lucky enough to be running on a host where your user id equals 1000, passing -u $(id -u) will just work; otherwise, which I assume is most cases, it will not

in short docker is doing what it's supposed to, and my uid does not resolve to the uid that codeserver is instructed to run as. We are discussing other approaches as passing the -u $(id -u) flag does not seem like something that will scale appropriately, particularly for third party images.

[ericcollazo]

after educating myself a bit on docker user and group management, this does not appear to be something that is fixable by codercom devs. I will be closing this issue. Here's a brief synopsis:

• coder (properly) adds a user to the image and ensures codeserver is executed as that user
• this user will resolve to 1000:1000 in /etc/passwd in the container per ubuntu defaults
• if you are lucky enough to be running on a host where your user id equals 1000, passing -u $(id -u) will just work; otherwise, which I assume is most cases, it will not

in short docker is doing what it's supposed to, and my uid does not resolve to the uid that codeserver is instructed to run as. We are discussing other approaches as passing the -u $(id -u) flag does not seem like something that will scale appropriately, particularly for third party images.

If you are building your own Docker image you can designate what user you want the container to use in your Dockerfile.

[satlus]

Unless I'm mistaken you would need to have a custom docker build for every user in the organization that wants to use code server with this approac. This could be in the thousands in our world, and is not scalable. The core requirement is dynamic uid/guid resolution to be mapped at runtime, not build time. Ideally a single hosted instance could support multiple users, obviating the need for this, which seems like it's being investigated:
#33

Until then we are looking at podman.io, or possibly creating our own image that includes a PAM module that could resolve our UIDs from a directory server. Or even potentially an approach like fixid: https://boxboat.com/2017/07/25/fixuid-change-docker-container-uid-gid/. Very early days for us.

[sr229]

Hey @satlus I did the usermode changelist for it and this seems to be similar to the OpenShift case as stated in #223. Kindly reopen as I would be happy to investigate and properly fix it

[satlus]

Cool, re-opened. I think I see the approach here per your openshift fork. I noticed that you're doing an append to the container /etc/passwd file based on uid:guid in the entry point script. I've done similar in my fork, but using a sudo groupmod so we don't keep appending duplicate entries:
master...satlus:satlus-nonrootuser

I'm currently at a very low bandwidth area and can't build the docker image to test - when I can I'll post back.

[kylecarbs]

Any update on this @satlus ?

[satlus]

I was able fiddle with this today, and I couldn't get an approach using sudo usermod or vanilla usermod, to work. I captured the UID:GID in container env vars, and then ran usermod in the entrypoint script prior to execution. the problem is that if you do this with the host user, you're not in /etc/passwd and usermod fails (sudo will fail as well for the same reason). More details here:
70424c8

disclaimer: I shouldn't be considered authoritative on this subject I'm experimenting. I'll play around a bit more, but including trying sr229's approach

[ibnesayeed]

If I supply -u (or --user) flag to keep file permissions correct as if I were to play with my files on the host, the service is failing to create a ./cache directory. Is it something that can be configured to create under the /tmp instead of the root of the file system?

$ mkdir /tmp/foo
$ cd /tmp/foo
$ docker run --rm -it \
  -u $(id -u):$(id -g) \
  -p 127.0.0.1:8443:8443 \
  -v $PWD:/home/coder/project \
  codercom/code-server --allow-http --no-auth
(node:6) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
ERROR { [Error: EACCES: permission denied, mkdir '/.cache']
  [stack]: 'Error: EACCES: permission denied, mkdir \'/.cache\'',
  [message]: 'EACCES: permission denied, mkdir \'/.cache\'',
  errno: -13,
  code: 'EACCES',
  syscall: 'mkdir',
  path: '/.cache' }

[satlus]

If you scroll horizontally in the example I posted that invokes the docker run command you'll see I pass volume mounts to make the directories writable. You'll need to do the same. I have examples in my fork:
https://github.com/satlus/code-server/blob/satlus-nonrootuser/DockerLaunchCommands.MD

I think you will still hit the shared process issue I originally reported, which is ultimately due to this:
#439 (comment)

[ibnesayeed]

I guess https://github.com/boxboat/fixuid can help resolve the UID/GID issue at least.

[MostHated]

I guess https://github.com/boxboat/fixuid ([ 9 hours ago](https://github.com/boxboat/fixuid/tree/0ec93d22e52bde5b7326e84cb62fd26a3d20cead)) can help resolve the UID/GID issue at least.

This looks great. I was just now coming across this same issue with mounted partitions. I am about to try that out right now. It seems extremely useful in many situations. Thanks for the link. : D