Remote extensions are not installed automatically from devcontainer.json

• VS Code Version: 1.55
• OS Version: Windows 10 Version 1909

Steps to Reproduce:

1. Use a devcontainer.json with configured extensions

{
    "name": "dockertoolchain",
    "service": "toolchain",
    "workspaceFolder": "/workspace",
    "dockerFile": "Dockerfile",
       "mounts": [ "source=/var/run/docker.sock,target=/var/run/docker.sock,type=bind" ],
    // Use 'settings' to set *default* container specific settings.json values on container create.
    // You can edit these settings after create using File > Preferences > Settings > Remote.
    "settings": {
        "terminal.integrated.shell.linux": "/bin/zsh"
    },

    // Add the IDs of extensions you want installed when the container is created in the array below.
    "extensions": [
        "ms-azuretools.vscode-docker",
        "ms-vscode.cmake-tools",
        "twxs.cmake",
        "llvm-vs-code-extensions.vscode-clangd",
        "dan-c-underwood.arm",
        "asciidoctor.asciidoctor-vscode",
        "streetsidesoftware.code-spell-checker",
        "marus25.cortex-debug",
        "cschlosser.doxdocgen",
        "eamodio.gitlens",
        "jebbs.plantuml",
        "zxh404.vscode-proto3",
        "ryanluker.vscode-coverage-gutters",
        "webfreak.debug",
        "ms-python.python",
        "nhoizey.gremlins"
    ]
}

2. Start remote container

Expected result: Extensions are installed in the container
Actual result: No extensions are installed.

This works with Remote-Containers 0.166.0 and VSCode 1.54.3 but not with 1.55.
It seems to be connected with some proxy issue.

Does this issue occur when all extensions are disabled?: The problem is with extensions

Remote extension output:
[18 ms] Remote-Containers 0.166.0 in VS Code 1.55.0 (c185983).
[...]
[7389 ms] Start: Run in container: (cat /etc/os-release || cat /usr/lib/os-release) 2>/dev/null
[7393 ms] NAME="Ubuntu"
VERSION="20.04.2 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.2 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
[7393 ms]
[7393 ms] Start: Run in container: cat /etc/passwd
[7397 ms] Start: Updating configuration state
[7397 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/test/.devcontainer
[7680 ms] Start: Setup shutdown monitor
[7681 ms] Forking shutdown monitor: c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\dist\shutdown\shutdownMonitorProcess \.\pipe\vscode-remote-containers-e90f2710084a4686308b9b2336ab05e1a8d41c73-sock dockerCompose Info c:\Users\jan\AppData\Roaming\Code\logs\20210401T114713\exthost1\ms-vscode-remote.remote-containers 1617270463130
[7697 ms] Start: Run in container: test -d /root/.vscode-server
[7701 ms]
[7701 ms]
[7701 ms] Exit code 1
[7702 ms] Start: Run in container: test -d /root/.vscode-remote
[7705 ms]
[7705 ms]
[7705 ms] Exit code 1
[7705 ms] Start: Run in container: set -o noclobber ; mkdir -p '/root/.vscode-server/data/Machine' && { > '/root/.vscode-server/data/Machine/.writeMachineSettingsMarker' ; } 2> /dev/null
[7709 ms]
[7709 ms]
[7710 ms] Start: Run in container: mkdir -p '/root/.vscode-server/data/Machine' && cat >'/root/.vscode-server/data/Machine/settings.json' <<'settingsJSON'
[7715 ms]
[7715 ms]
[7716 ms] Start: Run in container: test -d /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f
[7718 ms]
[7718 ms]
[7718 ms] Exit code 1
[7719 ms] Installing VS Code Server for commit c185983
[7720 ms] Start: Installing VS Code Server
[7720 ms] Start: Run in container: mkdir -p /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f_1617270470850
[7724 ms]
[7724 ms]
[7766 ms] Start: Run in container: (dd iflag=fullblock bs=8192 count=3843 2>/dev/null; dd iflag=fullblock bs=2463 count=1 2>/dev/null) | tar --no-same-owner -xz --strip-components 1 -C /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f_1617270470850
[9173 ms]
[9173 ms]
[9173 ms] Start: Run in container: mv -n /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f_1617270470850 /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f
[9176 ms]
[9176 ms]
[9176 ms] Start: Launching Remote-Containers helper.
[9176 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && gpgconf '--list-dir' 'agent-extra-socket'
[9350 ms] /home/jan/.gnupg/S.gpg-agent.extra
[9350 ms]
[9350 ms] Start: Run in container: gpgconf --list-dir agent-socket
[9353 ms] /root/.gnupg/S.gpg-agent
[9353 ms]
[9353 ms] Start: Run in container: gpgconf --list-dir homedir
[9356 ms] /root/.gnupg
[9356 ms]
[9356 ms] Start: Run in container: ls '/root/.gnupg/private-keys-v1.d' 2>/dev/null
[9359 ms]
[9359 ms]
[9359 ms] Exit code 2
[9359 ms] Start: Run in container: mkdir -p -m 700 '/root/.gnupg'
[9360 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/.ssh/known_hosts'
[9362 ms]
[9363 ms]
[9363 ms] Start: Run in container: cat <<'EOF-/tmp/vscode-remote-containers-68084168bf1bc62c6f72cfb94f5d1be50556f675.js' >/tmp/vscode-remote-containers-68084168bf1bc62c6f72cfb94f5d1be50556f675.js
[9363 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && gpgconf '--list-dir' 'homedir'
[9366 ms]
[9366 ms]
[9366 ms] Start: Run in container: cat <<'EOF-/tmp/vscode-remote-containers-server-68084168bf1bc62c6f72cfb94f5d1be50556f675.js' >/tmp/vscode-remote-containers-server-68084168bf1bc62c6f72cfb94f5d1be50556f675.js
[9375 ms]
[9375 ms]
[9376 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && DISPLAY='1' ELECTRON_RUN_AS_NODE='1' SSH_ASKPASS='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\scripts\ssh-askpass.bat' VSCODE_SSH_ASKPASS_NODE='C:\Program Files\Microsoft VS Code\Code.exe' VSCODE_SSH_ASKPASS_MAIN='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\dist\common\sshAskpass.js' VSCODE_SSH_ASKPASS_HANDLE='\.\pipe\ssh-askpass-0e0f6698dfa32bfdc5e38c11d977fc6b23628a8f-sock' DOCKER_CONTEXT='default' SSH_AUTH_SOCK='/tmp/ssh-FFSZDlsmv0mV/agent.99' VSCODE_SSH_ASKPASS_COUNTER='13' docker 'exec' '-i' '-u' 'root' '-e' 'REMOTE_CONTAINERS_SOCKETS=["/tmp/vscode-ssh-auth-68084168bf1bc62c6f72cfb94f5d1be50556f675.sock","/root/.gnupg/S.gpg-agent"]' '-e' 'REMOTE_CONTAINERS_IPC=/tmp/vscode-remote-containers-ipc-68084168bf1bc62c6f72cfb94f5d1be50556f675.sock' '23fd948281556acbfcc4d5454ab0e6531d1e5f78b293f02d9857c6fc89ca0561' '/root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/node' '/tmp/vscode-remote-containers-server-68084168bf1bc62c6f72cfb94f5d1be50556f675.js'
[9637 ms] Start: Run in container: # Test for /root/.ssh/known_hosts and ssh
[9644 ms] /home/jan/.gnupg
[9645 ms]
[9654 ms] /root/.ssh/known_hosts exists
[9654 ms]
[9654 ms] Exit code 1
[9654 ms] Start: Run in container: gpgconf --list-dir homedir
[9661 ms] /root/.gnupg
[9661 ms]
[9661 ms] Start: Run in container: command -v git >/dev/null 2>&1 && git config --system credential.helper '!f() { /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/node /tmp/vscode-remote-containers-68084168bf1bc62c6f72cfb94f5d1be50556f675.js $*; }; f' || true
[9662 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/.gnupg/pubring.kbx'
[9677 ms]
[9677 ms]
[9677 ms] Start: Preparing Extensions
[9677 ms] Start: Run in container: set -o noclobber ; mkdir -p '/root/.vscode-server/data/Machine' && { > '/root/.vscode-server/data/Machine/.installExtensionsMarker' ; } 2> /dev/null
[9682 ms]
[9682 ms]
[9688 ms] Extensions cache, install extensions: ms-azuretools.vscode-docker, ms-vscode.cmake-tools, llvm-vs-code-extensions.vscode-clangd, dan-c-underwood.arm, asciidoctor.asciidoctor-vscode, streetsidesoftware.code-spell-checker, marus25.cortex-debug, cschlosser.doxdocgen, eamodio.gitlens, jebbs.plantuml, zxh404.vscode-proto3, ryanluker.vscode-coverage-gutters, webfreak.debug, ms-python.python, nhoizey.gremlins
[9688 ms] Start: Run in container: test -d /root/.vscode-server/extensionsCache && ls /root/.vscode-server/extensionsCache || true
[9690 ms]
[9691 ms]
[9715 ms] Extensions cache, copy to remote: asciidoctor.asciidoctor-vscode-2.8.8, cschlosser.doxdocgen-1.1.0, dan-c-underwood.arm-1.5.0, eamodio.gitlens-11.3.0, jebbs.plantuml-2.14.4, llvm-vs-code-extensions.vscode-clangd-0.1.11, marus25.cortex-debug-0.3.12, ms-azuretools.vscode-docker-1.11.0, ms-python.python-2021.3.680753044, ms-vscode.cmake-tools-1.6.0, nhoizey.gremlins-0.26.0, ryanluker.vscode-coverage-gutters-2.7.2, streetsidesoftware.code-spell-checker-1.10.2, webfreak.debug-0.25.0, zxh404.vscode-proto3-0.5.3
[9926 ms] Start: Run in container: # Copy extensions to remote
[9978 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/.gnupg/trustdb.gpg'
[10306 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && gpg-connect-agent 'updatestartuptty' '/bye'
[10875 ms]
[10875 ms]
[10875 ms] Start: Run in container: for pid in cd /proc && ls -d [0-9]*; do { echo $pid ; readlink /proc/$pid/cwd ; readlink /proc/$pid/ns/mnt ; cat /proc/$pid/stat | tr "
[10936 ms] Start: Starting VS Code Server
[10936 ms] Start: Run in container: /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/server.sh --force-disable-user-env --use-host-proxy --port 0 --extensions-download-dir /root/.vscode-server/extensionsCache --install-extension ms-azuretools.vscode-docker --install-extension ms-vscode.cmake-tools --install-extension llvm-vs-code-extensions.vscode-clangd --install-extension dan-c-underwood.arm --install-extension asciidoctor.asciidoctor-vscode --install-extension streetsidesoftware.code-spell-checker --install-extension marus25.cortex-debug --install-extension cschlosser.doxdocgen --install-extension eamodio.gitlens --install-extension jebbs.plantuml --install-extension zxh404.vscode-proto3 --install-extension ryanluker.vscode-coverage-gutters --install-extension webfreak.debug --install-extension ms-python.python --install-extension nhoizey.gremlins --start-server
[11010 ms]

• Visual Studio Code Server
• Reminder: You may only use this software with Visual Studio family products,
• as described in the license https://aka.ms/vscode-remote/license

Extension host agent listening on 45769

[11011 ms] Start: Run in container: echo 45769 >/root/.vscode-server/data/Machine/.devport
[11014 ms]
[11014 ms]
[11018 ms] Forwarding local port 45769 to container port 45769
[11059 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/.gitconfig'
[11301 ms] [11:47:55] Extension host agent started.
[11350 ms] Start: Run in container: # Test for /root/.gitconfig and git
[11355 ms]
[11356 ms]
[11356 ms] Start: Run in container: # Copy /home/jan/.gitconfig to /root/.gitconfig
[11357 ms] Installing extensions...
[11362 ms]
[11367 ms]
[11367 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && cat '/home/jan/.config/git/config'
[11445 ms] Forwarding connection from port 58280 on local port 45769 to container port 45769
[11446 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && DISPLAY='1' ELECTRON_RUN_AS_NODE='1' SSH_ASKPASS='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\scripts\ssh-askpass.bat' VSCODE_SSH_ASKPASS_NODE='C:\Program Files\Microsoft VS Code\Code.exe' VSCODE_SSH_ASKPASS_MAIN='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\dist\common\sshAskpass.js' VSCODE_SSH_ASKPASS_HANDLE='\.\pipe\ssh-askpass-0e0f6698dfa32bfdc5e38c11d977fc6b23628a8f-sock' DOCKER_CONTEXT='default' SSH_AUTH_SOCK='/tmp/ssh-FFSZDlsmv0mV/agent.99' VSCODE_SSH_ASKPASS_COUNTER='15' docker 'exec' '-i' '-u' 'root' '-e' 'VSCODE_REMOTE_CONTAINERS_SESSION=49c37997-83ce-4dd5-a2fa-35f8bdc3a4761617270461677' '23fd948281556acbfcc4d5454ab0e6531d1e5f78b293f02d9857c6fc89ca0561' '/root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/node' '-e' '
[11834 ms] Start: Run in container: command -v git >/dev/null 2>&1 && git config --global credential.helper '!f() { /root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/node /tmp/vscode-remote-containers-68084168bf1bc62c6f72cfb94f5d1be50556f675.js $*; }; f' || true
[11840 ms]
[11840 ms]
[12101 ms] Forwarding connection from port 58285 on local port 45769 to container port 45769
[12102 ms] Start: Run: wsl -d Ubuntu-20.04 -e /bin/sh -c cd '/home/jan/test' && DISPLAY='1' ELECTRON_RUN_AS_NODE='1' SSH_ASKPASS='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\scripts\ssh-askpass.bat' VSCODE_SSH_ASKPASS_NODE='C:\Program Files\Microsoft VS Code\Code.exe' VSCODE_SSH_ASKPASS_MAIN='c:\Users\jan.vscode\extensions\ms-vscode-remote.remote-containers-0.166.0\dist\common\sshAskpass.js' VSCODE_SSH_ASKPASS_HANDLE='\.\pipe\ssh-askpass-0e0f6698dfa32bfdc5e38c11d977fc6b23628a8f-sock' DOCKER_CONTEXT='default' SSH_AUTH_SOCK='/tmp/ssh-FFSZDlsmv0mV/agent.99' VSCODE_SSH_ASKPASS_COUNTER='16' docker 'exec' '-i' '-u' 'root' '-e' 'VSCODE_REMOTE_CONTAINERS_SESSION=49c37997-83ce-4dd5-a2fa-35f8bdc3a4761617270461677' '23fd948281556acbfcc4d5454ab0e6531d1e5f78b293f02d9857c6fc89ca0561' '/root/.vscode-server/bin/c185983a683d14c396952dd432459097bc7f757f/node' '-e' '
[12350 ms] [11:47:56] [::ffff:127.0.0.1][abca487c][ManagementConnection] New connection established.
[12820 ms] [IPC Library: Pty Host] INFO Listing 0 persistent terminals, 0 total terminals
[12878 ms] [11:47:57] [::ffff:127.0.0.1][4a89b571][ExtensionHostConnection] New connection established.
[12907 ms] [11:47:57] [::ffff:127.0.0.1][4a89b571][ExtensionHostConnection] <203> Launched Extension Host Process.

[chrmarti]

You mention a proxy. Are you behind a network proxy?

You mention a proxy. Are you behind a network proxy?

Yep behind a corporate proxy. It seems to be connected with the issue. Installation works fine at "home" without any proxies.
The (startup) proxy is defined in the user settings:

"http.proxy": "http://localhost:3128"

After successful startup inside the docker image a different proxy has to be used (tunnelled through the docker desktop)

http://host.docker.internal:3128

The proxy inside the docker image is still working and installing the extension by hand inside the remote container is possible.
Nothing in this setup was changed.

[chrmarti]

Where do you configure the proxy for the container? (Maybe related: microsoft/vscode-remote-release#4812)

My understanding is, that for the extension downloading and installation only the proxy outside of the container is used (besides loading some dependency after startup). So I configured the proxy in the user settings.json with

"http.proxy": "http://localhost:3128"

This was enough to install the extensions - similar to installing extensions without any containers. The log itself does not indicate any connection issue, it just does not install the extension without any feedback. (edit: see answer below)
The logs for version 1.54.3 with Remote-Extension 0.163.2 are pretty similar, but after the ExtensionHostConnection it will just start installing the extensions:

[9007 ms] [13:13:25] [::ffff:127.0.0.1][568cfb8c][ManagementConnection] New connection established.
[9370 ms] [13:13:25] [::ffff:127.0.0.1][d4e5f9a2][ExtensionHostConnection] New connection established.
[9382 ms] [13:13:25] [::ffff:127.0.0.1][d4e5f9a2][ExtensionHostConnection] <197> Launched Extension Host Process.
[9756 ms] Installing extension 'dan-c-underwood.arm' v1.5.0...
[9841 ms] Installing extension 'asciidoctor.asciidoctor-vscode' v2.8.8...
[9926 ms] Installing extension 'ms-vscode.cmake-tools' v1.6.0...
[9928 ms] Installing extension 'ms-azuretools.vscode-docker' v1.11.0...
[9960 ms] Installing extension 'twxs.cmake' v0.0.17...
[10171 ms] Installing extension 'marus25.cortex-debug' v0.3.12...
[10230 ms] Installing extension 'jebbs.plantuml' v2.14.5...
[10311 ms] Installing extension 'cschlosser.doxdocgen' v1.1.0...
[10349 ms] Installing extension 'llvm-vs-code-extensions.vscode-clangd' v0.1.11...
[10405 ms] Installing extension 'eamodio.gitlens' v11.3.0...
[10542 ms] Installing extension 'webfreak.debug' v0.25.0...
[10543 ms] Installing extension 'zxh404.vscode-proto3' v0.5.3...
[10707 ms] Installing extension 'nhoizey.gremlins' v0.26.0...
[10828 ms] Installing extension 'streetsidesoftware.code-spell-checker' v1.10.2...
[11110 ms] Installing extension 'ryanluker.vscode-coverage-gutters' v2.7.2...
[11352 ms] Installing extension 'ms-python.python' v2021.3.680753044...
[11522 ms] [13:13:28] Installing extension: dan-c-underwood.arm
[11523 ms] [13:13:28] Installing extension: asciidoctor.asciidoctor-vscode
[11527 ms] [13:13:28] Installing extension: ms-vscode.cmake-tools
[11528 ms] [13:13:28] Installing extension: ms-azuretools.vscode-docker
[11528 ms] [13:13:28] Installing extension: twxs.cmake
[11528 ms] [13:13:28] Installing extension: marus25.cortex-debug
[11529 ms] [13:13:28] Installing extension: jebbs.plantuml
[11529 ms] [13:13:28] Installing extension: cschlosser.doxdocgen
[11530 ms] [13:13:28] Installing extension: llvm-vs-code-extensions.vscode-clangd
[11530 ms] [13:13:28] Installing extension: eamodio.gitlens
[11531 ms] [13:13:28] Installing extension: webfreak.debug
[11532 ms] [13:13:28] Installing extension: zxh404.vscode-proto3
[11533 ms] [13:13:28] Installing extension: nhoizey.gremlins
[11534 ms] [13:13:28] Installing extension: streetsidesoftware.code-spell-checker
[11535 ms] [13:13:28] Installing extension: ryanluker.vscode-coverage-gutters
[11536 ms] [13:13:28] Installing extension: ms-python.python
[11540 ms] [13:13:28] Downloaded extension: dan-c-underwood.arm undefined
[11541 ms] [13:13:28] Downloaded extension: asciidoctor.asciidoctor-vscode undefined
[11543 ms] [13:13:28] Downloaded extension: ms-vscode.cmake-tools undefined
[11545 ms] [13:13:28] Downloaded extension: ms-azuretools.vscode-docker undefined
[11546 ms] [13:13:28] Downloaded extension: twxs.cmake undefined
[11548 ms] [13:13:28] Downloaded extension: marus25.cortex-debug undefined
[11552 ms] [13:13:28] Downloaded extension: cschlosser.doxdocgen undefined
[11555 ms] [13:13:28] Downloaded extension: llvm-vs-code-extensions.vscode-clangd undefined
[11557 ms] [13:13:28] Downloaded extension: eamodio.gitlens undefined
[11559 ms] [13:13:28] Downloaded extension: webfreak.debug undefined
[11561 ms] [13:13:28] Downloaded extension: zxh404.vscode-proto3 undefined
[11566 ms] [13:13:28] Downloaded extension: nhoizey.gremlins undefined
[11568 ms] [13:13:28] Downloaded extension: streetsidesoftware.code-spell-checker undefined
[11571 ms] [13:13:28] Downloaded extension: ryanluker.vscode-coverage-gutters undefined
[11574 ms] [13:13:28] Downloaded extension: ms-python.python undefined
[...]

The proxy inside the container is currently not configured for VSCode, because it was not necessary. The docker image itself has some http_proxy/https_proxy configured.

I just rechecked and it seems related to (microsoft/vscode-remote-release#4812)
I get a similar error:

[2021-04-06 13:47:22.876] [remoteagent] [info] Extension host agent started.
[2021-04-06 13:47:22.981] [remoteagent] [error] Error: getaddrinfo ENOTFOUND marketplace.visualstudio.com
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:66:26)
[2021-04-06 13:47:23.778] [remoteagent] [info] [::ffff:127.0.0.1][e81ef468][ManagementConnection] New connection established.
[2021-04-06 13:47:24.043] [remoteagent] [info] [::ffff:127.0.0.1][f619c834][ExtensionHostConnection] New connection established.
[2021-04-06 13:47:24.048] [remoteagent] [info] [::ffff:127.0.0.1][f619c834][ExtensionHostConnection] <200> Launched Extension Host Process.

The image gets its proxy over a docker-compose file:

version: '3.1'
services:
  # Update this to the name of the service you want to work with in your docker-compose.yml file
  toolchain:
    image: [...]
    environment:
      - http_proxy=http://host.docker.internal:3128
      - https_proxy=http://host.docker.internal:3128
      - ftp_proxy=http://host.docker.internal:3128