We delegate this command to VS Code itself so it is probably an upstream bug, but maybe there is some issue in the way we call it or the way we configure the data directory.

I was not able to reproduce with these two Dockerfiles (I had to change the marketplace because Open VSX is currently down, but I omitted that part):

FROM debian:12
RUN apt-get update && apt-get install -y curl
RUN curl -fsSL https://code-server.dev/install.sh | sh
RUN code-server --install-extension vscodevim.vim

docker build -t code-server-base .

FROM code-server-base
RUN code-server --install-extension editorconfig.editorconfig

docker build -t code-server
docker run --rm -it -p 8080:8080 code-server bash
cat ~/.local/share/code-server/extensions/extensions.json

Doing so shows me both extensions in the extensions.json file. I am not sure what User/extensions.json is though, I do not have that file. I thought the only extensions.json file was in the extensions directory?

I also ran code-server with code-server --auth none --host 0.0.0.0 and I see both extensions in my sidebar.

What does your docker run command look like? Are you mounting anything over the data directory?

hey @code-asher thanks for your tests. Perhaps there's something being changed in the environment when I install the code-server extensions. I'm installing them through a private devcontainer feature -
When analyzing the layers with dive I can see that extensions.json gets modified on the second layer, so it doesn't detect the previous installed extensions.

extensions.json seems to be a file what registers the extensions installed, even if the directories exists, if they are not under that json file they won't show up.

This is the install.sh script im using to install the code-server extensions:

# Check if running as vscode, if not, switch to vscode to install the extensions
if [ "$(whoami)" != "vscode" ]; then
    SCRIPT_PATH="$(realpath "$0")"
    echo "Not running as vscode, attempting to switch user..."
    exec su - vscode -l -c "EXTENSION_IDS='$EXTENSION_IDS' \"$SCRIPT_PATH\" $*"
fi

printenv

echo "Existing installed extensions:"
code-server --list-extensions --show-versions

IFS=',' read -ra EXTENSION_IDS <<< "$EXTENSION_IDS"
for EXTENSION in "${EXTENSION_IDS[@]}"; do
    echo "Installing code-server extension: $EXTENSION"
    RETRIES=4  # Number of retries
    WAIT_TIME=2  # Waiting time in seconds between retries

    until [ $RETRIES -le 0 ]; do
        code-server --install-extension "$EXTENSION" && break
        RETRIES=$((RETRIES-1))
        echo "Failed to install $EXTENSION, retrying in $WAIT_TIME seconds..."
        sleep $WAIT_TIME
    done

    if [ $RETRIES -le 0 ]; then
        echo "Failed to install $EXTENSION after multiple attempts."
    else
        echo "$EXTENSION installed successfully."
    fi
done

# If there are no extensions to install, print a message
if [ ${#EXTENSION_IDS[@]} -eq 0 ]; then
    echo "No extensions to install."
fi

# Print installed extensions
code-server --list-extensions --show-versions

Hmm I created a new directory with the following .devcontainer/devcontainer.json:

{
  "image": "code-server-base",
  "features": {               
     "./test-feature": {
        "version": "1.0.0"
      }
    },
    "forwardPorts": [8080]
}

.devcontainer/test-feature/devcontainer-feature.json:

{
    "id": "test",
    "version": "1.0.0",
    "name": "test"
}

.devcontainer/test-feature/install.sh:

printenv
code-server --list-extensions --show-versions
code-server --install-extension editorconfig.editorconfig
code-server --list-extensions --show-versions

Then I ran:

$ devcontainer up --workspace-folder .
$ devcontainer exec --workspace-folder . code-server --list-extensions --show-versions
editorconfig.editorconfig@0.17.2
vscodevim.vim@1.29.0

So, I am seeing both the extension from the base image and the one installed by my feature. If you are able to drop a minimal reproduction I can run it and hopefully find the issue, but I think it is probably safe to say it is not a code-server or VS Code bug.