Ubuntu Core GG snap?

[wills721]

Describe the bug
Searching for Ubuntu Core Snap for Greengrass v2?

To Reproduce
[Steps to reproduce the behavior. If possible, provide a minimal amount of code that causes the bug.]
(https://snapcraft.io/aws-iot-greengrass)
Only v1 available and it is retired?

Expected behavior
Install greengrass v2 for Ubuntu Core using Snap (Ubuntu Core only supports Snap)

Actual behavior
Not available

Environment

• OS: Ubuntu Core 24
• JDK version:
• Nucleus version:

Additional context
Add any other context about the problem here.

E.g. what is the impact of the bug?

[patrzhan]

Hi, we currently do not officially support snaps for Greengrass v2. Although it may be possible for us to consider it in the future, we don't currently have plans for it.

[wills721]

So, that implies you also do not support Ubuntu Core (24, 22, etc). That would be how I would interpret this. Right?

[patrzhan]

Thank you for your interest in Greengrass snap support. We will take this feedback and prioritize it internally - it's already in our backlog. If you are working with a Technical Account Manager, please make sure to also surface this feature request with them.

In the meantime, while we don't have an officially supported snap, we have had success getting Greengrass running on Ubuntu Core. Here's an example snapcraft.yaml that you can use as a reference. Note that version and source should be updated in the example.

snapcraft.yaml:

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0

name: aws-iot-greengrass-v2
base: core20
# GGv2 version, such as 2.14.1
version: {VERSION}
summary: AWS supported software that extends cloud capabilities to local devices.
description: |
  AWS supported software that extends cloud capabilities to local devices.
grade: devel # must be 'stable' to release into candidate/stable channels
confinement: strict

# declare home plug to allow access to files owned by the user in the user’s home ($HOME) directory
plugs:
  home-for-greengrass:
    interface: home
    read: all
  docker-cli:
    interface: docker
  docker-executables:
    content: docker-executables
    default-provider: docker
    interface: content
    target: $SNAP/docker-env
  root-dot-docker:
    interface: personal-files
    write:
    - $HOME/.docker

parts:
  greengrass:
    # See 'snapcraft plugins'
    plugin: dump
    # Add source link, in format https://d2s8p88vqu9w66.cloudfront.net/releases/greengrass-{VERSION}.zip
    source: {SOURCE}
    stage-packages:
      - openjdk-8-jre-headless
    build-packages:
      # We need to replace dangling symlink for java ssl certs.
      - ca-certificates-java
    override-build: |
      # execute default build step
      snapcraftctl build

      cd "$SNAPCRAFT_PART_INSTALL/usr/lib/jvm" || exit 2

      # The java-8-openjdk-<arch> dir has a different name for each arch, so
      # we need a symlink that references the actual name.
      # Described in: https://forum.snapcraft.io/t/advanced-grammar-for-layouts-or-workaround/17177/4

      # This will be a symlink to the arch-specific openjdk directory.
      OPENJDK_DIR_SYMLINK="java-8-openjdk-arch-symlink"

      case $(arch) in
              x86_64)
              OPENJDK_DIR="java-8-openjdk-amd64"
              ;;
      esac

      ln -s "$OPENJDK_DIR" "$OPENJDK_DIR_SYMLINK" || \
      (echo "failed to link $OPENJDK_DIR_SYMLINK -> $OPENJDK_DIR" \
      && exit 4)

      # The cacerts under /etc won't be accessible after build-time,
      # so the symlink leading to them will become a dangling symlinnk.
      # To avoid this, we'll copy them to the java subdirectory.
      cp /etc/ssl/certs/java/cacerts \
              "$SNAPCRAFT_PART_INSTALL/usr/lib/jvm/$OPENJDK_DIR_SYMLINK/jre/lib/security/cacerts" \
              || exit 5
      cp /etc/ssl/certs/java/cacerts \
              "$SNAPCRAFT_PART_INSTALL/etc/ssl/certs/java/cacerts" \
              || exit 6
  wrapper-scripts:
    plugin: dump
    source: local-scripts/

layout:
  # symlink java
  /usr/bin/java:
    symlink: $SNAP/usr/lib/jvm/java-8-openjdk-arch-symlink/jre/bin/java

apps:
  greengrass:
    command: exec-loader.sh
    daemon: simple
    install-mode: disable
    plugs:
      - mount-observe
      - network-bind
      - process-control
      - hardware-observe
      - log-observe
      - home-for-greengrass
      - docker-cli
      - docker-executables
      - root-dot-docker

configure hook:

#!/bin/bash

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0

validate_greengrass_config() {
  greengrass_config="$(snapctl get greengrass-config)"

  # TODO: Add correct validation for config file
  if [ -z "$greengrass_config" ]; then
    echo "\"$greengrass_config\" is not a valid Greengrass config" >&2
    return 1
  fi
}
validate_greengrass_config

install hook:

#!/bin/bash

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0

# Set default value for greengrass config.
# For now, it doesn't matter if this is invalid as user will provide config during setup
snapctl set greengrass-config="$HOME/defaultconfig.yaml"

We have this exec_loader.sh script referenced in the snapcraft.yaml:

#!/bin/sh

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0

# This script is necessary because loader script needs to be executed from
# $SNAP_DATA/greengrass/v2/alts/current/distro/bin path.
# Referencing this path from the snapcraft.yaml file results in path does not exist errors

set -o xtrace

GREENGRASS_CONFIG="$(snapctl get greengrass-config)"

# cd into install dir
cd "$SNAP_DATA" || exit 1
mkdir -p $SNAP_DATA/greengrass/v2 || exit 2
java -Droot=$SNAP_DATA/greengrass/v2 -Dlog.store=FILE -jar $SNAP/lib/Greengrass.jar \
     --start false --init-config $GREENGRASS_CONFIG --component-default-user root:root || exit 3


cd "$SNAP_DATA/greengrass/v2/alts/current/distro/bin" || exit 4
# TODO: Avoid running executables from write dir like $SNAP_DATA. Instead try running them from $SNAP
exec ./loader

Please let me know if you have any other questions!

[wills721]

I am. His name is Randhir, Priyanka randhiip@amazon.com

Thank you I will give this a whirl.

Since AWS-CLI also is not supported -- are there any instructions here for setup after installation? I would imagine this snap for v2 also covers aws-cil?

[patrzhan]

For aws-cli, you may need to reach out on their repository for help setting up. I don't believe we have an example for a GGv2 snap that includes the aws-cli.

[wills721]

I actually already did. But, isnt aws-cli dependency to GGv2 snap? The only reason I asked was because I assumed it was.

[patrzhan]

Greengrass doesn't have a dependency on aws-cli, though you might find it useful to have for development like creating deployments usually that is done from your development device and not your Greengrass device. Are you thinking of the Greengrass CLI component? The Greengrass CLI component is also not required but can be helpful during development as well, but this would be a component that you can deploy once you have Greengrass up and running.

[wills721]

No. I guess I've been installing aws-cli unnecessarily along with gg. I get it now.

[wills721]

@patrzhan So I was able to successfully build your snap. I have my own aws-iot-greengrass-v2_2.14.1_arm64.snap. I needed to revise also the local-scripts location and the arch for aarch64 to get the right jdk (i'm using ubuntu desktop 24 arm64 on a pi).

However, I have several custom greengrass components. One in particular interacts with the serial port (/dev/ttyS0) relying also on using GPIO operations. I also need to enable I2C and disable serial console and enable serial hardware(I do this all normally with raspi-config). How would you recommend I configure all of this in the snap (interfaces?) so my custom component works properly?

[thomas-roos]

You could use also Yocto to build an image that has that settings to I2C etc. settings and Greengrass included. Just add another solution to the problem - here is an example image for Greengrass for Raspberry Pi: https://github.com/aws4embeddedlinux/meta-aws-demos/blob/master/meta-aws-demos/recipes-core/images/aws-iot-greengrass-demo-image/README.md
Also available for fast tryout as a binary: https://github.com/aws4embeddedlinux/meta-aws-demos/releases/tag/2025.02.07